Hawaii Agriculture Research Incorporated proposes to utilize a method for quantification of glycoside extracts from Stevia rebaudiana to better understand changes in synthesis during plant development. The overall objective is assessment of peak production of the commercially valuable glycosides during the plant growth cycle, leading to identification of a production cycle and harvest schedule that maximizes recovery of high levels of the non-caloric sweetener. A future objective is development of a field-based test kit suitable for farmers to provide real-time test results for harvest and propagation decision making. APPROACH: Evaluation of both biomass production and glycoside synthesis will enable assessment of the optimum time frame for harvesting in a tropical region such as Hawaii where daylength is short. Hawaii Agriculture Research Incorporated (HARI) will first establish when during plant development the economically important botanical extracts are highest, and evaluate peak periods of biomass accumulation in the plant to determine when harvesting would yield the greatest economic return to farmers. If needed, in phase II of this project, HARI will evaluate the feasibility of developing an immunoassay for accurate quantification of the glycosides present in extracts of Stevia rebaudiana. Non-technical summary: Stevia rebaudiana can be grown in Hawaii for year-round production of a high value non-caloric sweetener. Downturns in Hawaii's agricultural economy make it imperative that new crops and complimentary production methods be established. Owing to climatic conditions in Hawaii three or four potential harvest and re-growth cycles are feasible annually. A possible constraint to a multiple harvest cycle system is the rapid flowering observed in Hawaii grown stevia following field planting. Extracts of Stevia rebaudiana contain non-caloric, intensely sweet glycosides. It is not clear when these commercially valuable compounds reach a peak during plant development as a perennial crop in a tropical zone. This project will determine when levels of botanical extracts of economic importance are highest during plant development, and determine when peak biomass is achieved, in order to understand when to harvest for maximum economic return.
Keywords: stevia rebaudiana; stevioside; rebaudioside a; glycosides; biomass
