GENETIC ANALYSIS OF RESISTANCE TO POWDERY MILDEW IN BARLEY

To study the inheritance of resistance to powdery mildew in barley, four winter and facultative barley cultivars (Hebe, Afzal, Legia and Igri) along with six F1s, derived from monolateral diallel crossing, with Karaj isolate of the pathogen were examined in a complete randomized block design with three replications. The components of resistance including latent period and infection type were scored. Variance analysis revealed significant differences among genotypes for these two components. Among the parents, Igri possessed the greatest general combining ability for increasing the resistance. Among the hybrids, Afzal*Hebe and Afzal*Igri hybrids respectively possessed the most specific combining ability for increasing the resistance. The findings of the study showed that the frequency of dominant resistance genes was greater than non-dominant genes. General and specific inheritability were 98.3 percent and 36.5 percent respectively. The low figure for specific inheritability indicated that the type of selection would not be effective in decreasing the latent period and infection type characteristics. The extent of dominance for the two features of latent period and infection type were greater than 1, which confirms that genetic dominance and super-dominance were effective in controlling these two features.