UNIVERSITI PUTRA MALAYSIA

THE EFFECT OF LIGHT, FERTILISER AND PLANTING DENSITY ON THE GROWTH AND FLOWERING OF

ASYSTASIA GANGETlCA SUBSP. MICRANTHA

QUAH YIN THYE

FSAS 1997 9

THE EFFECT OF LIGHT, FERTILISER AND PLANTING DENSITY ON

THE GROWTH AND FLOWERING OF

ASYSTASIA GANGETlCA SUBSP. MICRANTHA

BY

QUAE YIN THYE

Thesis submitted to Faculty of Science and Environmental Studies

in Fulfilment of tr �equirement for the Degree of Mast ,r of Science,

Universiti Pertanian Malaysia

1997

III

ACKNOWLEDGMENTS

Thi s t he s i s r e s u l t e d from the i nt e r e s t gene ra t e d

at App l i e d Agr i cultural Re s e arch S dn B h d by the

f a s c i na t i ng wee d , As ys t a s i a , prima r i l y because of the

p roblem it is caus i ng in the p l a ntat i o n i ndu s t r y .

I w i s h t o thank the Head o f Agr i cu l tural

Re s e arch , Mr . Chew Poh S o o n for h i s e ncourageme nt ,

cons t ructive s ugge s t i o ns and i nt e r e s t i n the s tudy o f

t h i s wee d . Thank s are a l s o due t o Mr . Goh Kah Joo f o r

h i s k i nd a s s i s t ance i n s t at i s t i ca l a na l ys i s a nd

experime nt a l de s i gn and l a yout .

I wou l d li ke t o a c k nowl e dge Dr . Rut h K i ew f o r

h e r s upport a s we l l a s gui dance , i n .pa rt i cu l a r , i n

lo o k i ng at the b i o l ogy o f the we ed from di f f e r e nt

perspective s .

La s t ly , I thank the s t a f f at t he Appl i e d

Agricul tural Research Sdn Bhd who a s s i s t e d in f i e l d

and tr i a l wo rk , the t yp i ng o f t he report b y Ms Ali c e

Thoma s and i n part i cular , C i k No r a i ni Mohd No o r who

o rgani s e d the cutt ing o f pho t o c opy o f As y s t a s i a

l e ave s f o r l e a f area me a s urement , a nd i n p l o t t i ng o f

graph s , report l ayout and preparat i o n o f the rep o rt .

TABLE OF CONTENTS

PAGE

ACKNOWLEDGEMENT S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

LIST OF TABLES...................................... i v

LIST OF FIGURES..................................... v

ABSTRACT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

ABSTRAK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

CHAPTER

I INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

I I LI TERATURE REVIEW.............................. 4

Botanical name................................. 4

Competition to economic crops.. ..... ........... 7

Oil palm plantation. ............... . . . . . . . . . . 7

Cocoa plantation............................. 8

Pineapple cultivation...... ..... ..... ........ 8

Chemical control of Asystasia.................. 9

Animal grazing to control Asystasia............ 10

Research toda te. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

III MATERIALS AND METHODS.......................... 12

Treatments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Light conditions............................. 12

Plant density................................ 1 3

Fertiliser rate.............................. 1 3

Treatment combination........................ 15

Trial design and layout........................ 15

Shed and artificial shade-screen............. 1 7

Pot preparation for planting................. 1 7

Asystasia seeds.............................. 17

Watering, slug and insectide treatments..... 1 8

Wooden stake support......................... 19

Watering of pots............................. 19

Sampling schedule and parameters measured...... 19

Dry weight... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Leaf. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Stem/ lateral branches........................ 21

Roots........................................ 21

Leaf area.................................... 21

Inflorescence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Nutrient analysis............................ 22

Data analysis and presentation of results...... 22

Statistical analysis..... .................... 22

Presentation of results...................... 23

Discussion of results........ .... .... ........ 23

IV RESULTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Growth to Day 45............................... 25

Dry weight of plant -- Day 45................ 25

Partitioning of total dry weight -- Day 45... 26

Leaf size and area Day 45................. 28

Nutrient levels in plant tissues -- Day 45... 30

Reproduction -- Day 45....................... 36

Growth from Day 45 to Day 90.. ..... ............ 37

Dry weight of plant -- Day 90............... 37

Partitioning of total dry weight -- day 90... 39

Leaf size and area Day 90................. 41

Nutrient levels in plant tissues -- Day 90... 43

Reproduction -- Day 90... .................... 48

Growth from Day 90 to Day 135...... . . . . . . ...... 49

Dry weight of plant -- Day 135..... .......... 49

Partitioning of total dry weight -- Day 135.. 50

Leaf size and area Day 135................ 52

Nutrient levels in plant tissues -- Day 135.. 53

Reproduction -- Day 135...................... 58

Growth after Day 135.................. ......... 60

v

VI

DISCUSSION .................................... . 61

Plant growth in total dry weight............... 61

Phase 1 - Juvenile phase..................... 62

Phase 2 - Initial flowering.................. 63

Phase 3 - Intense flowering.................. 63

Phase 4 - Senescence phase................... 64

Nutrient contents of plant tissues............. 65

Nitrogen levels -- Trend over 135 days....... 65

Phosphorus levels -- Trend over 135 days..... 67

Potassium l evels -- Trend over 135 days...... 69

Magnesium levels -- Trend over 135 days...... 7 1

Comparison of Asystasia nutrient contents with other plants............................ 7 1

Flowering and reproduction..................... 74

Initial flowering............................ 7 4

Intense flowering............................ 74

Reduced flowering...... ...................... 7 5

Capsule production........................... 75

Partitioning of total dry weight............... 77

Asystasia as a weed............................ 80

Potential seed production...................... 80

CONCLUS ION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Addi tional tables......................... 92

VI TAE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

Table

1

2

3

4

5

6

7

8

9

10

11

LIST OF TABLES

Fertiliser programme ............................ .

Treatment combinations of pot trial ............. .

Schedule for destructive sampling ............. . . .

Incidence of flowering at Day 45 . . ... .. . . . ... . . . .

Asystasia dry wei ght and floweri ng at Day 90 . . . . .

Asystasia flowering and capsule production at Day 9 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Asystasia dry weight and flowering at Day 135 . . . .

Asystasia flowering and capsule production at Day 135 . . . . . . . . ........ . . . . . . . . .. . . . . . . ... . . . . . .... . . .

Comparison of nutrient levels of Asystasia with other plants ............................... . .... .

Asystasia potential capsul e production .......... .

Seed production potential of other weeds ....... . .

IV

Page

14

15

20

37

38

48

5 0

5 9

73

75

82

Figure

1

2

3

4

5

6

7

8

9

10

11

1 2

1 3

14

1 5

1 6

1 7

1 8

19

2 0

2 1

2 2

2 3

2 4

2 5

2 6

2 7

2 8

2 9

3 0

3 1

3 2

LIST OF FIGURES

Vegetat ive s ho o t s and t e rmina l l y bo rne i n f l o r e s cence of Asys t a s i a gan ge t i ca s ub s p . mi cran tha . . . . . . . . . . . . ... . . . ... . . .... . .. . . . . . . . . T r i a l l ayout and de s i gn . . . . . . . . . . . . . . . . . . . . . . . . .

Asys t a s i a dry we i ght at Day 4 5 . . . . . . . . . . . . . . . . . .

Part i t i on i ng o f Asys t a s i a dry we i ght at Day 4 5 . .

Leaf area o f As yst a s i a at Day 4 5 . . . . . . . . . . . . . . . .

Asys t a s i a n i t rogen leve l s at Day 4 5 . . . . . . . . . . . . .

Asys t a s i a phosphorus l evels at Day 4 5 . . . . . . . . . . .

Asys t a s i a pot a s s ium l eve l s at Day 4 5 . . . . . . . . . . . .

Asys t a s i a magne s ium l eve l s a t Day 4 5 . . . . . . . . . . . .

Asys t a s i a cal cium l eve l s at Day 4 5 . . . . . . . . . . . . . .

As ys t a s i a dry wei ght at Day 9 0 . . . . . . . . . . . . . . . . . .

Par t i t i o n i ng o f As y s t a s i a dry we i ght at Day 9 0 . .

Leaf area o f Asy s t a s i a at Day 9 0 . . . . . . . . . . . . . . . .

As ys t a s i a n i t rogen l eve l s at Day 9 0 . . . . . . . . . . . . .

As ys t a s i a pho spho rus l eve l s at Day 9 0 . . . . . . . . . . .

Asys t a s i a p o t a s s i um l eve l s at Day 9 0 . . . . . . . . . . . .

As ys t a s i a magne s i um leve l s at Day 9 0 . . . . . . . . . . . .

As ys t a s i a cal cium l eve l s at Day 9 0 . . . . . . . . . . . . . .

As y s t a s i a dry we i ght at Day 1 3 5 . . . . . . . . . . . . . . . . .

Part i t i oning o f As yst a s i a dry weight at Day 13 5 .

Leaf area o f As ys t a s i a at Day 1 3 5 . . . . . . . . . . . . . . .

As yata s i a n i t rogen leve l s a t Day 1 3 5 . . . . . . . . . . . .

As y s t a s i a phosphorus l eve ls at Day 13 5 . . . . . . . . . .

As yst a s i a p o t a s s i um l eve l s at Day 1 3 5 . . . . . . . . . . .

As ys t a s i a magnesium levels at Day 135 . . . . . . . . . . .

Asys t a s i a c a l c i um l eve l s at Day 13 5 . . . . . . . . . . . . .

Growth pha s e s o f As ysta s i a over 1 35 day s . . . . . . . .

Ni t rogen l eve l s o f As ys t a s i a ove r 13 5 days . . . . . .

Pho spho rus l eve l s o f As ys t as i a ove r 1 3 5 days . . . .

P o ta s s i um l evels o f Asys t a s i a ove r 1 3 5 days . . . . .

Magne s i um l eve l s o f Asys t a s i a ove r 1 3 5 days . . . . .

P a r t i t i oning o f As ys t a s i a dry we i ght ove r 1 3 5 days . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

5

1 6

2 6

2 7

2 9

3 1

3 2

3 4

3 5

3 6

3 8

4 0

4 2

4 3

4 4

4 5

4 6

4 7

4 9

5 1

5 2

5 4

5 5

5 6

5 7

5 8

6 2

6 6

6 8

7 0

7 2

7 8

Abstract of thesis submitted to the Senate of Universiti Pertanian Malaysia in fulfilment of the requirements for

the degree of Master of Science .

THE EFFECT OF LIGHT, FERTILISER AND PLANTING DENSITY ON

THE GROWTH AND FLOWERING OF

ASYSTASIA GANGETICA SUBSP. MICRANTHA

By

QUAH YIN THYE

Feb, 1 997

Chairman: Dr. Ruth Kiew

Faculty: Science and Environmental Studies

vi

Asystasia gangetica subsp . micrantha, commonly

known as Asystasia, is a prolif-tc weed that has

recently become problematic to the plantation

industry in Malaysia. The weed's success in invading

plantations over a wide geographical range is

attributed to its fast establishment, rapid growth

rate and early flowering .

The pot trial study of Asystasia showed the

weed I s life-cycle consists of four growth phases,

each of about 45-days' duration: namely phase 1

juvenile, phase 2 initial flowering, phase 3

intense flowering and phase 4 - senescent.

Phase 1 was characterised by rapid vegetative

growth with the first flower blooming by Day 42. The

vii

total dry weight for high-density (17 plants/pot)

plants under full sunlight and high soil nutrients

was 3 4 g/pot . The dry matter partitioning of

leaves: stems: roots was 40 : 28: 3 2 and the leaf index

was 5 .3 7. The weed's fast growth from seed

germination is one of its outstanding characteristics

and has made it highly successful in colonising

exposed sites brought about by land cui ti vation or

chemical spraying .

The second growth phase from Day 45 to 9 0 consisted

of both vegetative and flowering . The total biomass

has increased to 95 g/pot and dry matter partitioning

of leaves: stems: roots has changed to 3 1 : 3 7: 3 2.

Emphasis of dry matter allocation has shifted from

leaves to stems as the plant grew. This stage of

growth could also be considered the "building phase"

as the weed accumulated biomass and leaves for the

next stage of high reproduction . Leaf index has more

than doubled to 1 2 .8. Inter-plant competition has

affected flowering: low-density (1 plant/pot) plants

have higher capsule potential of

compared to only 3 4 capsules/pot

3 0 2 capsules/pot

for high-density

under open conditions with high fertiliser rates .

Phase 3 growth of Asystasia was primarily the

flowering and reproduction stage and these might be

considered the "climax" growth . The total dry matter

of 23 2 g/pot has more than doubled the previous phase

viii

but the capsule potential has increased many times.

Floweri ng was i ntense . Under open conditions, capsule

potential ranged from 3 2 5 to 1 0 78 capsules/pot while

under shade conditions, the potential was 2 85 to 82 0

capsules/pot . Dispersed seeds would become part of

the soil seed bank and ready to germinate at the next

growth opportunity and perpetuate future generations

of Asystasia. Dry matter partitioning of

leaves: stems:roots was 2 2 :3 6:4 2 . Leaf index has

increased to 19.8.

The last phase is senescence stage . Most of the

ripe capsules have dispersed their seeds and most

plants were chlorotic and suffering from considerable

die-back .

The noxious status of this weed is attributed

mainly to its ability to absorb high amount of soil

nutrients . At its "climax" growth by Day 1 3 5 , the

Asystasia biomass of 2 3 2 g/pot consisted of 5.4 g of

nitrogen, 0.4 g of phosphorus, 4 .1 g of potassium and

0.6 g of magnesium excluding the biomass produced as

capsules . Thus, cultivated crops that are heavily

infested with Asystasia are likely to face severe

competition for soil nutrients.

Abs t ra k t e s i s dikemukakan kepada S enat Uni ve r s i t i Pertanian Malays ia Unt uk Memenuhi Kepe r luan

Ija zah Ma s t e r Sain s

KESAN CAHAYA, BAJA DAN KEPADATAN TANAMAN KE ATAS PERTUMBUHAN DAN PEMBUNGAAN

ASYSTASIA GANGETICA SUBSP. MICRANTHA

O l eh

QUAH YIN THYE

Feb, 1997

Penge r us i : Dr . Rut h Kiew

Facul t i : S a i n s and Pengaji an Al am S e k i t a r

ix

Asys t a s i a gan ge t i ca s ubsp. micran tha atau

bi a s anya d i ke na l i s e bagai Asys t a s ia ada l ah rumpai

p r o dukt if yang berma s a l ah da l am i n du s t r i p e r l a dangan

di Ma lays i a pada mas a kini . Kej ayaan pence r o bo hannya

ke dal am l a dang ladang ada l ah di s e babkan o l eh kadar

pe rtumbuhannya yang pant a s dan kukuh s e rt a

p embungaannya yang awal .

Penga j i an yang dijalankan dalam pa su menunjukkan

bahawa rumpai i n i mempunyai 4 p e r ingkat p e r t umbuhan ,

i a i tu p e r i ng kat 1 - muda, p e r i ngka t 2- p e rmulaan

membunga , p e r i ngkat 3- giat membunga dan p e r i ngkat 4 -

layu . Jangka ma s a s e t iap p e r ingkat t e r s e but ada l ah

l e bi h kurang 4 5 hari .

Peringkat 1 menandakan p e r t umbuhan t ampang yang

cepat dengan bunga pertama be rkembang pada hari ke

x

42. Di bawah cahaya penuh dan kandungan nutrien

tanah yang tinggi, pokok- pokok yang di tanam dengan

kepadatan tinggi ( 1 7 pokok/pasu) memperolehi jumlah

be rat kering sebanyak 34 g/pasu . Nisbah bahan kering

daun: batang : akar

adalah 5 . 37.

adalah 40:28:32 dan indeks daun

Pertumbuhan yang cepat selepas

percambahan adalah salah satu sifat luar biasa yang

membolehkan rumpai ini berjaya menduduki kawasan

kawasan yang terdedah akibat dari cucuk tanam dan

penggunaan racun kimia.

Peringkat kedua adalah di antara hari ke 45 dan

ke 90. Peringkat ini melibatkan pertumbuhan tampang

dan pembungaan. Juml ah biomas bertambah ke 95 g/pasu

dan ni sbah bahan kering untuk daun: batang:akar

bertukar ke 30:37:32. Keutamaan peruntukan berat

kering berpindah dari daun ke

pertumbuhan . Peringkat ini

batang

boleh

dalam proses

juga dikenali

sebagai "fasa

mengumpulkan

seterusnya .

pembinaan" di mana rumpai

biomas

Indeks

untuk pertumbuhan

daun meningkat ke

ini

giat

12.8.

Persaingan antara pokok telah memberi kesan kepada

pembungaan: pokok-pokok yang ditanam dengan kepadatan

rendah (1 pokok/pasu ) mempunyai potensi sebanyak 302

kapsul/pasu berbanding dengan hanya

untuk pokok-pokok dalam kepadatan

34 kapsul/pasu

tinggi di bawah

keadaan terbuka dan kadar pembajaan yang tinggi .

Xl

Pe r i ngkat 3 pertumbuhan As y s tasia adalah pada

a s a l nya per i ngkat pembungaan dan penghasilan dan

b o l e h j uga di anggap s ebagai p e rtumbuhan "kemuncak".

Bukan s a ja j umlah berat ke r i ng meningkat dua ka l i

ganda k e 232 g/pasu b e rbanding dengan p e ri ngkat yang

lep a s t e t ap i p o t e n s i kap sul j ug a b e r t amba h b anyak

ka l i . Pembungaan ada l ah giat . Dal am keadaan t e rbuka,

poten s i kap sul b e rada dalam lingkungan 325 ke 1078

kapsul /pa su, manakal a dal am keadaan ge l ap , p o t e n s i nya

hanya s e t a ka t 285 ke 820 kap sul / pa s u . B i ji -b i ji yang

t e r s eb a r kemudian a kan be rada d a l am t anah dan s e d i a

untuk b e r cambah b i l a p e l uang t ib a d a n menj a d i

gene r a s i As y s t a s i a yang a kan datang . Ni sbah bahan

ke r i ng daun : batang : ak a r menjadi 22:36:42 a k ibat

penge luaran kap s u l . I nde k s daun b ertambah ke 19.8.

P e r i ngkat akhir i a l ah p e r i ngkat l ayu .

Kebanyakan kapsul t e l ah menyeba rkan b i ji -b i ji me r e ka

dan kebanyakan p o k o k ada l a h "chl o r o t i c" dan menga l ami

kema t i an pucuk yang agak hebat .

Keb o l ehan penye r apan kandungan nut ri e n t anah

yang t i nggi me rup akan s a l ah satu k e r o s akan ut ama

rumpai ini te rhadap

p e rtumbuhan "kemuncak"

t an aman- tanama n .

di hari ke 135,

Pada

b i oma s

As ys t a s i a s eb anya k 232 g / p a s u t e r s ebut mengandung i

5.4 9 Ni t rogen, 0.4 9 pho spho ru s , 4.1 g p o ta s s i um dan

0.6 9 magne s i um t i da k terma suk b i oma s kap sul . O l eh

i tu, mawa s an - kawa s an t anaman yang mempunyai p opul a s i

Asystasia yang tinggi akan mengalami pertandingan

yang hebat untuk nutrien-nutrien tanah.

CHAPTER I

INTRODUCTION

Asys t a s i a gange t i ca s ub sp . mi cran tha

( incorrectly known a s Asys t a s i a in t rusa) w a s

catego r i s e d a s a s e r i ous nox i o u s we ed i n o i l palm

p l antat i o n s i n Mal ays i a ( Raj aratnam e t al. ,

1 9 7 7 ) . Al though there are three taxa o f As yst a s i a

i n Peninsular Ma l ays i a , only s ub s p . mi cran tha i s

a problemat i c wee d .

The weed was at f i r s t f ound i n cent ral and

s outh Johore ( T eoh et al. 1 9 8 2 ; Chan , 1 9 8 4 ) but

has now spread t o a l l s t a t e s o f Peni n s u l a r

Ma l ays i a (Anon , 1 9 8 4; S ab e r i a n d Mu s a , 1 9 9 2 ) . At

pres ent , i n Peninsular Mal ays i a , As ys t a s i a 1S

s een a lmo s t e ve rywhere , f rom home garden s , a l o ng

roads i de s t o the e dge o f f o re s t . S ince 1 9 9 2 , i t

has a l s o been obs e rved i n o i l p alm p l antat i o n s

i n t h e Tawau-Lahad Datu regi on.

1

2

Al t hough t he we ed i s e a s i l y ki l l e d by a wi de

range o f he rb i c i de s ( Raj aratnam et al., 1977; T e o h et

a l . , 1 9 8 2 ) , i t s f a s t growt h, e a r l y f l owe r i ng and

ab i l i t y to spread and i nvade new s i t e s t hr oughout t he

count ry ha s made it one o f t he mo s t succe s s fu l weeds

i n Ma l ays i a .

In o rde r to cont r o l t he weed, a bette r

unde r s tanding o f i t s b i o l ogy i s e s s ent i a l . The re are

many aspects o f Asys t a s i a b i o l o gy t hat n e e d t o be

e l uc i dated of whi ch t he mo s t impo rtant and inte r e s t ing

are t ho s e r e l a t ing to its abi l i t y to comp e t e , s urvive

and spread. T he s e p r ima r i l y r e l at e d to growth, dry

matt e r p r o duct i o n and reproduct i o n unde r var i ou s

e nv i r onmental condi t i o n s . I n o rde r t o cont ro l t he s e

envi ronmental paramet e r s , a p o t t r i a l s tudy i s mo s t

suitab l e f o r t hi s purpo s e .

Quantitative s tudi e s o f Asys t a s i a gan ge t i ca

s ub s p . mi cran tha f o cu s s e d on t he e f f ect o f s hade ,

p l anting den s i t y and fert i l i se r application on :

( 1 ) P l ant growth ( dr y we i ght ) o f r o o t s , s t ems

and leave s ;

( 2 ) I n di vi dual l e a f s i ze and t o t a l l e a f area

p e r pot ;

3

(3) Partit ioning o f dry mat t e r int o l e ave s ,

s t ems and r o ot s ;

( 4 ) Nut r i ent uptake ( ni t rogen , pho sphorous ,

p o t a s s ium , magne s i um and calc i um) ; and

(5) Flowe r i ng and f ru i t ing .

4

CHAPTER I I

LITERATURE REVIEW

Botanical name

Asys t a sia ga nge t i ca sub s p . micra n tha b e l ongs t o

t h e Acanthaceae that wo r l dwi de i s made u p o f 3 5 7

gene ra and 4 3 5 0 spe c i e s ( Mabbe r l e y , 1 9 9 3 ) . About 3 5

genera comp r i s i ng 160 spe c i e s are f ound i n Peninsular

Mal ays i a ( Hende r s o n , 19 5 9 ) . In the genus As y s t a s i a , 70

spe c i e s are reco rded i n the t r op i c s ( Mabbe r l e y , 1 9 9 3 ) .

Three taxa grow l o c a l l y:

1 . Asys t a s i a gange t i ca (L) . T. Anders s ub s p .

micran tha(Nees) Ka lbessa.

Thi s p l ant ( fo rme r l y and i n c o r re c t l y known

a s A. i n trusa) , i s nat ive t o Af r i ca ( Ki ew

and Vo l l e s e n , i n p re s s ) .

This taxon is characte r i s e d b y a c o ro l l a

that i s " pure whi t e with a l a rge vi o l e t

spot o n t he l ower l ip , 1 . 4 1 .8 cm l o ng,

expanded about one t h i r d f r om t he ba s e ,

ap i ca l and l at e ra l l ob e s r e f l ex e d , l owe r

l o b e s s t rongl y p l eated" ( Ki ew and Vol l e s e n ,

i n p re s s ) . Figure 1 s hows a t yp i cal s h o o t o f

F i gure 1

5

s ubsp . micran tha that has jus t begun LO

produce f l owe r s .

I I

5cm

Ve getat i ve s h o o t s and t e rminal l y bo rne i n f l o r e s cence of Asys t a s i a gan ge t i ca s ubsp . micran tha ( Adap t e d from Raj aratnam et al., 1977)

6

2. Asysta sia gangetica s ubsp. gangetica

A nat i ve to India it is now a pan-tropica l

wee d ( Ki ew a n d Vo l l e s en , i n p re s s ) . T he

f l owe r o f thi s spe c i e s h a s many shade s f rom

p a l e ye l l ow to mauve and i s much l e s s

aggre s s ive i n i t s growth and s p r e a d t han

subsp . micrantha.

Unl i ke subsp . micran tha r thi s taxon has a

l a rge f l owe r and co ro l l a co l o ur that range s

f r om " . . . pale cream o r yell ow , r o s y c re am ,

p a l e o r dark purp l e , s omet ime s with ye l l ow

nectar gui de s in the ba s e of the throat , 2 . 5

- 3 . 5 cm l ong , expanded f rom the ba s e , lo be s

sp reading , l owe r l o be s not p le a t e d" ( Ki ew

and Vo l l e s e n , i n p re s s ) .

3 . Asysta s i a chelonoides

Thi s spe c i e s is cultivated as a pot p l ant ,

i t s f l owe r s be ing a s howy dar k p urp l e velvet

c o l o ur . I t i s o c c a s i o n a l l y see n i n home

ga rdens ( Hende r s o n , 1 9 5 9 ) .

For the e a s e o f di s cu s s i o n , s ubs e quent r e f e rence t o A.

gange t i ca

As y s t a s i a .

s ubsp . micrantha i s re f e r r e d t o a s

7

Competition to economic crops

As y s t a s i a i s a noxious wee d because it can ab s orb

l a rge amount s of s o i l nutr i ent s to the det r iment o f

cult ivated crop s . I t s rap i d spread and s e e d bank make

e radi cation di f f i cul t . Almo s t a l l agri cultural and

horti cultural s e ct o r s in thi s country are a f f e ct e d by

thi s we ed . Frequent weeding i s ne c e s s a r y otherwi s e the

cul t ivat e d s i t e s can ea s i l y be cove red with thi s

pro l i f i c wee d .

Oil palm plantation

As y s ta s i a

amount s o f

lS

s o i l

capab l e

nut r i en t s

o f immob i l i s i ng l a r ge

e sp e c i a l l y p o t a s s i um .

Raj aratnam e t al. (1 977) rep o r t e d f r om ob s e rvat i on s

ove r a 25 -month p e r i o d that o i l palm f ru i t yi e l d wa s

dep re s s e d b y 3 . 9 ton/ha .

Mo re recent l y , Na z e eb and Lo ong ( 1 992 ) found that

ove r a f ive-year p e r i o d there wa s n o s i gn i f i c ant

di f fe rence in yi e l d i n a f i e l d t r i a l of o i l p a lm

i n f e s t e d with As y s t a s i a . They concluded that Asystasia

wa s mo re vigorous i n the open than unde r the shaded

condi t i on s of mature o i l palm whe re t he we e d need not

be e radicated but could be kept a s " natura l " under-

s t o rey vegetat i on . Howeve r , they gave no

quant i f i ca t i o n of the amount of As ysta s i a p r e s ent no r

the ferti l i s e r s app l i e d i n the t r i a l , whi ch mak e s i t

di f f i cul t to a s s e s s the s eve r i t y o f compe t i t i on f o r

nut r i ents b y t h e we e d .

B

Cocoa plantation

Chung and Lam ( 1 9 9 1 ) repo rted that As y s t a s i a

s uppre s s e d the growth and yi e l d o f young co coa

p l antings .

Pineapple cultivation

As y s t a s i a wa s reported in t he p i neapp l e growing

region i n s outh Johore i n 1 9 7 5 and b e c ame s o

t roub l e s ome that i n 1 9 8 4 a s eminar speci f i c a l l y o n the

weed was he l d (Anon , 1 9 8 4 ) . T he we ed can cau s e a 1 9 . 2 %

reduction i n yi e l d i n p i neapp l e cv . 'Ma sme r a h ' ( Le e ,

1 9 8 6 ) .

Ano t he r problem with t hi s wee d i s that i t can

reach up to 1 . 5 me t r e s ( S abe r i , 1 9 8 9 ) and may

eventua l l y cove r the crop i f l e ft unc he c ked .

As ysta s i a i s con s i de red to be s imi l a r , i f not

mo re s e r i ous than o t he r ma j o r comp e t i t ive weeds i n t he

p l ant a t i o n s due to it s f a s t growth and spread, and i t s

abil il it y

nut r i ents .

i n ab s o rbing l a rge amount s o f s o i l

Examp l e s o f o t he r comp e t i t i ve weeds that can

suppre s s c r op y i e l d s e sp e c i a l l y for p l ant at i on crops

include :

9

Ischaemum muticum - Teo et al. (1989) reported a

yield increment o f 3 2 % when this weed was

e radicated f rom o i l palm f i e l d ;

Chromola ena odora t um Aya and Fayemi ( 1 9 8 2 )

repo rted s i gni f i cant increa s e o f o i l palm fruit

yi e l d when the weed was e radi cated ;

Mikan i a micran tha - Teoh and Chew ( 1 9 8 0 ) rep o r t e d

t h a t y i e ld o f o i l palm cou l d de c l i ne by 1 0% when

Mi kan i a be came p r e dominant ; and

Mikan i a mi cran tha and Impera t a cycl i n dri ca - Gray

and Hardon ( 1 9 6 7 ) reported a 2 0 % reduct i on of o i l

palm yi e l ds when the s e weeds we re domi nant .

Chemical control of Asystasia

As ysta s i a i s e a s i l y k i l l e d by a w i de range o f

s y s temi c he rb i c i d e s ( Ra j aratnam e t a l . , 1 9 7 7 ; T e o h e t

a l . , 1 9 8 2 ; Chung e t a l . , 1 9 8 4 ; Lee , 1 9 8 4 a ; Chong and

Mo s h i n , 1 9 8 6 ; and Teng and Teh , 1 9 9 0 ) .

Howeve r , r egene rat i o n from s e e d i s rap i d

following chemical spraying o f i n fe st e d areas

( Raj aratnam et a l . , 19 7 7 ; Teoh et a l . , 19 8 2 ) . At t emp t s

to cont r o l As y s t a s i a u s i n g p r e -eme rgence h e rb i c i de s

were un suc ce s s ful ( T eoh e t a l . , 1 9 8 2 ) .

Mo s t r e s e a r ch on chemi cal contro l s hows that

As y s ta s i a i s e a s i l y k i l l e d but l ong t e rm chemi c a l

control o f the weed has not been succe s s ful . T e o h e t

10

al. ( 1 9 8 2 ) and Raja ratnam et al . (1977) attributed

thi s t o the rap i d regenera t i o n f rom s e e ds .

Animal grazing to control Asystasia

I n 1 9 6 0 , sheep gra z i ng for wee d cont r o l i n rubbe r

p l antat i o n was i ntroduced, fo l l owed b y p i l o t s t udi e s

i n 1 9 6 8 ( Ve l ayuthan and Lim, 1 9 8 6 ) .

Arope et a l . ( 19 8 5 ) r e k i ndl e d i n t e r e s t i n sheep

gra z ing t o cont r o l we eds i n p l antat i on crops whe n they

reported a cost s aving of 15 - 2 5 % o n ove ra l l weeding

c o s t s for rubbe r cul t i va t i o n with a 1 5 % return on

i nve s tment . Al though Asy s t a s i a i s one of spe c i e s that

sheep graze on, i t wa s Ro s l ey (1 9 8 5 ) who spe c i f i ca l l y

advo cated sheep a s a b i o l o g i c a l cont r o l agent when h e

not i ce d that sheep p r e f e r r e d Asys t a s i a whi l e graz i ng

i n mi xed vege t a t i o n cove r i n the i nt e r rows o f rubbe r

t re e s .

As yst a s i a a s a fodder crop was found t o contain

7 - 2 0 % c rude protein dry ma t t e r content and 0 . 0 7 %

dige s t ible c rude p r o t e i n whi ch i s s u f f i c i ent t o mee t

t h e da i l y dietary protein requ i r ement f o r mo s t pha s e s

o f sheep product i on ( S uparj o and Wong , 1 9 8 8 ) .

Howeve r , Wong e t a l . ( 19 8 8 ) wa rned aga i n s t the

p o s s ib i l i t y o f copp e r tox i c i t y f o r sheep fed on

Asys t a s i a a l one , al though no c l inical s ymptoms we re

o b s e rved i n sheep that had h i gh l eve l s of coppe r