The effect of natural salinity on seed germination, seedling establishment growth and selected biochemical properties of Stevia rebaudiana Bertoni

Abstract

Abstract In dry and semi-arid climates, soil and water salinity reduces plant development and productivity. Due to salty land development and loss of arable land, identifying therapeutic plants resistant to salinity or substances that decrease its effects is crucial. This study examined the seed germination, seedling establishment, and antioxidant potential of a novel Stevia rebaudiana (Stevia UEM-13) variety to natural salinity. We also examined how salinity affected biochemical and physiological changes in two separate experiments to a CRD with four replications in laboratory and greenhouse. Five degrees of salinity treatments were examined in the natural saltwater Lake of Qom: Control, 4, 8, 12, and 16 ds.m− 1. The germination percent, root and shoot seedling dry weight, biochemical properties (medicinal content), and antioxidant enzyme activity were measured. Results indicate considerable impact of salt stress on germination, growth, biochemical, and physiological alterations (P ≤ 0.01). Increasing salinity stress to 16 ds.m− 1 decreased germination (95.08%), root and shoot length (43.93 and 80.88%), seedling dry weight (7.22%), and the best germination and growth index (88.00%) was found in controlled conditions. Shoot osmolytes increased with salinity stress. Example: Maximum protein (31.96%), POD (125%), SOD (64.36%), proline (115%), and soluble sugar (238%), observed at leaves sprout under salt stress (16 ds.m − 1). This study shows that salt stress increases secondary metabolites (phenolic chemicals), which modify stevia responsiveness and therapeutic qualities. Salinity stress enhanced antioxidant enzyme activity, carotenoids, anthocyanin, phenol, and malondialdehyde in shoots. The maximum activity was seen at a salinity stress level of 12 ds.m− 1. Changing irrigating procedures may modulate stevia's secondary metabolites (medicinal contents).