Effect of Drought Stress on Antioxidant Enzymes and Cell Death Related Traits in Resistant and Susceptible Wheat Cultivars at Grain Filling Stage

Drought is one of the major factors limiting crop production in Iran. Twenty Iranian wheat cultivars with wide range of sensitivity to drought, including 18 varieties of bread wheat and two varieties of durum wheat were used in two separate field experiments in 2009-2010 at the Experimental Station of College of Agricultural in Shiraz University. Each experiment was conducted as a randomized complete block design with three replications. The moisture level in one of the experiments was optimum (100% field capacity) while the second experiment was conducted under drought stress (45% field capacity). Several biochemical components including antioxidant enzymes and hydrogen peroxide and some physiological traits were analyzed in the two conditions. Drought stress significantly increased antioxidant activity at the grain filling stage. Superoxide dismutase activity showed the highest increase. Lipid peroxidation, hydrogen peroxide, electrolyte leakage and cell death increased significantly under drought condition, however membrane stability index decreased. Resistant cultivars showed the highest antioxidant activity and the lowest lipid peroxidation, hydrogen peroxide, and electrolyte leakage. This trend was reversed in the susceptible cultivars. Peroxidase and superoxide dismutase had a significant correlation with yield stability index. Hydrogen peroxide and cell membrane stability indices showed the highest correlation with yield stability index. Also Pishtaz and Alamut were selected respectively as the most resistance and susceptible cultivars.