Genetic Analysis of Quantitative Taits in Bread Wheat Under Normal and Moisture Stress Conditions

In order to study genetic of quantitative traits in wheat under normal and moisture stress conditions, several genetic parameters such as average degree of dominance, proportion and distribution of dominant and recessive alleles in all parents and dominance direction were evaluated in ten cultivars of bread wheat, using a half diallel. Parents and their hybrids were separately planted in a randomized complete block design under normal and moisture stress conditions in the second year. Results of analysis of variance in normal moisture condition showed genetic variation among genotypes for most of the traits except for tiller and fertile tiller number, awn length and 50% heading date, whereas in stress condition results of analysis of variance were not significant for awn length, 50% heading date, dry weight of root and flag leaf area. There were over dominance effect for number of spikelet per spike, number of kernel per spike, 1000- kernel weight, biomass, weight grain yield and harvest index, complete dominance for stomata number per unit of leaf area, and partial dominance for peduncle length, spike length and dry weight of root in normal moisture condition. The results in normal moisture condition also showed that all traits were controlled by dominant alleles, except number of stomata per unit of leaf area that was controlled by recessive alleles. In stress conditions there were over dominance effect for number of spikelet per spike, spike length and number of kernel per spike, complete dominance for number of stomata per unit of leaf area, and partial dominance for peduncle length, 1000- kernel weight, biomass, weight, grain yield and harvest index. In stress condition, all traits were controlled by dominant alleles except 1000-kernel weight that was controlled by recessive alleles.