Selenium and Salt Interactions in Black Gram (Vigna mungo L.): Ion Uptake, Antioxidant Defense System, and Photochemistry Efficiency

Salinity is a major abiotic stress which limits crop production, especially under rainfed conditions. Selenium (Se), as an important micronutrient, plays a vital role in mitigating detrimental effects of different abiotic stresses. The objective of this research was to examine the effect of Se fertilization on black gram (Vigna mungo) under salt stress. Our results showed that salt stress (100 mM NaCl) in leaves significantly induced oxidative damage and caused a decline in relative water content, chlorophyll (Chl), stomatal conductance (gs), photochemical efficiency (Fv/Fm), sucrose, and reducing sugars. A low dose of Se (1.5 ppm) significantly reduced hydrogen peroxide content, malondialdehyde formation, cell membrane damage, and also improved antioxidative enzyme activities, including superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and glutathione peroxidase under salt stress. Se-treated plants exhibited higher Chl, gs, Fv/Fm, sucrose, and reducing sugars than untreated plants in response to salt stress. In addition, Se application enhanced Se uptake and reduced Na+ uptake, but Cl remained unaffected. Our results indicated that a low dose of Se effectively alleviated salt damage via inhibition of Na+ uptake and enhanced antioxidant defense resulting in a significant decrease in oxidative damage, and maintained gaseous exchange and PS II function for sucrose and reducing sugars accumulation in black gram.