Effect of foliar application of ascorbic acid on antioxidant enzyme activities of mung bean (Vigna radiate L.) cultivars under water-deficit Stress

In order to investigate the effect of foliar application of ascorbic acid on the activity of antioxidant enzymes in mung bean (Vigna radiate L.) under water-deficit stress, a field trial was performed in a split-plot design arranged in completely randomized block design with three replications in the Education and Research Center of Natural Resources Safiabad, Dezful during the two cultivation years (2017 and 2018). Four levels of water-deficit stress treatments were considered in the main plots (25, 50, 75, and 100% of plant water requirement) and combined treatment of foliar application of ascorbic acid in three levels (control, 10, and 20 mM) and genotype including Omidbakhsh VC6173 and Partow cultivars as subplots. The results of mean comparison showed that the highest levels of superoxide dismutase and ascorbate peroxidase were observed in water-deficit stress of 25% water requirement and no foliar application of ascorbic acid. The highest activity of catalase enzyme was observed under water-deficit stress of 50% water requirement and no foliar application of ascorbic acid. Also, the highest activity of guaiacol peroxidase enzyme was observed in Omidbakhsh VC6173 cultivar under water-deficit stress of 25% water requirement and no foliar application of ascorbic acid. The highest glutathione peroxidase activity was observed in VC6173 cultivar under water-deficit stress of 75% water requirement and 10 mM foliar application of ascorbic acid. Results showed that dehydration stress significantly increased the activity of antioxidant enzymes while foliar application of ascorbic acid due to its antioxidant properties reduced the effects of stress and thus reducing the activity of antioxidant enzymes