Salt Tolerance in Mungbean Vigna radiata [L.] Genotypes: Role of Proline and Glycinebetaine

Salinity is one of the major environmental determinants of plant growth and productivity. A pot experiment was performed using six cultivars of mungbean [Vigna radiata L.] to evaluate the difference in their response to NaCl toxicity under growth chamber conditions. The pots containing reconstituted soil were supplied with different concentration of salinity [0, 50 and 100 mM NaCl]. Increasing concentration of NaCl in the soil resulted in decreased net photosynthesis, plant dry mass and seed yield. Maximum significant reduction in growth, photosynthesis and yield were observed with 100 mM NaCl in all the cultivars. Our results indicate that the cultivar Punt Mung is found to be more tolerant to salinity stress, recording higher net photosynthesis, plant dry mass and seed yield associated with low Na+ and Cl− content and high osmolyte accumulation in the plant leaves. Cultivar T44 experienced maximum damage in terms of reduction in net photosynthesis, plant dry mass and seed yield and emerged as a sensitive cultivar. The data of tolerance index of Punt Mung were found to be higher among all tested mungbean cultivars which indicate its higher tolerance to salinity. Better coordination of osmolytes and lower values of Na+ and Cl− protected Punt mung from NaCl toxicity, whereas lesser accumulation of osmolytes and higer values of Na+ and Cl− in T44 resulted in maximum damage. Cultivars of mungbean were ranked with respect to their tolerance to salinity: Punt mung > Pusa 9531 > Pusa Baisakhi > Samrat > SML 267> T44, respectively.