Gene Action, Heritability and Average Degree of Dominanc for Grain Yield and its Components in Durum Wheat

Four cultivars of durum wheat (Triticum durum Desf) were used in two crosses, the first, Leeds x Waha and the second Azeghar x Om rabi-3. The parent generations, first and second filial generations and first and second back crosses from each cross were used to study gene action, heritability, average degree of dominance and expected genetic advance for plant height, number of spikes, grain yield, weight of 100 grains and number of grains per spike. The results revealed that additive dominance model was adequate for weight of 100 grains in the two crosses, while additive, dominance and epistatic gene action played a significant role in the inheritance of other traits. Most of the studied traits revealed over dominance and high to medium narrow sense heritability. The values of expected genetic advance as percentage of the mean indicated that selection in the second filial generation will be effective to improve most of the studied traits.