Using Wheat Chromosomal Substitution Lines to Study Relationship between Yield and its Components under Water-Stress and Non-Stress Conditions

To evaluate relationship between grain yield and its components, two series of wheat`s substitution lines including substitution lines of ‘Timstein’ into genetic background of ‘Chinese Spring’ and ‘Red Egyptian’ into genetic background of ‘Chinese Spring’ and their parents were tested in a randomized complete block design with four replications under water-stress and non-stress conditions in a greenhouse in 2014. Stepwise regression analyses showed that yield components contributions for seed yield variation were not similar under water-stress and non-stress conditions. So that, under non-stress condition biological yield and harvest index and under water-stress condition the number of seeds per spike and number of spikes explained a higher percentage of variations for grain yield. Biological yield and harvest index were entered into model in three cases out of four regression analyses (two substitution lines series and two conditions) and thus it was deduced that these two traits are the most stable traits in explaining the variations observed for seed yield.Path coefficient analysis showed that biological yield and harvest index had direct and equal effects on seed yield at non-stress condition for two substitution line series. The highest direct effects on seed yield under stress condition for ‘Timstein’ substitution line series belonged to biological yield and harvest index and for ‘Red Egyptian’ substitution lines belonged to the number of seeds per spike and number of spikes. Cluster analysis, based on Ward method and by using Euclidian distance, classified two substitution line series under water-stress and non-stress conditions in three groups.