Investigating Stevia Germplasm in Georgia for Selecting Elite Stevia Germplasm

Stevia (Stevia rebaudiana), a perennial sweet herb from the Asteraceae family. It is safe for diabetics as it does not affect blood sugar levels, has no neurological/renal side effects associated with some artificial sweeteners, and is helpful in weight and blood pressure management. Stevia is a zero calorie sweetener and its leaves are 12-30% sweeter while Reb-A crystals from stevia leaves are 270-400% sweeter than the cane sugar. We have been investigating stevia germplasm to select a high quality (elite) stevia plant. We conducted our research on various stevia germplasm supplied by Sweet Green Field (SGF) LLC. We studied stevia for high % of germination, high biomass production per plant in middle Georgia condition and tested for higher sweetness in leaf extracts. We have investigated 22 different seed types. Results revealed six seed types (B, D, E, J, M, and P) as having higher germination percentage. 100% germination in P and M varieties was observed. High Performance Liquid Chromatography (HPLC) was used to analyze stevioside and rebaudioside A content in leaf extract. Variety J revealed the highest rebaudioside-A content. Seedlings were also used to develop a micropropagation protocol. Nodal segments were inoculated. While field research was carried out on germplasm propagated through seeds (approximately 25000 seedlings) of stevia and were provided by SGF LLC. We measured the height of each stevia plant and harvested manually each plant once the plants produced flowers and seeds to measure the fresh weight and dry weight of each plant. The fresh weight yield varied from 0.058-2.17 kg/plant and dry weight (whole plant) varied from 0.048-1.47 kg/plant. The plant height varied significantly from 25 – 145 cm. The plant with high biomass (2.17kg) was selected as field grown elite stevia plant for further study. Nodal segments and shoot apex were used as the explants for multiplication. Stevioside was tested through HPLC and was found higher than average. Brix results shows that the brix values varies plants to plants and found range from 7.0-12.7 being the highest in one of the selected stevia plant.