Physiological and morphological responses to abiotic stresses in two cultivars of Stevia rebaudiana (Bert.) Bertoni

Stevia rebaudiana (Bert.) Bertoni is cultivated for its sweet leaves as they contain steviol glycoside sweeteners such as stevioside and rebaudioside A. Two cultivars of S. rebaudiana, Shoutian-2 and Fengtian, were evaluated in a greenhouse for their tolerance to abiotic stresses. The seedlings were exposed to salinity, drought or waterlogging stresses for 4 weeks. The cultivars differed significantly in their biomass accumulation, tissue ion concentrations and steviol glycoside accumulation. The salt tolerant cv. Fengtian contained higher concentrations of K + which led to higher K + /Na + ratio in the leaves, as compared to the less salt tolerant cv. Shoutian-2. Reduced biomass accumulation in cv. Shoutian-2 coincided with increased Na + and Cl ˗ concentrations in the leaves. The waterlogging stress reduced growth of both cultivars, but the salinity stress increased rebaudioside A concentration in the tolerant cv. Fengtian, and the drought stress increased stevioside concentration in the cv. Shoutian-2. This study concludes that the two cultivars of S. rebaudiana differ in their tolerances to salinity and drought stresses. © 2019 South African Association of Botanists