Performance of 16 Stevia rebaudiana seed cultigens for glycosides and yield in North Carolina

Abstract

Currently, stevia (Stevia rebaudiana Bertoni) seeds are available to growers from many sources, but the origin of these populations is often unknown. Since stevia is a natural outcrosser, populations are heterozygous and heterogeneous. We were interested to characterize germplasm from 16 sources of stevia seeds for traits including yield, glycosides, and plant morphology, and then identify trait correlations. The cultigens evaluated were obtained from garden seed companies and commercial sources, and the trials were conducted for two years at two field locations. To quantify plant morphological traits, objective measurements were collected at two intervals to determine stem height, branching width, and leaf area. In addition, we screened for lodging and disease resistance, and yield before flowering stage. The cultigens tested were highly variable for yield and steviol glycosides, suggesting that a diverse genetic base is found among the population which is readily available to growers and breeders. High-yielding cultigens for biomass and glycoside concentration were identified. Cultigens with the highest yield and stability over years were seed-derived progeny from ‘Katupyry’, sourced from Stevia Store, and represent genetics useful in breeding for increased biomass. Cultigens with the highest glycoside level were NC-1003 and NC-1022, seed grown from Seed Savers, and could be used to improve desirable glycosides. This study highlights readily available seed cultigens that can be used to develop elite breeding populations.