Effect of Cutting off Irrigation at Flowering Stage on Physiological Characters, Yield and Yield Components of Wheat Genotypes in Shiraz

To evaluate the response of wheat genotypes to terminal drought stress and to identify drought tolerant and sensitive genotypes, 20 wheat genotypes were compared in two stress and normal conditions, in a field experiment carried out at the Experimental Farm of College of Agriculture, Shiraz University, Shiraz, Iran, as a split-plot arrangement using complete randomized blocks design with four replications, during 2008-9 growing season. Main plot was irrigation (normal irrigation and cutting off irrigation at flowering stage) and sub plot was 20 wheat genotypes. The results of ANOVA showed that there was highly significant difference among genotypes for all measured traits, indicating genetic variation among genotypes, which allowed genotype selection for drought tolerance. Comparison of traits’ means showed that the highest grain yield was obtained from Derakhshan cultivar (894.7 g/m2) in irrigation treatment and in drought conditions from M-73-6 genotype (442.1 g/m2). However, the least grain yield in both stress and non-stress conditions was obtained from Souraplata cultivar (362.4 and 149.7 g/m2, respectively). Results also showed that chlorophyll concentration of flag leaf was increased under drought conditions with the highest percentage in Yavarous cultivar (65.02%). Relative water content (RWC) for flag leaf was decreased under drought stress conditions and the highest reduction was found in Shiraz cultivar (31.06%). While there was no significant correlation between chlorophyll concentration and grain yield, RWC of flag leaf showed a significant correlation with grain yield of genotypes. Therefore, RWC could be used as a suitable index for screening drought tolerant wheat genotypes.