Biomass Yield of Stevia rebaudiana Grown on Hydroponic Systems using Different Nitrogen Rates

Stevia rebaundiana (Bert.) is an important source of natural sweetener. This perennial species belongs to the Asteraceae family and is native to certain regions of South America. Plant, extracts, and glycosides have been used for several years as natural sweeteners. Several studies revealed that Stevia exerts beneficial effects on human health, including antihypergycemic, antihypertensive, noncariogenic, anti-human rotavirus activities [1], while there is little information reported on crop production. It is important to mention that for pharmaceutical use, the plant material must be free of contamination from heavy metals, soil and soil-born organisms, herbicides and pesticides. Thus, hydroponics may provide a suitable growing system for high quality biomass production while allowing the regulation of secondary metabolism by managing the nutrient solution. Two experiments were carried out in the greenhouse at the University of Mississippi's Biological Field Station. The experimental design was a randomized complete block with a split-plot in time arrangement of the treatments, in which the main treatments were the growth systems (floating hydroponic versus soil) and the nitrogen level (200mg L^–1 and 300mg L^–1 of N in hydroponic; 20 and 70kg ha^–1 of N (ammonium nitrate) in soil-filled pots. Seedlings were transplanted in 07/24/09 and the first harvest was done in 09/14/09. Secondary treatments were conducted at harvest times (45 and 90 days after transplanting). Fresh and dried biomass, water consumption and macronutrients analysis were evaluated. In conclusion, the biomass yields were significantly higher using the hydroponic cultivation method as compared to soil and no significant differences were found between levels of nitrogen treatment. Acknowledgments: Partial financial support from the USDA Specific Cooperative Agreement No 58–6408–7-012. Reference: [1] Tadhani MB, Patel VH, et al. (2007)J Food Comp Anal, 20(3/4): 323–329.