Effect of chromium and cations concentration on stress enzymes in spinach crop grown under vertisol of central India

Interaction of chromium (Cr) metal ions with sodium (Na) and calcium (Ca) and their effect on the different plant enzymes in spinach were evaluated in a glass house experiment. Multi-metal toxicity hampers the crop's growth and affects the uptake kinetics of minerals and other substances from root to edible part. In this experiment, three levels of Cr (0, 50 and 100 mg/kg), Na levels (0, 40, 80 mM), and Ca levels (0, 2, 4 mM) were applied to Indian vertisol. The spinach crop was grown with recommended agronomic practices. Fully tender leaves were taken to measure stress enzymes (catalase, superoxide dismutase (SOD), peroxidase) of metals; and found to have a significant effect on metal toxicity in spinach crop. Increasing the Cr level up to 100 mg/kg significantly enhanced the activities of catalase, SOD, and peroxidase in spinach; whereas, a lower level of Ca and Na with 50 mg Cr/kg soil significantly (p < 0.05) didn't affect the stress enzymes level. However, increasing the salt ions concentration up to 4 mM of Ca and 80 mM of Na with 50 and 100 mg Cr/kg soil enhanced the catalase, peroxidase and SOD activities from 1.61 to 5.42 mg protein/min, 4.26-59.87 mg protein/min and 4.36-64.42 g/ fresh weight, respectively. The SOD activity was measured to be more than the catalase and peroxidase under the interactive effect of salt ions and Cr. Such an experiment is useful to identify a metal's toxic effect on crops grown under poor-quality natural resources for executing efficient management strategies for better crop yield.