Interactive effects of salicylic acid on enzymes of nitrogen metabolism in clusterbean (Cyamopsis tetragonoloba L.) under chromium(VI) toxicity

• Cr stress affected plant growth and nitrogen metabolism in clusterbean.
• Salicylic acid application alleviated Cr toxicity in clusterbean plants.
• Exogenous salicylic acid enhanced activities of nitrogen metabolism pathway enzymes and alleviates disorders caused by Cr stress.
• Salicylic acid could be a useful candidate for suppressed Cr uptake in plants under Cr stressed soil.

Chromium (Cr) toxicity is a major constraint to crop production. A pot experiment was conducted to examine the ameliorating effects of salicylic acid on Cr toxicity enzymes of nitrogen metabolism in clusterbean plant parts. For this study, salicylic acid (0.25 and 0.50 mM) was applied as foliar spray on control and Cr-stressed plants at 20, 35 and 55 days after sowing and its influence on Cr toxicity at vegetative, flowering and grain filling stages was examined. Cr treatment caused decrease in specific enzyme activity of nitrogenase, nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase and glutamate dehydrogenase in various plant organs at different growth stages with an increase in Cr(VI) levels from 0 to 2.0 mg Cr(VI) Kg−1 soil. However, exogenously added salicylic acid (0.25 and 0.50 mM) significantly alleviated Cr toxicity effects at all growth stages by increasing in enzymes specific activity. The treatments with 0.25 and 0.5 mM salicylic acid increased the specific activity of these enzymes in leaves, stem and root, when compared to those of Cr treatments alone.