Screening for drought tolerance in Iranian wheat genotypes (Triticum aestivum L.) using physiological traits evaluated under drought stress and normal condition

摘要

Cultivation of drought adapted genotypes is the best approach to avoid yield loss under water deficit condition. In order to screen for drought tolerance 82 Iranian wheat genotypes were evaluated by recording relative water content (RWC), days to maturity, leaf rolling and leaf silvering under stress condition in a field trial. In next experiment ten genotypes (six tolerant and four sensitive) selected from field experiment were assessed for drought adaptability measuring RWC, osmotic adjustment (OA), catalase (CAT) and peroxidase (POD) activity and stomatal characteristics. The genotypes were grown under normal and stress condition with three replications. There was high variability among genotypes in response to drought. Azadi and Ohadi showed significant enhancement in CAT activity while in POD activity maximum increase was recorded for Homa. Kohdasht (0.59MPa) and Arta (0.15MPa) had the highest and lowest OA, respectively. Higher OA ability indicates the potential for accumulating osmolytes in cells to absorb water more easily under stress condition. Stomatal closure in response to drought was more significant in Kohdasht and Arta while in Homa almost no change in stomatal closure was detected. Significant negative correlation (r = -0.65, p<0.05) was obtained between RWC and stomatal opening implying the dominance of stomatal conductance control for water retention in genotypes with higher RWC. The activity of POD in Homa, a drought sensitive genotype, was significantly high under stress condition. Presumably the scavenging of H2O2 may be the last defense barrier of this genotype against drought. Kohdasht had the highest ability of water retention under stress condition mostly due to its excellent OA and stomatal closure. These physiological characters can be transferred to high yield genotypes to improve drought adaptability.