Selenium fertilization to salt-stressed mungbean (Vigna radiata L. Wilczek) plants reduces sodium uptake, improves reproductive function, pod set and seed yield

Abstract

Salt stress is one of the vital reasons that adversely affect the productivity of crops, hence suitable approaches are needed to mitigate its negative effects on plants. Selenium (Se) has been reported to alleviate the salinity effects under lab conditions, but its effects in soil-grown salt-stressed plants have not been reported as yet. In a preliminary experiment, the comparative response of mungbean plants to different salt stress levels (imposed with NaCl) revealed nearly 50% reduction in pod number and seed yield per plant at 100mM concentration. Subsequent studies showed that 100mM NaCl caused significant damage to membranes, chlorophyll, photosynthetic ability, stomatal conductance and leaf water status. Se application at 1, 2.5 and 5ppm to salt-stressed plants revealed significant alleviation of stress damage with 1ppm Se concentration, resulting in enhanced pod number (32%) and seed yield plant−1 (30%). These plants accumulated significantly less Na+ (34.9%) in their leaves and anthers (10%) but Cl− accumulation was not affected. Se (1ppm)-treated salt-stressed plants showed improved reproductive function as indicated by pollen germination, pollen viability and pollen tube growth. Sucrose concentration and its metabolism improved in leaves and anthers of salt-stressed plants growing with 1ppm Se. The oxidative damage, measured as lipid peroxidation and hydrogen peroxide, was significantly lower in Se-applied salt-stressed plants. The activity of antioxidants such as catalase, ascrobate peroxidase, glutathione reductase and glutathione peroxidase was significantly improved with 1ppm Se application to salt-stressed plants. These findings indicated that Se treatment at low concentration increased Se uptake but reduced the Na+ uptake and, consequently improved the plant function in mungbean plants growing under salt stress.