Greenhouse production of Echinacea purpurea (L.) and E. angustifolia using different growing media, NO3

–/NH4+

ratios and watering regimes

Youbin Zheng1, Mike Dixon1, and Praveen Saxena2

1Controlled Environment Systems Research Facility, Department of Environment Biology, University of Guelph,Ontario, Canada N1G 2W1 ; and 2Department of Plant Agriculture, University of Guelph, Ontario, Canada.

Received 26 August 2005, accepted 22 March 2006.

Zheng, Y., Dixon, M. and Saxena, P. 2006. Greenhouse production of Echinacea purpurea (L.) and E. angustifolia using differ-ent growing media, NO3

–/NH4+ ratios and watering regimes. Can. J. Plant Sci. 86: 809–815. Current field cultivation and wild-har-

vest methods for the medicinal plant Echinacea are struggling to meet the requirements for a high-quality, uniformly produced crop forhuman consumption. To help meet this challenge, the potential of using a greenhouse production system for Echinacea production wasexplored. Echinacea purpurea (L.) Moench and angustifolia DC. var. angustifolia plants were grown in three types of greenhouse pro-duction systems: (1) deep flow solution culture (D), (2) pots with either Pro-Mix (P) or (3) sand (S). Plants were irrigated with one ofthree nutrient solutions containing NO3

–/NH4+ ratios of 7:1, 5:1 or 3:1, respectively. The plants grown in the Pro-Mix and the sand sys-

tems were either well-watered or subjected to periodical water stress. The results obtained after 12 wk of growth showed that Echinacearoot production in the greenhouse systems was comparable with or better than that in the field. Based on root and total biomass pro-duction, the Pro-Mix system was the best production system for both E. angustifolia and E. purpurea. In most cases, the NO3

–/NH4+

ratio did not have significant effects on the growth of either species. When effects were seen, however, higher NO3–/NH4

+ levels gen-erally resulted in greater leaf area, root and total biomass, and a higher root/shoot ratio. Mild periodic water stress did not affect theroot/shoot ratio or the root biomass in either species. The application of a periodic water stress reduced leaf area of both species, but areduction in total biomass was only observed in E. purpurea.

Key words: Echinacea, greenhouse production, hydroponic production, medicinal plant, NO3–/NH4

+ ratio, water stress

Zheng, Y., Dixon, M. et Saxena, P. 2006. Production en serre d’Echinacea purpurea (L.) et d’E. angustifolia avec diversmilieux de culture, rapports NO3

–/NH4+ et régimes hydriques. Can. J. Plant Sci. 86: 809–815. La culture en pleine terre et la

récolte de spécimens sauvages de plantes médicinales du genre Echinacea permettent difficilement de respecter les contraintes dequalité élevée et d’uniformité essentielles à la consommation humaine. Pour y remédier, les auteurs ont tenté d’établir si lesespèces de ce genre peuvent pousser en serre. Ils ont donc cultivé des plants d’Echinacea purpurea (L.) Moench et d’E. angusti-folia DC var. angustifolia en serre selon trois systèmes de production : 1) culture hydroponique profonde (D), 2) en pots dans lemélange Pro-Mix (P) ou 3) dans du sable (S). Les plants ont été arrosés avec une de trois solutions nutritives contenant un rapportde NO3

-/NH4+ de 7:1, 5:1 ou 3:1, respectivement. Les plants poussant dans le mélange Pro-Mix et le sable ont été soit copieuse-

ment arrosés, soit périodiquement soumis à un stress hydrique. Au bout de 12 semaines, les résultats indiquent que la productionde racines par les plants d’Echinacea cultivés en serre est comparable ou supérieure à celle des plants cultivés en pleine terre.Compte tenu de la biomasse des racines et de la biomasse totale, le système utilisant le mélange Pro-Mix s’avère le meilleur pourles deux espèces testées. Dans la plupart des cas, le ratio NO3

-/NH4+ n’a pas d’incidence significative sur la croissance. Quand on

observe des effets cependant, on remarque généralement qu’un rapport NO3-/NH4

+ plus élevé entraîne une augmentation de la sur-face foliaire, de la biomasse des racines et de la biomasse totale ainsi que du rapport racines/pousses. Un stress hydrique périodiquemodéré ne modifie le ratio racines/pousses ni la biomasse des racines chez aucune des deux espèces. Un stress hydrique périodiqueréduit toutefois la surface foliaire, bien que la biomasse totale ne diminue que chez E. purpurea.

Mots clés: Echinacea, serriculture, culture hydroponique, plantes médicinales, rapport NO3-/NH4

+, stress hydrique

Echinacea is not only popularly planted as an ornamental ingardens, but also widely used for its medicinal properties bothin North America and Europe (Barrett 2003; Li 1998). Thewide use of Echinacea for treating illness and enhancinghuman health is based on scientific research, which demon-strated that the extracts of Echinacea have significantimmunomodulatory functions (Barrett 2003). Echinacea wasthe best-selling herbal medicine with an estimated annual retailsale of more than US$58 million in the United States of

America (Blumenthal 2003) and an estimated annual sale ofUS$300 million worldwide.

There are 11 recognized taxa of Echinacea, and threespecies, E. angustifolia DC. var. angustifolia, E. pallida

809

Abbreviations: D, deep flow solution culture; P, hydro-ponic production system with pots containing ProMix; S,hydroponic production system with pots containing sand; s,periodic water stress; w, well-watered

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(Nutt.) and E. purpurea (L.) Moench, with known pharma-cological activity (McKeown 1999; Binns et al. 2002).Echinacea is a native plant of North America; however, nat-ural production is unable to meet the market demand(Lakshmanan et al. 2002). Field cultivation of herbal medi-cinal plants is facing many challenges (Murch et al. 2000)such as contamination by heavy metals (Raman et al. 2004),soil and soil-borne organisms, herbicides and pesticides(Letchamo et al. 2002), as well as roots of weed species andother plant materials. Field cultivation takes 2–3 yr fromseed to harvest, especially in cold climate zones such asCanada.

Recently, governments in Europe and North Americahave proposed more restrictive regulation of herbal medici-nal products. Canadian legislation, for example, has beenintroduced to improve the safety, quality and efficacy of nat-ural health products, and requires manufacturers and pro-ducers to provide standardized products free ofcontamination (Health Canada 2004).

The use of controlled environment systems offers a uniqueresolution for meeting both market demands as well as gov-ernmental regulations with regards to medicinal plant produc-tion. In controlled environments (e.g., greenhouses), the mainenvironmental parameters are routinely controlled to ensurehomogeneous and high-quality crop production. Producerscan also implement Good Manufacturing Practices to ensurethe quality of medicinal plant products to meet the highest pro-duction standards. However, information on cultural methodsand their effect on growth and yield is rather limited (Li 1998),and we are not aware of any published information on meth-ods of greenhouse production for Echinacea.

It is reported that root and overall plant growth are gener-ally greater with a mixture of NO3

– and NH4+ than with

either nitrogen form alone (Sady et al. 1995; Schortemeyerand Feil 1996). The optimum NO3

–/NH4+ ratio for plant

growth depends on species, and environmental conditions(Marschner 2002). The NO3

–/NH4+ ratio can affect not only

root development and morphology, but also the overall rootbiomass (Woolfolk and Friend 2003). Research also showedthat the NO3

–/NH4+ ratio can change the plant root/shoot

ratio (Bar-Tal et al. 2001).

It has been shown that root growth of some species can bestimulated, or at least maintained, at water potentials thatcompletely inhibit aerial growth (Sharp and Davies 1979;Pace et al. 1999). It is reported that controlled drought stressin field conditions increased Echinacea purpurea root dryweight (Gray et al. 2003).

The objectives of this study were (i) to evaluate the suit-ability of various greenhouse production systems for grow-ing Echinacea under controlled environment conditions; (ii)to determine the optimal NO3

–/NH4+ ratio for the produc-

tion of Echinacea in the above systems; (iii) to test thehypothesis that periodic water stress can increase Echinacearoot production in greenhouse production systems.

MATERIALS AND METHODSSeeds of Echinacea purpurea (L.) Moench and E. angusti-folia DC. var. angustifolia (Johnny’s Selected Seeds, Maine,USA) were sowed in plugs of 128 plug-trays with Pro-Mix(PGX, Premier Horticulture Inc., Quakertown, PA) on 2004Apr. 27. The trays were kept in the greenhouse and wateredas needed. When seedlings were at the 3–4 true leaves stage(2004 Jun. 23), they were transplanted to three different pro-duction systems. The three production systems were: (1)deep flow solution culture system (D), which has a layer ofStyrofoam (used for holding the plants) floating on a 7–9 cmdeep nutrient solution in subirrigation benches (366 cm long× 152 cm wide × 12 cm deep); (2) Pro-Mix system (P),which had one plant grown in a pot (2.5 L) containing Pro-Mix (PGX), and with one emitter (7.6 L h–1) in each pot forfertigation; (3) sand system (S), which had one plant in a pot(2.5 L) containing sand (No.16 Silica, Bell & MachenzieCo. Ltd., Hamilton, ON), and with a dribble-ring (the ringwas 10 cm in diameter, DR4–36, Dramm Corporation,Fenwick, ON) for fertigation. All the production systemshad the same plant density, a 22 cm gap between every twoplants (≈ 22 plants m–2). This density was chosen based onthe field research results of Parmenter and Littlejohn (1997).

Plants were fertigated with one of three nutrient solutionscontaining the following macronutrients (in µM): 2.0 P, 3.9Ca, 6.2 K, 2.1–4.2 S and 2.0 Mg; and micronutrients (inµM): 9 Mn, 0.8 Zn, 18.0 B, 0.5 Mo, 0.8 Cu and 50 Fe as Fe-

Table 1. Results of the analysis of variance for flower number (no./plant), leaf area (cm2/plant), root biomass (g/plant), total biomass (g/plant) androot/shoot ratio (R/S) of E. angustifolia grown under three NO3/NH4 ratios (3, 3:1; 5, 5:1 and 7, 7:1), three production systems (D, deep flow solu-tion culture system; P, Pro-Mix production system; S, sand production system) and two watering regimes (w, well-watered and s, periodically waterstressed)

Mean squares

Source df Flower no. Leaf area Root biomass Total biomass R/S

Replication 3 0.107 13236 0.9 2.8 0.02Treatment 14 0.054 174798*** 4.7*** 37*** 0.06***Error 42 0.05 6937 0.4 2.2 0.01D vs. P 1 0.14 1544777*** 49*** 350*** 0.12**D vs. S 1 0.11 589301*** 26*** 146*** 0.23***P vs. S 1 0.10 872150*** 7.8*** 142*** 0.23***3 vs. 5 1 0.001 831 0.8 0.1 0.023 vs. 7 1 0.03 20218 1.7 2.9 0.025 vs. 7 1 0.02 12851 0.2 1.9 0.00w vs. s 1 0.01 71036** 0.9 5.0 0.02

*, **, *** P < 0.05, P < 0.01 and P < 0.001, respectively.

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ZHENG ET AL. — GREENHOUSE PRODUCTION OF ECHINACEA 811

EDTA. The only differences among the three nutrient solu-tions were the NO3

–/NH4+ ratios, 7:1, 5:1 or 3:1, respective-

ly. The solutions had the following NO3–and NH4

+

concentrations (in mM): 7:1, NO3– 14.0 and NH4

+ 2.0; 5:1,NO3

– 13.3 and NH4+ 2.66; 3:1 NO3

– 12.0 and NH4+ 4.0. To

achieve the above different NO3–/NH4

+ ratios, the followingsalts were used: Ca(NO3)2, NH4NO3, KNO3 and K2SO4.There was one nutrient solution reservoir tank (1120 L) foreach nutrient solution treatment for both the P and S pro-duction systems. There were two reservoir tanks for eachnutrient solution treatment for the D system. The target pHwas 6.0, and the target EC was 1.8 dS m–1 for all the nutri-ent solutions. The pH of the solutions was restored to the

target value with H3PO4 or KOH and the EC was restored totarget value by adding 100 times concentrated stock solu-tions once a day or once every 2 d. Reservoir nutrient solu-tion samples were collected and analysed by HPLC once aweek, and the NO3

–/NH4+ ratios were restored to the target

values accordingly. Plants in the P and S systems were either well-watered

with the above nutrient solutions at all times (w), or sub-jected to periodic water stress (s). For the water stress treat-ment, plants were left to show initial signs of leaf wiltingbefore each fertigation. There were two periods of waterstress during this experiment. The first was started 2 wkafter transplanting to 6 wk after transplanting, and the sec-

Fig. 1. Leaf area, root and total biomass, root/shoot ratio of E. angustifolia under different treatments. For the X axis, D means deep flow solutionculture system; P means Pro-Mix system; S means sand system; 3, 5 and 7 mean the ratio of NO3

–/NH4+ are 3:1, 5:1 and 7:1, respectively; w means

well watered; s means water stress treatment. Data are mean of four replicates (20 subsamples). Bars bearing the same letter are not different at the5% level. Within each group (production system), trends with increasing NO3

– /NH4+ ratios were either not significant (NS) or significant [linear

(L) or quadratic (Q) responses at P ≤ 0.05 (*) or P ≤ 0.001 (***)].

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812 CANADIAN JOURNAL OF PLANT SCIENCE

ond was within 3 wk before harvesting. The experiment wasconducted in a greenhouse within a commercial complex(Science-Based Medicinal Plants, ON). The set point for thegreenhouse air temperature was 21/19°C (day/night) and thehumidity ranged from 70 to 80%.

The experimental design was a randomized complete blockwith four replications, 15 treatments, and 31 plants per plot.Each block contained the following treatments: three nutrientsolutions (with different NO3

–/NH4+ molar ratios), three pro-

duction systems (D, P and S) and two watering schedules(except the D system, all the plants were either well watered orperiodically subjected to drought stress).

Five plants from each plot were randomly harvested on2004 Sep. 22. Flowers of each plant were counted. Eachplant was separated into flowers, shoots and roots. Leaf areaof each plant was measured using a LI-3100 area meter (LI-COR, Inc., Lincoln, NE). Plant parts were dried to a con-stant weight at 37°C. Total dry weight was calculated as thesum of dry weights for all the plant parts.

Treatment effects were subjected to analysis of variance.Contrast analysis was used to test whether there was anysignificant difference between each two treatment group(e.g., D vs. P). Differences among means of treatments weretested by Duncan’s multiple comparison. Responses toNO3

–/NH4+ ratios were analyzed by orthogonal regression.

Statistical analysis was conducted using SAS software (9.1,SAS Institute, Inc., Cary, NC, USA, 2003).

RESULTS

E. angustifoliaPlants were harvested when they started to flower, with theflower number per plant ranging from zero to three.Statistical analysis showed that there was no treatmenteffect on flower numbers (Table 1). For both root and totalbiomass productions and leaf area, the P system was thebest, followed by S and then D (Fig. 1 and Table 1).However, the S system resulted in the highest root/shootratio, followed by the P system, and then the D system. Thenutrient solution NO3

–/NH4+ ratio did not have any effect on

total biomass production and root/shoot ratio in any of theproduction systems tested. There was a positive linear rela-

tionship between NO3–/NH4

+ ratio and root biomass pro-duction in the S system, but not in the other two productionsystems. Periodic water stress treatments did not have anyeffect on either root or total biomass in any of the produc-tion systems, while decreased leaf area and increasedroot/shoot ratio was observed in the S system within thetreatment of NO3

–/NH4+ ratio of 3:1.

E. purpureaAt harvest, most of the plants were at their full floweringstage. Plants in the D and P production systems were notsignificantly different in flower number, and the averagewas 6.3 ± 0.4 (mean ± SE) per plant. Meanwhile, plants inthe S system had significantly fewer flowers, averaging 0.4± 0.19 per plant, than the other two production systems(Table 2). Nutrient solution composition and water stresstreatments did not have any significant (P > 0.05) effect onflowering (Table 2). The P system produced significantlymore root biomass per plant than the S and D systems (Table2 and Fig. 2). The D system and S system did not have anysignificant difference in root biomass production. Differentproduction systems resulted in significant differences intotal biomass production and leaf area, with the P systemexhibiting the highest, followed by the D system, and thenthe S system. The S system resulted in the highest root/shootratio, followed by the P system and then the D system. Ahigh nutrient solution NO3

–/NH4+ ratio correlated with high

total biomass production in the deep flow system, as well ashigher root biomass and root/shoot ratio in the S system, andan increased leaf area per plant in the D system. Periodicwater stress reduced plant leaf area in the S system and totalbiomass production in the P system when the NO3

–/NH4+

ratio was 7/1, but had no effect on root biomass orroot/shoot ratio (Table 2 and Fig. 2).

DISCUSSIONTo produce high-quality medicinal plant products, con-trolled environment systems (e.g., greenhouses) may proveto be one of the best options Due to the high medicinallyactive phytochemical content, Echinacea root production isthe priority for producers. For plant root production, the fol-

Table 2. Results of the analysis of variance for flower number (no./plant), leaf area (cm2/plant), root biomass (g/plant), total biomass (g/plant) androot/shoot ratio (R/S) of E. purpurea grown under three NO3/NH4 ratios (3, 3:1; 5, 5:1 and 7, 7:1), three production systems (D, deep flow solutionculture system; P, Pro-Mix production system; S, sand production system) and two watering regimes (w, well-watered and s, periodically waterstressed)

Mean squares

Source df Flower # Leaf area Root biomass Total biomass R/S

Replication 3 6.4 100411 1.4 471*** 0.02Treatment 14 39*** 2596322*** 12*** 4.0 0.12***Error 42 1.5 36179 1.9 12 0.02D vs. P 1 4.3 9213090*** 71*** 675*** 0.08*D vs. S 1 256*** 890579*** 6.7 932*** 0.8***P vs. S 1 353*** 34304905*** 99*** 5919*** 0.8***3 vs. 5 1 4.5 65196 4.0 1.9 0.033 vs. 7 1 4.5 198708* 16** 32 0.09*5 vs. 7 1 0.00 36265 4.0 18 0.02w vs. s 1 5.2 331475** 6.0 304*** 0.01

*, **, *** P < 0.05, P < 0.01 and P < 0.001, respectively.

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ZHENG ET AL. — GREENHOUSE PRODUCTION OF ECHINACEA 813

lowing most commonly used greenhouse production sys-tems may be applied: pots with sand (S) or easy-to-washProMix (P), deep flow solution culture, nutrient film tech-nique or aeroponics. In this study, we tested growingEchinacea plants in P, S and D systems. Echinacea root pro-duction in this greenhouse trial was comparable with or bet-ter than those reported in field trials. For example, for E.purpurea, within 3 mo (from transplanting to harvesting),the P system produced 53.4 g fresh roots (6.5 g root bio-mass) per plant, the S system produced 17.9 g fresh roots(3.6 g root biomass) per plant and the D system produced

24.5 g fresh roots (3.2 g root biomass) per plant. In the field,near Mosgiel, New Zealand, within 17 mo, the highest yield(dry roots) per plant was c. 30 g (Parmenter and Littlejohn1997). In the Bekaa Valley, Lebanon over the four summermonths, the average roots fresh weight per plant rangedfrom 19.5 to 32.7 g (Barbour et al. 2004). In the UnitedStates of America, E. purpurea grown in the field for 10 moresulted in 81–90 g fresh root per plant (Dufault et al. 2003).Within greenhouses, especially modern greenhouses, grow-ing environment conditions can be easily controlled to meetplant requirements. Therefore, this production technique

Fig. 2. Leaf area, root and total biomass, root/shoot ratio of E. purpurea under different treatments. For the X axis, D means deep flow solu-tion culture system; P means Pro-Mix system; S means sand system; 3, 5 and 7 mean the ratio of NO3

–/NH4 are 3:1, 5:1 and 7:1, respec-tively; w means well watered; s means water stress treatment. Data are mean of four replicates (20 subsamples). Bars bearing the same letterare not different at the 5% level. Within each group (production system), trends with increasing NO3

–/NH4+ ratios were either not signifi-

cant (NS) or significant [linear (L) or quadratic (Q) responses at P ≤ 0.05 (*) or P ≤ 0.001 (***)].

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814 CANADIAN JOURNAL OF PLANT SCIENCE

should result in higher yields than in the field, especially incold climate regions with short growing seasons such asCanada.

In the field, Echinacea thrive in moderately rich and well-drained loam or sandy loam soil with a pH of 6–7 (Li 1988).In the present study, we used a nutrient solution that had apH of 6 and a moderate EC of 1.8 dS·m–1. Both Promix andsand are easy to drain. The production trial results showedthat the two species responded to the three production sys-tems differently. In terms of both roots and total biomassproductions, E. purpurea was much greater than E. angusti-folia regardless of the treatments. Based on root and totalbiomass productions, for E. angustifolia and Echinacea pur-purea the best production system was P, followed by S andD. Since the P system had the highest yield, and was moreforgiving and easier to manage, we would recommend the Psystem for growing Echinacea purpurea and E. angustifo-lia.

In most cases, NO3–/NH4

+ did not have significant effectson the growth of either species. When there was an effect,generally higher NO3

–/NH4+ resulted in higher leaf area,

root and total biomass, and root/shoot ratio (Figs. 1 and 2).Our results were similar to those of Woolfolk and Friend(2003), who grew Populus deltoides (Eastern cottonwood)in five nutrient solutions with NO3

–/NH4+ ranging from 0:1

to 4:1 and found that the 4:1 ratio resulted in the greatesttotal root length and specific root length. Flores et al. (2001)grew Lycopersicon esculentum Mill. (tomato) under green-house conditions with the nutrient solution NO3

–/NH4+

ratios set at 14:0, 6:1 and 2.5:1. Both the leaf and root freshweights were reduced when NO3

–/NH4+ decreased. Strojny

(1999) grew two cultivars of Maranta leuconeura in artifi-cial soil in pots under greenhouse conditions withNO3

–/NH4+ ratios of 19:1, 9:1, 3:1, 1:1 and 0.33:1, and did

not see any effect of NO3–/NH4

+ ratio on the growth andquality of older Maranta plants; however, they suggestedthat in the early stages, it is best not to exceed 5% NH4

+-N.The NO3

–/NH4+ ratio can influence nutrient solution and

growing substrate pH, especially in nutrient recirculatingsystems (Zheng et al. 2004). However, in the present exper-iment, the pH values in all the nutrient solutions, with threedifferent NO3

–/NH4+ ratios, were stable and sometimes did

not need to be adjusted for more than 3 d (data not show).Based on the results of the current study and previous stud-ies, it is suggested that NO3

–/NH4+ ratio of 7:1 or higher is

better for Echinacea production in greenhouse hydroponicsystems.

The results disproved our hypothesis that periodical waterstress can encourage Echinacea root growth. Water stress didnot have any effect on root/shoot ratio, nor did it have anyeffect on root biomass for either of the tested species. The peri-odic water stress reduced leaf area of both of the species andreduced the total biomass of Echinacea purpurea.

In conclusion, based on the measured plant growth para-meters, greenhouse hydroponic systems can be successfullyused for Echinacea plant production. The P system testedwas best for producing E. angustifolia and E. purpurea.With all three tested production systems, a NO3

–/NH4+ ratio

of 7:1 or higher is recommended.

ACKNOWLEDGEMENTWe are very grateful for the excellent technical support provid-ed by Sue Couling, Eric Wierenga, Tannis Slimmon, LinpingWang, Sriyani Peiris and Danuta Gidzinski . Calvin. Chongprovided valuable discussions during the writing of this paper.The financial support of Science-Based Medicinal Plants andthe Natural Sciences and Engineering Research Council ofCanada (NSERC) is gratefully acknowledged.

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