The Effect of Water Deficit Stress on Antioxidant Enzymes During Generative Growth Stages in Barley (Hordeum vulgare L.)

The effects of irrigation, dry farming and drought treatments on the activities of antioxidant enzymes including superoxide dismutase, ascorbate peroxidase, catalase and peroxidase in barley leaves at different generative growth stages under field conditions were investigated. Three senescence parameters including chlorophyll, total soluble protein and rubisco large subunit protein loss, were also studied in order to compare our results to those reported by other researchers. The results showed that leaf relative water content (RWC), chlorophyll and total soluble protein and rubisco large subunit protein content declined with leaf age and the effect of water deficit. The activity of superoxide dismutase declined with the progress of the leaf age on all treatments but ascorbate peroxidase activity declined with leaf age only in irrigated (control) plants. There were no significant differences among developmental stages in catalase activity in control plants, while catalase activity declined in the water dry farming and drought stress conditions. Peroxidase activity increased with the progress of senescence for all of treatments in such conditions. Water deficit stress triggered increases in antioxidant enzymes activities. Results showed that among all studied enzymes, peroxidase has a key role in increasing resistance to oxidative stress on both the senescence stages and drought stress condition in Hordeum vulgare.