Salicylic acid (SA) is known to affect photosynthesis under normal conditions and induces tolerance in
plants to biotic and abiotic stresses through influencing physiological processes. In this study, physiological
processes were compared in salt-tolerant (Pusa Vishal) and salt-sensitive (T44) cultivars of mungbean
and examined how much these processes were induced by SA treatment to alleviate decrease in photosynthesis
under salt stress. Cultivar T44 accumulated higher leaf Na+ and Cl− content and exhibited
greater oxidative stress than Pusa Vishal. Activity of antioxidant enzymes, ascorbate peroxidase (APX)
and glutathione reductase (GR) was greater in Pusa Vishal than T44. Contrarily, activity of superoxide
dismutase (SOD) was greater in T44. The greater accumulation of leaf nitrogen and sulfur through
higher activity of their assimilating enzymes, nitrate reductase (NR) and ATP-sulfurylase (ATPS) increased
reduced glutathione (GSH) content more conspicuously in Pusa Vishal than T44. Application of 0.5mM
SA increased nitrogen and sulfur assimilation, GSH content and activity of APX and GR. This resulted in
the increase in photosynthesis under non-saline condition and alleviated the decrease in photosynthesis
under salt stress. It also helped in restricting Na+ and Cl− content in leaf, and maintaining higher efficiency
of PSII, photosynthetic N-use efficiency (NUE) and water relations in Pusa Vishal. However, application of
1.0mM SA resulted in inhibitory effects. The effect of SA was more pronounced in Pusa Vishal than T44.
These results indicate that SA application alleviates the salt-induced decrease in photosynthesis mainly
through inducing the activity of NR and ATPS, and increasing antioxidant metabolism to a greater extent
in Pusa Vishal than T44.