In order to study inheritance of resistance to powdery mildew (Erysiphe graminis f.sp. hordei) in barely cultivars, Fl, F2 and F3 generations were made from Radical×Afzal and Cwb×Afzal crosses. At first leaf stage, all materials were inoculated with Gorgan pathogen race. Resistance components such as latent period, infection type and disease severity were recorded. Generation mean analysis with joint scaling test which simultanceously analyzes all generations was performed. The mean squares of generations were statistically significant for all traits. Although in majority of traits, gene effects including: additive (d), dominance (h), additive × additive (i) and dominance× dominance (1) were significant but the dominance gene effects were most important for inheritance of all traits. Average broad sense heritabilities through different formulas were between 9.87 and 0.99 for all traits. Degree of dominance being more than one confirmed dominance and overdominance gene effects.
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