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Wheat substitution lines of Cappelle into the genetic background of Chinese spring were tested in a completely randomized block desing with three replications for three years in College of Agriculture. Razi University of
Kermanshah. Data of grain yield and yield components were analyzed based on the concept that yield components are determined sequentially at different
stages in the ontology of plants and the hypothesis that the environmental
resources can be separated into the independent groups. The genotype¬environment interaction is then represented by three multiplicative terms which are composed of three genotypic and three environmental components. These components were estimated using the method of path coefficient analysis.!t was concluded thatt the relative contribution of the number of seed
per spike (V,.) in the genotype-environment interactions was higher than that
of number of spike per plant (V,) and seed weight (V,.). It was also observed that the sensitvity of number of seed per spike to the environmental tluctuations (ry) was less than that of the other two components (r, and r",) and hence play more important role in the phenotypic stability of
wheatSubstitution analysis showed that most of the genes controlling relative
contribution of number of sf:ed per spike (Vy) in the genotype-environment interactions and grain yield (W) are located on chromosome 6A Therefore, it is recommended to use 6A chromosome to simultaneously improve yield and yield stability in wheat.