Assesment of Relationships between Seed Yield and Some Morphophysiological Traits of Bread Wheat Genotypes under Rainfed and Supplementary Irrigation Conditions

Relationship, between seed yield and it morphological characteristics and their relative importance in 25 bread wheat genotypes under both rain-fed and supplementary irrigation conditions studied using a randomized complete block design with three replications were evaluated during growing seasons of 2014 and 2016 at the Kermanshah’s Sararud Rainfed Agricultural Research Station. Analysis of variance showed that all traits under study, except spike length, exhibited significant differences in rainfed and supplementary irrigation condition. In supplementary irrigation conditions, these traits showed higher values as compared to those of rainfed condition. The application of supplementary irrigation resulted in reduced leaf and canopy temperatures. The coefficients of simple correlation between the traits, for both of the rain-fed and supplementary irrigation systems, indicated that cell membrane stability, flag leaf length, straw yield, relative water content, 1000 seed weight, chlorophyll content, leaf and canopy temperatures were maximally correlated with the seed yield. Traits like straw yield and flag leaf length were inserted into the regression model of rainfed irrigation condition and traits such as the straw yield, flag leaf length, relative water content and spike yield were also inserted into the regression model of supplementary irrigation condition the results demonstrated that the former traits accounted for 0.741 of the seed yield variations and the latter traits explained 0.899 of the seed yield variation. Path coefficient analysis showed highest positive direct effect on seed yield in rain-fed condition, and straw yield and flag leaf length, relative water content, flag leaf length and spike yield in supplementary irrigation condition. Based on the results of this study, straw yield was found to be the most important indicator to select for higher yielding varieties of wheat under both rainfed and supplementar irrigation conditions.