Effect of terminal drought stress on grain yield and some morphological traits in 80 bread wheat genotypes

ABSTRACT: Genetic variation is the main basis of improvement in crops and plant breeding programs. So, in order to study genetic variation and terminal drought stress on grain yield and some morphological traits in bread wheat, an experiment was conducted on 80 irrigated bread wheat genotypes in a Randomized Complete Blocks Design (RCBD) with three replicates under normal and terminal drought stress conditions in Research Farm of the Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran during 2011-2012 cropping season. The results of analysis of variance indicated significant differences among genotypes for all studied traits in both normal and drought stress conditions. Terminal drought stress reduced grain yield, plant high, peduncle length, ratio of peduncle length to plant height, spike length and awn length as much as 23.48%, 1.23%, 2.17%, 0.97%, 2.58% and 2.55%, respectively. Based on grain yield, Ghods and Norstar were the best and worst genotypes when the ranking in both conditions and the percentage of reductions was considered. In addition, the percentage reduction of the most studied traits in Norstar was more than other genotypes due to drought stress. Whereas, Ghods was rather stable due to drought stress based on all studied traits. There were high positive significant correlation between plant height and peduncle length and between peduncle length and the ratio of peduncle length to plant height under both conditions. Under non-stress conditions, a positive and significant correlation of flag leaf length with plant height and peduncle length was found. Whereas, flag leaf width had negative significant correlation with peduncle length and the ratio of peduncle length to plant height. Although, there was a positive correlation between grain yield and flag leaf area, there was no significant associations between grain yield and other traits in both normal and drought stress conditions.