In 1995, five wheat cultivars, one susceptible and four resistance to yellow rust, were inter crossed using a half diallel fashion. In 1996, parents and Fl progenies were planted in a randomized complete block design with three replications. Components of resistance including latent period, pustule size and density, and infection type were evaluated. The results showed significant genetic differences between genotypes, indicating the presence of additive and non-additive effects of gene.’ 11w all characters. Combining ability analysis showed significant, MSgca, Msgca ratio for all characters indicating additive variance to he more important than non-additive variance. The diallel analysis as described by Jinks and Hayman showed that probalbly additive- dominance model can be appropriate and the results showed the presence of partial dominance. Broad and narrow sense heritability estimates ranged from 62% to 98% varieties. Cultivars M-73-3 and M-73-7 were resistant in adult stage and frequency of recessive genes in these cultivars were more than those of dominant genes. Thus, it can he concluded that these cultivars probably have durable resistance.
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