ETHEPHON-INDUCED ABSCISSION OF FLQRETS AND BERRIES IN
NORTH AMERICAN GINSENG (Panax quinquefolirLs L.)
A Thesis
Presented to
The Faculty of Graduate Studies
of
The University of Guelph
by
LAURA J. ROLSTON
In pmtial fulfilment of requirements
for the degree of
Master of Science
December, 2000
O Laura J. RoIston, 2000
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ETHEPHON-INDUCED ABSCISSION OF FLORETS AND BERRIES IN
NORTH AMERICAN GINSENG (Panax quinquefoiius L.)
Laura J. Rolston University of Guelph, 2000
Advisor: Professor J. T. A. Proctor
Ethrel(240 g L-' ethephon, 2-chloroethylphosphonic acid) and gibberellic acid
(GA3 and GA4+7) were applied to intact plants and excised tissues of 3-year-old American
ginseng (Panax quinqzïefolizïs L.). The effects of these plant growth regulators on
inflorescence and root development, floret abscission, root fiesh weight and leaf
chlorophyll were examined. Field-scale application of Ethrel(2.5- 1 0.0 L acre-') in mid-
to late June increased floret abscissioo. Ethrel at 2.5 L acre-' applied in 100 gal acre-'
water, reduced red beny fiesh weight by approxirnately 65%, increased total root fiesh
weights by about 15% and did not reduce leaf chlorophyll. Moderate to high
concentrations of Ethrel(5.0-10.0 L acre") reduced leaf chlorophyll and root fiesh
weight. GA3 and Ci&+, (100-200 mg L-') applied during bloom increased irrflorescence
expansion, and parthenocarpic development of the green berries. G&+7 treatment
iacreased root fiesh weight by 8-12% and maintained leaf chlorophyll until late in the
season. GA; and GA4+, applied four t h e s at 200 mg L-' resulted in approximately 48
and 98% loss of peremating bud dormmcy, respectively.
I would like to express my appreciation to my advisor Dr. John T. A. Proctor for
his guidance and advice, and an opportunity to pursue my graduate studies at the
University of Guelph. I gratefully acknowledge Dean Louttit for his technical support of
this research project. My sincere thanks to Dr. Austin Fletcher and Dr. Demis Murr for
theix evaluaîion of this manuscript.
Special thanks to Jeff Rice (JCK Farrns), Keith Rainey (Rainey Ginseng), Paul
Wismer and Rob Geier (Canadian Imperid Ginseng Inc.), Bob Arthur and Tony Quon
(Stonehenge Acres) and Fred VandenElsen for the use of their ginseng fields, and the
t h e and effort they contributed to the maintenance and management of the experimental
trials. 1 would also like to thank Aventis (Rhône-Poulenc) for their support of this project
through their donation of Ethrel for the field-scale trials.
1 am extremely thankful for the patience and encouragement of my parents, not to
mention their continuhg contributions of emotional and financial support towards the
completion of this degree. Thank you Mom, for teaching me to see past the surface in al1
things, physical, emotional and spiritual. Thank you Dad, for passing your knowledge of
horticulture down to me, it lias created a passion in me to last a lifetime.
Many new friends and fellow graduate students have touched my life and
irnproved it in countless ways since beginning this project, but 1 am especially gratefûl to
Nigel Armstrong for his love and support throughout this project. "What we cal1 the
beginning is often an end. And to make an end is to make a beginning. The end is where
we start frorn." (T.S. Eliot)
This research was supported in part by the Ginseng Growers Association of
Canada, a National Research Council/IRAP/YES Award, an Ontario Graduate
Scholarship in Science and Technology (OGSST) and post-graduate scholarships
awarded by the Horticulture Division of the Plant culture Department, including the
Mrs. Fred Bal1 Schlolarship, the Soden Mernorial Fellowship, and the Manton Memonal
Scholarship.
My Grandmother Hilda Rokton (nee Napier)
To laugh often and much; To win the respect of intelIigent peeple,
and the affection of children; To earn the appreciation of honest critics, and endure the betrayal of fdse fiiends;
To appreciate beauty; To fmd the best in others; To leave the world a bit better,
whether by a healthy child, a garden patch, or a redeemed social condition;
To know that even one life has breathed easier because you have lived.
This is to have succeeded.
- Ralph Waldo Emerson
TABLE OF CONTENTS Page
ACKNOWLEDGEMENTS
LIST OF TABLES
LIST OF FIGURES
LIST OF PLATES
GENERAL INTRODUCTION
CHAPTER 1. LITERATURE REVTEW
Taxonomy and Anatorny
Wstory of the North ~mer ican Ginseng Trade
Phytomedicinal Properties of Ginseng
Ginseng Production Requirements
Inflorescence Removd for Yield Increase
Mediation of Plant Senescence
Abscission Zones
Response of Abscission to Ethylene
Action of Ethylene in the Plant
Regdation of Ethylene Action
Ethrel as a Source of Exogenous Ethylene
Considerations for Using Ethrel as ;iii Abscission Agent
iii
CHAPTER 2. EXAMNNG ETHREL AS A FLOWER AND BERRY ABSCISSION AGEhTT FOR ROOT YELD INCREASES IN NOfCTH AMENCAN GINSENG (PANAX QUNQUEFOLIUS L.)
Introduction
Materials and Methods
Results and Discussion
CHAPTER 3. GBBERELLIN, BENZYLADENINE AND ETKREL EFFECTS ON LEAF CHLOROPHYLL, SEED HEAD AND ROOT DEVELOPMENT IN NORTH AMERICAN GINSENG (PANAX Q UINQUEFOLIUS L)
Introduction
Materials and Methods
Results and Discussion
GENERAL DISCUSSION
LIERATURE CITED
APPENDIX A
APPENDIX B
APPENDIX C
LIST OF TABLES
Table
CHAPTER 2
Ethephon and Ethrel treatments applied to plots of 3-year-old Amencan ginseng (Panax quinquefoZius L.) at Rainey Ginseng in 1998.
Ethephon and Ethrel treatments applied to plots of 3-year-old American ginseng (Panax quinquefolius L.) at JCK Farms in 1998.
Ethephon and Ethrel treatments applied to plots of 3-year-old Amencan ginseng ( P m quinquefolius L .) at Canadian Imperial Ginseng Inc. in 1998.
Ethrel treatments applied to plots of 3-year-old Amencan ginseng (Panax quinquefolius L.) at Stonehenge Acres in 1999.
Ethrel treatments applied to plots of Cyear-old Amencan ginseng (Panax quinquefolius L.) at Stonehenge Acres in 1999.
Ethrel treatments applied to plots of 3-year-old Amencan ginseng (Panax quinqzrefolius L.) at Rainey Ginseng in 1 999.
Ethrel treatments applied to plots of 3-year-old Amencan ginseng (Panax quinquefolius L.) at JCK Fanns in 1999.
Ethrel treatments applied to plots of 3-year-old American ginseng (Panax quinquefolius L.) at VandenElsen's in 1999.
Ethrel treatments applied to plots of 3-year-old American ginseng (Pana quinquefolius L.) aî Canadian Imperial Ginseng Inc. in 1 999.
Floret and berry drop fiom seed heads of American ginseng (Panax quinquefolius L.) after treatment with ethephon. Day 3 measurernents. Treatments were applied to seed heads fiom 3-year- old plants.
Berry total fiesh weight and counts from harvested seed heads of Arnerican ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatments were applied on June 24 and June 29, 1998 on JCK Fanns 3-year-old gardens.
Page
57
57
58
2.12 Root fÏesh weight in Amencan ginseng (Pa= quinquefolius L.) 62 treated with single and split applications of Ethrel or hand removal of inflorescences. Treatments were applied on June 24 and June 29' 1998 on JCK Farms 3-yearsld gardens.
2.13 Root fsesh weight in Amencan ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 26, 1998 on Canadian Irnperial Ginseng Inc. 3-year-old gardens.
2.14 Root fsesh weight in Amencan ginseng (Panax quinquefolius L.) 63 treated with single and split applications of Ethrel or hand removal of inflorescences. Treatments were applied on June 1 6 and June 26, 1998 on Rainey Ginseng 3-year-old gardens.
2.15 Leaf chlorophyll in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of i.n£iorescences. Treatrnents were applied on June 26, 1999 on Stonehenge Acres 3-year-ald gardens.
2.16 Leaf chlorophyll in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand rernoval of inflorescences. Treatments were applied on June 16, 1999 on Stonehenge Acres 4-year-old gardens.
2.1 7 Leaf chlorophyll in American ginseng ( P a n a quinquefolius L.) treated with Ethrel or hand rernoval of inflorescences. Treatments were applied on June 22, 1999 on Rainey Ginseng 3-year-old gardens.
2.18 Leaf chlorophyll in Amencan ginseng (Panax quinquefolius L.) 67 treated with single and split applications of Ethrel or hand removal of infiorescences. Treatments were applied on June 18 and June 24, 1999 on JCK F m s 3-year-old gardens.
2.19 Leaf chlorophyll in American ginseng (Panax quinquefolius L.) 68 treated with single and split applications of Ethrel or hand removal of inflorescences. Treatments were applied on June 21 and June 30, 1999 on VandenElsen 3-year-old gardens.
2.20 Berry total fiesh weight and counts fiom harvested seed heads of Arnerican ginseng (Panax quinquefolius L.) treated with Ethrel. Treatrnents were applied on June 26, 1999 on Stonehenge Acres 3- year-old gardens.
Berry fiesh weight and colour distri bution fiom harvested seed heads 69 of Amencan ginseng (Panax quinquefolius LJtreated with Ethrel. Treatments were applied on June 26, 1999 on Stonehenge Acres 3- year-old gardens.
Berry total fkesh weight and counts kom harvested seed heads of American ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 16, 1999 on Stonehenge Acres 4- year-old gardens.
Berry fiesh weight and colour distribution fiom harvested seed heads 70 of Anlericm ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 16, 1999 on Stonehenge Acres 4- year-old gardens.
Berry total fiesh weight and counts fkom harvested seed heads of Arnerican ginseng (Panax quinquefolius L.) îreated with Ethrel. Treatments were applied on June 22, 1999 on Rainey Ginseng 3-year- old gardens.
Berry fkesh weight and colour distribution fiorn harvested seed heads 71 of Arnerican ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 22, 1999 on Rainey Ginseng 3-yea.r- old gardens.
Berry total fiesh weight and counts fiom harvested seed heads of 72 Amencan ginseng (Panax qzrinquefolius L.) treated with single and split applications of Ethrel. Treatments were applied on June 18 and 24, 1 999 on JCK F m s 3 -year-old gardens.
Berry fiesh weight and colour distribution &om harvested seed heads 73 of American ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatments were applied on June f 8 and 24, Z 999 on JCK Farrns 3-year-old gardens.
Berry total fiesh weight and counts fiom harvested seed heads of 74 Amencan ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatrnents were applied on June 24 and July 1, 1999 on CIG 3-year-old gardens.
Berry fkesh weight and colour distribution fkom harvested seed heads 75 of Amencan ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatrnents were applied on June 24 and July 1, 1999 on CIG 3-year-old gardens.
2-30 Root f?esh weight in Amencan ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of inflorescences. Treatments were applied on June 26, 1999 on Stonehenge Acres 3-year-old gardens.
2.3 1 Root fiesh weight in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of inflorescences. Treatments were applied on June 16, 1999 on Stonehenge Acres 4-year-old gardens.
2.32 Root fiesh weight in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of uiflorescences. Treatments were applied on June 22, 1999 on Rainey Ginseng 3-year-old gardens.
2.3 3 Root fiesh weight in American ginseng (Pmax quinquefolius L.) treated with single and split applications of Ethrel or hand removal of inflorescences. Treatments were applied on June 18 and 24, 1999 on JCK Farms 3-year-old gardem.
2.34 Root fiesh weight in Amencan ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel or hand removal of inflorescences. Treatments were applied on June 24 and July 1, 1999 on CIG 3-year-old gardens.
CHAPTER 3
3.1 Bioassay Treatment Combinations
3 -2 1999 GA experimental spray treatrnents, concentrations and application dates
3 -3 1999 BA experimentd spray treaiments, concentrations and application dates
3.4 Effect of ethephon, BA, GA and various combinations on chlorophyll content of leddiscs of American ginseng (Panax quinqzrefolius L.).
3 -5 Leaf chlorophyll in American ginseng (Panax gzrinquefolius L.) treated with GA or hand removal of inflorescences. Treatments were applied in June, 1999 on JCK Farms 3-year-old gardens.
viii
Berry fiesh weight fiom harvested seed heads of Arnerican ginseng 121 (Panax quinquefolius L.) treated with GA. Treatments were applied in June, 1999 on JCK Farms 3-year-old gardens.
Berry number nom harvested seed heads of American ginseng (Panax 122 quinquefolius L.) treated with GA. Treatments were applied in June, 1999 on JCK Farms 3-year-old gardens.
Root fiesh weight and number in Amencan ginseng (Panax quinquefolius L.) treated with GA or hand removal of inflorescences. Treatments were applied in June, 1999 on JCK Farms 3-year-old gardens.
Occurrence of broken and new bud initials on harvested roots of 124 Amencan ginseng (Panm quinquefolius L.) treated with GA or hand rernoval of inflorescences. Treatments were applied in June, 1999 on JCK Farms 3-year-old gardens and roots were harvested and observed on September 28, 1999.
Seed head height (seed intact and seed rernoved) of Amencan ginseng 125 (Panax quinquefolius L.) treated with GA. Measured on July 29, 1999.
Seed head diameter (seed intact and seed removed) of American ginseng (Panax quinquefolius L.) treated with GA. Measured on July 7 and 29, 1999 respectively.
Pedicel and peduncle length of Amencan ginseng (Panax 127 quinq~efolius L.) treated with GA. Measured on July 29 and 7, 1999 respectively.
Leaf chlorophyll of Amencan ginseng (Panax quinquefolius L.) 128 treated with BA, ethephon, or hand removal of inflorescences. Treatments were applied in June, 1999 on JCK F m s 3-year-old gardens.
Berry total fiesh weight and number fiom harvested seed heads of American ginseng (Panax quinquefolius L.) îreated with BA and ethephon. Treatments were applied in June, 7999 on JCK Farms 3- year-old gardens.
Red, green and cul1 berry fiesh weight fiom harvested seed heads of 129 Arnerican ginseng (Panax quinquefolius L.) îreated with BA and ethephon. Treatments were applied in June, 1999 on JCK Farms 3- year-old gardens.
3-16 Red, green and cul1 beriy number fkom harvested seed heads of - 130 American ginseng (Panax quinquefolius L.) treated with BA and ethephon. Treatments were applied in June, 1999 on JCK Farms 3- year-old gardens.
3.17 Root fiesh weight and nurnber in Amencan ginseng (Panax quinquefolius L.) treated with BA, ethephon and hand removal of inflorescences. Treatments were applied in June, 1999 on JCK Farms 3-year-old gardens.
LIST OF FIGURES
Figure Page
Floral development and open florets of inflorescences of 3-year-old 81 Panax quinquefolius L. over the 1998 growing season.
Seed head Eesh weights of inflorescences of 3-year-old Panax 8 1 quinquefolius L. over the 1998 growing season.
Seed head diameter of inflorescences of 3-year-old Panax quinquefolius L. over the 1 998 and 1 999 growing seasons.
Peduncle Iength of ~ o r e s c e n c e s of 3-year-old P a n a quinquefolius 82 L. over the 1998 and 1999 growing seasons.
Ethylene evolution fiorn excised inflorescences o f 3 - year-old Panax 83 quinquefolius L. over the 1998 growing season. Inzflorescences were placed in solutions of either water (O) or 750 or 1500 mg/L of ethephon. Day 2 (A) and day 3 (B) measurements.
Effect of ethephon on berry removal in 3-year-old Panax quinquefolius L. Percent berry removal through ssngle and split applications, over five 1999 locations.
CHAPTER 3
Regression analysis of the relationship between SPAD-502 131 chlorophyll and total extractable chlorophyll of leaf discs of 3-year- old Panax quinquefolius L.
Regression analysis of the effect of ethephon bioassay treatments on 132 extractable total leaf chlorophyll (CHL A t B) of leaf discs of 3-year- old Panax quinquefolius L. Numerical data presented in Table 3.4. IZ2 = 0.83. CV = 7.90.
SPAD-502 chlorophyll of leaves of 3-year-old Panax quinquefolius L. 133 over the 1999 growing season, treated with 50 - 2130 mg/L GA3.
SPAD-502 chiorophyll of leaves of 3-year-old Panax quinquefolius L. 134 over the 1999 growing season, treated with 50 - SÛO mg/L G&+,.
3.5 Correlation between broken bud dormancy and new bud initiais per 135 - root at harvest on roots of Panax quinquefolius L. plants sprayed in 1999 with O, 50, 100 and 200 mg L - ~ GA3. Each point represents 10 roots, n = 48 for correlation analysis.
3.5 Correlation between broken bud dormancy and new bud initiais per 136 root at harvest on roots of Panax quinquefolius L. plants sprayed in 1999 with 0,50, 100 and 200 mg L-' GA4+,. Each point represents 10 roots, n = 48 for correlation analysis.
3 -7 Correlation between maximum pedicel length and bare seed head 137 height of inflorescences of Panax quinquefolius L:plants sprayed in 1999 with 0,50,100 and 200 mg L-' GA3 (A) and G&+7 (B).
3.8 Correlation between maximum pedicel Iength and bare seed head 138 diameter of inflorescences of Panax quinquefolius L. plants sprayed in 1999 with 0,50, 100 and 200 mg L ' ~ GA3 (A) and G&+7 (B).
xii
LIST OF PLATES
Page
CHAPTER 1
1.1 Typical harvesting procedure of ginseng root using mechanical ginseng harvester depositing fieshly dug roots on soi1 surface.
2.1 Spring ethephon application of 3-year-old Panax quinquefo~ius L. by 86 mechanical boom sprayer at Rainey Ginseng.
2.2 July 29, 1999 floret abscission of 3-year-old Panax quinquefolius L. 86 with 7.5 L acre-' Ethrel treatment appiied on June 16, 1999 at Stonehenge Acres,
2.3 Total berry harvest of 3 -year-old Pana quinquefolius L. treated with 88 0,750 x 1,750 x 2, and 1500 mg L-' Ethrel at JCK Farms in 1998.
2.4 Red berry harvest of 3-year-old Panax quinquefolius L. treated with 88 0, 2.5, 5.0, 7.5, and 10.0 L acre-' Ethrel at Rainey Ginseng in 1999.
CHAPTER 3
3.1 Leaf colour variation with field application of Ethrel (A) and leaf discs displaying £ive colour categories (1 - maroon, 2 - dark green, 3 - Iight green, 4 - red, and 5 - orange/yellow) used for SPAD vs. total leaf chlorophyll extractions (B).
3.2 Bioassay expenment Petri pIates showing variation in Ieaf chlorosis 142 of dark incubated 3-year-old Panax quinquefolius L. leaf discs treated with 750 (A) and 1500 (5) mg L-' ethephon.
3.3 Red and green seed produced by 3-year-old Panax quinquefolius L. 144 when treated with O (control), 100 x 1 (pre-bloom) , 100 x 3 (bloom) and 100 x 4 mg L-1 GA3 (A) and seed head with characteristic butterfly shaped seed (B). Note that green seed takes on a pale pink- orange hue towards end of growing season.
3.4 Range of perenating bud broken dormancy of Panax qzrinquefoZiz~s L. 146 roots treated with'GA. 8
3.5 Formation of new bud initials on perenating buds of Panax quinquefolius L. with loss of dormancy.
3.6 Increase in seed head heigfit, diameter and pedicel length of 248 inflorescences of 3-year-old Panax quinquefohs L. treated with 100 x 4 m g L-' GA3 and G&+7.
xiv
GENERAL INTRODUCTION . Punax quinquefolius L. (American ginseng) is a perennid herbaceous plant that is
valued widely throughout Asia for its medicinal properties. World-wide interest in this
native North American plant is increasing; current research is being conducted in many
areas including cultivation and production, disease and weed management, identification
of chernical components (ginsenosides), cliniczl evaluations of health benefits and
product development. Approximately 90% of Canadian-grown ginseng is exported
currently to Asia. However, in recent years a growing trend towards the use of herbal
medicines and traditional remedies has increased demand considerably in the North
American market.
Despite renewed interest in fiesh and processed ginseng products, current p+es
for roots and seeds have continued to decrease in recent years. Production costs and
labour are increasingly more expensive for the grower. For these reasons it is necessary
to develop new management practices and technologies to optimize returns on the crop.
h important practice currently used by Ontario growers involves the removal of
developing flowers, fniits and seeds. Manual @and) removal of the ginseng
inflorescences can be used to improve root Fesh weights of 3-year-old ginseng by 25-
30% (Proctor et al., 1999).
Recent investigations into chemical removal of ginseng flowers, berries and seeds
have shown ethephon to be effective in small-plot evaluations (Fiebig, 1999). Percentage
removal of the flowers and developing berries is comparable to hand rernoval, but with
additional detrimental effects of leaf chlorophyll loss, premature senescence and
abscission of the aerial parts of the plant. Successkl application of ethephon on a
commercial scale would require similar increases in root fiesh weight as a result of
flower and berry abscission, at considerably less expense than manual removal($2500
per ha).
This thesis explores the possibility of using ethephon on a field-scale, for
induction of ginseng infiorescence abscission. The specific objectives are: . 1) To determine if effective field-scale ethephon application recornmendations can be
created for the purpose of flower and berry removal in Amencan ginseng (Panax
quinquefoZius L.), which will increase root yield similar to the practice of manual
removal and will minimize the effects of premature senescence of the aerial portion
of the plant.
2) To determine the specific relationship between leaf senescence and leaf chlorophyll
content as measured by a SPAD-502 meter.
3) To quanti@ through bioassay methods the relationship between ethephon
concentration and chlorosis of excised leaftissue, and to determine if exogenous plant
growth regulators in combination with ethephon treatment c m delay senescence of
ginseng leaf tissue.
4) To quantify what effect exogenously appIied foriar sprays of GA and BA have on leaf
senescence, and inflorescence and root development in field-grown American
ginseng.
CHAPTER 1
LITERATURE REVIEW
Taxonomy and Anatomy
North Arnerican ginseng is taxonomically classified as P a n a quinquefolitls (L.),
although it is referred to also as P a n a quinquefolium (L.), Commonly called Amzncan
ginseng, the physiological properties of Panax quinquefolius grown commercially today
closely resemble those of the original wild American ginseng. Americm ginseng is a
perennial herbaceous plant (Proctor, 1996) from the Araliaceae family (Garnian, 1898;
Koehler, 19 22; Thompson, 1987; Oliver et al., 1992). Native to the mixed hardwood
deciduous forests of eastern North America (F'roctor and Bailey, 1987), ginseng thrives in
the cool, shaded environment of the forest understory. The natural range of American
ginseng extends in Canada fiom southeastern Ontario and Quebec southward dong the
eastern Coast of the United States to Louisiana, Alabama and Arkansas, and west to the
Mississippi River (Anon, 19%; Proctor, 1997).
A creamy white to light yellow fleshy root is the over-wintering structure of the
plant. The thick taproot root often develops secondary roots with age, and supports an
erect rhizome (Thompson, 1987; Oliver et al., 1992). The rhizome is Iocated just betow
the soi1 surface and produces a perenating bud, which develops into the aerial portion of
the plant (Thornpson, 1987). A typical mature ginseng shoot consists of a single stem,
30-60 cm high (But et al., 1995), which supports a whorl of palmately compound leaves-
The number of leaves corresponds to the age of the plant (Proctor, 1496). For exarnple, a
3-year-old plant generally possesses three leaves. Each leaf generally has five leaflets,
which are stalked, obovate-oblong, pointed and semte. Arising fkom the node where the
leafpetioles join the stem, there is a compound inflorescence supported on a peduncle.
The inflorescence consists of a simple umbel of srnall (Gmm), pale greenish-white
florets (Panton, 1891; Hu, 1980; Thompson, 1987). Each floret is composed of 5
creamy-white petals, 5 green sepals, 5 anthers, and 1 pistil (Hu, 1976). Four-year-old
Arnerica. ginseng inflorescences often possess 30-40 (Hu, t 976; Proctor, 1996) self-
pollinating florets (Lewis and Zenger, 1983; Schlessman, 1985; Anon, 29981, which are
individually supported on pedicels. The florets typically develop into bemes containing
2 seeds, but a range of 1-3 seeds is possible (Proctor, 1996; Anon, 1998). Hu (1 976)
pruvides a detailed description of fiirther botanical aspects of the plant. In this study,
North Amencan ginseng is referred to as Amencan ginseng, and the word 'ginseng'
refers to North American ginseng, unless otherwise stated.
History of the North Americaa Ginseng Trade
Sirnilarities in appearance between American ginseng and Oriental ginseng
(Panax C. A. Meyer) acted as a catalyst towards developing American ginseng
as a commercial crop. In 1716, Father Francis Lafitau, a Jesuit in Montreal, used a
description of Oriental ginseng from Pierre Jartowc, a French Jesuit who had observed the
harvest of Oriental ginseng in Manchuria, to find a plant in the Quebec forest which
closely resembled it. When roots were harvested, dried, and sent to China, they were
confirmed to be high quality ginseng (Evans, 1995).
The Chinese were eagerIy seeking the root and were quick to establish trade with
the colonies. American ginseng became an important Canadian export crop, second in
value at times only to the fur trade. However, Canadian trade was interrupted when, in
1752, the Chinese received and then refused an improperly dried shipment of the root
fiom French Canadian traders. Trade of ginseng root between Canada and China ceased
almost completely in the years that followed (Koehler, 19 12). Although the Chinese
continued trade relations with the Americans, it was not until the 1900s that Canadian
trade was able to resume at high levels.
The pnce for ginseng on the world market has been determined over the centuries
largely by supply and demand. In the 1700s, American ginseng was literally worth its
weight in gold (Panton, 1891 ; Duke, 1989). With the advent of commercial production
of ginseng and rapid transport, the pnce for the root has dropped from as much as $200Ab
($440kg) (Harding, 1908) to a fraction of its former asking price. In 1997, the average
Canadian export price on field-cultivated ginseng root was $22.1 Ab ($48.7/kg) (Statistics
Canada). Between 1996 and 1998 the export value has continued to decrease. In 1998
and 1999, the average export pnce for Ontario root was $18.9/lb ($41.7/kg) and $14-7Ab
($32.4/kg), respectively (Statistics Canada).
North American production of ginseng root continues to be high despite the
decrease in value of the crop. In 1999, the ginseng harvest in Ontario, British Columbia
and Wisconsin was approximately 4,000,000; 1 ,6OO,UOO; and <1,000,000 lbs (1,8 14,400;
725,760; and (453,600 kg) of dried root, respectively (Anon, 2000). Estimated Ontario
ginsecg farm gate values were between $50 and $1 10 million in 1994 (Proctor, 1994),
and have not decreased in past years. In 1999, the estimated fami gate value was $80
million. American ginseng is still prized highly in the Asian ginseng markets. The
inability of the market to recover to its strength of a decade ago has been attributed to an
excess of root, which is currently exceeding export demand, and to instability in the
Asian economy. A surplus of root can allow brokers to offer less than cornpetitive prices,
while o d y buying the best of what is available. Because Asian demand still drives the
rnajority of ginseng production, even the Iargest of Canadian growing operations have
been unable to realize the profits that once existed. However, Amencan production of
ginseng is expected to drop by up to 50% in 2001 (Schooley, 2000). Combined with a
high degree of crop failure and disease in 2000 this rnay result in lower volumes of
available ginseng than in previous years, and it has been speculated that the price for
ginseng root will begin to stabïiize or increase (Schooley, 2000).
Phytomedicinal Properties of Ginseng
The economic value of ginseng is related mainly to its wide consumption in Asian
counûies. Oriental ginseng has been consumed for its reputed medicinal properties in
Asia for thousands of years (Proctor and Bailey, 1987; Duke, 1989), and is a daily
necessity for millions of people. The name "ginseng" cornes fiom the Chinese word jen-
shen, which means literally c'man-wort" or "man-root" (Garman, 1898). This refers to
the general appearance of the mature root, which, due to the branchîng pattern of the
secondary roots, rnay resemble the shape of a man. The appearance and shape factor
highly in the folk-Iore surroundhg the root and its beneficial properties.
Many references have been made to the use of ginseng in Traditional Chinese
Medicine (TCM). Early legends of the curative powers of ginseng focused on the ability
of the herb to restore balance and strength and empower the body to heal itself through
supplying Qi (pronounced "chee"), or vitality (Hobbs, 1996). Ginseng is traditionally
used as a tonic with prophylactic, restorative, and aphrodisiac properties (Tylor, 1994).
m e n consumed in combination with other herbs ginseng is aiso thought to help fight
cancer, slow aging, protect against heart attack and other sudden illnesses, strengthen
digestion and reduce high blood pressure, among numerous other benefits (Parks, 1983).
Differences in the physiology of American and Oriental ginseng have added
M e r to ginseng foik-Iore. Properties of American ginseng are considered to be
different than those of Oriental ginseng. The two species are thought to norinsh
complementary Yin and Yang energies, respectively, in the body (Williams, 1996). This
may be suppoaed somewhat by distinct differences in the cornplement of ginsenosides in
each species (Betz et ai., 1984; Li et al., 1996; Smith et al., 1996; Lang et al., 1993;
Tanaka et al. 2986). These naturdly occurring saponins are considered to be the active
constituents in ginseng (Inornata et al., 1993; Yoshimatsu et al., 1996). As a result,
currently both ginseng species are regularly used for the preparation of treatments in
TCM.
According to several recent studies mainly with rats, Asian ginseng has antistress,
memory increasing, and antifatigue properties (Liu and Xiao, 1992), as well as
immunostimulation (Kim et al., 1999), liver-protective (Lin et al., 1995) and endurance-
enhancing (Wang and Lee, 1998) activities. By cornparison, Amerkm ginseng is
thought to increase sex drive (Murphy et al., 1998), memory and learning (Salim et al.,
1997), a d possess digestion-regalating properties (Yuan et al., 1998).
Although ginseng is esteemed among the oriental systems of medicine that have
arisen throughout East Asia, its acceptance in the Western world has been Iess successfÛi.
Skepticism of herbal remedies on the part of North Arnericans is due often to lack of
clinical studies and medical evidence to support their therapeutic efficacy (Levin et al.,
1997). However, recent research efforts appear to be securing a place for American
ginseng in the ever-present debate about the beneficial effects of giriseng consumpttion.
Through controlled human evaluations, Vuksan et al. (2000) indicated that the
consumption of American ginseng before meds reduces blood sugar. This appears to
have substantial implications for regdation of type II dEabetes. Such discoveries mark a
turning point in the demand for the crop in North Amerka, as research continues into the
possible cardio-protective, inununornodulatory, anti-fatigue and hepato-protective
benefits of ginseng consumption (But et al., 1995). In general, the local North Amencan
market wouId appear to be gaining strength, as herbal remedies continue to gain
popularity and Canadian federal regdation of herbal product quality is developed and
implemented.
Ginseng Production Requirements
Since the 1 8OOs, high demand for ginseng has p u t pressure on the wild
populations due to intensive harvesting of the root. Wildcrafting combined with a
reduction in the natural habitat of the plant with the development of farmland and urban
areas are the factors mainly responsible for depletion of the wild species (Charron and
Gagnon, 199 1). Although protection laws have been implernented in Ontario since 189 1,
ginseng is considered now to be a rare species in Ontario, and threatened or endangered
throughout Canada and the United States (Argus and White, 1982).
In order to meet demand for the increasingly hard to find root, commercial
production of ginseng was developed in the United States and Canada in the late 1800s.
In 1892, Clarence Hellyer of Waterford, Ontario was the first to cultivate ginseng gardens
in Ontario (Proctor, 1994). Ginseng production today requires many of the same culturai
inputs as it did 100 years ago. As an obligate shade plant, growing ginseng in Ontario
requires providing shade to the crop in a rnanner which simulates the natural forest floor
environment. Through the use of shade structures constnicted of either wooden lath or
polypropylene cloth, the crop is provided with approximately 70-80% shade (Anon,
1998). It is difficult, however, to duplicate other environmental conditions found in the
natural shade of the forest. Artificial shade does not Mly imitate the qudity of the
naturd shade, the soil temperatures or the relative humidity provided by the cover of a
hardwood forest.
Ginseng seed is produced by plants which are two or more years old (Anon,
1998); however, seed is usually harvested fiom three- and four-year-old plants. The
seeds are harvested in the fall, depulped and stratified in Iayers of sand in outdoor,
underground boxes. After one year in the stratification beds, the seeds are direct-seeded
in the fd l at a rate of approxirnately 100 kgha (90-100 Ibdacre) into raised beds of
fümigated soil (Anon, 1998). Fumigation is used to control nematodes and soil-borne
pathogens to which can reduce seedling ernergence and crop stand. Fa11 seeding provides
the seed with an additional cold stratification period in the field and completes the
required 18-22 months of alternating winter and summer temperatures (Anon, 1998).
Seeds gerrninate the followirig spring,
Afier fa11 seeding, the beds are covered with a Iayer of straw mulch up to 10 cm
deep, which remains on the crop through the next growing season, and is replaced each
fdl. The presence of a mulch layer sirnulates the forest floor environment, and is used to
protect seeds and roots from low soil temperatures in the winter, reduce soil temperature
and conserve soi1 moisture during hot, dry periods in the spring and summer, reduce soil
erosion fiom the beds, and reduce weed seed germination in the ginseng beds (Stathers
and Bailey, 1986; Anon, 1998). When weeds become a problem, both hand and chemical
weed control can be used, depending on the t h e of year and the growth of the crop.
However, Touchdown 480 (glyphosate) is the only herbicide registered currently for use
in ginseng (Anon, 1 999).
Chernical inputs are used for the control of diseases in ginseng, but onIy a few
fiingicides are registered for use in the crop (Anon, 1999). Most diseases of concern in
ginseng are fungal (Parke and Shotwell, 1989). Cool, moist growing conditions under the
artificial shade are ideal for the growth of Phylophthora, Rhizoctonia, Pythiurn,
Cylindrocarpon, Fusarium, Altemaria and Botrytis species. The plants are also
susceptible to nematode infection (Parke and ShotweU, 1989), rodents, slugs and some
insect species (Anon, 1999).
Cornmercidly-grown roots are harvested after three to five growing seasons, as
Ieaving the plants in production for greater numbers of years appears to increase
incidence of disease and plant loss. Current market demands have resuited in most
ginseng root being harvested after 3 years of production. The roots are harvested in Iate
auturnn, when the foliage has senesced and the root has entered winter dormancy.
Harvesting of the crop is done by means of a modified potato digger, which separates the
roots and deposits them on top of the soil surface (Plate 1.1). The roots are collected and
then sorted by hand. Cold storage of the roots at 1 to 5°C and relative humidity of greater
than 80% can be done for up to 4 weeks after harvest, and before washing. Removing
most of the soil through washing of the roots is done before drying, and together with the
refrigeration process can improve the colour and texture of the h a l dry root product
(Anon, 19%). Roots are dried in modified tobacco k i h at 3 8OC (1 00°F) and relative
humidity of 30% or less (Anon, 1998). Fresh roots are approximately 24-32% dry matter
(Gannan, 189 1 ; Anon, 1998), and are reduced to % of their original weight through the
drying process.
The appearance of the dried root is critical to the harvesting and grading process;
the closer the roots resemble the size, shape and colour and texture of a wild ginseng root,
the higher the pnce it wiU sel1 for. Roots are also considered for age, percent moisture,
taste and fÏeedom fiom disease (Anon, 1998). Factors such as climate, soi1 composition,
available nutrients and moisture, as well as the cultural and production inputs received
during the development and harvest of the plant determine its overall value. It is not yet
cornmon for roots to be purchased fkom growers based on ginsenoside content (Anon,
1998). Once harvested and ciried, the root is bought directly ftom the growers by Asian
brokers and exported, primarily to Hong Kong (Proctor et al., 1999).
Ontario is the largest producer of ginseng in Canada, but thriving industries also
exist in British Columbia and the eastern provinces. Although most of North Arnerica's
production of ginseng is now korn commercial gardens, this method in itself is labour
intensive and continues to provide challenges in the forms of drought, disease and quality
control.
Inflorescence Removal for Yield Increase
A considerable arnount of information on ginseng is still not known. There
continue to be studies evaluating genetic diversity (Cheung et al., 1994; Bai et al., 1997;
Boehm et al., 1999) of the crop as well as its ginsenosides and their reputed health
benefits (Schultz et ai., 1980; Pieralisi et al., 1991; Prieto et al., 1993; Goode et al., 1995;
Ren et al., 1995; Wang et al., 1999). Much of the current production research involves
areas of plant nutrition, disease prevention (Joy and Parke, 1995; Reeleder and Brammall,
1994, 1999, seed dormancy studies (Proctor and Louttit, 1995; Hovius, 1996), and
production techniques for the maxunization of root yield.
The practice of manual ginseng inflorescence removal has been used extensively
by growers for the purpose of increasing root yield. It was shown recentiy by Proctor et
al. (1999) that the manual removal of this reproductive siructure in early July increases
root fiesh weight of 3-year-old roots by greater than 25%. The consecutive removal of
inflorescences in years 3 and 4 resulted in a cumulative root fresh weight increase of
greater than 55%. Preventing reproductive growth dlows the plant to partition
photosynthates that othenvise would be used in flower, fh i t and seed development into
other parts of the plant (Nagarajah, 1975).
The reproductive organs of the plant act as strong sinks for plant photosynthates
(Crane, 1964; Kelly and Davies, 1988a). As these sinks develop, the diversion of
nutrients from the vegetative parts of the plant can result in slowing of vegetative growth
(Splittstoesser, 1970; Kelly and Davies, 1988a) through the redistribution of hormones
(Wareing and Seth, 1967) and nutrients (Eaton, 1955). If there are no reproductive sinks,
metabolism often declines in the leaves and there is a build up of different vegetative
storage proteins (Sklensky and Davies, 1993). Removal of developing flowers, fniits and
seeds caused redirection of growth back into the main stem, petioles and leaf lamina of
cotton (Nagarajah, 1975) and aIso the roots of Chrysanthernurn mor$oZiurn (Cockshull
and Hughes, 1 968).
Because ginseng has a determinate growth habit, the plant is Iimited in the
number of leaves it produces throughout the growing season. Removal of the
inflorescence will not allow for a substantial increase in either Ieaf area or number
through redistribution of photosynthate. Delaying senescence, rather than preventing it,
would be a more likely resdt of removing the developing reproductive structures
(Sklensky and Davies, 1993). It has been suggested that photosynthesis is increased by
the reduction of plant growth and the subsequent increased availability of hormones
(Wareing et al., 1968) and nutrients (Humphries, 1968). In addition, Fuits ieft to
develop on a plant increases the overall rate of decline of photosynthesis of older leaves
(Wareing and Seth, 2 967; Nagarajah, 1 975). Rerefore, gains in root yield through
inflorescence removal may be ackieved by increasing or maintaining the photosynthetic
rate of the ginseng plant, or altering the progress of natural senescence.
Mediation of PIant Senescence
Senescence is the tenn cornmonly used to describe the progressive degradative
changes leading to the aging and death of the whole plant (Sklensky and Davies, 1893).
The nutrient redistribution theory proposes that senescence is initiated by the onset of
reproductive development and is characterized by the salvage and/or redistribution of
plant nutrients fiom vegetative plant parts to either reproductive or perenating structures
(Noodén and Thompson, 198 1 ; Kelly and Davies, l988a, l988b; Sklensky and Davies,
1993). For this reason, the process of senescence can be delayed by the removd of
flowers and fruits (Sklenslq and Davies, 1993). Flowers, bits and seeds act as sinks for
nutrients and photosynthates in the plant. Removal of these developing reproductive
structures can alter the process of senescence. However, developing seeds do not cause,
but simply enhance, the decrease in photosynthate partitioning to vegetative tissues
(Kelly and Davies, 1988% l988b). In soybean, seed development is not necessary for the
initiation of senescence, although the presence of flowers and seeds affects both the
partitioning pattern and the rate of senescence (Schweitzer and Harper, 1985).
The initiation of plant senescence and the subsequent degradation of proteins and
O ther plant constituents (Thimann, 1 98Oa; Simon, 1 967) are controlled by bo th
environmentai and interna1 factors (Plaisted, 19%; Woolhouse, 1967). The most cntical
environmentai factors influencing plant senescence are photoperiod, temperature, and
fertility of the soi1 (Heinicke, 1934). In response to environmentai conditions, or as part
of the developmental process, plant hormonal levels mediate the commitment of plant
nutrients fiom senescent vegetative plant parts Ceopold et al., 1959; SMensky and
Davies, 1993; Hoad, 1995).
Al1 classes of plant hormone affect the course of senescence when applied
exogenously (Sklensky and Davies, 1993). In detached leaves or leaf discs, symptoms of
senescencs can be delayed by the application of growth substances, including cytokinins
(Richmond and Lang, 1957; Letham, 1967; Thimann, 1980b), airxins (Osbome and
Hallaway, 1964; Thimann, 1980b), or gibberellins (Fletcher and Osbome, 1966b;
Beevers, 1966; Proebsting et al. 1978; Goldthwaite, 1987). The effectiveness of any one
or combinations of these compounds is dependent on species and age of the leaf, and also
if the tissue is excised fiom the plant.
Visible characteristics of senescence include chlorosis or colouration of the leaves
and wilting of the pIant through inhibition of water uptake (Thimann and Satler, 1979%
1979b). Abscission of plant organs such as leaves and leaflets often occur in later stages
of senescence. Senescence of flowers often follows pollination uld is apparent through
petal discolouration, wiit and drop. Although somewhat contradictory to the nutrient
redistribution theory, abscission of bits can also occur in relation to senescence,
particularly in situations of environmental duence . Other quantitative indications of
senescence include reduction in total protein (Spencer and Titus, 1972), chlorophyll
(Butler and Simon, 1970), photosynthetic rate (Thimann, 198Oa; Sexton and Woolhouse,
1984), and RNA, DNA and dry weight (Murneek and Logan, 1932; Wollgiehn, 1967;
Beevers, 1968).
Abscission Zones
Ginseng is highly dependent on sexual reproduction and seed development as a
means of reproduction. It is not in the best interest of the plant to prevent reproductive
development through abscission of flowers or h i t s , even with the resuit of gains in root
size. However, in times of physioIogicai stress, inherent mechanisms in the plant allow
for the prevention of tkuit set. Abscission zones in the ginseng inflorescence are formed
quite early. Fiebig (1999) showed that florets in 3-year-old ginseng iïorescences had
begun to form abscission zones between the floret and the pedicel in late May, before
flowering and berry formation.
Specific structures called abscission zones exist in almost al1 plant parts, allowing
for the shedding of plant parts (Addicott, 1965; Kozlowski, 1973; Addicott, 1982; Weis
et ai., 199 1). Abscission of flowers, fruits and leaves can occur in connection with
senescence, for conservation of nutrients, for removal of parts of the plant which are
damaged, diseased or no longer functional, or in response to environmental factors such
as water stress and temperature. A distinct abscission zone exists in the pedicel of most
flowers (Stephenson, 198 l), which can lead to entire flower bud removal in a manner
similar to the shedding of flower parts such as petals, sep& stigmas and s ~ l e s (Crane et
al., 1982; Tripp and Wien, 1989; Wien et al., 1989).
Abscission zones are usudly composed of one or more discrete layers of small,
thin-walled parenchyma cells (Sexton and Roberts, 1982; Oberholster et al., 1991).
Separation of the plant organ occurs in a band of specialized celIs near the distal (furthest
fiom the stem) end of the abscission zone (Sexton et ai., 1985; Evensen et ai., 1993).
Additional methods of distinguishing abscission zones &orn neighbouring tissues include:
a) a visible region of swollen or constricted cells, b) examining for the presence of
specific proteins (Osborne et al., l984), higher amounts of ribosomes and rough
endoplasrnic reticuium (RER) (Lieberman et al., 1983), or c) a notable lack of
lignification in the cells of the stele (Polito and Lavee, 1980; Sexton et al., 1985).
The process of abscission begins with the synthesis of polysaccharide-
hydrolyzing enzymes such as polygalacturonase (Sexton and Roberts, 1982; Osborne,
1989) and cellulase (Horton and Osborne, 1967; Abeles, 1969; Ratner et al., 1969;
Pollard and Biggs, 1970; Biggs, 1971; Rasmussen, 1973; Lieberman et al., 1983; Tucker
et ai., 1984). These enzymes are secreted fiom the cytoplasm into the ce11 wall.
Polygalacturonase andor other pectin degrading enzymes degrade the middle lamella
(Morré, 1968; Valdovinos and Jensen, 1968; Valdovinos et al., 1972; Hanisch ten Cate et
al., 1973; Webster, 1973; Polito and Lavee, 1980) and cellulase is responsible for the
breakdown of cellulose in the ce11 walls (Reid et al., 1974). These wall-digestion
processes allow for swelling of the ce11 walis in one or more layers of the abscission zone
(Webster, 1973; Osborne and Sargent, 1976; Gates et al., 198 1 ; Addicott, 1982; Sexton
and Roberts, 1982; Sexton et al., 1983; Oberholster et al,, 1.991; Evensen et al., 1993).
The action of these enzymes and unequal pressures on either side of the separation layer
due to ce11 expansion results in an eventual break. This is a genetically controlled process
(Abeles and Holm, l966), evident by the accumulation of cellulase-specific mRNA in
abscission zone cells (L,ewis and Varner, 1970; Tucker et al., 198 8). Ethylene-induced
gene activation results in de novo synthesis of celiulase (Tucker et al., 1988).
Response of Abscission to Ethylene
Competence of a ce11 is defined as the ability of cells or tissues to respond in a
characteristic and specific manner to the sarne hormonal signal (Wareing, 1986).
Abscission zone celIs are able to respond to ethylene due to the 'target cels' concept:
cells formed during shoot development have the cornpetence to respond to ethylene
produced during senescence of the leaf, by producing hydrolytic enzymes (Wright and
Osborne, 1974; Osborne and Sargent, 1976). Ethylcne stimulates the synthesis of
cellulases and poiygdacturonases (Abeles, 1973; Huberman and Goren, 1979; Burns et
al., 1995; Bums et al., 1998, Kazokas and Burns, 1998), initiating the degradation of
adjacent ce11 walls, Ieading to separation and abscission of plant organs fiom the whoie
plant (Sexton and Roberts, 1982; Bnuriell et al., 1994).
Plant hormones are organic compounds synthesized in one part of the plant and
translocated to another part, where in very low concentrations they cause physiological
responses. The endogenous plant hormone ethylene has been irnplicated in many plant
developmental processes (Abeles, 1973) including senescence (McGlasson, 1970).
Plants are capable of regdating abscission of their own parts through the
production of relatively low concentrations of endogenous ethylene (Abeles, 1973;
Addicott, 1982). Flower senescence is often accompanied by a rapid increase in
endogenous ethylene production (Nichols, 1966; Nichols, 1968; Nichols et al., 1983;
Halevy et al., 1984). Ethylene stimulates the removal of flowers (Sexton et al., 1985),
young fruits (Noodén, 198O), mature h i t s (Lipe and Morgan, 1973), and leaves (Dunster
et al., 1980) in a variety of plant species. In the pedicels of tomato flowers, abscission is
stirnulated about 4 h after ethylene exposure (Roberts et al., 1984). In fkuits and leaves,
increases in celldase activity generally occur fiom 12 to >3Gh after ethylene exposure
(Pollard and Biggs, 1970; Greenberg et al., 1975; Tucker et al., 1988; Bonghi et al., 1992;
Ferrarese et al., 1995; Kazokas and Burns, 1998). Kowever, the concen~ation of
ethylene required to elicit a response varies depending on the species and type of plant
tissue studied.
Leaf tissue is Iess sensitive to Zow concentrations of ethytene than flowers and
fiuits. Flower tissue (Noodén, 1980), flower buds and young fruit (Hall et al., 1957) are
more responsive to ethylene-induced abscission than the Ieaves of the same plants. Lang
and Martin (1989) were able to stimdate abscission in olive bits with exogenously
applied ethylene gas at one-half the concentration required for a similar abscission
response in the leaves. This differentid response also exists between specific abscission
zones within flowers (Weis et al., 1991).
Ethylerie effects on flower tissue include opening of flowers, acceleration of petal
tissue senescence (Nichols, 2966; Kende and Baumgartner, 1974; Kende and Hanson,
1976; Suttle and Kende, 1978), and CO-ordination of petal abscission (Abeles, 1973;
Burdon and Sexton, 1993). Where abscission occurs in the pedicek of flowers, ethylene
promotes bud abscission through increases in cellulases and other hydrolytic enzymes
(Hanisch ten Cate and Bruinsrna, 1973a; Hanisch ten Cate et al., 1975b). Ethylene is
produced by plants to promote both chlorophyll loss in the ripening process of fMts
(Inimarin, l98Ob), and abscise mature fruits fiom the plant through stimulation of the
abscission process (Bug and Burg, 1962, l96Sa).
Conditions which promote opening and senescence in flowers, abscission in
flowers and yomg fruit, ripening and mature fruit abscission, and senescence in leaves
are al1 accompanied by increased ethylene synthesis. Ethylene production is induced also
in plants in response to environmental stress (Abeles, 1973; Yang and Pratt, 1978), such
as excess water (Jackson, l985), drought (Tietz and Tietz, l982), and elevated
temperatures (Abeles et al., 1992). SimiIar stresses have stirnulated flower abscission;
for exarnple, low soi1 water potential (Cochran, 1936; Apelbaum and Yang, 198 1) and
elevated temperatures (Rylski and Sigelman, 1982; Monterroso and Wien, 1990; Wien,
1990; Konsens et al., 199 1). Ethylene synthesis is promoted also by mechanicd stress
(Leopold et al., 1972), bruising or woundmg of plant tissues (Pratt and Goeschl, 1969),
and infestation with insect and disease organisms (Morgan, 1 9 8 6).
Action of Ethylene in the Plant
Ethylene is produced in the plant for the purpose of regdation of a number of
complex plant processes (Davies, 1995). It is derived fiom the amino acid methionine
through a complex biosynthetic pathway. Production of ethylene is dependent on the
presence of ATP, 1 -amino-cyclopropane- 1 -carboxylic acid (ACC) synthase, and oxygen.
ATP is required for the conversion of methionine to S-adenosyl-methionine (SAM). ACC
synthase catalyzes the conversion of SAM to ACC (Boller et al., 1979). Oxygen is
essentid in the synthesis of ethylene from ACC (Adams and Yang, 1979). It is at the
level of ACC synthase where we fhd a rate-lirniting step in the production of ethylene.
Experimental evidence supports this conclusion, since many of the same conditions and
chernicals which stimulate ethylene synthesis are also responsible for elevation of ACC
synthase activity in plant cells (Yang and Hof ian , 1984).
Just as oxygen is required for the biosynthesis of ethylene, the binding of ethylene
is also an aerobic process (Burg and Burg, 1965b). Other aspects ofethylene binding are
not well understood; however, it has been suggested that it involves only very weak Van
der Waal's forces (Abeles et al., 1972), and that ethylene binds with at least one type of
receptor protein (Goeschl and Kays, 1975) located in ce11 membranes (Napier and Venis,
1990; Sisler, 199Ca, 1990b). The number of receptors per cell, calculated based on one
species of receptor, and requiring only 0.1 pL/L to elicit half-maximal activity, would
indicate the presence of at least 500 ethylene binding sites (Abeles, 1973). Very low
ethylene concentrations within plant tissues are required to exert physiological effects in
plants. Concentrations in vivo of 1 pL/L are enough to produce haIf-maximal activity in
most plant responses to ethylene (Beyer et al., 1984). In one recent example, Fiebig
(1 999) has s h o w that 10 to 100 pL/L of ethylene induced complete floret abscission in
excised ginseng inflorescences.
Regulation of Ethylene Action
The concentration of ethylene required to elicit various responses in plants varies
considerably. These concentration dependencies suggest the existence of multiple
binding sites andor binding site specificity for different plant responses (Goeschl and
Kays, 1975). The degree of tissue sensitivity to ethylene can result from interactions
between factors such as carbohydrate reserve in the plant (Mayak and Dilley, 1979,
osmotic concentration of the tissue (Mayak et al., 1978), abscisic acid (Mayak and Dilley,
1976) or other plant hormones (Sacher, 1973).
The application of exogenous ethylene acts as a signal in many plants to stimulate
the synthesis of endogenous ethylene (Burg, 1962; Mayak and Hdevy, 1972). The
autocatalytic nature of ethylene in plants is comrnon to the process of senescence in fidly
developed mature plant organs (Nichols, 1968; Kende and Baumgartner, 1 974).
Increased tonoplast permeability in the vacuole and enhanced movement of vacuole
contents across the membrane to the cytoplasm have been demonstrated in response to
ethylene (Kende and Baumgartner, 1974; Hanson and Kende, 1976; Mayak et al., 1977).
Disintegration of the tonoplast due to ethylene exposure (Matile and Winkenbach, 1971)
is followed by loss of solutes and then water, leading to wilting and senescence of the
tissues (Borochov and Woodson, 1989).
The senescence effects achieved through autostimulation of ethylene occur only
once there is increased sensitivity of the tissues. Sensitivity to ethylene is regulated
through a balance of ethylene and auxin (Morgan, 1961; Morgan and Hall, 1962; Hall
and Morgan, 1964). Auxin is present at uihibitory levels in abscission zone cells, and is
generaily antagonistic to ethylene in the processes of senescence and abscission (Hall,
1 952). The first function of ethylene is to reduce the auxin available in the abscission
zones of the plant (Beyer, 1973; Beyer and Sweetser, 1974; Beyer, 1975a). This is
achîeved through destruction (Hall and Morgan, 1964; Morgan et al., 1968), binding
(Ernest and Valdovinos, l97l), synthesis inhibition (Valdovinos et al., l967), or transport
reduction of auxh (Beyer and Morgan, 1971). Until this balance of auxin is disrupted, no
amount of ethylene can prornote abscission (Abeles et ai., 1971 b).
Complete removal of auxin is not necessary to achieve an abscission response
(Morgan and Durham, 1972). However, by inhibiting auxin transported out of the leaves,
ethylene is able to exert greater influence on the abscission zone cells (Beyer, 1973).
With rising ethylene levels and declining auxin levels, a threshold is reached where
synthesis of hydrolytic enzymes begins (Beyer and Morgan, 1 97 1). Exposure of both the
leaf and the targeted abscission zone to ethylene is required for induction and secretion of
enzymes by the abscission zone cells (Horton and Osborne, 1967; Abeles, 1969; Jackson
and Osborne, 1970; Abeles and Leather, 1971).
Ethrel as a Source of Exogenous Ethylene
Although dif5erent plant tissues have evolved specific responses to the presence
of ethylene, the tendency of this gaseous plant growth regulator to rapidly disperse in an
agricultural setting prevents the application of specific concentrations of ethylene for
extemal regulation of the abscission response. Control of localized ethylene applications
were extremely difficult until the release of an experimental chemical cdled 2-
chloroethylphosphonic acid (ethephon, trade name Ethrel) by Amchem Products Inc
(Amchem Inc., Ambler, PA, U.S.A.) in 1 969. Introduction of this liquid-form chemical
(') provided a simplified method of exogenous ethylene applications (Cooke and Randd,
1968; Devlin and Demoranville, 1970).
(1 ) 2-chIoroethylphosphonic acid (Ethephon, Eîhrel, CEPA, CEPHA)
Cl - CH2 - CH2 - P03H2
Ethrel is a formulation of 24% (240 g L-') ethephon, a compound which breaks
d o m in plant tissues to release ethylene (Abeles, 1 973), a Cl- ion, and H ~ P o ~ - . Alkaline
pH and high temperature prornote the degradation of this chemical in the plant (Warner
and Leopold, 1 969; Blurnenfeld et al., 1978).
Ethrel is actively taken up in the transpiration stream and translocated to the
leaves, flowers and h i t s (Nickell, 1979; Lavee and Martin, 198 1 a). The release of
ethylene fiorn Ethrel-treated tissues produces plant responses similar to endogenous
ethylene (Cooke and Randall, 1968; Morgan, 1969; Warner and Leopold, 1969). The
presence of ethylene fiom thk source likely stimulates the plant to produce additional
endogenous ethylene due to its autocatalytic nature.
Ethylene is not an environmental hazard (Morgan, 1984), which makes Ethrel an
ideal exogenous plant growth regulator. Since its introduction, it has been used regularly
in research as a source of ethylene. Ethrel has been used for induction of flowering in
pineapples (Cooke and Randall, 1968) and mango bees (Chacko et al., 1972, 1974), as
well as promoting female fiower development in cucumber (McMurray and Miller, 1968;
Iwahon et al., 1969) and pumpkin (Splittstoesser, 1970). Abscission induced by Ethrel
application has been used for the removal of flowers and immature fniit in pumpkin
(Splittstoesser, 1 %'O), peach (Stembridge and Garnbrell, 197 1, Schneider, 1977) and
apple (Greene et ai., 1990). Stimulation of abscission zones with Ethrel can also decrease
the force required for harvest of mature h i t s of apple (Luckwill et al., 1976; Rogers and
Krestensen, 1973), sweet cherry (Bukovac, 198 l), walnut (Olson et al., 1977), and olive
(Reed and Hartmann, 1976; Epstein et al., 1977; Martin et al., 198 1).
Ethrel has been used commercially for the purpose of accelerating and promoting
uniform ripening of oranges, bananas (Russo et al., 1968) and late-season tornato f i t s
(Reid, 1987). It is used for the preharvest stimulation of colour developrnent in
cranberries (Devlin and Demoranville, 1970) and in curing tobacco leaves (Miles et al.,
1972; Long et al., 1974; Walker, 1977; Walker, 1985). In tobacco, ethylene shortens the
leaf ripening period (Kwaih et al., 1972; Moon and Sin, 1972; Long et al., 1974;
Congleton, 1978; Chakroborty et al., 1979), and reduces curing time of the leaves (Kwaih
et al., 1972; Domir and Foy, 1976; Chakroborty et al., 1979). Additional crops which
have benefited from the research and commercial use of Ethrel include wheat, barley
sugar cane, and cotton (Morgan, 1986).
Some evidence suggests that Ethrel is capable of enhancing root growth through
reduction of vegetative growth. Ethrel applications to cuttings of impatiens (Impatiens
balsamina L.) improved the quality of the root system (Tamari et al., 1998). Soffer et al.
(1989) reported similar effects of Ethrel on rooting for chrysanthemurns. Increased
rooting may have been due to the inhibitory effects of Ethrel on plant growth (Tarnari et
al., 1998). Ethylene also halts root elongation and increases root thickness (Jacksons,
199 1 ; Smalle and Van Der Straeten, f 997).
Of the varied responses in a number of plant crops tested, the following responses
of ginseng to Ethrel have been found thus far. Fiebig (2999) concluded that of several
compounds sprayed by hand on small plots, Ethrel sprays as a source of ethephon were
the most effective treatment for the removal of ginseng berries fiom the inflorescence in a
manner that resembled the practice of manual inaorescence rernoval. These sprays were
successful in reducing both the total mass of bemes harvested? as well as the total number
of red, ripe bemes developed per plant. This was achieved through stimulation of the
abscission zones in the pedicels of the inflorescence and/or by preventing growth of the
inflorescence entirely . Total berry weights decreased Iinearly with increasing ethephon
concentration. Of the bemes harvested, ethephon treatrnents reduced the percent red
bemes and increased the percent of immature florets. Sprays of 1500 to 4000 mg L -' ethephon were comparable tu hand removal in effectiveness at preventing red berry and
subsequent seed development. The same spray treatrnents resulted in considerable
darnage to the leaves with increasing concentratioli. Development of red pigments and
increased abscission of leaves was cornrnon at the highest application rates. At the
highest rates of ethephon application the peduncles and ~ c t e s c e n c e s browned and
shriveled up. Although the ethephon sprays appeared to cause early senescence and
abscission of the aerial portion of the plant at high rates of application, single applications
fiom 0-4000 mg L -' ethephon resulted in a quadratic increase in root weight with
maximal values around 1250 mg L ". Root weights were statistically sirnilar to the
manual removal at rates between 750 and 2000 mg L -'. In the same experiment,
increases in root weight were obtained through manual removal of the inflorescences
which were comparable or higher than the 26% estimated yield increase reported by
Proctor et al. (1999).
Considerations for Using Ethrel as an Abscission Agent
While Ethrel as a source of ethylene is convenient for field-scale application,
plant growth regulators are notonous for their ùiability to produce consistent results.
Through the manipulation of a naturally existing control mechanism, many other
interactions in the whole plant system also can be flected by changing the balance of a
specific hormone. For these reasons, there are distinct challenges to creating application
recornmendations for Ethrel.
Fiebig (1999) defmed an acceptable heshold for berry removd using Ettirel as a
spray treatment as: Greater than 75% removal of berries while causing less than 25%
damage to the leaves. The efficacy of exogenous hormone applications can be affected
by a nurnber of factors such as: a) the cornpound applied rnay not be identical chernical
to the endogenous hormone and thus behave differently, b) it may not be applied to the
site at which it is nomally synthesized, and c) application of the hormone may raise the
endogenous concentrations to uncharacteristically high levels (Hoad, 1995).
The efficacy of Ethrel applications are also very susceptible to environmental
stresses. Ethylene-induced abscission in leaves, flowers and h i t is sensitive to high
temperature (Yamaguchi, 1954; Olien and Bukovac, 1 978; Lavee and Martin, 198 1 a,
198 1 b). Heat and drought reçult in endogenous ethylene production by the plant, which
can amplie or mask effects fiorn exogenous ethylene application. Response of Ethrel-
treated leaves varies considerably with temperature at the time of spray application
(Lougheed and Franklin, 1972). Ethrel applied to Cotton leaves (14 pL/L for 24 hr) at
temperatures above 27°C is capable of inhibiting auxin transport by 70%, and promoting
high levels of leafabscission (Beyer, 1973). Drought rnay promote further dehydration
of the plant in response to too high levels of ethylene, through loss of integrity of the ce11
membranes and changes in water potential in the ce1Is (Weis et al., 1988).
The leaf blade is the initial target of exogenously applied ethylene, where
ethylene hc t i ons to reduce auxin available to the abscission zone by inhibiting auxin
transport out of the leaf. However, coverage of both the leaf blade and the petiole are
necessary to result in abscission. Ethylene inhibition of awcin transport in both the Ieaf
and petiole is necessary in order to &op auxin ievels in the abscission zone to a
sufficiently low level that ethylene can trîgger enzyme induction in the abscission zone
cells (Beyer and Morgan, 1971). In natural abscission, there is greater reduction of auxin
transport in the leaf and petioles of bean than in the stem tissue (Jackson and Osborne,
1970). If ethylene is applied to al1 parts of the pIant at once, auxin transport in the stem is
inhibited to a greater degree than in the petiole, preventing existing levels of auxin from
being removed f?om the petiole abscission zone (Ekyer, 1973). Therefore, thorough
coverage of the stems of plants rnay prevent the plant fiom abscising its leaves in
response to applications of Ethrel.
Although we c m rneasure the arnount of Ethrel being applied to the plants, there
is uncertainty as to the exact concentration of ethylene reaching the target tissue (Weis et
al., 1988). Variable abscission response in our applications may be due to metabolism or
breakdown of the abscission agent before it cm exert a biological effect (Davies et al.,
1976; Hoim and Wilson, 1977). Ethylene gas is metabolized into ethylene oxide (Jerie
and Hall, 1 978) b y at least two pathways in plant tissues (Giaquinta and Beyer, 1 977).
Other minor water-soluble metabolites may include ethylene glycol and its sugar
conjugate (Blomstrom and Beyer, 1979). The ability of the plant to remove ethylene
fiom plant tissues through metabolism rnay also increase with the age of the plant (Jerie
and Hall, 1978). However, aging flower tissue is more susceptible to ethylene-induced
abscission (Mayak and Kofianek, 1976; Evensen, 199 1). Therefore, the degree of injury
we see as a result of our applications also may be influenced by factors such as the
age/maturiq of the tissue being treated.
The inability of the plant to use or metabolize excess ethylene is evident with the
onset of premature senescence and abscission of flowers, fruits and leaves, and
subsequent effects on growth and flowering. High concentrations of Ethrel applied on
olive trees r e d t s in a high degree of leaf abscission followed by negligible flowering in
the following year (Hartmann et al., 1980). Similar residual effects of Ethrel sprays have
been recorded in ginseng. Fiebig (1999) noted that 3000 and 4000 mg 1 -' ethephon
sprayed on ginseng resulted in visibly smailer inflorescences on plants in the growing
season following treatment. The inflorescences were narrower, and contained fewer
florets than those of the controls, although leaves appeared healthy and matured similar to
the controls that had not been sprayed or manually deflowered. Certain degradation
products of Ethrel other than ethylene (Cl- and ~ ~ ~ 0 9 (Weis et al., 1988) may contribute
to the detrimental physiological eflects seen in the plant. - The most visible indication of senescence due to Ethrel treatrnent in ginseng is the
appearance of a purple tinge to the leaves, followed by the development of vivid yellow,
orange and red pigments. These pigments are similar to those seen in the senescing
leaves of deciduous trees in fall, and are oniy seen with high applications of the chernical.
Colour development in tobacco leaves due to Edirel application occurs only where the
spray has directly contacted the leaf tissue (Moon and Sin, 1972; Long et al., 1974). In
cranbemes, the appearance of red pigments in the vines after Ethrel application has been
attributed to the rapid s ynthesis of anthocyanins. Anthocyanin formation was increased
by 49, 65 and 64% with applications of 100, 500 and 1000 mg& respectively (Devlin
and Demoranville, 1970).
Plate 1.1 Typical harvesting procedure of ginseng root uskg mechanical ginseng harvester depositing fieshly dug roots on soi1 surface.
Plate 1.1.
3 1
CHAPTER 2
Examining Ethrel as a Flower and Berry Abscission Agent for Root Yield Increases
in North American Ginseng (Panax quinquefoiius L.)
Introduction
Ethylene is a naturally occurring plant growth regulator in plants, with the ability
to stimulate senescence and abscission of flowers (Sexton et al., 1985), young fi-uïts
(Noodén, 1980), mature fhits (Bug and Bug, 1962; Burg and Bug, 1965a), and leaves
(Dunster et al., 1980) in a variet/ of plant species. This response to ethylene is
autocatalytic in nature (Nichols, 1 968; Kende and Baumgartner, 1974). Application of
exogenous ethylene acts as a signal in many plants to stimulate the synthesis of additional
endogenous ethylene (Burg, 1962; Mayak and Halevy, 1972). For this reason, plants are
capable of regulating abscission of their vegetative and reproductive organs through the
production of reiatively low concentrations of endogenous ethylene (Abeles, 1973;
Addicott, 1982).
Ethrel is a commercial preparation produced by Rhone-Poulenc containhg 24%
(240 g L-') ethep hon. Ethephon (2-chloroethylphosphonic acid) is actively taken up in
the transpiration Stream and translocated to the leaves, flowers and h i t s (Nickell, 1979;
Lavee and Martin, 198 la), where it breaks down in plant tissues to release ethylene
(Abeles, 1973). The ethylene released fiom Ethrel induces plant responses similar to
those induced by endogenous ethylene (Cooke and Randall, 1968; Morgan, 1969; Wamer
and Leopold, 1969).
In some plant species, preventing reproductive growth allows the plant to partition
photosynthates that would othenvise be used in flower, fniit and seed development back
into the main stem, petioles and leaf lamina (Nagarajah, 1975), and roots (Cockshull and
Hughes, 1968). As a rnethod of increasing root mas, the practice of manual
inflorescence removal in ginseng has been adopted widely among Ontario growers.
Ginseng root fiesh weights c m increase 25-30 % as a resldt of manual inflorescence
removal in early July (Proctor et al., 1999). However, the option to remove
inflorescences by hand removal is becoming unavailable to some Ontario growers, due to
the increasingly prohibitive cost of manual labour (100% removal = $2500/ha). For L I S
reason, ethephon has been examined for its potential to induce flower removal.
Previous research indicates that ethephon sprays applied during inflorescence
development stimulates early abscission of ginseng flowers and immature berries in a
manner which resembles the practice of manual inflorescence removal (Fiebig, 1999).
She concluded that application of 1500 to 4000 mg L-L ethephon by means of a backpack
sprayer to small plots was successfül in reducing both the total mass of bemes harvested,
as well as the total nurnber of red, ripe berries developed per plant. This was achieved
through stimulation of the abscission zones in the pedicels of the inflorescence andor by
preventing growth of the inflorescence entirely. Although the ethephon sprays caused
early senescence acd abscission of the aerial portion of the plant at high rates of
application, single applications from 0-4000 mg L-l ethephon resulted in a quadratic
increase in root weight with maximal values being reached around 1250 mg L-' ethephon.
Root weights at ethephon rates between 750 and 2000 mg L-' were statistically similar to
manual inflorescence removal. In the sarne experiment, increases in root weight were
obtained through manual removal of the innorescences which were comparable or higher
than the 26% estimated yield increase reported by Proctor et al. (1999).
Ethephon at hi& concentrations applied to ginseng flowers in late June for the
purpose of ethylene-induced abscission, can result in the premature senescence and
abscission of the leaves. Senescence is evident by chlorosis of the leaves and the
appearance of red, orange and yellow pigments. Spray treatrnents of ethephon on
ginseng resulted in considerable development of red pigments and increased abscission of
leaves with increasing concentration (Fiebig, 1999). Senescence of the leaves would
normally be seen only toward the end of the growing season, when the ginseng plant
enters dormancy. Since ginseng achieves the majority of its root weight increase in the
later rnonths of summer (Proctor et ai., 1998), early leaf senescence may prevent the plant
fiom realizing increases in root fiesh weight. The effects of leaf senescence and
abscission are rninimized with the use of modest concentrations of ethephon (Fiebig,
1999).
Other obstacles to successful applications of ethephon may include achieving
adequate spray coverage and timing of the sprays in relation to flower development. The
dense growth habit of ginseng rnakes penetration of the sprays into the canopy and
thorough coverage a challenge. Coverage of the flowers, stems and petioles may be
important to the awiin gradients which mediate abscission. Direct contact of the sprays
with the abscission zones in the inflorescence rnay increase their efficacy (Fiebig, 1999).
The flowering pattern of the ginseng plant may provide another distinct challenge to the
success of the ethephon sprays. The individual florets on the inflorescence open
gradually between June and July fiom the outer to the innermost florets over several
weeks (Carpenter and Cottam, 1981; Proctor, 1987). For this reason, not al1 florets will
be open at the time of a single spray. The open stage is when the flowers are considered
to be most susceptible. Therefore, the ideal timing of application of ethephon is when
greater than 30% of the flowers are open (Fiebig, 1999), and must be observed carefully.
The large variation inherent in the development of this essentially wild-type crop makes
this a difficult target.
Although Ethrel as a source of ethephon can be used on a small-plot scale for the
removal of ginseng bemes and subsequent root yield increase (Fiebig, 1999), the
question remains to be answered whether or not these sprays can be eEectively applied
on a scde suitable to commercial production.
Specific Objective: The objectives of this investigation were (a) to examine the efficacy
of Ethrel concentration and application volume on ginseng flower and berry removal and
subsequent root yield increase, and (b) to create effective commercial-scale Ethrel
application recommendations which minirnize the effects of premaiure ginseng leaf
senescence.
Materials and Methods
1. Laboratory Experiments - Ethylene Evolution from Excised Seed Heads with
Exposure to Ethephon
The study was performed using seed heads fiom an established 3-year-old garden
owned by Canadian Imperia1 Ginseng Inc. (CIG), Iocated South of Budord, Ontario on
East !A Townline Road. Untreated seed heads with peduncles intact were barvested
randomly by snapping peduncles off cleanly where the peduncle joined the main stem
and whorl of leaves. Seed heads were placed in containers of de-ionized water and
transporîed to the laboratory.
Because the laboratory experiments were being conducted throughout the
growing season, it was necessary to make seasonal measurements of seed head
development. Additional seed heads were harvested Eom the same CIG 3-year-old
gardens. Harvested seed heads were assessed for total fresh weight, average floret
nurnber, percent of open florets, seed head diameter and peduncle lengths in 1998.
Additional measurements of seed head diameter and peduncle length were taken from
JCK Farms 3-year-old gardens in 1999 for cornparison.
Five seed heads were selected randomly for each replicate, and were placed
upright in small vials (peduncle end covered) containing a 50 mL solution of 0,750 or
1500 m g L-' ethephon. Ethre1(24%; 240 g L-' a i . ethephon) was used as a source of
ethephon and three replicates were used per ethephon treatment. Vials containing water
or treatment solution without seed heads were used as controls, to establish if the solution
itself was contributing ethylene to the headspace gas sarnple. Vials were sealed in 1 L
Mason jars with lids containing a rubber septum for headspace gas analysis.
The jars were randomized and lefi in a dark box at room temperature. Ethylene
release was measured at 48 and 72 hours after sealing the jars. Headspace gas was
analyzed for ethylene content by removing a 10 mL gas sarnple with a syringe and
injecting into a Hewlett Packard 5880A gas chromatograph (GC) equiped with a 6 ft (1.8
m) Porapak Q colurnn and flame ionization detector (FID). Injecter, column and detector
temperatures were 60, 80 and 320 OC, respectively. Nitrogen carrier gas flow rate was 22
mL min". Compressed air and standard ethylene samples were run pnor to headspace
samples to calibrate the GC. Ambient air samples were run to test background ethylene
levels. M e r 72 hours, floret and berry abscission was deterrnined by comting the
number of florets and bernes remaining on the seed heads.
Data were subjected to analysis of variance (ANOVA) using the General Linear
Models (GLM) program of SAS (SAS Institute, Cary, N.C.). All variables were tested
for normal distribution. Treatrnent means were compared using the Least Significant
Daerence (LSD) method of analysis. The leveI of significance used for al1 tests was -
P 5 0.05.
II. Field Experiments
Ail gardens used for this investigation were 3-year-old plantings of Panax
quinquefohs L. Ginseng gardens were planted on raised soi1 beds at commercial
spacing, and covered with straw mulch. The plants were grown under either wooden lath
or black polypropylene shade. Gardens were maintained by the individud growers
throughout the growing season, according to cornmon commercial practices, sirnilar to
those described by Proctor and Bailey (1987). Standard practices for fertilization and
disease control were Îoiiowed (Anon, 1998; Anon, 1999). Sprays were applied with
existing sprayer technology available at each grower location. Ethrel was used as a
source of ethephon in both 1998 and 1999.
A. 1998 Field Experirnents
Triais were conducted in 1998 in collaboration with 3 growers at 3 locations
throughout Southern Ontario between Paris and Waterford (Tables 2.1 - 2.3). Control
and treatment plots were arranged in sections of established 3-year-old gardens using a
randornized complete block design (RCBD) with 3 replicates. Plot lengths are listed in
Tables 2.1 - 2.3. Two controls were incorporated into the experimental design.
Unsprayed plots served as a treatment control and were allowed to develop seed heads.
Hand removal controls were also used to compare the effects of 100% removal of
inflorescences to control and ethephon-treated plots.
Spray treament concentrations used in 1998 were determined by optimum
concentrations suggested by Fiebig et al. (1998). A typical ginseng garden and sprayer
application of ethephon are shown in Plate 2.1. Spray treatments consisted of foliar
sprays of ethephon applied in various water volumes and with concentrations ranging
from 750 to 3000 mg L" (Tables 2.1 - 2.3). Corresponding rates in L acre-' were
modified by water volume of the respective spray applications and are reported in Tables
2.1 - 2.3. Sprays were applied at approximately 30% bloom. This date varied
according to location. No surfactants were used. Single and split applications of
ethephon were used to determine if the effects of the sprays were additive, and to attempt
to reduce the degree of leafdamage due to the ethephon applications. See Tables 2.1 - 2.3 for specific concentrations, water volumes and spray schedules used.
Inflorescences were harvested fi-om JCK Farms at commercial timing fiom 1 m
sections of each treatment. A subsampIe of approximately 100 florets and bemes was
taken per plot and sorted visually into 3 categories; red berries, green (unripe) berries and
culls (unpollinated florets). Counts were taken for total, red, green and cul1 bemes.
Roots were harvested at commercial timing. See Tables 2.1 - 2.3 for harvest date
and method. Excess soi1 was shaken off roots before measurement. AI1 roots were
counted and weighed individually to determine total yield per 1 m section within each
plot. Before and after rneasurement, roots were stored in cold air storage at 3 * 0.2 OC
until they were returned to the respective growers.
AU data were subjected to anaiysis of variance (ANOVA) using the Generd
Linear Models (GLM) program of the SAS stâtistical package (SAS Institute, Cary,
N C ) . Al1 variables were tested for normal distribution. Treatrnent means were
compared using the Least Significant DiEerence (LSD) rnethod of analysis. The level of
significance used for al1 tests was P 1 0.05.
B. 1999 Field Experiments
Trials were conducted in 1999 in collaboration with 5 growers at 6 locations
throughout Southern Ontario (Tables 2.4 - 2.9) between Paris and Waterford. Control
and treatment plots were arranged in sections of established 3- and 4-year-old gardens
using a randomized complete block design (RCBD) with 3 or 4 replicates. Plot lengths
are listed in Tables 2.4 - 2.9. Two controls were incorporated into the experimental
design. Unsprayed plots served as a treatment control and were aiiowed to develop seed
heads. Hand removal controls were also used to compare the effects of 100% removal in
debudded plots to control and ethephon-treated plots.
Spray treatment concentrations used in 1999 were determined by analysis of 1998
results. The treatments consisted of foliar sprays of Ethrel applied in various water
volumes and with concentrations ranging fiom 2.5 to 10.0 L acre-' (Tables 2.4 - 2.9,
Plate 2.2). Sprays were applied at approxùnately 30% bloom. This date varied according
to location. No surfactants were used. Single and split applications of ethephon were
used at some locations to determine if the effects of the sprays were additive, and to
attempt to reduce the degree of leaf damage due to the ethephon applications. See Tables
2.4 - 2.9 for specific concentrations, water volumes and spray schedules used.
In vivo chlorophyll measurements were taken at each location throughout the
growing season using a SPAD-502 meter (Minolta Camera Co. Ltd., Japan). Mean
SPAD measurements were determined by taking 10 random measurements fiom each
plot on each sampling date. SPAD measurements were taken fiom the center leafiet of
each leaf, avoiding the midrib and major veins. Visual observations of foliar damage due
to ethephon ireatrnent wire made at each location between June 26 and July 8, 1999.
Inflorescences were harvested from each location at commercial timing fiom 1 m
sections of each treatrnent and measured for total fkesh weight. Three categories of
florets and bemes were used; red berries, green (unripe) bemes and culls (unpolhated
florets). Culls were first screened out by size (0.60 cm diameter screen opening).
Remaining red and green bemes were then and sorted visually by coiour. Fresh weights
and counts were taken for red and green berries and culls for each plot.
Roots were harvested at commercial timing (Tables 2.4 - 2.9). Roots were
washed and air-dned before measurement. Al1 roots were counted and weighed
individually to determine total yield per 1 m section within each plot. Before and d e r
measurement, roots were stored in cold air storage at 3 & 0.2 O C until they were returned
to the respective growers.
Al1 data were subjected to analysis of variance (ANOVA) using the General
Linear Models (GLM) program of the SAS statisticd package (SAS Institute, Cary,
N.C.). Al1 variables were tested for normal distribution to determine if transformation of
the data was necessary. Transformations were required with only the berry harvest data.
A log(y) transformation resulted in normal distribution of the data. Analysis of variance
and mean separation procedures were repeated with the transformed berry data.
Treatrnent means were compared ushg the Least Signxcant DiEerence (LSD) method of
analysis. The 1eveI of significance used for chiorophyll (SPAD) treatment rneans, berry
and root harvest means was P < 0.05.
Results and Discussion
Growth Curve Characterization
The average number of fiorets per inflorescence for a 3-year-old plant at the CIG
location in 1998 was 48.5 (+10.2), slightly less than the mean 55 florets per seed head
rneasured by Fiebig (1999), and higher than the 30 to 40 florets per inflorescence stated
by Proctor and Bailey (1 987). Floral deveiopment progressed quickly through mid-June
to mid-July (Figure 2 4 , reaching 100 % open florets and developing fruit by mid-Juiy.
ApproximateIy 30 % opening of the flowers was achieved by rnid-June. In 1998
ethephon was appIied between 35 and 80 % bloom. High early season temperatures
contributed to an advanced season (-2 weeks early) where inflorescences developed more
quickly than anticipated, making application of ethephon sprays at optimum timing (30%
bloom) difficult. The percent open florets in 1998 resembles the sum of the separated
parameters of percent flowering and percent set f i t of Fiebig (1999).
Seed head fiesh weights increased rapidly during the month of July (Figure 2.2),
and reached a maximum weight of approximately 6 gram. Large increases in seed head
fiesh weight correspond to near 100 % opening of florets and subsequent development of
bemes. Ripening and easier abscission of the berries and seeds fiom the inflorescence by
the beginning of August caused the fiesh weights of the seed heads to decline.
Seed head diameter increased in a similar manner throughout the 1998 and 1999
seasons, and reached a final diameter of 32-35 mm (Figure 2.3), agreeing with Fiebig
(1 999). Peduncles also elongated in a similar manner in 1998 and 1999 (Figure 2.4) and
continued until approximately mid-July to a maximum length of approximately 140-1 60
mm. These findings concur with Fiebig (1999), who found that maximum peduncle
lengths ranged between 140 and 180 mm.
Floret drop
Ethephon increased removal of florets and bemes fiom the seed heads at both 750
and 1500 mg L-' ethephon (Table 2.10). Fiebig (1999) found that a dip bioassay elicited
approximately 100 % berry drop after 3 days, by placing seed head peduncles in 1500 mg
L-' ethephon on al1 dates tested between July 9 and August 18, 1997. Sprays of the same
concentration of ethephon were not as effective at inducing berry &op. By allowing the
seed heads in the 1998 ethyIene evolution experiment to take up the ethephon solution in
the transpiration stream, exposure of the seed heads for three days to 750 and 1500
mg L-I resulted in similar removal of florets and bemes. Ethephon at 750 and 1500 mg
L-' for 3 days was sufEicient to induce significant floret and berry drop cornpared to the
control at al1 dates tested. Complete removal was achieved by JuIy 20, 1998 for both
concentrations, a date which closely approximated the end of flowering (July 13) (Figure
2.1). Fiebig (1999) found that as the season progressed, lower concentrations of
ethephon were required to achieve 100% drop; however, her treatments involved sprays
timed well past the point of development she stated was the most vulnerable to ethylene,
and up to 2 months past the field application date. The results of application of ethephon
in the later weeks of August to seed heads could potentially be confounded by the release
of ethylene fkom the leaves of plants that are beginning to senesce towards the end of the
growing season (Park et al., 1990).
By using a bioassay method which allowed the seed head to take up the ethephon
solution through intact peduncles, coverage issues were avoided, and ethylene release due
to wounding of the peduncle was minimized. Because ethephon is actively taken up in
the transpiration stream and translocated to the leaves, flowers and fnùts (Nickell, 1979;
Lavee and Martin, 1981a), the bioassay method used here may approximate more closely
the biological effect of ethephon sprays in the field, compared to the spraying of excised
seed heads.
Ethylene evolution
Fresh weight of the seed heads increased 9- to 10-fold over a 30 day period (June
13-July 13). Cumulative levels of ethylene, uncorrected for seed head fiesh weight
showed huge increases in ethylene production throughout the season as the inflorescences
developed and gained fresh weight. Since ripening berries have increased water
requirements, heavier, larger seeci heads (more g r a m Gesh weight per seed head) may
take up more solution and subsequently (potentially) release more ethylene fiom both
ethephon treatment and natural responses. Therefore, it was necessary to examine the
ethylene production on a per gram fiesh weight basis.
Ethephon increased ethylene evolution fiom the excised seed heads of American
ginseng (Figure 2.5). Fiebig (1999) found that 1500 mg L-' ethephon sprays applied
directly to excised seed heads resulted in significantly higher ethylene evolution rates
after 24 hours. Ethylene production for the control treatment did not exceed 0.5 pL g-'
seed head fi-esh weight. This is in agreement with results of Fiebig (1 999), who showed
that ethylene evohtion rates from ginseng inflorescences that had been Ieft untreated
were below 1 p.L L" g fiesh weighfl. At ail six dates sampled throughout the season,
ethephon at 750 and 1500 mg L-' consistently resulted in significantly higher ethylene
evolution d e r 48 hours in treatment solution compared to the control. After 48 hours,
ethephon treatment at 1500 mg L-' released significantly more ethylene compared to 750
mg L-' (Table 2.1 1). However, after 72 hours, even greater accumulation of ethylene was
evident, and varied greatly over the approximately 15-week period. Ethylene production
fiom seed heads treated with 1500 mg Lml ethephon increased from approximately 4 to 9
pL g1 &esh weight when measured at 48 and 72 hours after experimental set up on June
23, 1998.
Treatment of the inflorescences with 1500 mg L-' ethephon compared to 750 mg
L-' between early June and early July increased ethylene production &er 72 hours.
However, a lack of differences in abscission rates between 750 and 1500 mg L-' ethephon
indicates that the amount of ethylene reteased by the inflorescences with ethephon
exposure of 750 mg L-' may be enough to saturate the abscission response. Fiebig (1999)
determined that the threshold of ethylene for floret bop, when released by the
inflorescence is 10 to 100 L-' ethylene. Application of ethephon above 750 mg L-'
Iikely affects other processes and responses not targeted by the treatment. Since Park et
al. (1 990) using Panax ginseng found that unripe ginseng berries evolve more ethylene
than ripe bemes, increases in ethylene production by mature inflorescences observed by
Fiebig (1999) towards the end of the growing season were due likely to a combination of
responses, hcluding the effects of ethephon-induced and natural inflorescence and plant
senescence. The lack of sharp increases in ethylene release as the bernes began to mature
and ripen supports the fmdings of Fiebig (I999), who concluded that ginseng produces
non-clirnacteric Guit.
By looking at the mean ethylene evolution per gram fiesh weight throughout the
season, there is a rapid drop in the ethylene production between June 13 and July 3 for
idorescences treated with 750 and 1500 mg L-1 ethephon. Peak ethylene production in
response to ethephon treatment corresponds to the commencement of flowering (mid-
June, see Figure 2 4 , and quickly decreases as greater nurnbers of flowers open.
Therefore, the greatest sensitivity to of the florets to ethylene is most likely in the pre-
bIoom stage of inflorescence development. A higher percentage of abscised florets on
July 3 compared to July 14 (Table 2.10) supports this conclusion.
1998 Field Experiments
In 1998, ethephon sprays were not as effective as anticipated. Applications of
ethephon in mg L-1 were complicated by the variation in water volume used for field
applications at each location, and resulted in lower Ethrel application rates than desired.
Ethephon sprays at 750,750 x 2 and 1500 mg L-' were equivalent to 1-78 to 3.55 L acre-'
Ethrel at ICK Farms (Tables 2.1 1 and 2.12) and 0.74 to 1 -47 L acre-' Ethrel at Rainey
Ginseng (Table 2.13). Ethephon sprays of 750, 1500 and 3000 mg L - ~ at CIG were
equivalent to 0.26, 0.52 and 1 .O4 L acre-' Ethrel (Table 2.14).
Concentrations of Ethrel below an effective range for berry removal were
responsible for the lack of success of the treatments. Comparable trials were performed
in 1997 in Vernon, B.C. by Penny Pearse and AI Smith of Panax Q Ginseng (Appendix
A). Ethrel sprays between O and 12.0 L acre-' were applied in 1000 L acre-' water. A
high degree of berry removal was observed with Ethrel sprays of 8.0 L acre-' and higher.
Comparison of the 1997 Vernon results with those fiom the 1998 Ontario trials supports
the conclusion that concentrations used in Ontario were too low.
Ethrel applied at 1.78 to 3.55 L acre-' at JCK Farms (Table 2.1 1) was ineffective
at reducing green and cul1 counts, or total berry eesh weight. The highest Ethrel
application (3.55 L acre-') resulted in 39 % removal of red berries (Plate 2.3), which was
the only result significantly lower than the control in terms of berry hanrest. ïhere was a
trend towards increasing percent removal with increasing concentration of ethephon.
Hand removal at Rainey Ginseng increased mean root fiesh weight by 40 %
(Table 2.13). This result exceeds the findings of Proctor et al. (1999) who found that
manual removal of the inflorescences of 3-year-old ginseng increased yield by at l e s t
25-30 %. Root number did not Vary, indicating an increase in root weight per plot
through either growth andor increased water uptake. A sirnilar increase did not occur at
JCK Farms.
1999 Field Experiments
Leaf chlorophyll (SPAD) measurements
The range of Ethrel concentrations used in the 1999 trials was selected in order to
create spray recommendations that were applicable for commercial application. It
included low (2.5 L/acre), moderate (5.0 and 7.5 L/acre) and high (1 0.0 L/acre) rates, in
single and split applications, in order to characterize a response cuve and determine
approximate thresholds for berry removal in ginseng. Fiebig (1999) qualitatively
assessed that concentrations of ethephon effective for berry removd similar to the
practice of manual hand removal of the inflorescences are ofien accompanied by a high
degree of plant damage. Therefore, the challenge was to find a commercial application
rate of Ethrel which removed sufficient florets and berries while minimizïng leaf damage.
Ethrel significantly reduced the chlorophyll levels of leaves of American ginseng
(Tables 2.15 - 2.19) when rneasured using a hand-held SPAD-502 rneter. The relationship
between SPAD-502 meter chlorophyll readings and extractable chlorophyll is discussed
in Chapter 3. Four weeks after spray h g (mid-late July), a significant linear relationship
over ail locations indicates the chlorophyll content of the leaves decreased with
increasing concentration of ethephon. Although variability existed across the five
experimental locations (r? = 0.63 to 0.78), the response was remarkably consistent. Low
Ethrel applications (2.5 L acre") showed minimal reduction in chlorophyll. Hand
removal treatments did not reduce leaf chlorophyll, and in one example, increased the
chlorophyll content of the leaves by 15-20 % (Table 2.15).
Leaf chlorosis due to Ethrel treatment has not been quantified previously;
however, Fiebig (1 999) suggested that increasing concentrations of ethephon applied to
3-year-old plants resulted in heightened reddening of the leaves. Through visual
observation she also concluded that multiple applications of ethephon appear to be
additive in tex-ms of leaf damage; multiple applications of 1500 mg L-1 etliephon (4.5 L
acre-' Ethrel) increased leaf darnage compared to single applications. However,
measurement of leafchlorophyll of multiple Ethrel applications with the SPAD-502
meter (Tables 2.18 and 2.19) indicates that the response is variable but not significant
when comparing 2.5 Oow) and 2 x 2.5 L acre-' or 5.0 (moderate) and 2 x 5.0 L acre-'
spray rates of Ethrel.
The advantage of applying Ethrel in spiit applications lies in the lower
concentrations applied to the crop using this method. By dividing the Ethrel application
into two sprays, there is an opportunity to both reduce foliar damage by use of lower
concentrations of a potentially phytotoxic chernical, and also allow for the application to
cover a greater nurnber of open florets on a gradually opening ginseng inflorescence. For
example, the effect of two subsequent sprays of 2.5 L acre-' Ethrel are more effective at
maintainhg leaf chlorophyll than a single spray of 5.0 L acre-'. Compared to a single
application of 5.0 L acre", a split application of 2 x 2.5 L acre-' Ethrel resulted in 12-1 8
% and 8-2 2 % Iess reduction in chlorophyll (Tables 2.18 and 2.19) after approxirnately 4
and 5-6 weeks respectively. At a concentration considered to be damaging to the plant
(10.0 L acre-'), differences in chlorophyll were not consistent and likely were confounded
by the high degree of le& senescence and abscission in the crop after 4-6 weeks.
Although Fiebig (1999) concluded that injury effects on leaves due to ethephon were not
consistent in the field, the relationship between Ethrel concentration and leaf darnage can
be easily defined through the use of SPAD-502 leaf chioropliyll rneasurements, and does
not appear to be as erratic as previously thought.
Berry harvest
Ethrel reduced berry fiesh weights and counts of Amencan ginseng in single and
split applications of 2.S,S.O, 7.5 and 10.0 L acre" (Tables 2.20 to 2.29, Figure 2.6). Red
and green berry counts, and red, green and cul1 and total fiesh weights al1 decreased
linearly as the concentration of Ethrel increased. Fiebig (1999) found that ethephon
reduced berry fiesh weight when applied to small plots (1 m) of field-grown plants using
a hand-held sprayer (Fiebig, 1 999). S he found that increasing ethephon concentration
resulted in linear decreases in berry subsample weight, either by floret removal or growth
prevention of the inflorescences, and that ethephon sprays of 1500 to 4000 mg L" (4.5 to
12.0 L acre-' Ethrel) were similar in floret and berry removal compared to hand removal
(100 % removal) treatments. Although no field-scale treatments of Ethrel resulted in 100
% mean removal, a high percent removal consistent with the 75 % threshold for berry
removal (see section 1.12 - literature review) was obtained with Ethrel sprays of 5.0 L
acre-' and higher. Ethrel sprays at 2.5,5.0, 7 5 and 10.0 L acre-' rernoved 46-68, 7 1-86,
79-92 and 86-95 % of total berry fresh weight, respectively (Plate 2.4). Since green and
cul1 berries wiIl not produce viable seed before the end of the season, red berry rernoval
is the most important indication of spray efficacy. Over al1 locations, 5.0 L acre-'
removed 76-94 % red berry counts and 82-97 % of red .berry fkesh weight. This
concentration was also effective at rernoving high counts and fkesh weights of green and
cul1 bemes. Sprays of 5.0 L acre'' or less also resulted in less than 25 % leafchlorophyll
loss 4 weeks afier spray application, in keeping with the threshold for berry removal
(Fiebig, 1999).
Split applications of 5.0y7.S and 10.0 L acre-' Ethrel did not significantly increase
berry removal, but instead closely approximated the removal eEects of the single
applications (Tables 2.26 - 2.29). This is consistent with the findings of Fiebig, (1999)
who found that ethephon applied &ce at 500 mg L-' (1 -5 L a d Ethrel) and a single
application of 1000 mg (3.0 L acre-' Ethrel) resulted in simila. total beny removal. In
this experiment, split applications of 2 x 2.5,2 x 3.75, and 2 x 5.0 L acre-' Ethrel resulted
in additive red berry removal (counts and fiesh weights) similar to 5.0, 7.5, and 10.0 L
acre-' respectively. The same spLit applications resulted in additive removal of total berry
fiesh weight at JCK Farms (Table 2.26) but not CIG (Table 2.28). This may be partly
explained by the extremely poor seed set in two of the three replicates in the CIG garden.
Fiebig (1 999) found that neither single nor multiple applications of ethephon decreased
the number of green berries per inflorescence, however this was not the case in the 1999
field experiments.
Root harvest
Hand removal of the ginseng idlorescence increased mean root fresh weight at
o d y two of the five locations harvested in 1999 (Tables 2.30 - 2.34). Mean fiesh weight
increased significantly by approximately 12 and 10 % at Stonehenge Acres (4-year-old)
(Table 2.3 1) and Rainey Ginseng (Table 2.32), respectively. In both locations, root
number did not vas) indicating an increase in root weight per plot through either growth
andor increased water uptake. Previous investigations have shown the practice of hand
removal increases mean root fiesh weight in 3-year-old ginseng by 25-30 % (Proctor et
al., 1999) or 22-37 % (Fiebig, 1999). Proctor et al., (1999) also concfuded that manual
idlorescence removal does not alter root size distribution. A significant increase in total
root fresh weight at Rainey Ginseng comparable to the mean root fiesh weight ùicrease is
consistent with the hdings of Proctor et al., (1999). However, increases in mean root
fiesh weight were not reflected in the total root fkesh weight at Stonehenge Acres,
showing an alteration in the distribution of root sizes h the 4-year-old roots at this
location.
Ethrel did not increase root yield as anticipated. Fiebig (1999) found that
concentrations of ethephon between 750 and 1500 mg L-' (2.27 and 4.5 L acre-' Ethrel)
were most successfid over 1996 and 1997 for floretmerry removal while still producing
the desired root weight increase. In 1999, increases in mean root fiesh weight with Ethrei
comparable to hand removal were aiso seen with 2.5 L acre-' at both Rainey Ginseng and
Stonehenge Acres (4-year-old). However, these increases were not in themselves,
significantly diffcrent from the controls. The only Ethrel treatment to result in increased
root yield compared to the control was seen at Rainey Ginseng (Table 2.32), where total
root fiesh weight increased significantly by 15 %. Root number in this treatment did not
Vary fiom the control or hand removal. Therefore, increases in root yield due to 2.5 L
acre-' Ethrel treatment at this location are amibutable to increases in mean root fiesh
weight. No Ethrel treatments exceeded root yield due to hand removal treament.
Despite adequate and increasing levels of floret and berry removal, there was a
subsequent overall reduction in root yield with increasing concenbation of Ethrel. Mean
andor total root fiesh weight decreased linearly in response to increasing concentration
of Ethrel, at al1 locations except Stonehenge Acres 3-year-old (Table 2.30). At this
location, maintenance of root yield is due most likely to the almost complete absence of
seed set on the entire garden.
Split applications of 7.5 and 10.0 L/acre (2 x 3.75 and 2 x 5.0) Ethrel resulted in
significantly higher root mean fiesh weights at JCK Farms (Table 2.33) compared to
single applications, although neither treatment exceeded the control or hand removal in
terms of root mean fresh weight. There is a trend towards slightly higher mean root fiesh
weight as a result of the split applications, but it is only evident at the highest
concentrations, in those treatments that wouid likely not be recommended for application
due to the high level of damage seen in the leaves.
Single and multiple applications of 2 S , 2 x 2.5, 5.0 and 2 x 5.0 L acre-' Ethrel
resulted in similar mean root fiesh weights, red berry fiesh weights, and total berry fiesh
weights at JCK Farms (Table 2.33). However, mean leaf chiorophyll decreased with 5.0
and 2 x 5.0 L acre-' compared to 2.5 and 2 x 2.5 L acre-'. Although the range of
concentrations used does not cause significant differences in berry and root harvest, the
visual impact of the spray treatments on the leaves was evident. 2.5 and 2 x 2.5 L acre"
treatments showed Iittle visual indication of leaf damage, whereas 5.0 and 2 x 5.0 L acre-'
treatments showed increasing leaf chlorosis and pigment development. Ethrel at 2 x 5.0
L acre-' displayed leaf symptoms comparable to the single 10.0 L acre-' rate. Leaf
damage at 5.0 and 2 x 5.0 L acre-' began to approach unacceptable levels after 4 weeks
and surpassed them after 6 weeks according to the threshold of 25 % injury defined by
Fiebig (1 999).
It is well established that endogenous ethylene production occurs in response to
stresses experienced by the plant (Abeles, 1973; Yang and Pratt, 1978). The abscission
response associated with exogenous ethylene appkation is complicated by additional
interactions of ethylene due to environmental influence. Drought (Tietz and Tietz, 1982)
and elevated temperatures (Abeles et al., 1992) result in increased levels of endogenous
ethylene production. The presence of ethylene gas can stimulate additional endogenous
production of ethylene due to its autocatalytic nature (See section 1.10, literature review).
High temperatures and lack of rainfall in the early part of the 1999 growing season
(Appendices B and C) may have contributed to higher endogenous levels of ethylene in
the plant, confounding the experimental concentrations of Ethrel being studied.
Ethrel sprays applied in 1999 in a similar range of concentrations as Fiebig (1999)
resulted in comparable floret and berry removal, but did not result in similar root yield
increases despite adequate berry removal and acceptable levels of leaf damage. Because
ethylene is responsible for multiple responses in the plant which are not entirely
understood, and endogenous and exogenous sources of ethylene may interact in
unpredictable ways, berry removal with the same commercial-scale treatments in less
stressfil growing conditions should be examhed.
Higher than normal endogenous levels of ethylene in the plant due to
environmental influences may have confounded the experimental concentrations of
Ethrel being studied. However, if this were the case, then hand removal treatrnents
should have been more consistent. The lack of expected root yield increases with hand
removal inclicates that environmental or other factors may have been more responsible for
the lack of root yieId results than the inefflcacy of the treatrnents.
Summary
Ethephon at 750 and 1500 mg L-' was applied to excised seed heads of field-
grown 3-year-old Amencan ginseng on six dates throughout the 1998 season. Evolution
of ethylene and abscission of flowers and berries fiom the treated seed heads was
measured. Additional measurements of florets per inflorescence, % open florets and
devefoping fruit, seed head fiesh weights, diameters, and peduncle Iengths were taken
throughout the season in order to relate differences in ethylene evolution with the stages
of innorescence development.
Production of ethylene (@ g-L fresh weight) by untreated seed heads did not
increase significantly over the season. Ethephon treatment at 750 and 1500 mg L-'
increased cumulative ethylene release by the seed heads. Ethylene production after 48
hours was increased with i500 mg L-' compared to 750 mg L-'. After 48 hours, ethylene
evolution by the seed heads was constant throughout the development of the
inflorescence. However, after 72 hours differences in ethylene production as a result of
the developmental stage of the i~orescences were evident. The method of ethephoo
uptake by the excised peduocles requires greater than 48 hours for the chernical to reach
susceptible tissue and to be released in the form of ethylene. Peak ethylene production in
response to ethephon treatment corresponds to the earliest stage of floral development
(-40% open flowers). Ethephon at both 750 and 1500 mg L-' resulted in similar high
percentages of floret drop. Fiebig (1999) found that rates of 500-1 500 mg L-' gave best
results for berry removai ushg a comparable dip bioassay method. She also found that
higher concentrations (3000-4000 mg L-') were required using spray methods.
Ethrel was used as a source of ethephon in the 1999 field-scale applications.
Single and split spray applications of Ethrel at concentrations between 0.26 and 3.55 L
acre" were applied to field-grown 3-year-old Arnerican ginseng (Panax quinquefolius L.)
in 1998. Too low concentrations of Ethrel applied in 1998 resulted in poor flower
removal response and necessitated revision of application rates the following year. In
1999, single and split sprays of Ethrel at concentrations behveen 2.5 and 10.0 L acre-'
were applied to field-grown 3- and 4-year-old Arnencan ginseng ( P a n a quinquefolius
L.). Fiebig (1999) found that use of a &actant did not increase the efficacy of ethephon
sprays in ginseng therefore, surfactants were not used for any of the Ethrel sprays. In
1999, leaf chlorophyll of Ethrel-treated plants decreased linearly with increasing
concentration of Ethrel, consistent with the visuai observations of Fiebig, 1999. Split
applications of moderate concentrations of Ethrel were more effective at maintaining leaf
chlorophyll than comparable single applications. Ethrel at 5.0 L acre-' or higher
displayed leaf damage at unacceptable levels 4-6 weeks after the sprays were applied.
Analysis of berry harvest at end of 1999 season found that berry fresh weights and counts
also decreased hearly with increasing concentration of Ethrel in 1999. Split applications
of Ethrel did not improve berry removal, but closely approximated the removal achieved
with single applications. This result contradicts the earlier findings of Fiebig, (1 999),
who found that single applications were more effective than multiple applications when
considering parameters of floretherry removal and root fiesh weight.
Manual removal of the inflorescences resulted in small increases (10-12%) in root
yield at oniy ~o locations (Stonehenge Acres 4-year-old and Rainey Ginseng) in 1999.
No haad removal treatrnents achieved the predicted 22-37% increase in mean root fiesh
weight (Proctor et al., 1999; Fiebig, 1999). Similarly, berry removal through Ethrel
application did not increase root yields as anticipated. The lack of appropriate increases
with hand rernoval suggests that additional factors including the environmental
conditions in 1999 may have afTected the plant response to inflorescence removal. Mean
and total root fiesh weights decreased linearly with increasing concentration of Ethrel.
Split applications at moderate to high concentrations (7.5 to 10.0 L acre-' Ethrel) resulted
in higher root yields compared to comparable single applications.
Fiebig (1 999) defmed an acceptable threshold for berry removal using ethephon
as: Greater than 75% removal of bemes while causing less than 25% damage to the
leaves. Although 5.0 L acre-' Ethsel was effective for 75% or greater seed removal,
perhaps 75-1 00% berry removal is not necessary for optimization of root yield in field-
applications of Ethrel. The most effective treatment for increasing root yield compared to
controls and hand removal; 2.5 L acre-' Ethrel applied in 40-100 gal acre-' water,
achieved only 50-56% total berry removal, with minimal leaf darnage.
Split applications of low to moderate concentrations of Ethrel show improved
chlorophyll retention in the leaves, comparable berry rernoval and potentially higher root
yields compared to single applications. Therefore, split applications may have greater
potential than single applications for the development of rninor-use registration
guidelines. The field-scale flower and beny removal ability of Ethrel suggests that Ethrel
sprays, properly integrated into ginseng management practices, could be a valuable tool
for Ontario growers.
Table 2.1. Ethephon and Ethref treatrnents applied to plots of 3-year-old American ginseng (Panax quinquefolizrs L.) at Rainey Ginseng in 1 998.
Keith Rainey, Rainey Ginseng Location(s) South of Scotland, Highway 24 Shade Type Wood Garden Dimensions 385' row length (35 panels x 1 l'), rows run N-S Plot Length W ( 4 panels x 1 1') Spray Date(s) Split applications, June 1 6/98, June 26/9 8 Ethephon (Ethrel) Rates 750,750 x 2, 1500 mg L - ~ (0.74,0.74 x 2, 1.47 L acre-') Water Volume 125 gal/acre (567 L acre-') Sprayer Details 150 p.s.i., maximum tank volume 2 x 125 gal, 2.4 mph TemperatureITime June 16/98 29°C' June 26/98 28°C @ 9:10 am Berry Harvest Date August 18/98 Root Harvest Date October 6/98 Harvest Method MachineLhand
Table 2.2. Ethephon and Ethrel treatrnents applied to plots of 3-year-old Arnerican ginseng (Panax quinquefolius L.) at JCK Farms in 1 998.
Jeff Rice, JCK Farms Location(s) Shade Type Garden Dimensions Plot Length Spray Date(s) Ethephon (Ethrel) Rates Water Volume Sprayer Details Temperaturerrime Berry Harvest Date Root Harvest Date Harvest Method
North of Burford Wood -600' row length (1 8 panels), rows run N-S -200' length x 12'4" width Split applications, June 24/98, June 29/98 750,750 x 2, 1500 mg L-' (1 -78, 1-78 x 2, 3.55 L acre-') 52 gal/acre 60-70 p.si., maximum tank volume 125 gallons (US) Jure 24/98 27"C, June 29/98 25°C August 24/98 September 29/98 Machine
Table 2.3 Ethephon and Ethrel treatrnents applied to plots of 3-year-old Amencan ginseng (Panax quinquefolius L.) at Canadian Imperia1 Ginseng Inc- in 1998.
Paul WismerRob Geier. Canadian Imperia1 Ginseng; Inc. Location(s) Shade Type Garden Dimensions Plot Length Spray Date(s) Ethephon (Ethrel) Rates Water Volume Spraj-:r Details Temperaturdïime Berry Harvest Date Root Harvest Date Harvest Method O ther Comments
South of Burford, East !4 Townline Road Black plastic 432' row length, rows nui N-S 144' Split applications, June 26/98, July 1 /98 750, 1500,3000 mg L-' (0.26,0.52, 1.04 L acre'') 1 8 -4 gal/acre 40 p.s.i., maximum tank volume 500 gallons, 3.33 mph July 1 15OC @ 6:OO am August 18/98 October 6/98 Machine No hand removd treatment
Table 2.4 Ethrel treatments applied to plots of 3-year-old American ginseng (Panax quinquefolius L.) at Stonehenge Acres in 1999.
Bob ArthudTony Quon, Stonehenge Acres - Location 1 Location(s) East of Scothnd, Jenkins Road Crop Age 3-year-old Shade Type Black plastic Garden Specifics Rows run N-S Plot Length, Reps 48' (1 panel per treatment), 3 replicates Hand Removal Date Last week of May Spray Date@) Single application, June 26/99 Ethrel Rates 2.5, 5.0, 7.5, 10.0 L acre-' Water Volume 40 @acre Sprayer Details Maxirnum tank volume 300 gal Temperature/Tirne 22°C @ 8:30 am Berry Harvest Date August 1 1 /99 Root Harvest Date September 15/99 Harvest Method Machine Other Cornrnents No seed set on 3-year-old garden
Table 2.5 Ethrel treatments applied to plots of 4-year-old American ginseng (Panax quinquefolius L.) at Stonehenge Acres in 1999.
Bob ArthudTony Quon, Stonehenge Acres - Location 2 Location(s) East of Teeterville, Wyndham Road No. 5 Crop Age 4-year-O Id Shade Type Black plastic Garden Specifics Rows run N-S Plot Length, Reps 24' (1 panel per treatment), 3 replicates Hand Removal Date Last week of May Spray Date@) Single application, June 16/99 Ethrel Rates 2.5, 5.0, 7.5, 10.0 L acre-' Water Volume 40 gdacre Sprayer Details Maximum tank volume 300 gal TemperatureAlme 20°C @ 12:00 pm Berry Harvest Date August 11/99 Root Harvest Date Octo ber 5/99 Harvest Method Hand O ther Cornments Sparse occurrence of nematodes in 4-year-O ld garden
Table 2.6 Ethrel treatments applied to plots of 3-year-old American ginseng (Panax quinquefolius L.) at Rainey Ginseng in 1 999.
Keith Rainey, Rainey Ginseng Location(s) South of Scotland, Highway 24 Crop Age S hade Type Garden Specifics Plot Length, Reps Hand Removal Date Spray Date(s) Ettirel Rates Water Volume Sprayer Details Ternperature/Time Berry Hanrest Date Root Harvest Date Harvest Method
3 -year-old Wood (9ft high) Rows run E-W 44' (4 panels x 1 1 '), 4 replicates June 5/99 Single application, June 22/99 2.5, 5.0, 7.5, 10.0 L acre-' 10 1 gal/Acre Maximum tank volume, 2 x 125 gallons 24°C @ 9:20 am August 24/99 October 15/99 Machine
Other Comments Good seed set in garden
Table 2.7 Ethrel treatrnents applied to plots of 3-year-oId American ginseng (Punux quinquefolius L.) at JCK Fanns in 1999.
Jeff Rice, JCK Fanns Location(s) Crop Age Shade Type Garden Specifics Plot Length, Reps Hand Removal Date Spray Date@) Ethrei Rates Water Volume Sprayer Details Temperature/Time Berry Harvest Date Root Harvest Date Harvest Method
North of Burford 3 -year-old Wood Rows run N-S 192' (4 panels x 48'), 3 replicates 3rd week of June Split applications, June 18/99, June 24/99 2.5,2.5 x 2, 5.0, 3.75 x 2, 7.5, 5.0 x 2, 10.0 L acre-' June 18/99: 48 gallacre, June 24/99: 45.75 gal/acre Maximum tank volume, 125 gallons (US) June 28/99 22°C @ 10:QO am, June 24/99 27°C @ 9:00 am August 24/99 October 2 1/99 Machine
Other Comments Heavy clay soil, very wet at harvest t h e
Table 2.8 Ethrel treatments applied to plots of 3-year-old American ginseng (Panax quinquefolius L.) at VandenElsenYs in 1 999.
Fred VandenEIsen Location(s) South of Scotland Crop Age 3-year-old Shade Type Black plastic Garden Specifics Rows run N-S Plot Length, Reps 3 replicates Hand Removal Date No hand removal Spray Date(s) Split applications, June 2 1/99 and June 3W99 Ethrel Rates 2.5,2.5 x 2, 5.0, 3.75 x 2, 7.5, 5.0 x 2, 10.0 L acre-' Water Vo lurne 40 gaVacre Sprayer Details 100 p.si., 3.93 mph, 1100 rpm Temperature/Time June 21/99 27°C @ IO:30 am, June 30199 19°C @10:00 am Berry Harvest Date No harvest of bemes Root Harvest Date No harvest of roots Harvest Method No harvest of roots Other Cornrnents Severe granular fertilizer burn on leaves
Table 2.9 Ethrel treatments applied to plots of 3-year-old American ginseng ( P a n a quinquefohs L.) at Canadian h p e d Ginseng Inc. in 1999.
Paul Wismer/Rob Geier, Canadian Imperia1 Ginseng, Inc. Location(s) Beal F m , South of Burford Crop Age 3 -year-old Shade Type Black plastic Garden Specifics Rows run N-S Plot Length, Reps 48'(2 panels x 24'), 3 replicates Hand Removal Date June 16/99 Spray Date(s) Split applications, June 24/99, July 1 /99 Ethrel Rates 2.5,2.5 x 2,5.0,3.75 x 2, 7.5, 5.0 x 2, 10.0 L acre-' Water Volume 8.3 gdacre Sprayer Details Boom sprayer, 35 p.s.i., 20.0 US gaVAcre, XR 110 02 flat fan Temperature/Time June 24/99 24OC @ 9:OO am, July 1/99 20°C @ 9:OO am Berry Harvest Date August 18/99 Root Harvest Date October 12/99 Harvest Method Machine Other Cornments Very little seed set towards center of garden (reps 1 and 2)
Hand removal taken fkom other section of garden
Table 2.10. Floret and berry drop from seed heads of American ginseng (Panax q&zquefolius L.) after treatrnent with ethephon. Day 3 measurements. Treatments were applied to seed heads ftom 3-year-old plants.
Ethephon Mean Remaining FloretdSeed Head
(mg L-'1 July 3 July 14 July 20 Control 10.1 ay 44.4 a 24.6 a
1 500 2.0 b 6.4 b 0.0 b - Mean of 48 -5 flore& per seed head
Y - Within columns, means followed by the same letter are not significantly different using LSD (P 1 0.05)
Table 2.1 1. Berry total fkesh weight and counts f?om harvested seed heads of American ginseng (Pana quinquefoZius L.) treated with single and split applications of Ethrel. Treatments were applied on June 24 and 29, 1998 on JCK Farms 3-year-old gardens.
Ethrel Mean Berry Counts 6 acre-') Totalz Red Green Cul1 ControI 117.4 ay 25.2 b 42.0 a 50.2 ab
3.55 114.3 a 15.4 c 39.7 a 59.2 a - Total berry counts based on sum of red, green and cul1 counts
Y - Within columns, means followed by the same letter are not significantly different using L S D (P 1 0.05)
Table 2.12. Root fiesh weight in Amencan ginseng (Pancx quinquefolius L.) treated with single and split applications of Ethrel or hand removal of inflorescences. Treatrnents were applied on June 24 and 29, 1998 on JCK Farms 3 -year-old gardens.
Ethrel Fresh Weight (g) Mean Root (L acre-') Mean Total Number
Control 25.9 abz 2819 ab 110 a Hand Removai 27.6 a 2944 a 107 a
- Within colurnns, means followed by the sarne letter are not significantiy different using LSD (P 5 0.05)
Table 2.13. Root fiesh weight in American ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied June 26, 1 998 on Canadian Imperia1 Ginseng Inc. 3 -year-old gardens.
Ethrel Fresh Weight (g) Mean Root (L, acre-') Mean To ta1 Nurnber Control 22.0 a' 1077 c 48.7 c
0.26 21.6 a 1697 ab 78.7 a 0.52 24.5 a 1559 b 63.7 b 1-04 23.4 a 1943 a 83.3 a
- Within colurans, means followed by the same letter are not signîficantly dinerent using LSD (P 5 0.05)
Table 2.14. Root fiesh weight in American ginseng (Panax quinquefolius L.) treated with single and split Ethrel treatments or hand removal of idorescences. Treanments were applied on June 16 and 26, 1998 on Rainey Ginseng 3- yes-dd gardens.
Ethrel Fresh Weight (g) Mean Root (L acre-') Mean Total Number Controi 17.2 bz 810 b 47.3 a
Haud Removal 24.1 a 1403 a 58.7 a 0.74 17.1 b 982 ab 58.0 a
0.74 x 2 15.3 b 1115 ab 72.3 a
1.47 15.2 b 1080 ab 69.0 a ' - Withui colurnns, rneans followed by the sarne letter are not significantly different
using LSD (P I (0.05)
Table 2.15. Leaf chlorophyll in American ginseng (Panax quinquefoolius L.) treated with Ethrel or hand removal of inflorescences. Treatments were applied - - on June 26, 1999 on Stonehenge Acres 3-year-old gardens.
Etluel Mean Chlorophyll (SPAD) (L July 22 August 5
Hand Removal 46.7 ay 45.1 a
37.6 b 30.1 bcd 31.4 bc 25-7 cd 23.8 d
Q NS NS ' - Treatments were applied at 49 % open florets Y - Within columns, means followed by the same letter are not significantly dif5erent
using LSD (P 1 0.05) " - Ethrel treatment means (exchding hand removal) analyzed by single-degree-of-
fkeedom contrasts NS, ** Effect not significant or significant at P 1 0.01 respectively
Table 2.16. Leaf chlorophyll in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of bflorescences. Treatments were applied on June 16, 1999 on Stonehenge Acres 4-year-old gardens.
Ethrel Mean Chlorophyll (SPAD) (L acre")' July 8 July 20 Au@ 6
Hand Rernoval - 33.0 ay 33.3 a
0.0 2.5 5.0 7.5 10.0
Significance " L Q
' - Treatrnents were applied at 55 % open florets Y - Within columns, means followed by the same letter are not significantly different
using LSD (P S 0.05) " - Ethrel treatment means (excluding hand removal) analyzed by single-degree-of-
fieedom contrasts NS, *, ** Effect not significant or significant at P 10.05 or 0.01 respectively
Table 2.17. Leaf chlorophyll in American ginseng ( P a n a quinquefolius L.) treated with Ethrel or hand removal of inflor&ences. -T're&&ents were applied on June 22, 1999 on Rainey Ginseng 3-year-old gardens.
Ethrel Mean Chlorophyll (SPAD) acre-')' July 20 August 6
Hand Removal 32.4 ay 32.9 ab
Q NS NS - Treatments were applied at 45 % open florets
Y - Within colurnns, means followed by the same letter are not significantly different using LSD (P 1 0-05)
" - Ethrel treatrnent means (excluding hand removal) anaiyzed by single-degree-of- freedom contrasts
NS, ** Effect not significant or signifîcant at P < 0.01 respectively
Table 2.1 8. Leaf chiorop hyll in American ginseng (Panax quinquefolius L .) eeated with single and spLit applications of Ethrel or hand removal of inflorescences. Treatments were appiied on June 18 and June 24, 1999 on JCK Farms 3 -year-old gardens.
Ethrel Mean Chlorophyll (SPAD) (L acre-')= Jdy 22 August 5
Hand Removal 36.0 abY 36.1 a
Q NS NS - Treatments were applied at 35 and 55 % open florets
Y - Within columns, means followed by the sarne letter are not significantly different using LSD (P 1 0.05)
- Single application Ethrel treatment means (excluding hand removal) analyzed by single-degree-of freedom conQasts
NS, * * Effect not significant or significant at P S 0.0 1 respectively
Table 2.19. Leaf chlorophyll in Arnerican ginseng (Panax quinquefolius L.) treated with single and split applications of Ëthrel or h&d &~&vaI of inflorescences. Treatments were applied on June 2 1 and 30, 1999 on
- -
VandenEIsen 3-year-old gardens.
Ethrel Mean Chlorophyll (SPAD) (L acre-')= July 20 August 6
Hand Removal - 32.6 a
0.0 2.5
3 -75 5.0 7.5 10.0
Significance " L
23.6 b 21.3 bcd 16.5 e
33.8 a 22.8 bc 19.2 cde 20-9 bcd 21.7 bc 17.6 de
Q * ** ' - First spray treatment was applied at 3 1 % open florets Y - Within columns, means followed by the same letter are not significantly different
using LSD (P 1 0.05) " - Single application EthreI treament means (excluding hand removal) analyzed by
single-degree-of fieedom contrasts *, * * Effect significant at P 5 0.05 or 0.0 1 respectively
Table 2.20. Berry total fiesh weight and counts fiom hwested seed heads of Amencan ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 26, 1999 on Stonehenge Acres 3-year- old gardens.
Ethrel Total Red Green (L acre-')" Frwt (g) % RemY Counts %Rem Counts % Rem
0.0 88.8 - 65.7 - 236.3 - 2.5 48.1 45.8 38.7 42.1 119.3 49.5 5.0 22.9 74.2 16.0 75.6 68.7 70.9 7.5 11.1 87.5 5.0 92.4 25.7 89.1 10.0 12.3 56.1 4.0 93.9 30-0 87.3
Significance " L * <= ** ** Q NS NS NS
Data log(y) transformed: original data shown above ' - Treatments were applied at 49 % open florets Y - Percent removal based on controls within respective columns " - Ethrel treatment means anaiyzed by single-degree-of-fieedorn contrasts NS, ** Effect not significant or signincant at P 9 0.01 respectively
Table 2.21. Berry fiesh weight and colour distribution from harvested seed heads of Arnerican ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 26, 1999 on Stonehenge Acres 3-yea.r- old gardens.
Ethrel Red Green Cul1 (L acre-')' Frwt (g)' % RemY Frwt (g) % Rem Fnvt (g) % Rem
0-0 26.7 - 23 .O - 3 8 -6 -
10.0 1.2 95.7 2.3 90.3 8.9 77.0 Significance "
Data log(y) transformed: onginal data shown above ' - Treatments were applied at 49 % open florets Y - Percent removal based on controls within respective columns " - Ethrel treatment means analyzed by single-degree-of-£keedom contrasts NS, ** Effect not significant or significant at P 1 0.01 respectively
Table 2.22. Berry total fiesh weight and counts fiom harvested seed heads of Amencan ginseng (Panax quinquefolius L.) treated with Ethrel. Treatrnents were applied on June 16, 1999 on Stonehenge Acres 4-year- old eardens.
Ethrel Total Red Green (L acre-')' Fnÿt(g) % RemY Counts %Rem Counts %Rem
0.0 65.5 - 32.3 - 141.3 - 2.5 32.1 52.0 4.7 85-6 80.3 43 -2 5.0 14.0 78.6 2.7 91.7 3 1.3 77.8 7.5 13.6 79.2 10.0 69.1 27.7 80.4 10.0 9 -4 85.6 0.0 100.0 15.0 89.4
Significance " L ** a a*
Q * NS NS
Total and green (not red) data log(~) t&formed: original data shown above ' - Treatrnents were applied at 55 % open florets Y - Percent removal based on controls within respective columns " - Ethrel treatment means analyzed by single-degree-of-freedom contrasts NS, *, ** Effect not significant or significant at P 10.05 or 0-01 respectively
Table 2.23. Berry fresh weight and colour distribution from harvested seed heads of Amencan ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 16, 1999 on Stonehenge Acres 4-year- old gardens.
Ethrel Red Green Cul1 (L acre-')" Frwt (g)Y % RemY Frwt (g) %Rem Frwt(g) %Rem
0.0 15.9 - 12.7 - 36.9 - 2.5 1.6 90.0 6.8 46.3 23.7 35.8 5 .O O -4 97.3 1.7 86.6 11.9 67.8 7.5 3.1 80.5 2.4 81.3 8.1 78 .O 10.0 0.0 100.0 1 .O 92.1 8.4 77.2
Significance " L * ** ** O NS NS *
Green and cul1 (not red) data log(y) transformed: origind data shown above ' - Treatments were applied at 55 % open florets Y - Percent removal based on controls within respective columns - Ethrel treatment means analyzed by single-degree-of-fieedorn contrasts
NS, *, ** Effect not significant or significant at P 1 0.05 or 0.0 1 respectively
Table 2.24. Berry total fiesh weight and counts fiom harvested seed heads of Amencan ginseng (k quinquefolius L .) treated with Eîhrel. Treatments were applied on June 22, 1999 on Rainey Ginseng 3-year-otd gardens.
Ethrel Total Red Green (L acre-')' Frwt (g) % RemY Counts %Rem Counts % Rem
10.0 9.0 95.3 6.5 98.1 43 .O 91 .S Significance
Q NS NS NS Data log(y) transformed: original data shown above ' - Treatments were applied at 45 % open florets Y - Percent removal based on controls within respective columns " - Ethrel treatment means analyzed by single-degree-of-fieedorn contrasts NS, ** Effect not significant or siecant at P I 0.01 respectively
Table 2.25. Berry fiesh weight and colour distribution from harvested seed heads of American ginseng (Panax quinquefolius L.) treated with Ethrel. Treatments were applied on June 22, 1999 on Rainey Ginseng 3-year-old gardens.
Ethrel Red Green CuIl (L acre-')' Fnvt (g) % R e d Fnvt(g) % Rem - Fnvt (g) % Rem
10.0 1.5 98.8 4.3 89.5 3.2 86.8 Significance "
Data log(y) transformed: original data shown above ' - Treatments were applied at 45 % open florets Y - Percent removal based on controls within respective colurnns - Ethrel treatment rneans analyzed by single-degree-of-Eeedom contrasts
NS, ** Effect not significant or significant at P 5 0.01 respectively
Table 2.26. Berry total fiesh weight and counts fiom harvested seed heads of Amencan ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatrnents were applied on June 18 and 24, 1999 on JCK Farms 3-year-old gardens.
Ethrel To ta1 Red Green (L, acre-')' Frwt (g) % RemY Counts %Rem Counts %Rem
5.0 x 2 25.6 bc 86.8 12.0 bcd 95.4 117.0 b 82.5
Data log(y) transformed: original data shown above - Treatrnents were applied at 35 and 55 % open florets
Y - Percent removal based on controls within respective columns " - Within columns, rneans followed by the sarne letter are not signïficantly different
using LSD (P 1 0.05) - Single application Ethrel treatrnent rneans analyzed by single-degree-of fieedom contrasts
NS, ** Effect not significant or significant at P 5 0.01 respectiveIy
Table 2.27. Berry fiesh weight and colour distribution f?om harvested seed heads of Amencan ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatments were applied on June 18 and 24, 1999 on JCK Farrns 3-year-old gardens.
Ethrel Red Green Cul1 (L acre")' Frwt (g) % Remy Frwt (g) %Rem Fnvt(g) % Rem
2.5 x 2 11.2 bcX 89.7 13.5 b 70.8 20.1 b 49.5 3.75 x 2 3.9 bcd 96.4 11.8 b 74.4 15.3 b 61 -7 5.0 x 2 4.8 bcd 95.6 7-4 bc 83.9 13.4 b 66.3
0.0 108.1 a - 46.1 a - 39.8 a - 2.5 39.0 b 63.9 19.8 b 57.0 20.6 b 48.2 5.0 5.3 bcd 95.1 8.0 bc 82.7 12.0 b 69.8 7.5 3.3 cd 97.0 10.0 bc 78.3 13.2 b 66.9 10.0 1.5 d 98.6 3.1 c 93.2 4.8 c 88.1
Significance " L ** ** ** 0 NS NS NS
Data log(y) transformed: original data shown above ' - Treatrnents were applied at 35 and 55 % open florets Y - Percent removd based on controls within respective columns " - Within columns, means followed by the same letter are not significantly different
using LSD (P 1 0.05) - Single application Ethrel treatrnent means analyzed by single-degree-of freedom
contrasts NS, ** Effect not significant or significant at P 2 0.01 respectively
Table 2.28. Berry total fiesh weight and counts fiom harvested seed heads of American ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatments were applied on June 24 m d July 1, 1 999 on CIG 3-year-old gardens.
Ethrel Total Red Green (L acre-')' Frwt (a) 96 Remy Counts % Rem Counts % Rem
2.5 x 2 27.6 bcdX 77.1 27.7 b 84.7 103.3 bcd 64.9
0.0 120.7 a - 180.7 a - 294.7 a - 2.5 38.5 b 68.1 22.7 bc 87.5 160.7 ab 45 -5 5.0 34.6 bc 71.3 32.7 b 8 1.9 134.3 bc 54.4 7.5 24.3 bcd 79.9 17.7 bc 90.2 98.3 bc 66.6 10.0 13.4 cde 88.9 12.3 bc 93.2 45.3 cd 84.6
Significance " L ** * * Q NS NS NS
Data log(y) transformed: original data s h o w above z - First spray treatment was applied at 57 % open florets y - Percent removal based on controls within respective columns " - Within columns, rneans followed by the same letter are not signifïcantly different
using LSD (P 1 0.05) - Single application Ethrel treatment rneans analyzed by single-degree-of Ereedom
contrasts NS, *, ** Effect not significant or significant at P 10.05 or 0.01 respectively
Table 2.29. Berry Çesh weight and colour distribution fiom harvested seed heads of Arnerican ginseng (Panax quinquefolius L.) treated with single and split applications of Ethrel. Treatments were applied on June 24 and July 1, 1999 on CIG 3-year-old gardens.
Ethrel Red Green Cull (L acre-')E Frwt (g) % R e d Fnvt (g) % Rem Frwt (g) %Rem
2.5 x 2 9.4 bX 8 6.4 9.1 bc 72.6 9.1 bc 50.8 3.75 x 2 1.1 c 98.4 2.0 d 94.1 4.4 d 76.3 5.0 x 2 2.3 bc 96.6 3.2 cd 90.4 5.5 cd 70.4
Control 69.1 a - 33.1 a - 18-5 a - 2.5 9.6 b 86.0 13.0 b 60.8 15.6 a 14.4 5.0 11.5 b 83 -4 12.0 bc 63 -7 11.1 ab 40.1 7-5 6.2 bc 9 1.1 6.5 bcd 80.4 11.6 ab 37.3 10.0 4.2 bc 93.9 3.7 cd 88.9 5.6 bcd 70.0
Significance " L * * * Q NS NS NS - --
Data log(~) transfo&ed: original data shown above z - First spray treatment was applied at 57 % open fiorets Y - Percent removal based on controls within respective columns " - Within columns, means followed by the sarne letter are not significantly different
using LSD (P 5 0.05) - Single application Ethrel treatment rneans analyzed by single-degree-of fieedom
contrasts NS, * Effect not significant or significant at P 10.05 respectively
TabIe 2.30. Root fiesh weight in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of'inflorescences. Treatments were applied on June 26, 1999 on Stonehenge Acres 3-year-old gardens.
Ethrel Mean To ta1 Mean Root (L acre-')' Frwt (g) %Y Frwt (g) YO Number
Hand Remx
0.0 2.5 5.0 7.5 10-0
Significance L Q
- Treatments were applied at 49 % open florets Y - Percent fresh weight based on controls within respective columns - Hand removal treatment
" - Within columns, means followed by the sarne letter are not significantly different using LSD (P 1 0.05)
- Ethrel treatment means (excluding hand removal) analyzed by single-degree-of fieedom contrasts
NS Effect not signifiant
Table 2.3 1. Root fiesh weight in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of inflorescences. Treatments were applied
- -
on June 16, 1999 on Stonehenge Acres 4-year-old gardens.
Ethrel Mean Total Mean Root
Hand RemX 30.4 a" 110.1 4170 ab 98.1 137
0.0 27.6 bc 100.0 4249 a 100.0 154 2.5 28.2 ab 102.2 3728 c 87.7 133 5 .O 26.3 bcd 95.3 4211 a 99.1 160 7.5 24.7 d 89.5 3823 c 90.0 156 10 .O 25.1 cd 90.9 3888 bc 91.5 155
Signifixcance L * NS NS Q NS NS NS
- Treatments were applied at 55 % open florets Y - Percent fiesh weight based on controls within respective columns " - Hand removal treatment
- Within columns, means followed by the same letter are not significantly different using LSD (P 5 0.05)
- Ethrel treabnent means (excluding hand removal) analyzed by single-degree-of fieedom contrasts
NS, * Effect not significant or significant at P 10.05 respectively
Table 2.32. Root fiesh weight in American ginseng (Panax quinquefolius L.) treated with Ethrel or hand removal of inflorescences. Treatments were applied on June 22, 1999 on Rainey Ginseng 3-year-old gardens.
Ethrel Mean Total Mean Root (L acre-')' FAvt (g) %Y Frwt (g) YO Number
Hand Rem" 21.4 a" 111.5 3104 a 124.3 146
z - Treatments were applied at 45 % open florets Y - Percent fiesh weight based on controls within respective columns " - Hand removal treatment " - Within columns, means followed by the same letter are not significantly different
using LSD (P 10.05) - Ethrel treatrnent means (excluding hand removal) analyzed by single-degree-of
freedom contrasts NS, * Effect not significant or significant at P 10.05 respectively
Table 2.33. Root fiesh weight in Amencan ginseng (Pana quinquefolius L.) treated with single and split applications of Ethrel or hand removal of inflorescences. Treatments were applied on June 1 8 and 24, 1999 on JCK Farms 3-year-old gardens.
Ethrel Mean Total Mean Root
(L Frwt (g) %Y Frwt (g) ?40 Number Hand Remx 23.9 a" 101.7 2797 a 106.2 117 a
2.5 x 2 22.8 ab 97.0 2619 ab 99.4 115 a 3.75 x 2 21.8 ab 92.8 2275 abc 86-4 104 a 5.0 x 2 21.3 bc 90-6 2200 bc 83 -5 103 a
0.0 23.5 a 100.0 2634 ab 100.0 112 a 2-5 22.3 ab 94.9 2384 abc 90.5 107 a 5 .O 23.1 ab 98-3 2151 bc 81.7 94 b 7.5 19.4 cd 82.6 2304 abc 87.5 120 a 10.0 18.1 d 77.0 1914 c 72.7 106 a
Significance L ** * NS Q NS NS NS
- Treatments were applied at 35 and 55 % open florets Y - Percent Çesh weight based on controls within respective columns - Hand removal treatment - Within columns, means followed by the same letter are not significantly different
using LSD (P 1 0.05) - Single application Ethrel treatment means (excluding hand removal) analyzed by
single-degree-of eeedom contrasts hTS, *, ** Effect not significant or significant at P 10.05 or 0.01 respectively
Table 2.34. Root fiesh weight in Amencan ginseng (Panax qztinquefolius L.) treated with single and split applications of Ethrel or hand removal of inflorescences. Treatments were applied on June 24 and July 1, 1999 on CIG 3-year-old gardens. --
Ethrel Me&- Total Mean Root
Hand RemX 20.2 bcw 86.0 2413 ab 95.2 120 ab
2.5 x 2 20.4 bc 86.8 2781 a 109.8 138 a 3-75 x 2 19.4 c 82.6 2515 ab 99.3 130 ab 5.0 x 2 21.5 abc 91.5 2200 b 86.8 104 b
' - First spray treatrnent was applied at 57 % open florets Y - Percent fkesh weight based on controls within respective colurnns - Hand removal treatrnent - taken Eom far side of garden, not RCBD
" - Within columns, means followed by the sarne Letter are not significantly different using LSD (P 5 0.05)
- Single application Ethrel treatment means (excluding hand removal) analyzed by single-degree-of freedom contrasts
NS, * Effect not significant or significant at P I 0.05 respectiveIy NOTE treatrnents NS for rnfi-wt, reps significant
1998 Floral Development - Floret Opening
A 100 : v
! 80 i
i 60 /
l 40 1
i
20 ' 1 l
O i w v A
14-May 3-Jun 23-Jun 13-Jul 2-Aug 22-Aug Il-Sep
Date
Figure 2.1. Floral development and open florets of inflorescences of 3-year-old Panax quinquefolius L. over the 1998 growing season.
11998 Seed Head Fresh Weights
14-May 3-Jun 23-Jun 1 3-Jul 2-Aug 22-Aug Il-Sep
Date
Figure 2.2. Seed head fiesh weights of inflorescences of 3-year-old Panax quinquefolius L. over the 1998 growing season.
Seed Head Diameter
40 ;
Poly. (1 998)
Date
Figure 2.3. Seed head diameter of inflorescences of 3-year-old Panax quinquefolius L. over the 1998 and 1999 growing season
Peduncle Length
Date
Poly. (1 998)
- . Poly. (1 999)
Figure 2.4. Peduncle length of inflorescences of 3-year-old Panax quinquefolius L. over the 1998 and 1999 growing semons.
(A) Ethylene Evolution - Day 2
12 , j + H20 control I
Date
(B) Ethylene Evolution - Day 3
12 1
+ H20 control
1 7 5 0 mg/L WH -
, 4- 1500 mg/L ETH *
1 .4 A A A A O A A A -- A --
A v
3-Jun 17-Jun 1-JuI 1 5-Jul 29-JuI 12- AU^ Date
Figue 2.5. Ethylene evolution from excised inflorescences of 3-year-old Panax quinqzrefoZitis L. over the 1998 growing season. Inflorescences were placed in solutions of either water (O) or 750 or 1500 mg/L ethephon. Day 2 (A) and day 3 (B) measurements.
Berry Removal with Ethephon - 1999
120 , 8
t
! i
+ single
a split
Ethrel (UAcre)
Figure 2.6. Effect of ethephon on berry removal in 3-year-old Pana quinquefolius L.. Percent berry rernoval through single and split applications, over five 1999 locations,
Plate 2.1 Spring ethephon application of 3-year-old P a n a quinqztefoZius L. by mechanical boom sprayer at Rainey Ginseng.
Plate 2.2 July 29, 1999 floret abscission of 3-year-old Panax quinquefoZius L. with 7.5 L acre'' Ethrel treatrnent applied on June 16, 1999 at Arthur Brothers.
Plate 2.2.
86
Plate 2.3 Total berry harvest of 3-year-old Panax quinquefolius L. treated with 0,750 x 1,750 x 2, and 1500 mg L-' Ethrel at JCK Farms in 1998.
Plate 2.4 Red berry harvest of 3-year-old Panax quinquefolius L. treated with O, 2.5, 5 .O, 7.5, and 10.0 L acre-' Edirel at Rainey Ginseng in 1999.
Plate 2.4.
8 8
Gibberellin, Benzyladenine and Etbrel Effects on Leaf Chlorophyll, Seed Head and
Root Development in North American Ginseng (Panax quinquefolius L.)
Introduction r
Exogenously applied ethylene stimulates abscission of flowers, fhîts and leaves
(Noodén, 1980; Reid, 1987; Fiebig, 1999). However, ethylene also promotes leaf
senescence in many plant species (Noodén and Leopold, 1978). Ethylene inhibits
photosynthesis (Taylor and Gunderon, 1986), accelerates the degradation of chlorophyll
(Duuster et al., 1980), and increases the biosynthesis of certain carotenoids postal and
Leopold, 1967; Wheaton and Stewart, 1973) and anthocyanins (Hale et al., 1970; Devlin
and Demoranville, 1970; Proebsting and Mills, 1969). Concentrations of ethephon (as a
source of ethylene) required to achieve high percentages of berry removal in ginseng
often result in premature chlorophyll loss, development of red, orange and yeIlow
pigments in the leaves, and abscission (Fiebig, 1999). Loss of leaf greemess may reflect
either the degradation of existing chlorophyll andor declining photosynthetic rates in the
plant. Reduction of chlorophyll may impair photosynthetic processes, leading to a
reduction in carbon fixation by the plant. The atypical loss of le& chlorophyll seen with
ethephon application generally precedes leaf senescence, and is a-n important indicator of
overail plant health. Therefore, methods of minimizing leaf colouration and damage due
to ethephon treatment need to be investigated.
Control of leaf senescence through plant hormone action has been reviewed
extensively (Noodén and Leopold, 1978; Thimam, 198Oa; S toddart and Thomas, 1 982).
Symptoms of senescence c m be delayed in detached leaves or leaf discs by the
application of cytokinins (Richmond and Lang, 1957; Letham, 1967), auxins (Osborne
and Hallaway, 1964), or gibberellins (Fletcher and Osborne, 1966a; Beevers, 1966).
Although all classes of plant hormone affect the course of senescence when applied
exogenously (Sklensky and Davies, 1993), the effects of plant growth regulators on Ieaf
senescence are dependent on species, type and physiological age of the plant tissue.
Cytokinins are endogenous adenine-derivative plant growth regulators with roles
in several plant processes, including ce11 division, chloroplast development, bud
differentiation, shoot initiation and leaf growth, and senescence (Brault and Maldiney,
1999). Leaf senescence has been correlated with decreased endogenous cytokinin in the
leaves (Van Staden et al., 1988), and is delayed by exogenous applications of cytokinins
(Halevy et al., 1966) in both presenescent and senescent tissue (Singh et al., 1992).
Eisinger (1977) concluded that cytokinins decrease plant sensitivity to ethylene. Other
findings showed that declining levels of foliar cytokinin sensitize soybean leaf tissue to a
senescence factor derived fiom developing seeds (Noodén et ai., 1990). FoIiar
applications of benzyladenine (BA), a synthetic cytokinin, delayed senescence in attached
leaves of bean (Fletcher, 1969; Adedipe et al., 1 Wl), oat (Thimann et al., 1974) and
soybean (Lindoo and Noodén, 1978). Previous investigations into the eRects of
cytokinins on ginseng showed that foliar sprays or soi1 drenches of thidiazuron, a
phenylurea compound with very high cytokinin activity, increased stem length and
diarneter, and shoot and root weight of ginseng (Proctor et al., 1996).
Both cytokinins and gibberellins arc synthesized by the isoprenoid pathway, and
show some similarities in their biological activity. Pigment changes occurring within
plastids (chlorophyll, carotenoids) and in the vacuole (anthocyanins) are induced by
ethylene and arrested by exogenous gibberellins and cytokinins (Goldschmidt, 1974,
1980). Fletcher (1969) demonstrated that senescence in bean leaves (Phaseolus vuZgaris)
is retarded by the application of gibberellins. In addition to interferkg with degradation
of chlorophyil, gibberellins also induce green chloroplast development (Goldschmidt,
1974) and reduce the biosynthesis of carotenoids and anthocyanins pos ta l and Leopold,
1967, ProebsGng and Mills, 1969, Abdel-Gawad and Romani, 1974). However, the
senescence retarding effect of gibberellins has been dernonstrated more widely with fruits
than leaves, and is known to occur in only a limited number of plant species (Noodén and '
Leopold, 1978). Other common physiological effects of gibberellins in the developing
pIant include ce11 elongation and increasing internode length (Davies, 1995; Graebe,
1987). Previous investigations into the effects of gibberellins in ginseng have been
limited mostiy to seed donnancy studies (Hovius, 1996).
For determination of leaf damage, commonly used measurements include: visual
colour ratings, chlorophyll extraction and in vivo chiorophyll measurements. However,
visual assessrnent of leaf greenness is subjczl,ve and often cannot be accurately
quantified, and conventional chlorophyll extraction methods in aqueous acetone, ethanol
or similar organic solvents are time consurning and invasive to the plant (McKinney,
1941 ; White et ai., 1960; Bruinsrna, 196 1). A portable SPP3-502 chlorophyll meter
(Minolta Camera Co. Ltd., Japan) is potentially useful for in vivo chlorophyil
measurements in ginseng. The instrument allows the investigator to take multiple
chlorophyll readings over the developrnent of a plant without darnage to the tissue, and
these numbers correlate with actual chlorop hy ll concentration deterrnined b y traditional
extraction methods (Marquard and Tipton, 1987). In studies with single species, a strong
correlation between extractable CHL and SPAD readings has been established, and the
relationship can be described by a single linear regression (Yadava, 1986; Tenga et al.,
1989; Dwyer et al., 199 1). However, both Yadava (1 986) and Marquard and Tipton -
(1987) in sirnilar investigations using multiple species of plants, suggest that a strong
correlation between CHI, concentration and SPAD may be species-specifïc. For this
reason, individual regression equations should be developed for any given species to
maximize the accuracy of estimating leaf chlorophyll (Marquard and Tipton, 1987).
Ginseng is an obligate shade plant with a distinct physiology and photosynthetic
range. It requires a light intensity of approximately 3000-6000 Iwc (Duke, 1989), or
approximately 30% full sunlight (Proctor, 1980; Stathers and Bailey, 1986; Proctor and
Baiiey, 1987; Proctor et ai., 1988; Proctor et al., 1990; Persons, 1995; Proctor, 1996) for
growth' Panax quinquefoliz~s L. has not been used previously in any comparable
chlorophyll studies. Therefore, it is necessary to determine if a significant relationship
exists between the total extractable chlorophyll in the leaves and SPAD-502 chlorophyll
meter readings for this species.
Specific Objective: The objectives of these experiments were (a) to determine the
relationship between SPAD-502 chlorophyll meter measurements and extractable
chlorophyll, (b) to assess the utility of the meter to identi@ significant differences in leaf
greenness in North American ginseng, and (c) to detemiine the effectiveness of
exogenously applied foliar spray applications of gibberellin and benzyladenine on leaf
greenness, and inflorescence and root development in North American ginseng.
Materials and Methods
1. Relationship Between SPm-502 in vivo Chlorophyll Measurements and
Extractable Chlorophyll in Ginseng
The study was performed using leafsamples fiom the Ethrel field trial garden at
JCK Farms on July 28, 1999. Treated and untreated leaves were coliected to obtain a
range of leaf colour due to Ethrel treatment. Leaves were harvested randomly by
snapping off cleanly at the base of the petiole, and placing in containers of de-ionized
water for transport to the laboratory
Five leaf colow categorïes were determined: dark green, light green, maroon, red,
and orange/yellow (Plate 3.1). Leaf discs 15 mm in diameter in each colour category
were cut f?om leaves using a cork borer, avoiding midrib, major veins and damaged
tissue. Three leaf discs were selected rmdomly per colour category. The mean fiesh
weight of a leaf disc in each colour category was determîned fiom the remaining cut leaf
discs. Soon after cutting, each disc was individually measured three times for
chlorophyll (CHL) concentration using a SPAD-502 chlorophyll meter (Minolta Camera
Co. Ltd., Japan). The SPAD-502 meter estimates CHI, by measuring the amount of light
transmitted through a small area (2 x 3 mm) of leaf tissue. The light is measured at peak
wavelengths of the CHL-absorbing regions of the spectnun (440 and 670 nrn) (Dwyer et
al., 199 l), generating unitless numbers.
Before taking individual measurements, the rneter was set to zero by taking a
measurernent without any sample in the sample slot. Three SPAD-502 measurements
were taken fiom different locations on a respective leaf disc. For each leaf disc, average
CHI, content was calculated fi-om the three SPAD-502 measurements. Yadava (1986)
used similar methods to determine concentration of total CHL in leaf discs fiom 22
species of plants.
Following measurements on SPAD-502, the samples were transferred to labelled
50 m . plastic centrifuge tubes with caps for CHL extraction. Extraction rnethods were
adapted fiom Evans (1983), who extracted CHL in 80 % acetone and had adapted
Amon's (1949) modification of the method of McKinney (1941), who aiso had provided
equations @mol CHIA = 22.22 D645 +9.057 D663) to evaluate the molar concentrations
of total CM, ( C m a and b) in the tissue extracts. Ethanol was chosen as the extraction
solvent rather than acetone, as Fletcher and Osborne (1966b) used 80 % ethanol for CHI,
extraction fYom leaf discs of Taraxacum oflcinale.
Each disc was homogenized for 45 seconds on high speed in 10 mL of 80%
ethanol using a homogenizer (Kinematica GmbH, Switzerland). The grinding
mechanism was cleaned and rinsed with deionized water between samples. Samples
were centrifuged for 20 minutes on high setting to separate leaf tissue fiom solution,
Supernatant was decanted into 15 mL sterilized vials and measured imrnediately at 663
(CHL a), 645 (CHL b) and 470 (carotene) nrn with a B e c b a n DU-65 spectrophotorneter
using 10 mm path length cuvettes. Each replicate was sampled 3 times. These values
were used to determine concentration of total CHL in rnicrograms per gram (pg g-') of
leaf fiesh weight. Total CHL was established as the surn of the C m a and b
measurernents. Mean total CHL was calcdated fiom the 3 extract measurements of each
sample.
Mean total CHL (pg g%esh weight) was plotted against the respective mean
values of SPAD-502 readings for the individual leaf discs. Correlation between SPAD-
502 and leaf CHL was determined using Pearson's coefficient. From this correlation, a
regression equation (Y = a + bx) was developed.
II. Bioassay Experiment
To investigate the effect of Ethrel, cytokinins and gibberellins on CHL levels in
excised ginseng leaves, bioassay methods were deterrnined and used. The study was
performed using plant material fiom an established 3-year-old garden owned by
Canadian Imperia1 Ginseng Inc. (CIG), located South of Burford, Ontario on East !4
Townline Road. Untreated leaves were harvested randomly by snapping leaves off
cleanly at the base of the petiole. Leaves were placed in containers of air-temperature de-
ionized water and transported to the laboratory. Leafdiscs 15 mm in diameter were
removed fkom the leaves using a cork borer, avoiding the leafmidrib and major veins.
The mean fiesh weight of a sample of five leaf discs each was determined.
Following bioassay methods from Fletcher and Osborne (1966b), five leaf discs
were selected randomly for each replicate, and placed in Petri plates on 7 cm diameter
filter paper saturated with test solutions. The abaxial surface of the leafdisc was in
contact with the moist filter paper. Treatments were 10 rnL of total solution per replicate,
and consisted of combinations of 250 to 500 rng~- ' ethephon, 100 r n g ~ - l BA (Sigrna-
Aldrich Canada Ltd.) and 200 mgL? GA (ProGibb plus 2x - Abbott Laboratories) (Table
3.1 for treaiment combinations used). A control was used which consisted of 10 mL of
deionized water. Three replicates were used per treahnent. The Petri dishes were
covered, randomized in a plastic box to maintain high hurnidity, and stored in darkness
for 5 days at room temperature. After removing the treated leaf discs fkom dark
incubation, the samples, consisting of 5 leaf discs each, were transferred to labelled 50
mL plastic centrifuge tubes with caps for CHL extraction and determination as outlined
previously .
Data were subjected to analysis of variance (ANOVA) using the General Linear
Models (GLM) procedure of the SAS statisticai package (SAS Institute, Cary, N.C.). Al1
variables had a normal distribution and no transformations were necessary. Where
appropriate, regression anaiysis of growth regulator effects was performed. Treatment
means were dso compared using the Least Significant Difference (LSD) method of
analysis. The level of significance used for al1 tests was P 10.05.
III. 1999 Field Experiments - Rice Short Plots
Three-year-old ginseng (Panax quinquefolius L.) was used in 1999 to determine
the effects of Ethrel, BA and GA on in vivo measurements of leaf C H ' , seed head, and
root development. The study was performed using plant material fkom two blocks of an
established garden at JCK Farms, North of Burford, Ontario. The plants were grown
under wooden lath shade at a height of 1.9 meters, providing approximately 75% shade to
the crop, planted on raised soi1 beds at commercial spacing, and covered with straw
mulch. The gardens were rnaintained by Jeff Rice of JCK Farms, throughout the growing
season, according to comrnon commercial practices, similar to those descrïbed by Proctor
and Bailey (1987)- Standard practices for fertiiization and disease control were followed
(Anon, 1998; Anon, 1999).
Sprays were applied with an 8.5 L Hudson backpack sprayer fitted with a Teejet
nozzle (80015) at approximately 2 kg cm-' pressure. Approximately 300 rnL of solution
was applied per meter of row. Plots were sprayed in moming temperatures, on calm
days, to the point of nui-off. No wetting agents were added to these solutions.
In vivo CHL rneasurements were taken using a SPAD-502 rneter as described in
Chapter 2. Leaves and seed heads were not sampled in the 25 cm from the ends of each
plot to create a buffer zone in the event of spray drift.
Seed heads were harvested at commercial timing, on August 24, 1 999, from 1 m
sections of each treatment plot and measured for total fresh weight. Bemes and
unpollinated florets were also screened, sorted and measured for counts in the manner
described in the 1999 berry harvest, Chapter 2. Roots were harvested by hand at
commercial timing, on Septernber 28, 1999, £iom 1 rn sections. Al1 roots were washed
and air-dried before measurement. Roots were counted and weighed individually to
determine total yield per treatment. Before and after measurement, roots were stored in
cold air storage at 3 & 0.2 OC until they were returned to the grower.
A. 1999 GA Experiment
Control, hand removal and GA treatment short plots were arrmged in a section of
the established garden using a randomized complete block design (RCBD) with 3
replicates. Spray treatments consisted of 50 to 200 mg L - ~ pre- and post-bloom GA,
applied from 2 sources, GA3 (Activol - Norac Concepts) and G k t 7 (Procone - Abbott
Laboratories). Spraying solutions contained adequate arnounts of GA3 and G&+7 to
achieve the desired final concentrations. Concentrations of GA3 and G&+7 used,
volumes applied, and times of treatment are listed in Table 3.2.
GA3, Activol(1 tablet = lg a.i. gibberellic acid 5-10% w/w), alternative name:
BERELEX tablets, Composition: Gibberellic Acid and Adipic Acid
G&+,, Procone (42 g a.i. per L gibberelüns G4+7,4.0% w/w), inert carrier
Plots were 3.0 rn in Iength and each treated plot was divided in two. One-half of
each plot provided plants for seed head sampling throughout the season, the other half
was used for in vivo CHL measurements, as weil as seed and root harvest at the end of
the season. The seed head was defined as the portion of the inflorescence which supports
the developîng bemes on the pedicels, and included the base of the seed head where the
peduncle and seed head attach. Seed heads were measured on July 7 for peduncle length
and intact seed head diameter, and on July 29 for bare seed head diameter, seed head
height (seed intact and seed removed) and maximum pedicel length. Examination of seed
heads with seed intact and seed removed was necessary because seed size and shape
varied with GA treatments.
At each sarnpling date, 10 seed heads per treatment with peduncle attached were
selected randornly fiom within the plots. In vivo CHL measurements were taken from d l
plots using a SPAD-502 meter on June 18,24, July 7,22, Aug 5,24 and September 15.
Additional counts were taken of dormant and broken pere~at ing buds to determine the
effect of GA sprays on bud dormancy.
Data analysis was performed using Analysis of Variance using general linear
models procedure of SAS (SAS Institute, Cary, N.C.). Al1 variables were tested for
normal distribution to determine if transformation of the data was necessary. Natural
logarithrnic transformations were utilized as needed and the analysis of variance and
mean separation procedures were repeated with the transformed data. Where appropriate,
regression analysis of growth regulator effects was performed. Treatment means which
included growth regulator and hand removal effects were also cornpared using the Least
Significant Difference (LSD) method of analysis. The level of significance used for al1
tests was P 1 0.05. Dinerences in perennating bud counts were further analyzed with
Duncan's multiple range test-
B. 1999 BA and Ethrel Experiment
Control, hand removal and PGR treatment shoa plots were arranged in a section
of the established garden using a randomized complete block design (RCBD) with 4
replicates. Spray treatments consisted of combinations of 100-200 mg L" BA (Sigrna-
Aldrich Canada Ltd.) and 1500-3000 mg L-L ethephon. Ethrel (Rhône Poulenc) was used
as a source of ethephon. The spraying soiutions contained adequate amounts of BA to
achieve the desired final concentration. Concentrations of BA used, volumes applied, and
times of treatment are listed in Table 3 3.
BA, 6-benzylaminopurine solution, lmg/rnL, carrier solution: 1 normal Sodium
hydroxide
Ethrel, 24% ethephon (2-chloroethylphosphonic acid)
Plots were 1.5 m in length. In vivo CHI, measurements were taken fiom al1 plots
throughout the season using a SPAD-502 meter on June 15,21,30, July 7, 22, August 5,
17, and September 15.
Data anaiysis was perfomed using Analysis of Variance using generai linear
models procedure of SAS (SAS Institute, Cary, N.C.). Al1 variables were tested for
normal distribution to determine if transformation of the data was nccessary. Natural
logarithmic transformations were utilized as needed and the analysis of vviance and
mean separation procedures were repeated with the transformed data. Where appropriate,
regression analysis of growth regulator eRects was performed. Treatment means which
included growth regulator and hand removal effects were also compared using the Least
Signincant Difference (LSD) method of analysis. The level of significance used for aU
tests was P 1 0.05.
Results and Discussion
SPAD-502 in vivo Chlorophyll Measurements vs. Extractable Chlorophyll
SPAD-502 CHL measurernents varied with colour intensity of ginseng leaves as
did extracted CHI, (pg g-L fiesh weight) fiom the same leaves. Regression analysis
showed a quadratic relationship (r2 = 0.98) (Figure 3.1) between SPAD-502 values and
extractable CHI,. Yadava, (1 986) found a significant linear correlation between SPAD
and pmol m'2 total CHL (CHL a + b) among a selection of 9 peach cultivars (Prunus
persica L.), with widely variable leaf colours (r = 0.7 1). Marquard and Tipton, ( 1 987)
also found that CHL concentration calculated on a leaf area basis was linearly related to
SPAD for data collected on twelve individual species (2 = 0.83 to 0.97).
Although Marquard and Tipton found that the linear relationship (r2) behveen
SPAD values and extractable CHL was weaker when CHL content was expressed on a
weight basis, the correlation value found for this experiment exceeded those values seen
in earlier evaluations. This may be a reflection of the variation in extraction techniques
used; whether or not extraction invohed maceration of the tissue, and in what solvent.
CHL determination by transforrning SPAD-502 readings into CHL concentration using
the regression equation provides a convienient and non-destructive method of directly .
measuring leaf CHL of field-grown ginseng.
Bioassay Experiment
Ethephon reduced Ieaf CHL of excised leaf discs (Table 3.4). The regression
lines are listed with Figure 3.2. The significant quadratic relationship indicates the mean
total CHL (CKL A + CHL B) content of the Ieafdiscs decreased with increasing
concentration of ethephon plate 3.2). This supports the visual observations of Fiebig
(1 999) who found qualitatively that heightened reddening of ginseng leaves resulted in
response to higher concentrations of ethephon sprayed on 3-year-old plants. Senescence
of leaves in response to exogenous applications of ethylene is attributed to an increase in
tonoplast perrneability (Matile and Winkenbach, 1971), followed by enhanced rnovement
of vacuole contents across the membrane to the cytoplasm (Kende and Baumgartner,
1974; Hanson and Kende, 1976; Mayak et al., 1977). Loss of membrane integrity of the
tonoplast results in a Ioss of solutes and water fiom the cells and leads to wilting and
senescence of the tissues (Borochov and Woodson, 1989).
Cytokinins protect against the process of senescence through maintenance of
ch~oroplast and rnitochondrial membrane integrity (Mayak and Hdevy, 1974; Thirnann,
1987). Cytokinins, and to a lesser degree, gibberellins, control the senescence of excised
leaves and leaf discs of tobacco (Singh et al., 1992). Although Fletcher and Osborne
(1966b), using a similar bioassay method to the one used here, found that CEIL retention
in treated Taraxacum leafdiscs was greater with increasing concentrations of GA3, the
same was not true for leaf discs of ginseng. Addition of GA3 to the bioassay solution did
not result in leaf discs retaining significantly more CHL compared to the conh-01 af3er 5
days, and did not alter Ioss of leaf CHL over the concentrations studied. However leaf
discs with BA added to the ethephon bioassay solutions, retained more CHI, than
ethephon alone. Although mean total CHL levels continued to decrease with increasing
concentration of ethephon, regression anaiysis showed that the quadratic decrease in
mean total CHL was significantly different fiom the control (P < 0.001). Mean total
CHL decreased similarly for control, BA and GA treatments at O and 250 mg L-'
ethephon, followed by increased CHL retention for BA-treated leaf discs compared to
control and GA treatments at 375 and 500 mg L-' ethephon. These fuidings agree with
previous research demonstrating that the application of cytokinin to fiuiting soybean or
rice plants is successfil in delaying, but not preventing, senesence (Noodén et al., 1979;
Ray et al., 1983).
1999 Short Plot Experiment - GA
SPAD-502 Chlorophyil Measurements
Leaf CHL levels varied throughout the season. In control and GA treated plots,
CHL levels increased fiom - 3 1 to - 41 SPAD-502 LU& between June 7 and July 7, and
decreased thereafter (Figures 3 -3 and 3 -4). According to measurements of seed head
development taken in 1998 and 1999 (See Chapter 2), mid-July corresponds to
approximately 100% open florets and initial fi-uit set, and the beginning of rapid increase
in seed head &esh weight. Thus, by rnid-July, the 3-year-old ginseng plant is entering the
phase of h i t and seed development. Fruit and seed development in the plant requires a
diversion of a large amount of the resources of the plant, and may be partly responsible
for the graduai decrease in leaf CHL, levels.
Leaf CHL varied with source and concentration of GA applications (Table 3 -5).
As the season progressed, SPAD-502 measurements revealed that leaf CHL was being
maintained at a higher level compared to the control as a result of GA4+, sprays. On more
than one sarnpling date, leaf CHL increased quadraticaily as the concentration of
increased. GA3 treatment in the bioassay experiment (see above) did not retard leaf CHL
loss of excised leaf discs, and GA3 field sprays were not effective at increasing or
maintahhg leaf CKL levels. The results of the field triais are consistent with the
findings of Han (1 997), who found that treatment with solutions contaiaing GAe7
prevented the development of leaf yellowing in cold-stored Easter Lily (Lilium
Iongz$?orum Thunb.), whereas solutions of gibberellic acid (GA3) were not effective.
Although no GA sprays were capable of completely preventing chlorophyll Ioss entirely,
the small(8 - 1296) increase in mean leaf chlorophyll induced by the GA4+7 treatment
throughout the last half of the growing season suggests the possibility of M e r
application of Ght7 in ginseng.
Berry fresh weight and number
Both green beny tresh weight and number increased quadratically as the
concentration of GA3 increased (Tables 3.6 and 3.7). Similar increases in green berry
number, but not green berry fresh weight, were seen with Ght7 sprays. GA3 and G&+7
had no effect on red, cull or total berry h-esh weight or nurnber, however there was a
trend toward decreasing red and cull berry number. Tt was observed throughout the
season that GA-treatment \vas causing the developing berries to increase in size in an
atypica! manner. Green bemes were larger than the cüll or green seed seen in the control,
but flattened across the width of the berry. The green berries also lacked seed
development within the berry (Plate 3.3). These sanie bemes did not set seed or ripen by
harvest time. GA3 sprays induced parthenocarpic (seedless) fn i t development and
increase berry size (Miele et al., 1978), as well as reduce f i t set and increase berry drop
in 'Thompson seedless' grapes (Coombe, 1976; Ben-Tal, 1990). Although Lynn and
Jensen, (1966) reported th& bloom-time sprays of 10 or 20 ppm GA3 in 'Thompson
seedless' grapes reduced the average number of bemes per cluster by approximately
20%, a similar thuining effect of gibberellic acid was not evident in ginseng.
Root meadtotal fresh weight and nurnber
Both mean and total root fiesh weight increased linearly as the concentration of
GA4+7 increased (Table 3.8)- Sprays of 200 mg L-' G&+, applied 4 tirnes throughout
inflorescence development @re-bloom and bloom) resulted in a 10% increase in mean
root fiesh weight and a 20% increase in total root fiesh weight. Sirnilar increases were
not seen with GA3 sprays. Regression analysis showed no effect of either GA3 or G&+7
on root number.
The largest differences in root fiesh weight occurred between the highest
application rates of GA and the control(16.9 and 16.6 vs. 15.1 g, Table 3 -9). Few
differences were seen with the timing of the GA sprays. Early application of 100 mg L-'
GA3 and G h t 7 ( lx pre-bloom) resulted in comparable mean and total root fiesh weight
to multiple applications of the same concentration (3x bloorn). Combination of 100
mg L-1 GA3 and G&+, pre-bIoom and bloorn sprays (4x) resulted in comparable mean
and total root fiesh weight to pre-bloom sprays alone.
No significant increase in mean or total root fresh weight was seen wifh hand
removal. Small plots showed no more benefit with hand removal than larger, field-scale
trials run in the same season. Proctor et al. (1999) stated that ginseng root fresh weights
increased 25 to 30 percent by the end of the season as a result of manual inflorescence
removal in early July. Therefore, this result fùrther suppoas the theory that physiological
stress due to low rainfd and high temperatures may have been partly responsible for the
lack of root yield increase in the 1998 and 1999 field trials.
Perennating bud counts
GA applications increased loss of dormancy in perennating buds on harvested
roots of ginseng (Plate 3.4). Occurrence of premature expanding of perennating buds
increased quadratically as concentration of both GA3 and G&+7 increased (Table 3 -9).
Dormancy loss appears to occur to a lesser degree with GA4+,- Based on an average of
one perennating bud per root, GA3 at 200 mg L-' applied four times (pre-bloom and
bloom) resulted in 98% loss of dormancy (buds broken). Whereas G&+7 at 200 mg L - ~
applied four times resulted in only 48% loss of dormancy. Even the lowest rate of GA3
applied 100 mg L-' (pre-bloom - xl) resulted in approximately 46% of buds breaking
dormancy. Sirnilar applications of G4+7 resultzd in only 1 1% loss of dormancy.
Occurrence of broken bud dormancy in the control plots was approxirnately 2%. This
rate of bud break fdls below the 5 - 8% rate of bud break that can be attributable to
fluctuations in Fa11 temperatures (Anon, 1998). Fa11 premature bud development has
been seen previously in one- year-old ginseng plants, and causes root reserves to be
redisûïbuted to the developing shoot, which would otherwise be used for the next years
growth. This loss of dormancy of the perennating bud is considered detrimental for the
survival of this perennial crop through the winter months (Anon, 1988). In addition, a
higher occurrence of broken perennating buds due to GA3 treatment, with a subsequent
loss of stored nutrients in the root may be responsible for lack of root fresh weight
increases comparable to those seen in GAe7 treatments. A trend towards linear gain in
root fiesh weight due to multiple applications of GA3 was not significant.
GA applications increased the occurrence of new bud initials on harvested roots
of ginseng (Table 3.9, Plate 3 S). New bud initial number increased quadratically as the
concentration of both GA3 and GA4+7 increased. Occurrence of new initials is strongly
reIated to the occurrence of bud break, the number of broken buds showed a positive
correlation with the development of new bud initials (Figures 3.5 and 3.6). As broken
bud numbers increased, so did new bud initial numbers. A stronger correlation between
bud break and new bud initials exists for concentrations of O to 200 mg L-' GAJ (r = 0.93)
than compared to G&+, (r = 0.44). Loss of dormancy of the perennahg bod due to GA
sprays stimulates the development of a new bud initials to replace the broken bud, and in
some cases, multiple new initials. Although the occurrence rate of multiple-stemmed
plants in Panax ginseng C.A. Meyer is less than 4%, it has been dernonstrated that
ginseng plants c m be encouraged to develop several adventitious buds through artificial
darnage to the perennating bud. Application of 100 to 400 mg L-' B9 solution (another
plant growth regulator) once per rnonth for 4 months, fiom the 1 of May, resulted in
the development of 2 to 4 adventitious buds (Hong et ai., 1995). An increased number of
stems per plant have the potential to increases stem and leaf area, and perhaps also the
rate of photosynthesis and subseqent gain in biomass of the ginseng plant. However, it is
unknown if the adventitious buds developed through the GA treatments would develop to
the point where they could survive the winter and gerrninate the follo-wing spring to fonn
a multi-stemmed ginseng plant. Therefore, premature Ioss of bud dormancy in the
ginseng plant has the potential to be very detrimental to the development of the plant.
Seed Head Measurements
By July 29, one month d e r the last GA sprays, maximum seed head height
increased quadratically as concentrations of both GA3 and G&+7 increased (Table 3.10).
A similar relationship was seen when comparing seed heads with seeds intact or
ïemoved. GA3 sprays loosen clusters of 'Thompson seedless' grape through
inflorescence expansion (Mosesian and Nelson, 1968). Pérez and Gomez, (1998) used
GA3 treatments applied to 'Thompson seedless' grapes 2 weeks before bloom for bunch
elongation, and applied at full bloom for bunch thinning.
Intact and bare seed head heights of plants treated four times @re-bloom and
bloom) with 100 mg L-' GA3 were larger than those treated with 100 mg L-' one time
(pre-bloom) or three times (bloom). No significant height difference occurred between
pre-bloom and bloom treated seed heads. A similar relationship was evident with G&+7
applications, however 100 mg L-' applied three times (bloom) resulted in similar
increases in seed head height compared to 100 mg L-' GA4+, applied four tirnes (pre-
bloom and bloom). It appears that the effects of multiple applications of GA on seed
head height are additive.
By July 29, one month after the last GA sprays, maximum seed head diameter
(seeds removed) increased quadratically and linearly as concentrations of GA3 and G&+,
increased respectively (Table 3.1 1). Sprays of 100 mg L" GA3 and G h t 7 applied once
@re-bloom) and 4 times @re-bloom and bloom) showed no significant differences in
either intact or bare seed head diameter. However, seed heads treated with 100 mg L-l
GA3 applied 3 times (bloom) had diameters approximately 10% smaller than those
treated and 4 times @re-bloom and bloom). This indicates that early application may be
the most important factor in increasing inflorescence expansion in ginseng. This may be
due to the age, degree of lignification of cells, and stage of developrnent of the pedicels.
GA increased pedicel length in a similar manner to seed head height and diameter.
By Jdy 29, one month after the last GA sprays, maximum pedicel length increased
quadratically as concentrations of both GA3 and G&+, increased respectively (Table
3.12). Maximum pedicel length showed a positive correlation with seed head height and
diameter (seeds removed) for both GA3 and GA4+,. AS pedicel lengdi increased, so did
overall height and diameter of the seed head. A stronger correlation existed between
pedicel length and bare seed head height (r = 0.92 to 0.98) compared to bare seed head
diameter (r = 0.82 to 0.88) (Figure 3.7 and 3.8).
The large increase in mean seed head height, diameter, and pedicel length (Plate
3.6) induced by GA rnay have benefits for growers, including fewer berries lost due to
injury or crowding on the inflorescence, and better spray coverage of the inflorescence
for disease control or ethephon sprays.
Peduncle length
Increasing GA concentration had few effects on peduncle length (Table 3.12).
Multiple applications of 100 mg L-' GA3 pre-bloom and bloom (x4) sprays did not
increase peduncle lengths cornpared to pre-bloom (xl) and bloom (x3) sprays alone.
However, applications of 100 mg L-' GA3 (x4) and 200 mg L-L G&+7 (x4) uicreased
peduncle length compared to the control (P 1 0.10). Field-grown ginseng is a very
heterogeneous crop, large variation in peduncle length within the plots confounded any
increase in peduncle length due to GA treatment.
1999 Short Plot Experiment - BA
SPAD-502 Chlorophyll Measurements
Ethephon applications reduced leaf CHL of field-grown 3-year-old ginseng
(Table 3.1 3), consistent with results fiom the 1 999 field-scale experiment. B y August 5,
six weeks d e r ethephon application, sprays of 1500 and 3000 mg L - ~ ethephon reduced
leaf CHL by 14 and 23 percent, respectively. These differences became less pronounced
over the remainder of the sampling dates, most likely due to the natural senescence of all
the ginseng leaves towards the end of the growing season. Split applications of 1500 mg
L-' (x2) ethephon did not prevent CHL loss compared to single applications of 3000 mg
L-' ethephon over any of the sarnpling dates.
An application of 100 mg L - ~ BA prior to ethephon applications was not effective.
over any of the sampling dates, at increasing or mahtaining leaf CHL levels compared to
ethephon sprays alone. These results are not consistent with those fiom the bioassay
experiment, where BA in solution with 3 75 and 500 mg L-l ethephon maintained mean
total CHL levels in excised leaf discs better than 375 and 500 mg L-' ethephon alone.
Fletcher et al. (1970) found that treating intact primary leaves of bean plants with
benzyladenine (BA) allowed the leaves to retain photosynthetic assirnilates. They
showed that retardation of leaf senescence by BA is associated with a high retention (70
to 80%) of photosynthetic products, an effect lasting for several weeks after treatment.
The BA solution may have been detrimental to the intact ginseng plant, leaf CHL levels
significantly decreased with BA trzatrnent 10 days after application, but recovered to
control Ievels a week later, for the remainder of the season. Visual observations of the
BA expenment revealed that al1 spray concentrations of BA caused leaf damage in the
form of isolated spots of Ieaf buni, simi1a.r in appearance to fertilizer burn within one
week of spraying. Leaf darnage seen as a result of BA applications on the plants may be
attributable to toxic effects of the 1 -normal sodium hydroxide carrier solution.
Berry fresh weight and counts
Ethephon applications reduced fiesh weight and number of red, green, cull and
total berries (Tables 3.14, 3.15 and 3.16j, consistent with results fiom the 1999 field-scale
experirnent. Applications of 2 x 1500 and 3000 mg L-' ethephon did not M e r reduce
red or green berry fresh weight or number compared to single sprays of 1500 mg L-'
ethephon.
BA applications alone did not have any effect on red, green, cul1 or total berry
fiesh weight or number, however BA, when sprayed pnor to 2 x 1500 and 3000 mg L-'
ethephon, decreased green berry fresh weight, and green and cull berry number,
compared to ethephon sprays alone.
Root meadtotal fresh weight and number
BA treatment had no effect on root development (Table 3.17). Ethephon
applications did not increase mean or total root fi-esh weight, any increases seen with
2 x 1500 mg L-' ethephon are attributable to the decrease in root number with that
treatment, whether lost to disease or other factors. BA applications did not increase mean
or total root fiesh weight, and BA sprayed pnor to ethephon did not increase rnean or
total root fiesh weight compared to ethephon sprays alone.
Hand removal of the inflorescences increased total root fkesh weight
(approximately 1 1 %), but not mean root fresh weight, a contradiction to the lack of hand
removal increases in the GA experirnent, which was Iocated in a different section of the
same garden. The increase in total root eesh weight in the BA expehen t was
comparable to those increases seen in the 1999 ethephon field eials at Rainey's and
Arthur Brothers.
Summary
Extraction methods were used to determine the relationship between leaf colour
and chlorophyll content of 3-year-old Arnencan gkseng (Panax quinquefohs L.) in
1999. A positive quadratic relationship (y = 2.2x2 + 1 9 . 3 ~ + l72.9,? = 0.98) exists
between SPAD-502 readings and leaf total chlorophyll (pg g-' fiesh weight). Speceing
this relationship for ginseng aliows for a rapid method of quantiQing leaf chlorophyll as
an indication of overall plant health, which can be used on field-grown plants without
harvesting or Ieaf damage.
Bioassay methods were used to determine the ef3ect of ethephon on loss of
chlorophyll fiom leaf discs of 3-year-old Amencan ginseng (Panax quinquefolii<s L.) in
1999. Ethephon at 250,375 and 500 mg L'I was applied to excised discs of leaftissue.
Combinations of ethephon and BA at 100 mg L - ~ or GA at 200 mg L-' were aiso applied
to leaf discs, to determine ifchlorophyll loss due to the ethephon treatments could be
delayed or prevented with the use of complementary plant growth regulators. Ethephon
reduced mean total chlorophyll in the treated leaf discs. Ethephon in combination with
both BA and GA also reduced mean total chlorophyll, however the application of BA in
the bioassay reduced the rate of chlorophyll loss.
GA at 50, 100 and 200 mg L" was applied to field-grown 3-year-old American
ginseng (Panax quinquefolius L.) between 1 and 4 times, before and d d g bloom in
1999. GA3 and GA4+7 were examined as potential sources of GA. Consistent with the
known effects of GA on ce11 elongation and increasbg intemode length Gavies, 1995;
Graebe, 1 987), applications of both GA3 and G&+, ( ~ 4 ) four times to the developing
inflorescences increased maximum pedicel length, and seed head diameter and height. A
stronger correlation existed between maximum pedicel length and seed head height (r =
0.92 to 0.98) compared to seed head diameter (r = 0.82 to 0.88) as a result of both the
GA3 and G&+7 sprays.
Towards the end of the growing season (mid-July to mid-September), the effects
of the GA sprays on leaf chlorophyll were evident. G&+T at 50, 100 and 200 mg L - ~ (x4)
increased leafchlorophyll quadraticaily, and until harvest of the roots in September,
G&+7 at 200 mg L - ~ (x4) maintained higher chlorophyll levels in the leaves (8 to 12%)
compared to the control. Consistent with the findings of Han (1997) in studies with the
senescing leaves of Easter lily, GA3 sprays were not effective at maintaining leaf
chlorophyll.
Application of GA to the young inflorescences induced parthenocarpic (seedless)
green berry development. GA3 at 50, 100 and 200 mg L-' (x4) increased green berry
fiesh weight and number, but had no effect on red, cul1 or total berry fiesh weight and
number. GA4+7 applied at similar concentrations also increased green berry nurnber but
not fiesh weight, and had no effect on red, cul1 or total berry fiesh weight or number.
During the growing season, there is cornpetition between fruit growth and vegetative
growth for the carbohydrates produced in the photosynthetic organs. Lack of seed
development in the green bemes may allow for a greater proportion of the carbohydrates
to be partitioned into vegetative or root growth.
Analysis of root k s h weights at the end of the 1999 growing season found that
at 50, 100 and 200 mg L-' linearly increased mean and total root fresh weight, with
no differences in root number. However, GA3 treated plants did not show similar
increases. Because gibberellins are commonly used in several commercial crops for the
purpose of breaking bud dormancy, it was necessary to evaluate the effect of the GA
sprays on the domancy of the ginseng root's over-wintering peremating bud.
Examination of the condition of the harvested roots showed that GA treatments tiad
altered the proportion of buds prematurdy breaking dormmcy. Both GA3 and ehi7 at
50, 100 and 200 mg L ' ~ (x4) quadratically increased the incidence of broken buds,
however GA3 sprays resuited in twice as many buds breaking compared to G&+7 sprays.
Similar to the breaking of bud dormancy, both GA3 and GA4+, treatments resulted in an
increased number of new bud initials forrning per root, with the number of new initials
per root increased two-fold by the GA3 sprays compared to G&+,. A stronger.correlation
between broken buds and new initials for GA3 (r = 0.93) compared to G&+7 (r = 0.44)
suggests that more of the root carbohydrate reserve may be used up by the breaking of
bud dormancy through the GA3 treatments.
Expansion of the inflorescences and the occurrence of parthenocarpic beny
development as a result of the GA3 and G A + , applications mimics the response seen in
commercial applications of GA3 to 'Thompson seedless' grapes (Miele et d., 1978).
Fiebig (1999) suggested that in order for floral abscission to occur, the plant growth
regulator must be in direct contact with the abscission zones located on the pedicels at the
base of each flower. Inflorescence expansion would allow for better spray coverage of
the inflorescences if used pnor to ethephon treatment, and may alIow for use of Iower
concentrations of ethephon more effectively. A less dense inflorescence may also benefit
from increased air circulation and less crowding of the developing berries, subsequently
reducing the incidence of fimgal disease (e-g. Botrytis).
Additional benefits of G&+, sprays include maintenance of leaf chlorophyll,
dthough it is not presently known if the 8 to 12 % increase in leaf chlorophyll with
multiple applications of 200 mg L-' GA4+7 is sufficient to offset premature leaf
senescence due to ethephon applications. Increases in root f'kesh weight due to the G h t 7
treatments rnay be the result of the combined effects of ce11 elongation, maintenance of
leaf chlorophyll, seedless green berry development, and lower incidence of perennating
buds breaking dormancy and new bud initiais. However, in order to achieve significant
root fresh weight increases, higher application rates of G&+7 are needed, and the loss of
dormancy of the perennating buds on the roots at these rates could result in a subsequent
return growth of ody 50% of plants the following year. Further evaluations are
necessary to determine if this treatment can be used on a perennial crop such as ginseng,
in combination with ethephon, as an annual treatment, or only on those plants which will
be harvested in the same year.
BA at 100,2 x 100 and 200 mg L-' was applied to field-grown 3-year-old
Arnerican ginseng (Pana quinquefoZius L.) in 1999. Additional sprays of BA at 100 mg
L-' was in combination with ethephon at 1500,2 x 1500 and 3000 mg L-' were also
applied. BA sprays at 2 x 100 and 200 mg L-' did not maintain or improve leaf
chiorophyll compared to sprays of 100 mg L". Contrary to the bioassay results, BA
sprays in combination with ethephon sprays were not effective at maintaining leaf
chiorophyll levels compared to ethephon sprays alone. Although Singh et al., (1992)
found that the principal cytokinin bases zeatin and dihydrozeatin were more effective
than gibberellic acid and awcin in retarding senescence in tobacco leaves, BA in 1 N
NaOH as a source of cytokinin was not effective for ginseng field-scale applications.
Analysis of berry fiesh weight and number at harvest showed that concentrations
of BA between 100 and 200 mg L-' had no effect on red, green, culi or total berry fiesh
weight or nurnber. BA at 100 mg L-' in combination with 2 x 1500 and 3000 mg L-L
ethephon improved berry removal; with decreased green and cul1 berry fiesh weight and
fewer green and cd1 bemes rernaining on the inflorescence. Similar increases in removal
were not seen with red berry fiesh weight or number. No increases in berry removal
translated into subsequent increases in root fkesh weight at harvest.
Contrary to the results of the bioassay, G&+, applied to the intact leaves of
ginseng delayed leafchiorosis and senescence, whereas BA did not. In bean (Phaseolus
vulgaris L.), exogenously applied GA moved with the assirnilate Stream in the phloem to
sink tissue (Chin and Lockhart, 1965). By initially conducting experiments on dark-
incubated, excised leaf tissue, the source-sink relationship in the plant was eliminated,
and may have contributed to a different pattern of senescence or response than would be
seen in a Iight-exposed whole plant (Thimam, 1987; Han, 1997).
Although BA does not appear to be as effective ss G&+7 for retardation of leaf
senescence when applied as a preventative treatment, application of similar cytokinin
sprays at a later t h e in the senescence of the leaves may be more productive. Han
(1997) fomd that BA and GA treatment in Easter lily (Lilium longiflorurn Thunb.),
instead of being applied preventatively can be delayed until the first visible signs of leaf
chlorosis and senescence. She also found that commercial products containing G&+7
(Provide) or a combination of GA4+7 and BA (Promalin) nearly prevented the
development of leaf yellowing. Evidence from the bioassay and 1999 field experiments
would support examining Promalin or other similar commercial products as a source of
both GA4+, and BA for M e r complementary plant growth regulator studies in field-
grown ginseng.
Table 3.1 . Bioassay Treatment Combinations
Treaûnent No. Ethrel (mgE1) BA (rngL1) GA3 mg^-') 1 Control - - -
2 250 - - 3 375 - - 4 500 - - 5 - 1 O0 - 6 250 100 - 7 375 1 O0 "
8 500 1 O0 - 9 - - 200 IO 250 - 200 I l 375 - 200 12 500 - 200 13 - 100 200
Table 3 -2. 199 9 GA experimental spray treatments, concentrations and application dates
Treatment Concentration (mg L - ~ ) Application Date(s) 1 Control - None 2 Hand Removal - June 7 3 GA; pre-bloom 1 O0 June 7 4 GA3 bloom 1 O0 June 15,21,29 5 G h t 7 pre-bloom 1 O0 June 7 6 GA4+, bloom 100 June 15,21,29 7 GA3 50 June 7,15,21,29 8 GA3 100 June 7,15,21,29 9 GA3 200 June 7, 15,21,29 IO G&+7 50 June 7,I5,21,29 I l G&+7 100 June 7,15,21,29 12 G&+7 200 June 7, 15,21, 29
Table 3 -3. 1999 BA experimental spray treatments, concentrations and application dates
Treatment l Treatrnent 2 mg L'~ BA AppLication Date mg L" Ethrel Application Date
f Control - - - 2 Hand Removal - - June 18 3 1 O0 June 4 - - 4 100 x 2 June 4, 1 1 - - 5 200 June 4 - - 6 100 June 4 1500 June 18 7 200 June 4 1500 x 2 June 18,25 8 1 O0 June 4 3000 June 18 9 - - 1500 June 18
10 - - 1500 x 2 June 18,25 11 .. - 3000 June 18
Table 3.4. Effect of ethephon, BA, GA and various combinations on chlorophyll content of leaf discs of American ginseng (Panax quinquefolius L.).
Treatment Treatment Mean Total Chlorophyll (ch1 A + ch1 B) No. (mg L-9 (ug fkesh weight)
I Water control 1076.0 a b z 2 250 ethephon 3 375 ethephon 4 500 ethephon
100 BA 100 BA / 250 ethephon 100 BA / 375 ethephon 100 BA / 500 ethephon
Significancey L Q
200 GA 200 GA / 250 ethephon 200 GA / 375 ethephon 200 GA / 500 ethephon
S ignificanceY L Q
- Within colurnns, means followed by the same letter are not significantly different using LSD (P < 0.05)
Y - Grouped treatment means (ethephon, BA + ethephon, and GA + ethephon) analyzed by single-degree-of-keedom contrasts
NS, ** Effect not significant or significant at P 10.01 respectively
Table 3.5. Leaf chlorophyll in American ginseng (Panax quinquefolius L.) treated with GA or hand removal of inflorescences. Treatinents were applied in June, 1999 on JCK Farms 3-year-old gardens.
Treatinent Mean Chloropliyll (SPAD-502) (mg L") June 18 June 24 July 7 Iuly 22 Aug 5 Aug 24 Sept 15
Control 36.5 a " 38.4 bc 40.7 abc 36.0 c 39, t ab 36.5 bc 33.4 cd Hand Removal 36.6 a 40.0 abc 39.6 c 36.7 bc 37.2 b 34.2 cd 32.6 cd 100 GA3 pre-bloom (xl) Y 35.0 ab 39.8 abc 40.5 abc 36.1 c 37.7 b 36.2 bcd 32.9 cd 100 GA3 bloom (x3) 34.7 ab 39.7 abc 39.8 bc 37.3 abc 38.4 ab 37.3 ab 32.2 d 100 GA4t7 pre-bloom (xl ) 34.7 ab 39.6 abc 39.7 bc 36.7 bc 38.4 ab 35.5 bcd 33.0 cd 100 GA4t7 bloorn (x3) 35.7 ab 40.2 abc 41.7 ab 37.5 abc 38.9 ab 37.4 ab 37.1 ab
Control 50 GA3 (x4)
100 GA3 ( ~ 4 ) 200 GA3 (x4)
Significance L Q
38.4 bc 40.5 ab 39.9 abc 40.7 a
40.7 abc 40.3 abc 4 1 .O abc 40.0 abc
36.0 c 38.4 abc 36.9 bc 39.0 ab
36.5 bc 39.2 a 35.4 bcd 36.9 ab
Control 50 GA4t7 (x4)
100 GA4+7 ( ~ 4 ) 200 GA4+? ( ~ 4 )
Significance L Q
38.4 bc 38.3 c 39.7 abc 39.5 abc
40.7 abc 42.0 a 41.1 abc 4 1.3 abc
36.0 c 38.3 abc 39.5 a 38.9 ab
36.5 bc 35.9 bcd 33.8 d 37.5 ab
33.4 cd 34.1 bcd 35.5 abc 37.4 a
- Within columns, means followed by the same letter are not significantly different using LSD (P ' 0.05) Y - Sprays applied once (xl) on June 7,3 times (x3) on June 15,2 1,29, or 4 times (x4) on June 7, 15,21,29 - Grouped treatment means (not including hand reinoval) analyzed by single-degree-of-freedom contrasts
NS, * Effect not significant or significant at P S 0.05 respectively
Table 3.6. Berry fiesh weight fiom harvested seed heads of American ginseng (Panax quinquefolius L.) treated with GA. Treatments were applied in June 1999, on JCK Farms 3-year-old gardens-
Treatment Mean Berry Fresh Weight (g) ' (mg L-'1 Red Green C d Total
Control 3.5 abc y 3.0 cd 3.2 abc 4.3 abcd 100 GA3 pre-bloom (xl) 2.7 cd 3.2 cd 3.2 bc 4.1 de 100 GA3 bloom (x3) 3.8 a 3.8 b 3.2 abc 4.7 a 100 GA4+, pre-bloom (xl) 2.6 cd 1.8 e 3.2 bc 3.7 e 100 Ght7 bloom (fi) 3.7 ab 3.1 cd 3.4 a 4.5 abc
Control 3.5 abc 3.0 cd 3.2 abc 4.3 abcd 50 GA3 (x4) 3.0 abcd 3.8 b 3.0 c 4.5 ab 100 GA3 (x4) 2.7 bcd 4.3 a 3.1 bc 4.7 a 200 GA3 (x4) 3.1 abcd 4.2 ab 3.0 bc 4.7 a
S ignincance L NS NS NS ** Q* NS ** NS NS
Control 3.5 abc 3.0 cd 3.2 abc 4.3 abcd 50 G&+7 ( ~ 4 ) 3.4 abcd 2.8 d 3.2 ab 4.2 bcd
1 O0 G&+7 (x4) 2.6 cd 3.2 c 3.1 bc 4.1 cde 200 G&+7 (~4) 2.5 d 3.8 b 3.2 bc 4.4 abcd
Significance L NS NS NS NS Q NS NS NS NS
- Data transformed ln(ytl), transfomed data shown Y - Within columns, means followed by the sarne letter are not significantly different
using LSD (P 1 0.05) - Sprays applied once (xl) on June 7 , 3 tirnes (x3) on June 15,21,29, or 4 M e s (x4) on
June 7,15,21,29 " - Grouped GA treatrnent means analyzed by single-degree-of-fieedom contrasts NS, ** Effect not sigrilficant or significant at P 5 0.0 1 respectively
Table 3.7. Berry number fiom harvested seed heads of American ginseng (Panax quinquefolius L.) treated with GA. Treatments were applied in June 1999, on JCK Farms 3-year-old gardens.
Treatment Mean Berrv Number
(mg L-'1 Red " Green C d Total Control 100 GA3 pre-bloom (xl) 100 GA3 bloorn (x3) 100 G&+7 pre-bioom (xl) 100 GA4t7 b100m ( ~ 3 )
Control 50 GA3 (x4)
100 GA3 (x4) 200 GA3 (x4)
Significance L Q
Control 50 G&+7 ( ~ 4 )
100 G&+7 ( ~ 4 ) 200 G&+7 ( ~ 4 )
Significance " L Q
4.3 ab (72-7) 3.7 abcd (61.0) 3-4 bcd (40.7) 3.8 abcd (50.3)
4.3 ab (72.7) 4.1 abc (64.0) 3.3 cd (36.3) 3.2 d (29.0)
1889 ab 1761 abcd 1554 abcd 1792 abc 1935 a
1889 ab 1307 d 1575 abcd 1394 cd
NS NS
1889 ab 1686 abcd 1337 cd 1423 bcd
NS NS
2260 ab 2220 abc 2259 ab 1924 bc 2381 ab
2260 ab 1996 abc 2524 a 2199 abc
NS NS
2260 ab 1994 bc 1729 c 2080 abc
NS NS -
- Data transformed h(yf 1), original red berry means represented in brackets Y - Within columns, means followed by the same letter are not significantly different
using LSD (F' 1 0.05) " - Sprays applied once (xl) on June 7 , 3 times (x3) on June 15,21,29, or 4 times (x4) on
June 7, 15,21,29 " - Grouped GA treatment means analyzed by single-degree-of-fieedom contrasts NS, *, ** Effect not significant or significant at P 5 0.05 or 0.01 respectively
Table 3.8. Root fresh weight and nurnber in Amencan ginseng (Pana quinquefolius L.) treated with GA or hand removal of uiflorescences. Treatments were applied in June 1999, on JCK Farms 3 -year-old gardens.
Treatment Root Fresh Weight (g) Root
(mg L-9 Mean Total Number Control 15.1 bcdZ 2448 bc 163 ab Hand Removal 15.5 abcd 2457 bc 161 ab 100 GA3 pre-bloom (xl) Y 16.6 abc 2741 abc 167 ab 100 GA3 bloorn (x3) 17.3 a 2805 ab 163 ab 100 pre-bloom (xl) 15.9 abcd 2412 c 152 ab 100 GA4+, bloom (x3) 15.9 abcd 2670 abc 169 ab
Control 15.1 bcd 2448 bc 163 ab 50 GA3 (x4) 16.4 abcd 2528 bc 256 ab
100 GA3 (x4) 16.7 abc 2655 abc 160 ab 200 GA3 (x4) 16.9 ab 2471 bc 149 b
Significance " L NS NS NS
Q NS NS NS
Control 15.1 bcd 2448 bc 163 ab 50 GA4+7 (x4) 14.7 d 2527 bc 174 ab
100 GA417 ( ~ 4 ) 15.0 cd 2526 bc 169 ab 200 G&+7 ( ~ 4 ) 16.6 abc 2936 a 177 a
Significance " L * * NS
Q NS NS NS - Within colurnns, means followed by the same letter are not significantly different
using LSD (P 5 0.05) Y - Sprays applied once (xl) on June 7 , 3 times (x3) on June 15,21,29, or 4 times (x4) on
June 7, 15,21,29 - Grouped GA treatment means (excluding hand removal) analyzed by single-
degree-of-freedom contrasts NS, *, Effect not significant or significant at P S 0.05 respectively
Table 3.9. Occurrence of broken and new bud initials on harvested roots of American ginseng (Panax quinquefolius L.) treated with GA or hand remval of inflorescences. Treatments were applied in June 1999, on JCK Farms 3- year-old gardens and roots were harvested and observed on September 28, 1999.
Treatment Root ~ e r & n a t i n ~ Ë u d Mean Counts
(mg L-9 Broken Broken (%) New Bud InitialdRoot Control 0.02 g 2 Hand Removal 0.02 g 2 100 GA3 pre-bloom (xl) Y 0.46 d 46 100 GA3 bloom (x3) 0.70 c 70 100 GA4+, pre-bloorn (xl) 0.11 fg I l 100 G&+, b100m ( ~ 3 ) 0.18 f 18
Control 0.02 g 2 50 GA3 ( ~ 4 ) 0.69 c 69
1 O0 GA3 (x4) 0.81 b 81 200 GA3 (x4) 0.98 a 98
Significance " L ** Q **
Contro 1 50 G&+7 (~4)
1 O0 GA4+, ( ~ 4 ) '
200 GA4+7 (~4) Significance
L O
' - Withh columns, means followed by the sarne letter are not signincantly different using LSD (P 10.05)
Y - Sprays applied once (xl) on June 7 ,3 times (x?+on June 15,21,29, or 4 times (x4) on June 7, 15,21,29
" - Grouped GA treatment means (not including hand removal) analyzed by single- degree-of-freedom contrasts
** Effect significant at P 5 0.01
Table 3.10 Seed head height (seed intact and seed removed) of Amencan ginseng (Panax quinquefoZius L.) treated with GA- Measured on July 29, 1999.
Treatrnent Mean Seed Head Height (mm)
(mg L-'1 Seed Intact Seed Removed Control 17.2 e Z 12.3 d 100 GA3 pre-bloom (xl) Y 28.8 bc 100 GA3 bloom (x3) 27.0 bcd 100 G&+, pre-bloom (xl) 23.0 d 18.5 c
100 G h t 7 bloom (x3) 25.7 cd 18.7 c
Control 50 GA3 (x4)
1 O0 GA3 (x4) 200 GA3 (x4)
Significance " L
Q
Control 50 G&+7 ( ~ 4 )
1 O0 G&+7 ( ~ 4 ) 200 Gh+7 ( ~ 4 )
Significance " L Q
' - Within columos, means followed by the same letter are not signincantly different using LSD (P 5 0.05)
Y - Sprays applied once (xl) on June 7,3 times (x3) on June 15,2 1,29, or 4 times (x4) on June 7, 15,21,29
" - Grouped GA treatment rneans analyzed by single-degree-of-freedom contrasts ** Effect significant at P 1 0.0 1
Table 3.1 1. Seed head diarneter (seed intact and seed removed) of American ginseng (Panax quinquefolius L.) treated with GA. Measured on Jdy 7 and 29, 1999, respectively.
Treatment Mean Seed Head Diameter (mm) (mg L-'1 Seed Intact Seed Removed
Conbol 30.4 e z 20.8 e 100 GA3 pre-bloom (xl) Y 100 GA3 bloom (x3) 100 GF4+7 pre-bloom (xl) 100 Ght7 bloom (x3)
Control 50 GA3 (x4)
100 GA3 (x4) 200 GA3 (x4)
Significance L Q
Control 50 GA4+7 ( ~ 4 )
1 O0 G&+7 ( ~ 4 ) 200 G&+7 ( ~ 4 )
Significance L
30-4 e 37.1 a 36.6 ab 36.1 abc
30.4 e 33.0 d 34.4 bcd 37.0 a
29.3 abc 26.5 cd 25-8 cd 24.2 de
20.8 e 28.3 bcd 32.2 ab 26.5 cd
20.8 e 25.7 cd 29.2 abc 33.2 a
Q NS ** ' - Within columns, means followed by the same letter are not significantly different
using LSD (P 10.05) Y - Sprays applied once (xl) on June 7,3 times (x3) on June 15,21,29, or 4 times (x4) on
June 7, 15,21,29 * - Grouped GA treatrnent means analyzed by single-degree-of-freedom contrats NS, ** Effect not significant or s i a c a n t at P 10.01 respectively
Table 3 -12. Pedicel and peduncle length of Amencan ginseng (Panax quinquefolius L.) treated with GA. Measured on July 29 and 7, respectively.
Treatrnent Mean Maximum Pedicel Mean Peduncle
(mg L-9 Length (-1 Lent.@ (mm) Conirol 9.5 f " 128 b 100 GA3 pre-bloom (xl) Y 18.8 bc 134 ab 100 GA3 bloom (x3) 16.7 bcde 130 b 100 Ght7 pre-bloom (x 1) 13.7 e 143 ab 100 Ght7 bloorn (x3) 15.0 cde 137 ab
Conirol 50 GA3 ( ~ 4 )
1 O0 GA3 ( ~ 4 ) 200 GA3 (x4)
Significance * L
Q
9.5 f 17.2 bcde 23.7 a 18.7 bc
Control 9.5 f 128 b 50 GA4+7 ( ~ 4 ) 14.7 de 137 ab
1 O0 GA4+7 ( ~ 4 ) 17.7 bcd 136 ab 200 Ght7 ( ~ 4 ) * 19.7 b 150 a
Significance " L ** NS
Q ** NS
- Within columns, means followed by the sarne letter are not significantly different using LSD (P 1 0.05)
Y - Sprays applied once (xl) on June 7,; times (x3) on June 15,21,29, or 4 times (x4) on June 7, 15,21,29
- Grouped GA treatrnent means analyzed by single-degree-of-fkeedom contrasts NS, ** Effect not significant or significant at P 5 0.01 respectively
Table 3.1 3. Leaf chlorophyll of An~erican ginseng (Panax qirinqucfoliics L.) treated with BA, etheplion or hand removal of inflorescences. Treatmeiits were applied in June 1999, on JCK Farms 3-year-old gardens.
Treatnient Mean Clilorophyll (SPAD-502) (mg L") June 15 June 21 June 30 July 7 July 22 Aug 5 h g 1 7 Sept15
Control 36.0 a 36.1 ab 37.1 ab 37.6 a 36.1 a 37.6 a 32.6 c 30.2 abc Iland Renioval 34.9 abc 36.8 a 37.7 a 38,O a 37.8 a 37.2 a 33.6 bc 3 1.6 a
35.5 ab 35.3 bc 37.6 a 38.8 a 37.6 a 36.8 a 34.9 ab 32.8 a 34.2 bcd 36.3 ab 37.7 a 38.3 a 37.3 a 37.6 a 36.3 a 31.2 ab
C
N 00 200 BA 33.1 d 36.0 abc 36.7 abc 38.1 a 36.4 a 36.3 a 35.0 ab 30.5 ab
100 BA t 1500 ETH 33.8 cd 34.6 c 34.9 d 34.8 bc 32.0 bc 32.5 b 30.6 cde 27.3 cde 100 BA + 1500 ETH (x2) 35.7 ab 36.0 abc 35.5 cd 35.5 b 32.5 bc 28.8 cd 28.7 ef 28.4 bcd 100 BA t 3000 ETH 34.2 bcd 36.1 ab 35.7 bcd 33.8 c 30.1 d 27.9 d 28.0 f 24.0 f 1500 ETH 34.9 abc 36.4 ab 35.5 bcd 35.0 bc 33.1 b 32.2 b 30.9 cd 27.2 de 1 500 ET14 (x2) 35.3 abc 35.6 abc 36.7 abc 35.8 b 3 1.2 cd 30.5 bc 29.6 def 24.4 ef 3000 ETH 36.4 a 36.5 ab 36.9 abc 34.6 bc 30.9 cd 29.1 cd 28.0 f 26.7 def - Within columns, means followed by tlie same letter are not significantly different using LSD (P 5 0.05)
Y - Sprays applied twice (x2)
Table 3.14. Berry total fiesh weight and number fiom harvested seed heads of Amencan ginseng (Panax quinquefolius L.) treated with BA and ethephon. Treatments were applied in June 1999, on JCK Farms 3-year- old gardens.
Treatment Meau Total Berry (Red + Green + Cull) ' (mg L-9 Fresh Weight (g) Number
Control 4.7 a Y (1 13 -5) 8.2 a (3522) 100 BA 4.7 a (1 16.2) 100 BA (x2) 4.7 a (127.1) 200 BA 4.6 a (102.0) 100 BA + 1500 ETH 3.3 b (26.3) 100 BA + 1500 ETH (x2) 2.8 cd (16.3) 100 BA + 3000 ETH 2.4 d (1 1.8) 1500 ETH 3.2 b (23.9) 1500 ETH (x2) 3.1 bc (21.5) 3000 ETH 3.0 bc (19.9) 7.2 bc (1376)
z - Data transformed h(y+l), onginal means represented in brackets Y - Within columns, means followed by the same letter are not significantly different
using LSD (P ,< 0.05)
Table 3.15. Red, green and cul1 berry fiesh weight fiom harvested seed heads of American ginseng (Panax quinquefolius L.) treated with BA and ethephon. Treatments were applied in June, 1999 on JCK Farms 3-year- old gardens.
Treatment Mean Berry Fresh Weight (g)
(mg L“) Red Green Cull Control 3.5 a Y (38.2) 3.8 a (43.2) 3.5 a (32.1) 100 BA 3.7 a (46.3) 100 BA (x2) 3.6 a (64.6) 200 BA 3.4 a (32.9) 100 BA + 1500 ETFT 0.9 bc (2.0) 1 O0 BA i- 1500 ETH (x2) 0.9 bc (2.0) 100 BA i- 3000 ETH 0.8 bc (1.6) 1500 ETH 0.8 bc (1.4) 1500 ETH (x2) 0.7 c (1.1) 3000 ETH 1.2 b (2.7) 2.2 b (8.1) 2.3 c (9.2) ' - Data transforrned ln(y+l), original means represented in brackets Y - Within columns, means followed by the same letter are not significantiy different
using LSD (P 5 0.05)
Table 3.16. Red, green and cul1 berry number fiom harvested seed heads of American ginseng (Panm quinquefolius L.) treated with BA and ethephon. Treatïnents were applied in June, 1999 on JCK Famis 3-year-old gardens.
Treatment Mean Berry Nuniber ' (mg L-'1 Red Green Cul1
Control 4.3 a Y (85.8) 6.2 a (490.0) 8.0 ab (2946.5) 100 BA 4.5 a (1 15.5) 6.2 a (501.8) 7.9 ab (2741 -5) 100 BA (x2) 4.5 a (148.5) 6.1 a (439.3) 7.7 b (2308.3) 200 BA 4.2 a (74.8) 6.1 a (449.0) 8.2 a (3509.3) 100 BA + 1500 ETH 1.5 bc (6.0) 4.7 b (1 14.3) 7.3 c (1486.8) 100 BA + 1500 ETH (x2) 1.7 bc (7.3) 3.9 cd (57.0) 6.9 d (1030.0) 100 BA + 3000 ETH 1.7 bc (6.3) 3.8 d (51.0) 6.3 e (625.3) 1500 ETH 1.7 bc (5-0) 4.4 b (90.0) 7.3 c (1519.5) 1500 ETH (x2) 1.3 c (4.0) 4.5 b (85.8) 7.3 c (1439.8) 3000 ETH 2 .1b (8.3) 4.3 bc (76.8) 7.1 cd (1291.0) - Data transformed ln(y+l), onginal means represented in brackets
Y - Within columns, rneans followed by the sarne letter are nct significantly different using LSD (P 1 0.05)
Table 3.17. Root fresh weight and number in Amencan ginseng (Pana quinquefolizrs L.) treated with BA, ethephon and hand removal of inflorescences. Treatments were applied in June, 1999 on JCK Farms 3-year-old gardens.
Treatment Root Fresh Weight (g) Root
(mg L-9 Mean Total Nurnber Control 16.3 bc 23 10 bcd 144 abc Hand Removal 17.6 ab 2575 a 147 abc 100 BA 15.8 cd 2568 ab 166 a 100 BA (x2) 16.2 bc 2070 de 129 cd 200 BA 15.9 bcd 2449 abc 155 ab 100 BA + 15G0 ETH 15.9 cd 2240 cd 142 bc 100 BA + 1500 ETH (x2) 14.9 cd 2308 bcd 155 ab 100 BA + 3000 ETH 14.5 d 2212 cd 153 ab 1500 ETH 16.1 bcd 2447 abc 153 ab 1500 E X (a) 18.3 a 1879 e 108 d 3000 ETH 16.0 bcd 2134 de 134 bc ' - Within columns, means followed by the same letter are not significantly different
usuig LSD (P 1 0.05)
Leaf Disc Bioassay - Mean Total Chlorophyll
200 300 400 500
Ethephon (rnglL)
Ethephon
B A + ETH A GA+ ETH
--- Poly. (Ethephon)
Poly. (BA + ETH) - . - . Poly. (GA + ETH)
Figure 3.2. Regression analysis of the effect of etheplion bioassay treatmeds on extractable total leaf chlorophyll (CHL A+B) of leaf discs of 3-year-old Panax quinqicefoliics L. Numerical data presented in Table 3.4. R2 = 0.83, CV = 7.90.
GA3 SPAD Measurernents - 1999
i + control
j-i-50 l
i+ioo i*200
Date
Figure 3 -3. SPAD-502 chlorophyll of leaves of 3-year-old Panax guinquefolius L. over the 1 999 growing season, treated with 50, 1 00 and 200 mg/L GA3.
GA4+7 SPAD Measurements - 1999
i
i 29 ,
31-May 22-Jun 14-Jul 5-Aug 27-Aug 18-Sep
Date
Figure 3.4. SPAD-502 chlorophyll of leaves of 3-year-old Panax quinquefolius L. over the 1999 growing season, treated with 50, 100 and 200 mg/L GA4+7.
Mean Broken Buds per Root
Figure 3.5. Correlation between broken bud domancy and new bud initials per root at harvest on roots of P a n a quinquefolius L. plants sprayed in 1999 with O, 50, 100 and 200 mg/L GA3. Each point represents 10 roots, n = 48 for correlation anaiysis.
Mean Broken Buds per Root
Figure 3.6 Correlation between broken bud dormancy and new bud initials per root at harvest on roots of Panax quinquefolius L. plants sprayed in 1999 with 0,50, 100 and 200 mg& GA4+7. Each point represents 10 roots, II = 48 for correlation analysis.
Maximum Pedicel Length (mm)
Figure 3.7a. Correlation between maXLmum pedicel length and bare seed head height of inflorescences of Panax quinquefolius L- plants sprayed in 1999 with 0,50, 100 and 200 m g / ' GA3.
5 i
5 I O 15 20 25 30 35 1 Maximum Pedicel Length (mm)
6 , I
i I
Figure 33%. Cordation between maximum pedicel Iength and bare seed head height of inflorescences of Panax quinquefolius L. plants sprayed in 1999 with 0,5O, 100 and 200 mg/L GA4+7.
Maximum pedicel length (mm)
Figure 3.8a. Correlation between maximum pedicel length and bare seed head diameter of inflorescences of Panax quinquefolius L. plants sprayed in 1999 with 0,50, LOO and 200 mg/L, GA3.
! i
5 10 15 20 25 30 35 i Maximum Pedicel Length (mm) I
Figure 3.8b. Correlation between maximum pedicel length and bare seed head diameter of inflorescences of Panax quinquefolius L. plants sprayed in 1999 with 0,50, 100 and 200 mg/L GA4+7.
Plate 3.1 Leaf colour variation with field application of E*hel (A) and leaf discs displaykg five colour categories (A - maroon, 8 - dark green, C - light green, D - red, and E - orange/yeiiow) used for SPAD vs. total leaf chlorophyll extractions (B).
Plate 3.1a.
Plate 3.1 b.
140
Plate 3.2 Bioassay experiment Petri plates showing variation in leaf chlorosis of dark incubated 3-year-oid Panax uinquefoZius L. leaf discs treated 9 with 750 (A) and 1500 (B) mg L- ethephon.
Plate 3.2a.
Plate 3.2b.
Plate 3.3 Red and green seed produced by 3-year-old Panax quinquefolius L. when treated with O (control), 100 x 1 @re-bloom) , 100 x 3 (bloom) and 100 x 4 mg L" GAJ (A) and seed head with characteristic butterfly shaped seed (B). Note that green seed takes on a pale pink-orange hue towards end of growing season.
Plate 3.3a
Plate 3.3b.
144
Plate 3 -4 Range of perenating bud broken dormancy of Panax quinquefolius L. roots treated with GA.
Plate 3.5 Formation of new bud initials on perenating buds of Panax quinquefolius L. with loss of dormancy.
Plate 3.4.
Plate 3.5.
Plate 3 -6 Increase in seed head height, diameter and pedicel length of inflorescences of 3-year-old Pana quinqzrefolius L. treated with 100 x 4 mg L-' GA3 and G&+7.
Plate 3.6.
GENERAL DISCUSSION
An important practice of ginseng (Panax quinquefolius L.) crop production
currently used by Ontario growers involves the removal of developing flowers, f i t s and
seeds for subsequent root yield increase. In some plant species, preventing reproductive
growth alIows the plant to partition photosynthates back into the growth of the vegetative
and root portions of the plant (Nagarajah, 1975; Cockshull and Hughes, 1968). Manual
@and) removal of the ginseng inflorescences Unproves root fiesh weights of 3-year-old
ginseng by 25-30% (Proctor et ai., 1999).
Because dried root is sold and exported prirnady on an individual root weight
basis, larger root size resdts in greater marketsbility and economic return. Although
cultivating the crop for four and five years can result in substantially larger root sizes
compared to the 3-year current Ontario industry standard, it dso greatly increases the
potential for crop loss through disease and other factors. Ginseng is a crop requiring
intensive agricuitural inputs including acreage, soi1 treatments, shade structures, chemical
requirements, and labour. Hand rernoval of the inflorescences alone costs the ginseng
grower $2500 per hectare. One way to reduce inputs into the crop could be to develop
less expensive, chemical treatments to replace hand removal.
Proctor (199a) first suggested that ethephon might be an efïéctive abscission
agent for ginseng. Subsequent research has shown foliar sprays of Ethrel as a source of
ethephon, in small plot evaluations, induces floraI abscission, with subsequent hcreases
in root fiesh weight comparable to hand removal (Fiebig, 1999). Through histological
studies, Fiebig (1999) showed that application of ethephon at 1500 mg L - ~ induced
quicker formation of abscission zones within 24 hours of treatrnent. However, ethephon
concentrations required to induce these responses are ofien accompanied by premature
senescence and abscission of the Ieaves in the whole plant.
The objectives of this study were 1) to evaluate Ethrel as a source of ethephon and
compare field-scale rates of EthreI application as an dternative to manual inflorescence
removal in ginseng by determining its effects on leaf senescence, berry removal and root
yield, and 2) to examine how to improve efficacy, and rninimize premature senescence
effects of ethephon through the use of other exogenous sources of plant growth regulators
such as GA and BA.
FoIiar sprays of Ethrel reduced leaf chiorophyll (SPAD) of field-grown ginseng.
This is consistent with the results of the bioassay, which demonstrated îhat mean total
CHL (CHL A + CHL B) content of the leaf discs decreased with increasing concentration
of ethephon. In this investigation the leaves of Ethrel-keated plants were noticeably less
green, with more yellow, orange and red pigmentation as a result of increasing
concentration. It was determined fiom the growers' comments that, based on the visual
appearance of the crop, Ethrel sprays above 5.0 L acre'' displayed unacceptable levels of
leaf damage &er four to six weeks. Split applications of moderate concentrations of
Ethrel were more effective at maintaining leaf chlorophyll than comparable single
applications. By determining a quadratic relationship (r2 = 0.98) between leaf colour and
leafchlorophyll content, it is now possible to relate the visible effects of the Ethrel sprays
directly to leaf chlorophyll darnage.
Berry fiesh weights and counts were dso reduced as a result of the Ethrel sprays.
Over al1 1999 locations, 5.0 L acre-' removed 76-94% red beny counts and 82-97% of
red berry fiesh weight. High removal levels as a result of the field sprays are attributed to
high ethylene evolution fiom the seed heads (see Ch 2, ethylene evolution) on exposure
to Ethrel. Root fiesh weights were also reduced with increasing concentration of EthreI.
Increases in root fiesh weight as a result of either hand or Ethrel-induced removal were
seen at only two locations, and did not approach the same degree of root fkesh weight
increase seen in previous investigations. Similar to the findings of Fiebig, (1999), Ethrel
applied between 5.0 to 10.0 L acre-' was the most successful for floret and berry rernoval
cornpared to hand removal, but was not effective at similarly increasing root fkesh
weight. This may be a reflection of the loss of leaf chlorophyll seen with these
concentrations. Split applications of Ethrel at moderate to high concentrations (7.5 to
10.0 L acre-') resulted in sunilar berry removal but higher root yields compared to single
applications.
The 1999 field-scale treatrnents included a wide range of Ethrel concentrations
(0.0 to 10.0 L acre-') applied in water volumes of 38 to 460 L acre-' (8.3 to 10 1 gal
acre"), encompassing the recornmendations of Fiebig (1999). The most comparable
treatment to her results in terms of increasing root yield compared to the control and hand
removal best results were seen at Rainey Ginseng, where Ethrel at 2.5 L acre'' was
applied in 460 L acre'' (101 gal acre-') water. However, none of the sprays resulted in
comparable increases in root fiesh weight. Lack of appropriate root yield increases with
hand removal over most locations in 1999 provides evidence that environmental factors
such as high temperature and Iow rainfdl affect root development in ginseng. Similar
Iack of response with Ethrel sprays, coupled with high levels of leaf darnage suggests that
the effect of Ethrel under variable environmental conditions should be investigated before
commercial recommendations are made available. Ethrel applied in sirnilar hot, dry
conditions as the 1999 growing season may induce endogenous ethylene prgduction in
the stressed plant, in addition to the autocatalysis of ethylene due to the Ethrel
applications. Since Ethrel applied at 5.0 L acre-' or higher under these conditions has
detrimental effects on root weight and root number, then the highest Ethrel
concentrations should be 5.0 L acre-' under such conditions.
Application of f o l k sprays of GA increased seed head height and diameter,
maximum pedicel length, and seedless green berry number. Although GA3 and
showed sirnilar promoting effects on seed head expansion and parthenocarpic green berry
development, GA4+7 also demonstrated maintenance of leaf chlorophyil, increased root
fiesh weight, and a 50% lower incidence of peremating buds breaking dormancy.
Contrary to the 1998 results of the bioassay, field-applied G&+7 as a source of GA delays
leaf chlorosis. Previous studies have suggested that G& may have additional and
potentially greater biological effects (Swain and Olszewski, 1996), than most of the
approximately 100 identified plant and fungi-based gibberellins (Sponsel, 1995). Results
fiom the addition of GA4+7 to the 1999 field experiments confirm this. Inclusion of
Ghi7 in future bioassay evaluations will provide more information on maintenance of
ginseng leaf chlorophyll in excised leaf tissue. When applied as a spray, sprays
appear to have greater application in ginseng production compared to GA3. Further
evaluation of the effects of GA4+; in combination with Ethre! may allow growers to
improve spray coverage of the infiorescences for better abscission response and promote
root development while rninimizing the senescence effects of the Ethrel treatments.
Mthough preliminary bioassay results showed that BA in combination with
ethephon maintained leaf chlorophyll in excised leaf tissue better than ethephon alone,
pre-treatment of the ginseng plant with BA prior to ethephon treatment did not show
simila. positive results. A nurnber of limitations in the BA study led to the results being
inconclusive. The analysis was only done in 1999, it was performed as a replicated
experiment but did not combine al1 possible treatment combinations, and the source of
BA used in the bioassay was formulated in a carrier with apparent toxic effects on the
leaves when applied as a field spray. This study needs to be repeated over multiple years
with carefid atîention to experimental design, timing of the sprays and BA source before
any conclusive results about BA effects on retarding leafsenescence c m be stated.
Through this research, guidelines for field-scale application of Ethrel as a seed
removal agent on Amencan ginseng have been developed. Ethrel or any other source of
ethephon, is not currently registered for minor-use application in ginseng, and several
factors must still be taken into consideration before commercial recommendations can be
hplemented; including the residual effects of ethephon on plant regrowth, return bloom
and seed germination. Fiebig (1 999) found qualitatively that ethephon applications
showed residual effects on the next year's shoot growth and inflorescence development.
Until sufficient studies on these factors have been completed, application of ethephon on
crops required for seed harvest is not recommended. With continued research and
evaluation the abscission effects of ethephon, and the encouraging prelirninary results of
the G&+, sprays, there exists the potential for an important integrated management too!
for Ontario ginseng production in the future.
LITERATURE CITED
Abdel-Gawad, H. and R. J. Romani. 1974. Hormone-induced reversal of colour change and related respiratory effects in ripening apricot b i t s . Physiol. Plant. 32: 161- 165.
Abeles, F. B. 1969. Abscission: Role of ceildase. Plant Physiol. 44:447-452.
Abeles, F. B. 1973. Ethylene in Plant Biology. Academic Press, New York.
Abeles, F. B. and R. E. Holm, 1966. Enhancement of RNA synthesis, protein synthesis and abscission by ethylene. Plant Physiol. 4 1 : 1337- 1 342.
Abeles. F. B. and G. R Leather. 1971. Abscission control of cellulase secretion by ethylene. Planta 97:87-9 1.
Abeles, F. B., J, H. Ruth, L. E. Forrence, and G. R. Leather. 1972. Mechanisms of hormone action. Use of deuterated ethylene to rneasure isotopic exchange with plant material and the biological effects of deuterated ethylene. Plant Physiol. 49:669-67 1.
Abeles, F. B., G. R. Leather, L. E. Forrence, and L. E. Craker. 1971. Abscission: regdation of senescence, protein synthesis, and enzyme secretion by ethylene. HortScience 6:371-376.
Abeles, F. B., P. W. Morgan, and M. E. Saltveit Jr. 1992. Ethylene in Plant Biology, znd ed. Academic Press, Inc. San Diego, California.
Adams, D. 0. and S. F. Yang. 1977. Methionine metabolism in apple tissue. Implication of s-adenosylmethionine as an intermediate in the conversion of methionine to ethylene. Plant Physiol. 60:892-896.
Adams, D. 0. and S. F. Yang. 1979. Ethylene biosynthesis: identification of 1- aminocyclopropane- 1-carboxyiic acid as an intermediate in the conversion of methionine to ethylene. Proc. NatI. Acad. Sci. USA 83:7755-7759.
Addicott, F. T. 1965. Physiology of abscission. p. 1094-1 126. Ln: W. Ruhland (ed.). Encyclopedia of Plant Physiology. Vol. 15, Part 2. Springer-Verlag, Berlin.
Addicott, F. T. (Ed.). 1982. Abscission. University of California Press, Berkeley.
Adedipe, N. O., L. A. Hunt, and R. A. Fletcher. 1971. Effects of benzyladenine on photosynthesis, growtti, and senescence of the bean plant. PhysioI. Plant. 25:151- 153.
Anon. 1998. Ginseng Production Guide for Commercial Growers, 1998 Edition. Associated Ginseng Growers of British Columbia, British Columbia Ministry of Agriculture, Fisheries and Food, Victoria.
Anon. 1999. Publication 6 10, 1999-2000 Ginseng Pest Controi Recornmendations. Ontario Ministry of Agriculture, Food and Rural Affairs.
Anon. 2000. 1999 Annual Report to Ontario Agricultural Services Coordinating Committee, Ontario Horticdtural Crops Research and Services Committee. Jan 14,2000. Ontario Ministry of Agriculture, Food and Rural Mairs.
Apelbaum, A. and S. F. Yang. 198 1. Biosynthesis of stress ethylene induced by water deficit- Plant Physiol. 68594-596.
Argus, G. W. and D. J- White- 1982. Atlas of the Rare Vascular Plants of Ontario. Botany Division, National Museum of Natural Sciences, Ottawa.
Amon, D. 1. 1949. Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Betu vulgaris. Plant Physiol. 24: 1-1 5.
Bai, D., J. Brandle, and R. Reeleder. 1997. Genetic diversity in North Arnerican ginseng (Panax quinquefolius L.) grown in Ontario detected by RAPD analysis. Genome 40:lll-115.
Beevers, L. 1966. Effects of gibberellic acid on the senescence of leaf discs of Nasturtium (Tropaeolum rnajus) Plant Physiol. 4 1 : 1074-1 076.
Beevers, L. 1968 .Growth regulator control of senescence in leaf discs of nasturtiurn (Tropaeolzrm majus), p. 14 17-143 5. In: F. Wighûnan and Ci. Setterfield (eds.). Biochemistry and Physiology of Plant Growth Substances. Runge Press Ltd., Ottawa.
Ben-Tal, Y. 1990. Effects of gibberellin treatments on ripening and berry drop fiom Thompson Seedless grapes. Amer. J, Enol. Vitic. 4-1:142-146.
Bet~; J. M., A. H. Der Morderosian and T. M. Lee, 1984. Continuing studies on the ginsenoside content of commercial ginseng products by TLC and HPLC. II, p. 65- 83. In: J.T.A. Proctor (ed.). Proc. 6" North American Ginseng Conference, Guelpii, ON, June 1984, Guelph, Ontario, Canada.
Beyer, E. M. 1973. Abscission. Support for a role of ethylene modification of auxin transport. Plant Physiol. 52: 1-5.
Beyer, E. M. Jr. 1975. Abscission: The initial effect of ethylene is in the leaf blade. Plant Physiol. 55323-327.
Beyer, E. M., Jr. and P. W. Morgan. 1971- Abscission: the role of ethylene modification of auxin transport. Plant Physiol- 48:208-212.
Beyer, E. M., Jr. and P. B. Sweetser. 1974. Abscission: the primary site of action of ethylene is in the leafblade. Proc. Beltwide Cotton Prod. Res. Conf. p65.
Beyer, E. M., Jr., P. W. Morgan, and S. F. Yang. 1984. Ethylene, p. 1 1 1 - 126. In: M.B. Wilkins (ed.). Advanced Plant Physiology. Pitman, London.
Biggs, R. H. 197 1. Citrus abscission. Hodcience 6:3 88-392.
Blomstrom, D. C. and E. M. Beyer, Jr. 1979. Pea seedlings convert ethylene to ethylene glycol. Plant Physiol. 63(suppl.):67.
Blumenfeld, A., E. Epstein, and Y. Ben-Tal. 1978. Ethylene treatrnent and abscission of olive fruits. HortScience 13:47-48.
Boehm, C. L., H. C. Harrison, G. Jung, and J. Nienhuis. 1999. Organization of American and Asian ginseng germplasm using randomiy amplified polyrnorphic DNA (RAPD) markers. J. Amer. Soc. Hort. Sci. 124:252-256.
Boller, T., R. C. Herner, H. Kende, 1979. Assay for and enzymatic formation of an ethylene precursor, 1 -arninocyclopropane- 1 -carboxylic acid. Planta 145 :293-303.
Bonghi, C., N. Rascio, A. Ramina, and G. Casadoro. 1992. Cellulase and poiygalacturonase involvement in the abscission of leaf and h i t explants of peach. Plant Mol. BioL 20:839-848.
Borochov, A. m d W. R. Woodson. 1989. Physiology and biochemistry of flower petal senescence. Horticultural Reviews 1 1 : 15-43.
Brault, M. and R. Maldiney. 1999. Mechanisms of cytokinin action. Plant Physiology and Biochemistry 3 7:403-4 12.
Bruinsrna, J. 196 1. -4 comment on the spectrophotometnc determination of chlorophyll. Biochim. Biophys. Acta 52576-578.
Brummell, D. A., C. C. Lashbrook, and A. B. Bennett. 1994. Plant endo-P-1,4- glucanases: Structure, properties and physiological function. Amer. Chem. Soc. Symp. Ser. 566: 100- 129.
Bukovac, M. J. 198 1. Performance of daminozide and ethephon when applied in low- volume sprays to s o u and sweet cherry. Acta Hort. 120:25-29.
Burdon, J. N. and R. Sexton. 1993. Ethylene CO-ordinates petal abscission in red raspberry (Rubus idaeus L.) flowers. Annals of Botany 72:289-294.
S. P. 1962. The physiology of ethylene formation. AMU. Rev. Plant Physiol. 13 :265-302.
S. A. and E. A. Burg. 1962. Role of ethylene in fruit ripening. Plant Physiol. 37:179-189.
S. A. and E. A. Burg. 1965a. Relationships between ethylene production and ripening in bananas. Bot. Gaz. 126:200-204.
S. A. and E. A. Burg. 1965b. Ethylene action and the ripening of h i t s . Ethylene influences the growth and deveIopment of plants and is the hormone which initiates fruit ripening. Science 148: 1 190- 1 196.
Burns, J. K., C. J. Naim, and D. J. Lewandowski. 1995. Ce11 wall hydrolase activity and cellulase gene expression during abscission of 'Valencia' citms fruit and leaves. Proc. Fla, State Hort. Soc. 108:254-258.
Burns, J. K., D. J. Lewandowski, C. J. Naim, and G. E. Brown. 1998. Endo-1'4-B- glucanase gene expression and cell wall hydrolase activities during abscission of 'Valencia' orange. Physiol. Plant. 102: 217-225.
But, P. P. H., S. Y. Hu, and H. Cao. 1995. The ginseng plant: products, and quality, p. 24- 34. In: W.G. Bailey, C. Whitehead, J.T.A. Proctor, and J.T. Kyle (eds.). Proc. Int. Ginseng C o d Vancouver 1994, Canada.
Butler, R. D. and E. W. Simon. 1970. Ultrastructural aspects of senesence in plants. Adv. Geron. Res. 3:73-129.
Carpenter, S. and G. Cottarn. 198 1. Growth and reproduction of Arnerican ginseng (Panax quinquefolius) in Wisconsin, U.S.A. Cm. J. Bot. 60:2692-2696.
Chacko, E. K., R. R. Kohli, and G. S. Randhawa. 1972. Studies on the effect of 2- chloroethane phosphonic acid (Ethrel) on mango (Mnngzifera indica L.). 1. FIower induction in "Off' year in Langra trees. Indian J. Hortic. 29: 1-4.
Chacko, E. K., R. R. Ko hli, R. Dore S warny, and G. S. Randhawa. 1 974. Effect of 2- cliloroethylphosphonic acid on flower induction in juvenile mango (Margzyera indica) seedlings. Physiol. Plant. 32: 1 88-1 90.
Chakroborty, M. K., S. R. Prabhu, and T. K. Smanarayama. 1979. Effect of Ethrel on ripening, curing and physiochemical characteristics of flue-cured tobacco. Indian J. Agric. Sci. 49520-525.
Charron, D. and D. Gagnon. 199 1. The demography of northern populations of Pana quinquefolium (Amencan ginseng). J . Ecology 79:43 1-445.
Cheung, K. S., H. S. Kwan, P. P. H. But, and P. C. Shaw. 1994. Pharmacognostical identification of Amencan and Oriental ginseng roots by genomic finger-printing using arbitrarily primed polymerase chah reaction (AP-PCR). :wrnal of Ethnopharmacology 42:67-69.
Chin, T. Y. and 3- A. Lockhart. 1965. Translocation of applied gibberellin in bean seedlings. Amer. J. Bot. 52:828-833.
Cochran, H. L. 1936. Some factors influencing g-rowth and fruit setting in the pepper (Capsimm fiutescens L .). Corne11 Agricultural Experiment Station, Memoir 1 90.
Cockshull, K. E. and A. P. Hughes. 1968. Accumulation of dry matter by Chrysanthernurn rnorifolii after flower removal. Nature 2 1 7:979-980.
Congleton, W. F, 1978. Effects of transpIanting date, variety, nitrogen rate and ethepbon on yield, quality, sugar and alkaloid concentrations, and harvest period on flue- cured tobacco. MSc thesis, North Caroha State Univ., Rdeigh, N. C.
Cooke, A. R. and D. 1. Randall. 1968.2-Haioethanephosphonic acids as ethylene releasing agents for the induction of flowering in pineapple. Nature 2 1 8 :974-975.
Coombe, B. G. 1976. The Development of Fleshy Fruits, p. 507-528. In: W. R. Briggs, P. B. Green and R. L. Jones (eds.). Annuai Review of Plant Physio!ogy and Molecular Biology. Annual Reviews Inc. Pa10 Alto, California. Vol. 27.
Crane, J. C. 1964. Growth substances in fruit setting and development. Annu. Rev. Plant Physiol, l5:303-326.
Crane, J. C., B. T. Iwakira, and T. S. Lin. 1982. Effects of ethephon on shell dehiscence and flower bud abscission in pistachio. EortScience 17:383-384.
Davies, P. J. 1995. The plant hormones: their nature, occurrence, and functions, p. 1-38. In: P.J. Davies (ed.). Plant Hormones: Physiology, B iochemistry and Molecular Biology. znd ed. Kluwer Acadernic Publishers, Netherlands.
Davies, F. S.' W. C. Cooper, and R. E. Holm. 1976. The effect of four abscission chernicals on orange h i t and leaf ethylene prociuction. J. Amer. Soc. Hort. Sci. 101:651-653.
Devlin, R. M. and E, Demoranville. 1970. Influence of 2-chloroethylphosphonic acid on anthocyanin formation, size and yield in Vacciniurn macrocarpon cv. Early B lack. Physiol. Plant. 23 : 1 13 9-1 143.
Dornir, S. C . and C. L. Foy. 1976. Effect of ethephon on ripening, curing and chernical constituents of flue-cured tobacco. Tob. Sci. 20: 158-1 62.
Dostal, Ei. C. and A. C. Leopold. 1967. Gibberellin delays ripening of tomatoes. Science 158:2579-1580.
Duke, J. A. 1989. Ginseng: a concise handbook. Reference Publications, Inc., Algonac MI.
Dunster, K. W., R. A. Fosse, J. D, Lavoy, and P. A, Jarinko. 1980. Proc, Beltwide Cotton Prod. Res. Conf., Nat. Cotton Council, Memphis, Tem 38 1 12, USA.
Dwyer, L., M. Tollenaar, and L. Houwing. 1991. A nondestructive method to rnonitor leaf greenness in corn. Cam J. Plant Sci. 71 :505-509.
Eaton, F. M. 1955. Physiology of the Cotton plant. Annu. Rev. Plant Physiol. 6:299-328.
Eisinger, W. 1977. Role of cytokinins in carnation flower senescence. Plant Physiol. 59:707-709.
Epstein, E., 1. Klein, and S. Lavee. 1977. The fate of 1,2-'4~-chloroethyl-phosphonic acid (ethephon) in olive (Olea europaea). Physiol. Plant. 3933-37.
Emest, L. C . and J. G. Valdovinos. 1971. Replation of auxh levels in Coleus blumei by ethylene. Plant Physiol. 48:402-406.
Evans, B. 2995. Ginseng and the new world order, p. 309-3 12. In: W.G. Bailey, C. Whitehead, J.T.A. Proctor, and J.T. Kyle (eds.). Proc. Int. Ginseng Conf. Vancouver 1994, Canada.
Evans, J. T. 1 983. Nitrogen and photosynthesis in the flag leaf of wheat (Triticum aestivum L.). Plant PhysioL 72297-302.
Evensen, K. B. 199 1. Ethylene responsiveness changes in Pelargonium x domesticurn florets. Physiol. Plant. 82:409-412.
Evensen, K. B., A. M. Page and A. D. Stead. 1993. Anatomy of ethylene-induced petal abscission in Pelargonium x hortorum. Annals of Botany. 7 1 559-566.
Ferrarese, L., L. Trahotti, P. Moretto, P. P o l v e ~ o de Laureto, N. Rascio, and G. Casadoro. 1995. Differential ethylene-inducible expression of cellulase in pepper plants. Plant Mol. Biol. 29:73 5-747.
Fiebig, A. E. 1999. Inflorescence development of American ginseng: abscission zones and ethephon. M.Sc Thesis, Univ. of Guelph, Guelph, Ontario.
Fletcher, R. A. 1969. Retardation of leafsenescence by benzyladenine in intact bean plants. Planta 89: 1-8.
Fletcher, R. A., G. Hofstra, and N. O. Adedipe. 1970. Effects of benzyladenine on bean leaf senescence and the translocation of 14~-assi~i lates . Physiol. Plant. 23: 1 144- 1148.
Fletcher, R. A. and D. J. Osborne. 1965. Regulation of protein and nucleic acid synthesis by gibberellin during leaf senescence. Nature 207: 1 176-1 177.
Fletcher, R. A. and D. J. Osborne. 1966a. Gibberellin, as a regulator of protein ribonucleic acid synthesis during senescence in Ieafcells of Taraxucum oflcinde. Can. J. Bot. 44:739-745.
Fletcher, R. A. and D. J. Osborne. 1966b. A simple bioassay for gibberellic acid. Nature 2 1 1 :743-744.
Garman, H. 1898. Ginseng, it's nature and culture. Univ. of Kentucky Agr. Bul. 78.
Gates, P., J. N. Ya~rood, N. Harris, M. L. Smith, and E. Boulter. 1981. Cellular changes in the pedicel and peduncle during flower abscission in Vicia fuba, p. 299-3 16. in: Thompson R. (ed.). Vicia faba: physiology and breeding. The Hague, Martinus Nijhoff, Dordrecht, Netherlands,
Giaquinta, R. and E. Beyer, Jr. 1977. 14cz~4: distribution of 14~-labe1ed tissue metabolites in pea seedlings. Plant Ce11 Physiol. 18: 14 1-148.
Goeschl, J. D. and S. J. Kays. 1975. Concentration dependencies of some effects of ethylene on etiolated pea, peanut, bean and cotton seedlings. Plant Physiol. 55~670-677.
Goldschmidt, E. E. 1974. Hormonal and molecular regdation of chloroplast senescence in Ciirus peel, p. 1027-1 033. In: 8fi International Conference on Plant Growth Substances, Tokyo, 1973. Hirokawa Publishing Co., Tokyo.
Goldschmidt, E. E. 1980. Pigment Changes Associated with Fruit Maturation and Their Control, p. 207-217. In: K. V. Thimann (ed.). Senescence in Plants, CRC Press Inc., Boca Raton, Florida.
Goldthwaite, J. J. 1987. Hormones in plant senescence, p. 553-573. In: P. J. Davies (ed.). Plant Hormones and their Role in Plant Growth and Development. Martinus Nij hoff, Dordrecht, Netherlands.
Goode, R. C., D. Chatha, and J. Baker. 1995. The effects of ginseng on physical performance in human subjects, p. 3 13-3 17. In: W.G. Bailey, C. Whitehead, J.T.A. Proctor, and J.T. Kyle (eds.). Proc. Int. Ginseng Conf. Vancouver 1994, Canada.
Graebe, J. E. 1987. Gibberellin biosynthesis and control. Annu. Rev. Plant Physiol. 38: 4 1 9-465.
Greenberg, J., R. Goren, and J. Riov. 1975. The role of cellulase and polygalacturonase in abscission of young and mature Shamouti orange k i t s . Physiol. Plant. 34: 1-7.
Greene, D. W., W. R. Autio, and P. Miller. 1990. Thinning activity of benzyladenine on several apple cuitivars. J. Amer. Soc. Hort. Sci. 115594-400.
Hale, C. R., B. G. Coombe, and J. S. Hawker. 1970. Effects of ethylene and 2- chloroethylphosphonic acid on the ripening of grapes. Plant Physiol. 45:620-623.
Halevy, A. H., D. R. Dilley, and S. H. Wittwer. 1966. Senescence inhibition and respiration induced by growth retardants and N~-benzyladenine. Plant Physiol. 41 :1085-1089.
Halevy, A. H., C. S. Whitehead, and A. M. Kofranek. 1984. Does pollination induce corolla abscission of cyclamen flowers by promoting ethylene production? Plant Physiol. 75: 1090-2 093.
Hall, W. C. 1952. Evidence on the auxin-ethylene balance hypothesis of foliar abscission. Bot. Gaz. 1 13 :3 10-322.
Hall, W. C . and P. W. Morgan. 1964. Auxin-ethylene interrelationships, p. 727-745. In: J. P. Nitsch (ed.). Régulateurs Naturels De La Croissance Végétale. Centre National De La Recherche Scientifique, Paris.
Hall, W. C., G. B. Truchelut, C. L. Leinweber, and F. A. Herrero. 1957. Ethytene production by the Cotton pIant and its effect under experimental and field conditions. Physiol. Plant. 10:306-3 17.
Han, S. S. 1997. Preventing postproduction leaf yellowing in Easter My. J. Amer. Soc. Hoa. Sci. 122969-872.
Haisch ten Cate, Ch. H. and J. Bruinsma. 1973. Abscission of flower bud pedicels in Begonia. 1. Effects of plant growth regulating substances on the abscission with intact plants and with expla~ts. Acta Bot. 22:666-674.
Hanisch ten Cate, Ch. H., J. J. L. van der PIoeg-Voogd, and J. Bruinsma. 1973. Abscission of flower bud pedicels in Begonia. III. Anatornical pattern of abscission. Acta Bot. 22:68 1-685.
Hiïnisch ten Cate, Ch. H., J. van Netten, J. F. Dortland, and J. Bruinsma. 1975. Ce11 wall solubilization in pedicel abscission of Begonia flower buds. Physiol. Plant. 3 3 :276-279.
Hanson, A. D. and H. Kende. 1976. Methionine metabolism and ethylene biosynthesis in senescent flower tissue of moniing glory. Plant Physiol. 57528-537.
Harding, A. R. 1908. Ginseng and Other Medicinal Plants. A. R. Harding, Columbus, O hio.
Hartmann, H. T,, K. W. Ontz, and J. A. Beutel. 1980. Olive prodution in California. Univ, of California, Davis. Leafiet 2474.
Heinicke, A. J. 1 934. Photosynthesis in apple Ieaves during late fa11 and its si@cance in annual bearing. Proc. Amer. Soc. Hort. Sci, 22:77-85,
Hoad, G. V. 1995. Transport of hormones in the phloem of higher plants. Plant Growth Regdation 16: 173-1 82.
Hobbs, C. 1996. The Ginsengs - A User's Guide. Botanica Press, Santa Cruz, California.
H o h , R. E. and W. C. Wilson- 1977. Ethylene and finit loosening from combinations of Ciirus abscission chemicals. J. Amer. Soc. Hortic Sci 102576-579,
Hong, Y., M- Wang, L. Peng, and X. Zhao. 1995. The deveIopment of ginseng cultivation in Jilin, China, p. 390-396. In: W.G. Bailey, C. Whitehead, J.T.A. Proctor, and J.T. Kyle (eds.). Proc. Int. Ginseng Conf. Vancouver 1994, Canada.
Korton, R. F. and D. J. Osborne. 1967, Senescence, abscission, and cellulase activity in Phaseolus vzilgaris. Nature 2 14: 1086- 1 O8 8.
Hovius, M. 1996. Spring seeding of American ginseng using temperature and growth regulators to overcome dormancy. MSc thesis, Univ. of Guelph, Guelph, Ontario.
Hu, S. Y. 1976. The Genus Panax (Ginseng) in Chinese Medicine. Econ. Bot. 30:ll-28.
Hu, S. 1980. Biological and cytologicd foundation for better ginseng to more people, p. 171 -1 79. In: Proc. 2nd International Ginseng Symposium.
Hubeman, M. and R. Goren. 1979. Exo- and endo-cellulase and polygalacturonase in abscission zones of developing orange fruits. Physiol. Plant. 45: 189-196.
Humphries, E. C . 1968. The effect of growth regulators, CCC and B9, on protein and total nitrogen of bean leaves (Phaseo lus vulgaris) during development. Ann. Bot. 32:497-507.
Inomata, S., M. Yokoyama, Y. Gozu, T- Shimizu, M. Yanagi. 1993. Growth pattern and ginsenoside production of Agrobacterizim-transfonned Panax ginseng roots. Plant Ce11 Rep. l2:68 1-686.
Iwahori, S., J. M. Lyons, and W. L. SMs. 1969. Jnduced femaleness in cucumber by 2- chIoroethanephosphonic acid. Nature 222:27 1-272.
Jackson, M. B. 1985. Ethylene and responses of plants to soi1 waterlogging and submergence. Ann. Rev. Plant Physiol. 3 6: 145- 174.
Jackson, M. B. and D. J. Osborne. 1970. Ethylene, the natural regulator of leaf abscission. Nature 225: 10 19- 1022.
lacksons, M. 1 99 1. Ethylene in root growth and development. In: A. Mattoo and J. Suttle (eds.). The Plant Hormone Ethylene. Boca Raton, Florida.
Jerk, P. H. and M. A. Hall. 1978. The identification of ethylene oxide as a major metabolite of ethylene. Proc. Roy. Soc. London, Ser. B 200:87-94.
Joy, A. E. and J. L. Parke. 1995. Biocontrol of Alternaria leaf blight on Amencan ginseng by Burkholderia Cepacia AMMD, p. 93-100. In: W.G. Bailey, C. Whitehead, J.T.A. Proctor, and J.T. Kyle (eds.). Proc. Int. Ginseng Cod. Vancouver 1994, Canada.
Kazokas, W. C. and J. K. B u s . 1998. Cellulase activity and gene expression in Cims £kit abscission zones during and after ethylene treatment. J. Amer. Soc. Hort. Sci. 123:78 1-786.
Kelly, M. 0. and P. J. Davies, 1988a. Photoperiodic and genetic control of carbon partitionhg in peas and its relationship to apical senescence. Plant Physiol. 86:978-982.
Kelly, M. 0. and P. J. Davies. 1988b. The control of whole plant senescence. CRC Critical Reviews in Plant Sciences 7: 13 9- 1 73.
Kende, H. and B. Baurngartner. 1974. Regdation of aging in flowers of lpornoeo [ricolor by ethylene. Planta 1 16279-289.
Kende, H. and A. D. Hanson. 1976. ReIationship between ethylene evolution and senescence in morning glory flower tissue. PIant Physiol. 57523-527.
Kim, Y. R., S. Y. Lee, B. A. Shin, and K. M. Kim. 1999. Panmginreng blocks morphine-induced thyrnic apoptosis by lowering plasma corticosterone level. Gen. Pharmacol. 32:647-652.
Koehler, J. H. 1912. Ginseng and Goldenseal Growers Handbook. Paul F. Stolze, Blankbook MFR. Wausau, Wisconsin.
Konsens, I., M. Ofir, and J. Kigel. 1991. The effect of temperature on the reduction and abscission of flowers and pods in snap bean. Ann. Bot. 67:391-399.
Kozlowski, T. T. 1973. The Shedding of Plant Parts. Academic Press, New York.
Kwaih, B. H., E. Y. Sin, and L. Hew. 1972. Accelerating effect of 2- chloroethylphosphonic acid foliar applications on leaf rnatunty. Kor. J. Bot. 15:l-6.
Lang, G. A. and G. C. Martin. 1989. Olive organ abscission: Fruit and leaf response to applied ethylene. J. Amer. Soc. Hort. Sci. 114:134-138.
Lang, W. S., 2. C . Lou, and P. P. H. But. 1993. High-performance liquid chrornatographicai analysis of ginsenosides in Panax ginseng, P. quinquefoliurn and P. notoginseng. J. Chinese Pharm- Sci. 3 : 13 3 - 143.
Lavee, S. and G. Martin. 1 98 1 a. In viîro studies on ethephon-induced abscission in olive. 1. The eEect of application period and concentration on uptake, ethylene evolution, and Ieaf abscission. J. Amer. Soc. Hort. Sci. 106: 14-1 8.
Lavee, S. and G. Martin. 198 1 b. In vitro studies on ethephon-induced abscission in olive. II. The relation between ethylene evolution and abscission of various organs. J. Amer. Soc. Hort. Sci. 106: 19-26.
Leopold, A. C., K. M. Brown, and F. H. Emerson. 1972. Ethylene in the wood of stressed trees. HortScience 7:7 15.
Leopold, A. C., E. Niedergang-Kamien, and J. Janick. 1959. Experimental modification of plant senescence. Plant Physiol. 34570-573-
Letham, D. S. 1967. Chemistry and physiolog of kinetin-like compounds. Annu. Rev. PIant Physiol. 18349-364.
Levin, J. S., T. A. GIass, L. H. Kushi, J. R. Schuck, L. Steele, and W. B. Jonas. 1997. Quantitative methods in research on complementary and alternative medicine: a methodological manifesto. NIH Offke of Alternative Medicine. Med. Care 35: 1079-1094.
Lewis, L. N. and J. E. Varner. 1970. Synthesis of cellulase during abscission of Phaseol~cs vulgaris leaf explants. Plant Physiol. 46: 1 94- 1 99.
Lewis, W. and V. Zenger. 1983. Breedhg systems and fecundity in the American ginseng, Panax quinquefoliurn (Araliaceae). Amer. J . Bot. 70:466-468.
Li, T. S., G. Mazza, A. C. Cottrell, and L. Gao. 1996. Ginsenosides in roots and leaves of American ginseng. J. A ~ c . Food Chem. l4:7 17-720.
Lieberman, S. J., J. G. Valdovinos, and T. E. Jensen. 1983. A rnorphometric study on the effects of ethylene treatment in promoting abscission of tobacco flower pedicels. Plant Physiol- 72583-585.
Lin, J. H., L. S. Wu, K. T. Tsai, S. P. Leu, Y. F. Jeang, and M. T. Hsieh. 1995. Effects of ginseng on the blood chemistry profile of dexamethasone-treated male rats. Amer. J. Chin. Med. 23:167-172.
Lindoo, S. J. and L. D. Noodén. 1978. Correlation of cytokinins and abscisic acid with monocarpic senescence in soybeans. Plant Ce11 Physiol. 19:997-1006.
Liu, C. X. and P. G. Xiao. 1992. Recent advances on ginseng research in China. J. Ethnopharmacol. 36:27-3 8.
Long, R. C., J. A. Weybrew, W. G. Woltz, and C. A. Dum. 1974- Effects of 2- chloroethyl phosphonic acid on the development and maturation of flue-cured tobacco. Tob. Sci. 18:73-75.
Lougheed, E. C. and E. W. Franklin. 1972. Effects of temperature on ethylene evolution fiom ethephon. Can. J. Plant Sci. 52:769-773.
Luckwill, L. C., R. D. Child, and H. Campbell. 1976. Effect of growth regulators on fruit quality. Rep. Long Ashton Res. Stn for 1972.
Lynn, C. D. and F. L. Jensen. 1966. Thinning effects of bloom-time gibberellin sprays on Thompson Seedless table grapes. Arner. J. Enol. Vitic. 17:283-289-
Mapson, L. W. and D. A. Wardale. 1972. Role of indolyl-3-acetic acid in the formation of ethylene from 4-methylmercapto-2-oxobutyric acid by peroxidase. Phytochernistry 11:1371-1387.
Marquard, R. D. and J. L. Tipton. 1987. Relationship between extractable chlorophyll and an in situ method to estimate leafgreenness. HortScience 22:1327.
Martin, G. C., S. Lavee, and G. S. Sibbett. 1981. Chemical loosening agents to assist mechanicd harvest of olive. J. Amer. Soc. Hort- Sci. 106325-330.
Matile, P. and F. Winkenbach. 1971. Function of lysosomes and lysosomal enzymes in the senescing corolla of the morning glory (@omoea purpznea). J. Exp. Bot. 22:759-77 1.
Mayak, S. and D. R. Dilley. 1975. Effect of sucrose on response of cut carnation to kinetin, ethylene, and abscisic acid. J. Amer. Soc. Hortic. Sci. 10 1 583-585.
Mayak, S. and D. R. DiUey. 1976. Regulation of senescence in carnation (Diunthus cagmphyllus). Effect of abscisic acid and carbon dioxide on ethylene production. Plant Physiol, 58:663-665.
Mayak, S. and A. H. Halevy. 1972. Interrelationships of ethylene and abscisic acid in the control of rose petal senescence. Plant Physiol. 50341-346.
Mayak, S . and A. H. Halevy. 1974. The action of kinetin in improving the water balance and delaying senescence processes of cut rose flowers. Physiol. Plant. 32330- 336.
Mayak, S. and A. M. K o b e k . 1976. A l t e ~ g the sensitivity of carnation flowers (Dianthus caryophyhs L.) to ethylene. J. Amer. Soc. Hortic. Sci. 101:503-506.
Mayak, S., A. M. Kofianek, and T. Tirosh. 1978. The effect of inorganic salts on the senescence of Dianthus caryophyllus flowers. Physiol. Plant. 43 :282-286.
Mayak, S., Y. Vaadia, and D. R. Dilley. 1977. Regdation of senescence in carnation (Dianthus caryaphyllus) by ethylene. Mode of action. Plant Physiol. 59 5 9 1 -593.
McGlasson, W. B. 1970. The Ethylene Factor, p. 475-5 19. In: A. C. Hulme (ed.). The Biochemistry of Fruits md their Products, Vol. 1, Academic Press, London.
McKinney, G. 1941. Absorption of light by chlorophyil solutions. J. Biol. Chem. 140:3 15-322.
McMurray, A. L. and C. H. Miller. 1968. Cucumber sex expression modified by 2- chloroethanephosphonic acid. Science 162: 1396-1 397.
Miele, A., R. J. Weaver, and J. Johnson. 1978. Effect of potassium gibberellate on b i t - set and development of Thompson Seedless and Zinfandel grapes. Amer. J. Enol. Vitic. 29:79-82.
Miles, J. D., G. L. Steffens, T. P. Gaines, and M. G. Stephenson. 1972. Flue-cured tobacco yellowed with an ethylene-releasing agent prior to harvest. Tob. Sci. l6:7 1-74.
Monterroso, V. A. and H. C. Wien. 1990. Flower and pod abscission due to heat stress in beans. J. Amer. Soc. Hort. Sci. ll5:63 1-634.
Moon, D. K. and E. R. Sin. 1972. Effect of 2-chloroethylphosphonic acid on ripeniog and total alkaloid content of tobacco leaves. Korean Soc. Crop Sci. J. 12:43-48.
Morgan, P. W. 1961. The interaction of ethylene and auxin in Cotton and grain sorghum. PhD Thesis, Texas A and M Univ., College Station, Texas.
Morgan, P. W. 1969. Stimulation of ethylene evolution and abscission in cotton by 2- chloroethanephosphonic acid. PIant Physiol. 44:337-34 1.
Morgan, P. W. 1984.1s Ethylene the Natural Regulator of Abscission? p. 23 1-240. In: Y. Fuchs and E. Chalutz (eds.). Ethylene: biochernical, physiological and applied aspects. Nijfioff, The Hague,
Morgan, P. W. 1986. Ethylene as an Indicator and Regulator in the Developrnent of Field Crops. p. 375-379. In: M. Bopp (ed.). Plant Growth Substances, 1985. Springer- Verlag, Berlin.
Morgan, P. W., E., Jr., Beyer, and H. W. Gausman. 1968. Ethylene effects on auxin Physiology, p. 1255-1273. In: F. Wightman and G. Setterfield (eds.). Biochemistry and Physiology of Plant Growth Substances. Runge Press Ltd., Ottawa, Canada.
Morgan, P. W. and J. 1. Durham. 1972. Abscission: Potentiatingaction of auxin transport inhibitors. Plant Physiol. 50:3 13-3 18.
Morgan, P. W. and W. C. Hall. 1962. Effect of 2.4-dichlorophenoxyacetic acid on the production of ethylene by cotton and grain sorghum. Physiol. Plant. l5:420-427.
Morré, D. J. 1968. Ce11 wall dissolution and enzyme secretion during Ieaf abscission. Plant Physiol. 43: 1545-1 559.
Mosesian, R. M., and K. E. Nelson. 1968. Effect on 'Thompson Seedless' fruit of gibberellic acid bloom sprays and double girdling. Amer. J. Enol. Vitic. 19:37-46.
Murneek, A. E. and J. C. Logan. 1932. AutumnaI migration of nitrogen and carbohy-drate in the apple tree. IMo Univ. Agr. Exp. Sta. Res. Bul. 171.
Murphy, L. L., R. S. Cadena, D. Chavez, and J. S. Ferraro. 1998. Effect of American ginseng (Panax quinquefolium) on male copulatory behavior in the rat. Physiol. Behav. 64:445-450.
Nagarajah, S. 1975. Effect of debudding on photosynthesis in leaves of cotton. Physiol. Plant. 33 28-3 1.
Napier, R. M. and M. A-Venis. 1990. Receptors for plant growth regulators: Recent advances. Journal of Plant Growth Regulation 9: 1 23-126.
Nichols, R. 1966. Ethylene production during senescence of flowers. J. Hortic. Sci. 4 1 :279-290.
Nichols, R. 1968. The response of carnations (Dianthus caryophyllus) to ethylene, J. Hortic. Sci. 43:335-349.
Nichols, R., G. Bufler, Y. Mor, D. W. Fujino and M. S. Reid. 1983. Changes in ethylene production and 1 -aminocyclopropane- 1 -carboxylic acid content of pollinated carnation flowers. J. Plant Growth Regul. 2: 1-8.
Nickell, L. G. 1979. Controlling biological behavior of plants with synthetic plant growth regulating chemicals, p. 263 -279. In: N. B. Mandava (ed.). Plant Growth Substances. Amencan Chernical Society, Washington.
Noodén, L. D. 1980. Senescence in the Whole Plant, p. 2 29-258. In: K. V. Thimann (ed.). Senescence in Plants. CRC Press Inc., Boca Raton, Florida.
Noodén, L. D., J. J. Guiamet, S. Singh, D. S. Letham, J. Tsuji, and M. J. Schneider. 1990. Hormonal control of senescence, p. 537-546. In: R- P. Phanis and S. B. Rood (eds.). Plant Growth Substances, 1988. Springer-Verlag, New York.
Noodén, L. D., G. M. Kahanak, and Y. Okatan. 1979. Prevention of monocarpic senescence in soybeans with awcin and cytokinins: an antidote for self- destruction. Science 206:841-843.
Noodén, L. D. and A. C. Leopold. 1978. Phytohormcnes and the endogenous regulation of senescence and abscission, p. 329-369. In: D. S . Letham, P. B. Goodwin and T. J. V. Higgins (eds.). Phytohormones and Related Compounds: A Comprehensive Treatise. Vol. 2. ElseviedNorth Holland, Amsterdam.
Noodén, L. D. and J. E. Thompson. 198 1. Aging and senescence in plants, p. 105. In: C. E. Finch, R. C. Adelman, G. M. Martin, and E. J. Masoro (eds.). Handbook of the Biology of Aging. Van Nostrand Reinhold, New York.
Oberholster, S. D., C. M. Petersen, and R. R. Dute. 1991. Pedicel abscission of soybean: cytological and ultrastructural changes induced by auxin and ethephon. Can. J. Bot. 69:2177-2 186.
Olien, W. and M. Bukovac. 1978. The effect of temperature on rate of ethylene evolution fiom ethephon and fiom ethephon-treated leaves of s o u cherry. J. Amer. Soc. Hort. Sci. 103 : 199-202,
Oiiver, A., B. van Delfsen, B. Van Lierop, and A. Buonassissi. 1992. Arnerican Ginseng Culture in the Arid Climates of British Columbia. British Columbia. Ministry of Agriculture Fisheries and Food.
Olson, W. H., G. S . Sibbet, G. L. Carnhill, and G. C. Martin. 1977. Lower ethephon rates effective in walnut harvest. Calif. A g . 3 1 :6-7.
Osborne, D. J. 1989. Abscission. CRC Critical Reviews in Plant Sciences 8:103-129.
Osborne, D. J. and H. M. Hallaway. 1964. The auxin, 2,4-dichlorophenoxyacetic acid as a regulator of protein synthesis and senescence in detached leaves of Prunus. New Phytol. 63:3 34-337.
Osborne, D. J., M. T. McManus, and J. Webb. 1984. Target Ceils for Ethylene Action, p. 197-212. In: J. A. Roberts, G. A, Tucker (eds). Ethylene and plant development. Butterworths, London.
Osborne, D. J. and J. A. Sargent. 1976. The positional dserentiation of ethylene- responsive ceils in rachis abscission zones in leaves of Sambucus nigra and their growth and ultrastructural changes at senescence and separation. Planta (Berl) 130:203-210.
Panton, J. H. 1891. Ginseng. 17" Annual Report of OAC. p. 23-26.
Park, H., M. Lee and C. Lee. 1990. Ethylene release of Panax ginseng in relation to plant part and various conditions. Korean 5. Ginseng Sci. 14: 122- 125.
Parke, J. L. and K. M. Shotwell. 1989. Diseases of Cultivated Ginseng. Department of Plant Pathology, Univ- of Wisconsin-Madison. p. 1 6.
Parks, M. 1983. China: new pep fiom old tonics. Los Angeles Times. (Jan. 8). 102; 1, col 1,47 col in.
Pérez, F. J. and M. Gomez. 1998. Gibberellic acid stimulation of isoperoxidase fiom pedicel of grape. Phytochernistry. 48:4 1 1-4 14.
Persons, W. S. 1995. Amencan ginseng famiing in its woodland habitat, p. 78-83. Ln: W. G. Bailey, C. Whitehead, J. T. A. Proctor, and J. T. Kyle (eds.). Proc. Int. Ginseng C o d Vancouver 1994, Canada.
Pieralisi, G., P. Ripari, and L. Vecchiet. 199 1. Effects of a standardized ginseng extract combined with dimethylarninoethano 1 bitartrate, vitamins, rninerals, and trace elements on physical performance during exercise. Clinical Therapeutics 13 : 3 73- 382-
Plaisted, P. H. 1958. Some biochemical changes during development and aging ofAcer platanoides L. leaves. Contrib. Boyce Thompson Inst. 19:245-254.
Polito, V. S. and S. Lavee. 1980. Anatornical and histochemical aspects of ethephon- induced leaf abscission in olive (Olea europaea L.). Bot. Gaz. 141 :413-417.
Pollard, J. E. and R. H- Biggs. 1970. Role of cellulase in abscission of Cihws h i t s . J. Amer. Soc. Hortic. Sci. 95:667-673.
Pratt, H. K. and J. D. Goeschl. 1969. Physiologicd roles of ethylene in pIants. Amu. Rev. Plant. Physiol. 2O:H 1-584.
Pneto, J. G., E. Ferniindez, P. A. Redondo, A. Ferrando, L. Vila, J. Voces, J. del Estal, and A. 1- Alvarez, 1993. Korean red ginseng in exhaustion exercise, p. 17 1-1 78. In: Proc. of the 6" Int. Ginseng Symp., Korea Ginseng Research Inst., Seoul, Korea.
Proctor, J. T. A. 1 980. Some aspects of the Canadian culture of ginseng (P. quinquefolius L.), particularly the growing environment, p. 39-47. In: Proc. 3rd Int. Ginseng Symp., Korea Ginseng Research Inst., Seoul, Korea.
Proctor, J. T. A. 1987. Pollination and kuit set in American ginseng (Panax quinquefolium L.). Proc. Entomol. Soc. Ont. 1 18: 167-1 70.
Proctor, J. T. A. 1994. Ginseng: The 'Made in the Shade' Curative? Agri-food research in Ontario. Decernber.
Proctor, J. T- A. 1996. Ginseng: old crop, new directions, p. 565-577. In: J. Janick (ed.). Progress in new crops, Proc. Third National Symposium, New Crops: new opportunities, new technologies. ASHS Press, Alexandria, VA.
Proctor, J. T. A. 1997. Ginseng, p. 25-36. In: R. Bevzins and C. Richter (eds.). Richters 1" Commercial Herb Growing Conference, Oct 26, 1996. Richters, Goodwood, Ontario.
Proctor, J. T. A. 1998. Persona1 communication
Proctor, J. T. A. and W. G. Bailey. 1987. Ginseng: Industry, botany and cuIture. Hort. Reviews 9 : 1 8 7-23 6 .
Proctor, J. T. A. and D. Louttit. 1995. Stratification of Amencan ginseng seed: embryo growth and temperature. Korean J, of Ginseng Sci. 19: 17 1-174.
Proctor, J. T. A., T. S. Wang, and W. G. Bailey. 1988. East meets west; cultivation of Amencan ginseng in China. HortScience 23 :968-973.
Proctor, J. T. A., T. Slimmon, and P. K. Saxena. 1996. Modulation of root growth and organogenesis in thidiazuron-treated ginseng (Panax quinquefolium L.). Plant Growth Regul. 5: 1-8.
Proctor, J. T. A., J. C . Lee, and S. S: Lee. 1990. Ginseng production in Korea. HortScience 25:746-750.
Proctor, J. T. A., D. C. Percival, and D. Louttit. 1999. Idlorescence removal afTects root yield of Amencan ginseng. HortScience 34:82-84.
Proebsting, E. L., Jr. and H. H. Mills, 1969. Effects of Zchloroethane phosphonic acid and its interaction with gibberellic acid on quality of 'Early Italian' prunes. J. Amer. Soc. Hort. Sci. 94943-446.
Proebsting, W. M., P. J. Davies, and G. A. Marx. 1978. Photoperiod-induced changes in gibberellin metabolism in relation to apical growth and senescence in a genetic line of peas (Pisum sativzrm L.), Planta 141:23 1-238.
Rasmussen, K. 1973. Changes in cellulase and pectinase activities in fruit tissues and separation zones of Citnis treated with cycloheximide. Plant Physiol. 5 1:626-628.
Ratner, A., R Goren, and S. P. Monselise. 1969. Activity of pectin esterase and cellulase in the abscission zone of Citms leaf explants, Plant Physiol. 44: 17 17- 1723.
Ray, S., W. A. Mondal, and M. Choudhuri. 1983. Regdation of Ieafsenscence, grain filling and yield of rice by kinetin and abscisic acid. Physiol. Plant. 59:343-346.
Reed, N. R. and H. T. Hartmann. 1976. Histochemical and ultrastructural studies of Mt abscission in the olive after treatment with 2-chloro-ethyl-tris-(2-methoxyethoxy)- silane. J. Amer. Soc. Hort. Sci. 101 :633-637.
Reeleder, R. D. and C. R. A. BrammaI. 1994. Pathogenicity of Pythiurn species, Cylindrocarpon destructans, and Rhizoctonia to ginseng seedlings in Ontario. C m . J. of PIant Pathol. 16:3 1 1-3 16.
Reeleder, R. D. and C. R. A. Brammal. 1995. Root rots and damping-off of ginseng seedlings in Ontario, p. 141-143. In: W.G. Bailey, C. Whitehead, J.T.A. Proctor, and J.T. Kyle (eds.). Proc. Int. Ginseng C o d Vancouver 1994, Canada-
Reid, M. S. 1987. Ethylene in plant growth, development, and senescence, p. 257-279. In: P.J. Davies (ed.). Plant Hormones and their Role in Plant Growth and Development, Martinus Nij hoff, Boston.
Reid, P. D., H. G. Strong, F. Lew, and L. N. Lewis. 1974- Cellulase and abscission in the red kidney bean (Phaseolus vulgaris). PIant Physiol. 53:732-737.
Ren, G. X., J. H. Zhao, Y. J. Yang, Y. P. Wang and Z. T. Yang. 1995. Chernical components and physiologicd activities of a tonic beverage of American ginseng, p. 169-1 72. In: W.G. Bailey, C. Whitehead, J.T.A. Proctor, and J.T. Kyle (eds.). Proc. Int. Ginseng Cod. Vancouver 1994, Cmada.
Richmond, A. E. and A. Lang. 1957. Effect of kinetin on protein content and survival of detached Xanthium leaves. Science 125650-65 1.
Roberts, J. A., G. A. Tucker, and M. Maunders. 1984. p. 267. In: J. A. Roberts and G. A. Tucker (eds.), Ethylene and plant development, Buttenvorths, London.
Rogers, B. L. and E. R. Krestensen. 1973. Preharvest drop of 'Stayman' apples as influenced by SADH in d i b e and concentrate form. HortScience 8:3 14-3 15.
Russo, L., H. C. Dostal, and A. C. Leopold. 1968. Chernical stimulation of f i t ripening. Bioscience 18:109.
Rylski, 1. And M. Sigelman. 1982. Effecb of different diumal temperature combinations on fruit set of sweet pepper. Sci. Hort. 17: 101-106.
Sacher, J. A. 1973. Senescence and postharvest physiology. Annu. Rev. Plant Physiol. 24:197-3 10.
SaLim, K. N., B. S. McEwen, and K. Chao. 1997. Ginsenoside Rb1 regulates ChAT, NGF and trkA rnRNA expression in the rat brai.. Brain Res. Mol. Brain. Res. 47: 177- 182.
Schlessman, M. 1985. Floral biology of Amencan ginseng (Panm quinquefolium). Bul. Torr. Bot- Club 1 12: 129-133.
Schneider, G. W. 1977. Studies on the mechanism of M t abscission in apple and peach. J. Amer. Soc. Hort. Sci. 102: 179-1 8 1.
Schooley, J. 2000. Personal communication.
Schultz, F. H., R. Lowe, and R. A. Woodley. 1980. A possible effect of ginseng on serurn HDL cholesterol. Federated Proceedings 3 9554.
Schweitzer, L. E. and J. E. Harper. 1985. Effect of a multiple factor source-sink manipulation on nitrogen and carbon assimilation by soybean. Plant Physiol. 78:57-60.
Sexton, R. and J. A. Roberts. 1982. Ce11 biology of abscission. Annu Rev. Plant Physiol. 33: 133-162,
Sexton, R. and H. W. Woolhouse. 1984. Senescence and abscission, p. 469. In: M. B. Wilkins (ed.). Advanced Plant Physiology. Pitman Press.
Sexton, R., L. N. Lewis, A. J. Trewavas, and P. Kelly. 1985. Ethylene and abscission, p. 173-196. In: Roberts, J. A., Tucker, G. A. (eds). Ethylene and plant development. Buttenvorths, London.
Sexton, R., W. A. Struthers, and L. N. Lewis. 1983. Some observations on the very rapid abscission of the petals of Geraniurn robertianurn L. Protoplasma 1 16: 179-1 86.
Simon, E. W. 1967. Types of leaf senescence. Syrnp. Soc. Expt. Biol. 2 1 :215-230.
Singh, S., D. S. Letham, and L. M. S. Palni. 1992. Cytokinin biochemistry in relation to leaf senescence. VII. Endogenous cytokinin levels and exogenous applications of cytokinins in relation to sequential leaf senescence of tobacco. Physiol. Plant. 86:3 88-397.
Sisler, E. C. 1990a. Ethylene-binding components in plants. In: A. K. Mattoo and J. C. Suttle (eds.). The Plant Hormone EthyIene. CRC Press, Boca Raton, Florida.
Sisler, E.C. 1 99Ob. Ethylene-bïnding receptors - 1s there more than one? p. 193-200. In: S. Rood and R. P. Pharis (eds.). Plant Growth Regdators 1988. Springer-Verlag, Berlin.
Sklensky, D. E. and P. J. Davies. 1993. Whole Plant Senescence: Reproduction and Nutrient Partitioning. p. 335-366. In: J. Jankk (ed.). Horticultural Reviews. Vol 15.
Smalle, J. and D. Van Der Straeten. 1997. Ethylene and vegetative development. Physiol. Plant. 1 OO:593-605.
Smith, R. G., D. Caswell, A. Caniere, and B. Zieke. 1996. Variation in the ginsenoside content of American ginseng, Panax quinquefolius L., roots. Can. J. Bot. 743616- 1620.
Soffer, H., S. Mayak, D. W. Burger, and M. S. Reid. 1989. The role of ethylene in the inhibition of rooting under low oxygen tensions. Plant Physiol. 89: 165- 168.
Spencer, P. W. and J. S. Titus. 1972. Biochemical and enzymatic changes in apple leaf tissue during auturnnal senescence. Plant Physiol. 49:746-750.
Splittstoesser, W. E. 1970. Effects of 2-chloroethylphosphonic acid and gibberellic acid on sex expression and growth of purnpkins. Physiol. Plant. 23:762-768.
Sponsel, V. M. 1995. Gibberellin biosynthesis and metabolism, p. 66-97. In: P.J. Davies (ed.). Plant Hormones; Physiology, Biochernistry and Molecular Biology. Kluwer, Dordrecht, The Netherlands.
Stathers, R. 5. and W. G. Bailey. 1986. Energy receipt and partitionhg in a ginseng shade canopy and mulch environment. Agricultural and Forest Meteorology 37: 1 - 14.
Stembridge, G. E. and C. E. Gambrell. 1971. Thinnïng peaches with bloom and post bloom applications of 2-chl,oroethylphosphonic acid. J. Amer. Soc. Hort. Sci. 96:7-9.
Stephenson, A. G. 198 1. Flower and fruit abortion: Proximate causes and ultimate fùnctions. Annu. Rev. Ecology and Systematics 12:253-279.
Stoddart, J. L. and H. Thomas. 1982. Leaf senescence, p. 592-636. In: D. Boulter and B. Parthier (eds.). Encyclopedia of Plant Physioloey, New Series. Vol. 14A. Springer-Verlag, Berlin.
Suttle, J. C. and H. Kende. 1978. Ethylene and senescence in petals of Tradescantia. Plant Physiol. (Bethesda) 62:267-27 1.
Swain, S. M. and N. E. Olszewski. 1996. Genefic analysis of gibberellin signal transduction. Plant Physiol. 1 12: 1 1-1 7.
Tamari, G., L. Pappa, T. Zered, and A. Borochov. 1998. Effects of ethrel and gibberellin on impatiens plants. Sci- Hort, 76:29-35,
Tanaka., O., R. Kasai, and T. Monta. 1986. Chemistry of ginseng and related plants: recent advances. Abstracts of Chinese Medicines 1 : 13 0- 152.
Taylor, G. E. and C. A. Gunderson. 1986. The response of f o l k gas exchange to exogenously applied ethylene. Plant Physiol. 82:653-657.
Tenga, A. Z., B. A. Marie, and D. P. Ormrod. 1989. Leaf g r e e ~ e s s meter to assess ozone injury to tomato leaves. HortScience 24:s 14.
Thimann, K. V. l98Oa. The Senescence of Leaves, p. 85- 1 15. In: K. V. Thimam (ed.). Senescence in Plants. CRC Press Inc., Boca Raton, Flonda.
Thimam, K. V. (Ed.). 1980b. Senescence in Plants. CRC Press, Boca Raton, Fla.
Thimann, K. V. 1987. Plant senescence: A proposed integration of the constitiuent processes. Proc. X Annu. Symp. Plant Physiol. 10: 1-19.
Thimam, K. V. and S. O. Satler. 1979a. Relation between leaf senescence and stomatal closure: Senescence in light. Proc. Natl. Acad. Sci. USA 76:2295-2298.
T h a n n , K. V. and S. O. Satler. 1979b. Relation between leaf senescence and stomatal opening: senescence in darkness. Proc. Natl. Acad. Sci. USA 76:2770-2773.
Thimam, K. V., R. M. Tetley, and T. V. Thanh. 1974. The metabolism of oat leaves during senescence. II. Senescence in leaves attached to the plant. Plant Physiol. 54:859-862.
Thomson, W. W. and K. A. Plan-Aloia. 1987. Ul~astnictural changes associated with senescence, p. 20-30. In: W. W. Thomson, E. A. Nothnagel, and R. C. Huffdcer (eds.). Plant Senescence: its biochemistry and physiology. Amencan Society of Plant Physiologists, Rockville, MD.
Thompson, G. A. 1987. Botanical characteristics of ginseng, p. 1 1 1 - I 36. In: L. E. Craker and J.E. Simon (eds.). Herbs, Spices, and Medicind Plants: Recent Advances in Botany, Horticulture, and Pharmacology. Volume 2. Oryx Press, New York.
Tietz, D. and A. Tietz. 1982. StreP im Pflanzenreich. (Stress in the plant kingdom.) Biologie in unserer Zeit 1 2 1 13-1 19.
Tx-îpp, K. E. and H. C. Wein. 1989. Screening with ethephon for abscission resistance of flower biids in bel1 pepper. HortScience 24:655-656.
Tucker, G. A., C. B. Schindler, and J. A. Roberts. 1984. Flower abscission in mutant tomato plants. Planta 160: 164-1 67.
Tucker, M. L., R. Sexton, E. del CampilIo, and L. N. Lewis. 1988. Bean abscission cellulase. Plant Physiol, 88: 1257-1262.
Tylor, V. E. 1994. Basic principles, p. 1-15. In: Herbs of Choice: The Therapeutic Use of PhytochemicaIs, Haworth Press Inc,, Binghamton, N.Y.
Valdovinos, J, G., T. E. Jensen. 1968. Fine structure of abscission zones. II. Ce11 wdI changes in abscising pedicels of tobacco and tomato flower pedicels. Planta 83 :295-302.
Valdovinos, J. G., L. C. Ernest, and E. W. Henry. 1967. Effect of ethylene and gibberellic acid on auxin synthesis in plant tissues. Plant Physiol 42: 1803-1 806.
Valdovinos, J. G., T. E. Jensen, and L. M. Sicko. 1972. Fine structure of abscission zones. IV. Effect of ethylene on the ultrastructure of abscission cells of tobacco flower pedicels. Planta 1 O2:324-3 3 3.
Van Staden, J., E. L. Cook, and L. D. Noodén. 1988. Cytokinins and senescence, p. 28 1 - 328. In: L. D. Noodén, and A, C, Leopold (eds.). Senescence and Aging in Plants. Academic Press, San Diego.
Vuksan, V., J. L. Sievenpiper,V. V. Y. Koo, T. Francis, U. Beljan-Zdravkovic, Z. Xu, and E. Vidgen. 2000. American ginseng (Panax quinquefolius L) reduces postprandial glycemia in nondiabetic subjects and subjects with type 2 diabetes me1 litus. Arch. Intemal Med. 160: 1009- 10 13.
Walker, E. K. 1977. Influence of ethephon on flue-cured tobacco. Can. J. Plant Sci. S7:8 19-827.
Walker, E. K. 1985. Effects of ethephon on flue-cured tobacco as influenced by rates of ethephon and fedlizer application a d seedling age at transplanting. Can, J. Plant Sci. 6573 1-741.
Wang, L. C. and T. F. Lee. 1998. Effect of ginseng saponuis on exercise performance in non-trained rats. Planta Med. 64: 13 0- 13 3.
Wang, X., J. T. A. Proctor, Y. Kakuda, S. KrishnaRaj, and P. K. Saxena. 1999. Ginsenosides in Arnerican ginseng: Cornparison of in v i h o derived and field- grown plant tissues. Journal of Herbs, Spices and Medicinal Plants 6: 1-1 0.
Wareing, P. F. 1986. Plant Ce11 Responses and the Role of Growth Substances, p. 1-9. In: M. Bopp (ed). Plant Growth Substances, 1985. Springer-Verlag, Berlk
Wareing, P. F., M. M. Khalifa, and K. J. Treharne. 1968. Rate-limiting process in photosynthesis at saturating light intensities. Nature 220:453-457.
Wareing, P. F. and A. K. Seth. 1967. Ageing and senescence in the whole plant. Syrnp. Soc. Exp. Biol. 21543458.
Wamer, H. L. and A. C. Leopold. 1969. Ethylene evolution fkom 2-chloroethyl- phosphonic acid. Plant Physiol. 44: 156-1 58.
Webster, B. D. 1973. Ultrastructural studies of abscission in Phaseolus: Ethylene effects on ce11 walls. Amer. J. Bot. 60:436-447.
Weis, K. G., R. Goren, G. C. Martin, and B. D. Webster. 1988. Leaf and inflorescence abscission in olive. 1. Regulation by ethylene and ethephon. Bot. Gaz. 149591- 397.
Weis, K. G., B. D. Webster, R. Goren, and G. C. Martin. 1991. Innorescence abscission in olive: Anatomy and histochernistry in response to ethylene and ethephon. Bot. Gaz. 15252-58.
Wheaton, T. A. and 1. Stewart. 1973. Optimum temperature and ethylene concentration for postharvest development of carotenoid pigments in citrus. J. Amer. Soc. Hort. Sci, 98337-340.
White, £2. C., 1. D. Jones, and E. Gibbs. 1960. Determination of chlorophylls, chlorophyllides, pheophytines, and pheophorbides in plant materials. J. Food Sci. 28:43 1-436.
Wien, H. C. 1990. Screening pepper cultivars for resistance to flower abscission: a cornparison of techniques. HortScience 25: 1634- 163 6.
Wien, H. C., A. D. Tumer, and S. F. Yang. 1989. Hormonal basis for low light intensity- induced flower bud abscission of pepper. J. Amer. Soc. Hort. Sci. 1 l4:98 1-985.
Williams, T. 1996. p. 180-1 8 1. Zn: The Complete Illustrated Guide to Chinese Medicine - A Comprehensive System for Health and Fitness. Element Books ttd., Shaftesbury, Dorset, Great Britain.
Wollgiehn, R. 1967. Nucleic acid and protein metabolism of excised leaves, p. 23 1-246. In: H. W. Woolhouse (ed.). Aspects of the Biology of Ageing. Cambridge University Press.
Woolhouse, H. W. 1967. The nature of senescence in plants. Syrnp. Soc. Exp. Biol. 21:179-213.
Wright, M. and D. J. Osborne. 1974. Abscission in Phaseolus vulgaris: the positional differentiation and ethylene-induced expansion growth of specidised cells. Planta (Berl) 120:163-170.
Yadava, U. L. 1986. A rapid and nondestructive method to determine chlorophyll in intact leaves. HortScience 21 : 1449-1450.
Yamaguchi, S. 1954. Some interrelations of oxygen, carbon dioxide, sucrose and ethylene in abscission. PhD thesis, Univ. of California, Los Angeles.
Yang, S. F. and N. E. Hofmian. 1984. Ethylene biosynthesis and its regdation in higher plants. Annu. Rev. Plant Physiol. 35:155-189.
Yang, S. F. and H. K. Pratt. 1978. p. 595. In: G. Kahl (ed). Biochemistry of wounded plant tissues. Gmyter, Berlin.
Yoshimatsu, K., K. Yamaguchi, and K. Shirnomura. 1996. Traits of Panm ginseng hairy roots after cold storage and cryopreservation. Plant Ce11 Rep. l5:555-560.
Yuan, C. S., J. A. Wu, T. Lowell, and M. Gu. 1998. Gut and brain effects of American ginseng root on brainstem neuronal activities in rats. Amer. J. Chin. Med. 26:47- 55.
APPENDIX A Data supplied by Penny Pearse and Allen Smith for 1997 field application of Ethrel in Vernon, B.C. Sprays applied in 1 O00 L/acre (220 gal/acre). Reproduced with permission fiom Allen Smith, Panax Q Ginseng.
O Tl-
Mean air and soi1 temperatures for the 1999 Arnerican ginseng ethephon field-trials at Jeff Rice, JCK Farms, near Burford, Ontario.
APPENDIX C Mean air temperatures and total monthly precipitation recorded by the University of Guelph automated weather data summary at Simcoe Station for the summers of 1998, 1999 and 2000. Reproduced with permission fiom Alan McKeown, Simcoe Station, University of Guelph.
Mean Air Temperature - Sirncoe Station
Date
Total Monthly Precipitation - Simcoe Station
Jun Jul
Month
