Impact of glycine betaine on salinity tolerance of stevia (Stevia rebaudiana Bertoni) under in vitro condition

Abstract

Stevia (Stevia rebaudiana Bertoni), with great potential as a natural sweeteners source, has a high content of sweeteners, which are up to 150 times sweeter than sugar, but virtually with no calories. Stevia also suitable to be cultivated in semiarid climates and coastal areas, which are characterized by the low quality of the irrigation water. Soil salinity occupies a prominent place among the soil problems that threaten the sustainability of agriculture over a vast area in the world. Glycine betaine is an osmoprotectant, that plays an important role and accumulates rapidly in many plants during salinity or drought stress. In order to evaluation of glycine betaine amending effects on salinity stress in stevia under in vitro condition, a factorial experiment was conducted in 2015. Four NaCl levels, including 0, 50, 75 and 100 mM, along with 0, 1, 12.5, 25 and 50 mM of glycine betaine concentrations were used in Murashige and Skoog (MS) medium. The results showed that salinity levels had significant reduction effects on plant height, root length, shoot fresh weight, number of leaf, total chlorophyll, rebaudioside A and stevioside of the stevia genotype. Due to increasing of glycine betaine, levels all the traits were increased. Owing to amending effect of glycine betaine, its high concentrations made less hazarding effects of salinity on the researched traits. The highest mean value of rebaudioside A (10.62rt) and stevioside (23.38rt) determined at 50 mM of glycine betaine with 0 mM of NaCl concentration.