Plant Growth Is Stimulated by Tea-Seed Extract
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HORTSCIENCE 45(12):1848–1853. 2010. ponents in the products, their physiological effects on plants, possible environmental ef- fects, product stability under different environ- Plant Growth Is Stimulated by ments, etc. Combining the scarce scientific literature with less validated producer infor- Tea-seed Extract: A New Natural mation on natural growth enhancers shows that the growth-enhancing effect of different Growth Regulator? products can be roughly divided into three categories; first, compounds that claim to Marianne Andresen enhance nutrient availability, by adding it University of Copenhagen, Department of Agriculture and Ecology, with the product, by facilitating nutrient avail- Højbakkega˚rd Alle´ 13, 2630 Ta˚strup, Denmark ability through the addition of microbes or substrates for microbes, or by adding a com- Nina Cedergreen1 pound claimed to facilitate nutrient uptake University of Copenhagen, Department of Basic Science and Environment, [U.S. Patent 6254654; gamma aminobutyric acid; Plant Growth Enhancer P-307; ODC Thorvaldsensvej 40, 1871 Frederiksberg, Denmark (organically derived colloidals)]. Second are Additional index words. growth stimulation, yield increase, tea seed, Camellia sp., plant compounds that in some unspecified way de- extract, strawberry, hormesis crease damage by pests (Plant Growth En- hancer P-307; ODC); and third are compounds Abstract. Various plant extracts are being marketed claiming to enhance both crop yield that interfere with the plant hormone system and quality and being environmentally friendly. However, these claims are rarely either directly or indirectly through microbes documented by scientific data. In this study, we investigate the growth regulatory effect (Fine Agrochemicals Ltc) (Ali et al., 2009). of Tea Seed Powder (TSP), a saponin-rich waste product from tea seed (Camellia sp.) Because natural growth enhancers are often oil production. The product was tested in various concentrations on Lemna growth and mixtures of a variety of compounds, many are as a soil and spray application on growth of pot grown beet, mustard, oat, and barley. likely to have multiple functions in terms of Finally, two treatments, 0.2 g TSP/L dry soil and weekly sprays with TSP solutions simultaneously improving nutrient availability, corresponding to 1.5 g TSP/m2, were tested for effects on strawberry yield. The results providing fungicidal and insecticidal effect, showed significant growth-enhancing effects on the sterile Lemna of ’20% above and possibly also hormonal effects. However, control, demonstrating that the growth increase was a plant physiological response to to be able to optimize the use of such products TSP rather than an indirect effect of TSP affecting pests and diseases or improving and their effect as well as to ensure manufactur- nutrient uptake. Soil-treated, pot-grown beet, oat, and barley plants showed signifi- ing and marketing a credible and environmen- cant biomass increases in the range of 27% to 41% above control at concentrations tally sustainable product, it is important to of ’0.3 g TSP/L dry soil, whereas increases of 14% to 26% were observed in plants know what effect is generated in the plant and sprayed with 0.15 to 1.5 g TSP/m2. Sprayed strawberries had a 38% higher berry yield in its growth environment. compared with control plants in 2008, whereas no difference in leaf number and area, The company Nor-Natur is marketing number of runners, and inflorescences were detected. In 2009, there were no significant products based on extracts from saponin- observable differences between sprayed plants and controls. Soil-treated strawberry containing plant parts. The products have plants, however, showed a decrease in leaf number in 2008 and in strawberry yield in been shown to enhance the yield of tomatoes, 2009. The study concludes that TSP has pronounced and direct physiological effects on cucumbers, and strawberries and to possess plants, which can both increase and decrease growth and yield depending on the applied fungicidal effects (Nor-Natur APS, 2003, dose. The growth-enhancing effect could be used commercially to improve crop yield; 2004; Wagentrisl, 2003). The producer, Nor- however, because TSP is also known to be very harmful to earthworms, possible en- Natur, states that their products lead to an vironmental effects of the use of TSP in agriculture and horticulture must be considered improved uptake of nutrients from soil and air; before use. are effective against fungal infections, nema- todes, and pathogens; and that they stimulate plant growth (http://www.nornatur.net/uk/, Within the agricultural and horticultural tors are all phytohormones and fall into the Nor-Natur APS, 2003, 2004; Wagentrisl, industry, high yield and high-quality crops following categories: auxins, gibberellins, cy- 2003). Whether the claimed growth-stimulating are of major commercial and economic im- tokinins, abscisic acid, and ethylene. Recently, effectoftheproductsisaresultoftheirabil- portance. The demands for increased yield however, several other hormonal compounds ity to combat pests or of a direct action on the and improved quality can be met through im- such as oligosaccharins, brassinosteroids, physiology of the treated plant, or both, is provements in crop genotypes by selection, jasmonates, salicylates, and polyamines have unknown. breeding, and genetic engineering and by also been shown to have growth-regulating Therefore, the objective of this study was improvement of the crop growth environ- properties (Basra, 2000). Natural products are to investigate the growth-regulating potential ment through irrigation, fertilization, and the also distributed for their growth-regulating of water extracts of TSP, one of the ingredi- use of plant protection products. Chemical effects, mainly as growth stimulators (see for ents used in the products from Nor-Natur. growth regulators are also one of the tools examples: http://www.nornatur.net/uk/; http:// TSP is a granulated waste product from Asian used to improve both crop growth and qual- www.agrigro.com/). tea oil production. The product contains dried ity. Commercially registered growth regula- Growth-stimulating natural products are seeds of the species Camellia sp., whose oil typically produced by small companies with- had been extracted. TSP contains high amounts out means to verify their products’ specificity of saponins, which are believed to be the and efficacy in farm trials or by scientific biologically active fraction of the extract Received for publication 7 Sept. 2010. Accepted research. The products are mainly sold for (Mølgaard et al., 2000; Pelah et al., 2002; for publication 15 Sept. 2010. use in home gardens and small-scale pro- Sparg et al., 2004). Saponins are one important We sincerely acknowledge Nor-Natur for provid- duction systems, and the lack of knowledge class of plant secondary metabolites, which ing TSP as well as for helping out with the straw- berry experiments in 2009 and for the comments about product specificity and efficiency ham- are connected to the plant’s natural defense of two anonymous reviewers whose comments pers their credibility. As a result of the men- system (Wu et al., 2005). Tea seed saponins improved the manuscript considerably. tioned reasons, scientifically documented are triterpenoid saponins, and so far 20 differ- 1To whom reprint requests should be addressed; effects are scarce for natural growth enhancers ent saponins have been identified from the e-mail [email protected]. as is information about the active com- seeds of the Japanese tea plant (Camellia 1848 HORTSCIENCE VOL. 45(12) DECEMBER 2010 GROWTH REGULATORS sinensis) (Chaicharoenpong and Petsom, 2009; camera alongside a reference area and placed nozzles, a pressure of 4 bar, and a spraying Morikawa et al., 2007). Although there are in the growth cabinet. After 7 d, the plants volume of 150 LÁha–1. All above-ground bio- studies investigating the toxicity of saponins, were photographed again and leaf surface mass was harvested 8 d after spraying, dried few systematic investigations have been pre- area at Days 0 and 7 were determined digi- at 80 °C, and weighed. sented on the growth-stimulating activity of tea tally using pixel counts of the leaf area com- Strawberry tests. The strawberry cultivar, seed saponins on plants. pared with the known reference area using Honeoye (Fragaria ·ananassa Duchesne), In this study, we systematically tested the the computer program Corel photo paint 12. was obtained as plantlets from Svanemose- growth-regulatory effects of TSP applying a Surface area increase was calculated as fold ga˚rd in Roskilde, Denmark. The plantlets were three-step approach. At first, laboratory tests increase [frond size day seven (cm2)/frond size planted in June 2008 in sphagnum peatmoss investigated growth effect on sterile Lemna day 0 (cm2)] because this gives the most (Pindstrup substrate; Pindstrup Mosebrug AS) plants. In this test system, indirect effects of sensitive end point in terms of measuring and were watered as described previously. pests and diseases can be excluded as well as possible growth increases (Belz et al., 2008). From June to the end of Aug. 2008, the mean an effect of improved nutrient uptake because Relative growth rates of controls were calcu- day:night temperatures in the greenhouse were the plants are grown under non-limiting nu- lated according to: (ln AT –lnA0)/T, where 25 ± 3:20 ± 3 °C. The light:dark ratio was 16 ± trient conditions. Second, the product was A0 is the initial surface area and AT is the 2:8 ± 2 h, the relative humidity was 30 ± tested in greenhouse studies on four different surface area at time T (T = 7). 10%:50 ± 10%, and the irradiance ranged terrestrial plant species and by two different Species sensitivity tests. The species sen- from 200 to 800 WÁm–2. application methods. This allowed investi- sitivity soil and spray tests were carried out The TSP concentrations used in the straw- gating possible species differences in sensi- from the middle of April to the middle of berry soil and spray test were selected tivity toward the product and the efficiency May 2008 in a 20 °C climate-controlled green- according to previous test results as 0.2 g of soil versus leaf application.