Potassium Nutrition Induced Salinity Mitigation in Mungbean [Vigna radiata (L.) Wilczek] by Altering Biomass and Physio-Biochemical Processes

The present investigation was conducted to explore the role of potassium nutrition in improving biomass and physio-chemical alterations to reduce the adverse effects of salinity in mungbean. A sand-culture experiment was carried out under different salinity levels (0, 50, and 100 mM NaCl) with two levels of potassium (0 and 50 mM K2SO4) and two mungbean cultivars (NM-92 and Ramzan), and the alterations in mungbean biomass and metabolic activities were investigated. The results suggested that salinity significantly reduced the biomass, nitrate reductase activity (NRA), nitrite reductase activity (NiRA), total soluble proteins, chlorophyll a, chlorophyll b, total chlorophyll, nitrogen, potassium, calcium, magnesium, and phosphorous contents in both mungbean cultivars in comparison to the control. However, K2SO4 at 50 mM significantly improved all the parameters in both mungbean cultivars except for the sodium content. A significant increase in the total free amino acids, carotenoids, and sodium content in both mungbean cultivars was observed due to salt stress. Moreover, principal component analysis and heatmaps were developed individually for both mungbean cultivars to assess the variability and correlation among the studied attributes under all applied treatments. Under saline conditions, the mungbean ‘Ramzan’ showed more marked reductions in almost all the growth parameters as compared to ‘NM-92’. The results suggest that the application of K2SO4 ameliorates the adverse effects of salinity by regulating osmolyte production, NRA, and NiRA, thus promoting plant growth and productivity.