Water stress effect on the activity of antioxidant enzymes at the generation stages of barley (Hordeum vulgare L.) on the field condition

this study examines the hypothesis that antioxidant enzymes are involved in alleviating theoxidative damage on plant developmental process on generative stage caused by an increase in reactive oxygen species under water stress. Therefore, effect of water stress on the enzyme activity of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) were analyzed by spectrometric and gel assay procedures at generation stages of barley (5 stages) in field condition. The experiment was conducted according to randomized complete block design with three replications and was analyzed on the complete factorial (3 different stress × 5 developmental stages× 5 genotypes). According to the variance analysis, all simple and interaction effects have significantly difference in almost all traits. The amount of total protein and chlorophyll content were significantlydeclined with the progress of plant growth. Activities of all enzymes were increased in initial growth stages and decreased in later growth stages. The reduction of activities was significantly high, while these activities had no intensive difference with the initial stages. In general, activity of antioxidant enzymes was increased compared to high reduction of total protein content in the cell. In such condition, both APX and CAT showed a high level of expression to protect the cells from oxidative damage especially at drought stress and dry farming conditions. Kinetic assays were confirmed by isozymic analysis using gel assay. From the results of this investigation, it can be concluded that the studied antioxidant enzymes may have a role to protect plant cells from active oxygen species caused by drought stress at the dry farming condition.Antioxidant enzymes, Senescence, Water stress, Barley, Growth stages.