Physiological responses of seven varieties of soybean [Glycine max (L.) Merr.] to salt stress

In agriculture, salinity is one of the most significant abiotic stresses that plants confront and harms agricultural productivity, physiological, growth and development processes. In the present study, there were 7 different varieties of soybean (Ajmeri, William-82, D.A, PSC-60, Rawal-1, NARC-1 and NARC-2,) were tested under NaCl concentration level (0 mM and 150 mM) to determine their physiological performance under control and experimental conditions. The present investigation aimed to select salt tolerant varieties. Under salt stress, different varieties have differed significantly in the biological yield, chlorophyll contents, antioxidant activity and ionic concentrations. The results showed that among the seven varieties evaluated NARC-1 and NARC-2 are producing higher biological yield and antioxidant activity than others under 150 mM NaCl. NARC-1 and NARC-2 under 150 mM NaCl concentration produced significantly higher biomass in comparison with other varieties and similarly enhance the antioxidant activity by decreasing the catalase activity. The relative water content (RWC) of plants was measured 15, 30, 45 and 60 days after the treatment was applied, as well as at harvest time, along with the grain yield and characters related to yield. The 7 different soybean varieties tested showed significant differences in grain yield and yield-associated characters when exposed to NaCl salinity. The salinity had a greater impact on Ajmeri and William than on NARC-1 and NARC-2. Under salt stress, the grain yield of the NaRC-1 and NARC-2 varieties was 70% and 65% respectively, while the yields of the Ajmeri and William varieties were 41% and 38% respectively. The salinity-induced decrease in grain yield was traced to fewer pods per plant, fewer seeds per pod and a lighter weight per 100 grains. However, the number of pods per plant was most affected compared to the other characters. It was also observed that Na+ ion concentrations were elevated in the shoot under salt stress in all varieties. However, NARC-1 and NARC-2 showed low salt concentration in shoot as compared to other varieties. SDS-PAGE revealed significant variations in the protein profile of seedling soybean varieties. NARC-1 and NARC-2 have shown a unique banding pattern under salt stress with a molecular weight of 60 and 130 kDa. The results indicate that salinity (NaCl) triggered an antioxidant response in tolerant varieties (NARC-1 and NARC-2) of Glycine max (L.). This study suggested that both varieties have more capability and appropriate survival under salt stress as compared to other varieties.