Role of Gibberellic Acid and Indole 3-Bytyric Acid in Improving Salinity Tolerance in Two Horse Gram Cultivars.

Abstract

Salinity stress is one of the most detrimental environmental stresses affecting growth and physiology in horse gram. The seedling growth performance of plants stressed by salinity can be improved by seed priming with plant growth hormones. In the present study, the effects of increasing salinity levels (100 and 150 mM NaCl) alone or in combination with gibberellic acid (GA₃) and indole 3-butyric acid (IBA) were investigated in two commonly grown horse gram [Macrotyloma uniflorum (Lam.) Verdc] cultivars (Dapoli 1 and Rajapur) at the seedling stage under laboratory conditions. Results revealed that NaCl-induced salinity stress significantly decreased the root length, shoot length, and total length in both Dapoli 1 and Rajapur cultivars. Seed priming with GA₃ (100 ppm) and IBA (50 ppm) significantly enhanced root length, shoot length, and total length of salinity-stressed seedlings. Improved seedling growth performance was associated with increased proline content after seed priming with GA₃ and IBA in both cultivars. NaCl-induced salinity stress increased oxidative stress by enhancing the levels of H₂O_2. Seed priming with GA₃ and IBA significantly decreased the H₂O₂ content in both cultivars_. Catalase and Peroxidase enzyme activities were significantly increased and decreased in the salinity-stressed Rajapur cultivar, respectively. Seed priming with GA₃ and IBA significantly developed high antioxidative capacity as indicated by improved activities of these enzymes in the Rajapur cultivar compared to Dapoli 1. Overall results suggested that seed priming with GA₃ and IBA alone or in combination is an effective, environmentally sustainable way to mitigate salinity stress in different horse gram cultivars.