Influence of Exogenous Salicylic Acid and Nitric Oxide on Growth, Photosynthesis, and Ascorbate-Glutathione Cycle in Salt Stressed Vigna angularis

The present study was carried out to investigate the beneficial role of exogenous application of salicylic acid (1 mM SA) and nitric oxide (100 μM NO) in preventing the oxidative damage in Vigna angularis triggered by salinity stress. Salinity (100 mM NaCl) stress reduced growth, biomass accumulation, chlorophyll synthesis, photosynthesis, gas exchange parameters, and photochemical efficiency (Fv/Fm) significantly. Exogenous application of SA and NO was affective in enhancing these growth and photosynthetic parameters. Salinity stress reduced relative water content over control. Further, the application of SA and NO enhanced the synthesis of proline, glycine betaine, and sugars as compared to the control as well as NaCl treated plants contributing to the maintenance of tissue water content. Exogenous application of SA and NO resulted in up-regulation of the antioxidant system. Activities of enzymatic antioxidants including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), as well as the content of non-enzymatic components, were more in SA + NO treated seedlings as compared to control and salinity stressed counterparts resulting in significant alleviation of the NaCl mediated oxidative damage. Content of nitrogen, potassium, and calcium increased due to SA and NO under normal conditions and NaCl stress conditions while as Na and Cl content reduced significantly.