Efficacy of 24-epibrassinolide in improving the nitrogen metabolism and antioxidant system in chickpea cultivars under cadmium and/or NaCl stress

•Role of epibrassinolide in the amelioration of cadmium and salt stress solely or in synergy was investigated.•The combination of the stress (NaCl + Cd) was most toxic.•The toxic effects were more pronounced in the GNG-1581 variety than PDG-4.•The EBL increased the activity of the enzymes of nitrogen metabolism and antioxidant system.•The foliage of PDG-4 sprayed with EBL at 10-8 M solution significantly mitigated the ill effects of Cd and NaCl stress.

In the present study, we aimed to investigate the effect of foliar spray of 24-epibrassinolide (EBL) on nitrogen metabolism, antioxidant system, photosynthetic characteristics and chlorophyll fluorescence in two varieties (PDG-4 and GNG-1581) of Cicer arietinum L. under cadmium (Cd; 50 μM) and/or NaCl (100 mM) stress. The results showed that the exogenous application of EBL as foliar spray significantly alleviated the inhibitory effects on photosynthesis and increased total chlorophyll content, net photosynthetic rate, stomatal conductance, internal CO2 concentration, transpiration rate and maximum quantum yield of PSII under Cd and/or NaCl stress. In addition, EBL application also enhanced the activities of nitrogenase, glutamate synthase, glutamine synthetase and glutamate dehydrogenase enzymes under both stress and stress free conditions. Moreover, application of EBL also increased antioxidant enzyme activities and the proline content in both stress and stress free plants. These results suggest that EBL could alleviate the combined stress induced harmful effects on photosynthesis and nitrogen metabolism through an increase in the antioxidant system that lead to improved growth of plants.