Evaluating the Relationship between Distributions of Photosynthetic Assimilates Related Traits and Grain Yield in Wheat Genotypes under Terminal Drought Stress Conditions

In order to study the relationships among traits and grouping genotypes of wheat, 11 promising lines of winter wheat along with Orum, Zareh, Mihan, Zarrin and peshgam cultivars were evaluated under two levels of irrigation (complete irrigation and cutting irrigation from flowering to maturity) at Agricultural Research Station of Miandoab during 2013-2014 and 2014-2015 growing seasons. The experiment was conducted as a split plot based on randomized complete block design with three replications. Results showed that the correlation of grain yield was significantly positive with stem weight, peduncle weight, spike weight and harvest index in both conditions. In normal moisture conditions correlation of grain yield with source limitation and limitation of sink by removing the leaves was significantly negative while in water stress conditions its correlation with remobilization rate and contribution of remobilization was significantly positive. Results of regression analysis showed that in normal conditions spike weight, sinks limitations by removing flag leaf and other leaves and in water stress conditions remobilization rate, stem weight and contribution of remobilization justified 61 and 65 percent the variations in grain yield, respectively, and they were identified as traits affecting grain yield. Based on the result of Cluster analysis the genotypes were divided into five groups in normal conditions and into four groups under stress condition. In factor analysis through principal component analysis, three factors were identified in both conditions that explained 71.40 and 65.79 percent of data variations in normal and water stress conditions, respectively.