Inheritance and Combining Ability of ‎‎Yellow Rust Rresistance in some Bread Wheat Commercial Cultivars and Advanced Lines

Wheat yellow rust caused Puccinia striiformis Westend f. sp. tritici is one of the most economically important diseases of wheat in Iran and wordwide. In order to determine the heritability، gene action and estimate of genetics parameters for yellow rust resistance components، six bread wheat cultivars and advance lines including Pishtaz، MV17، Moghan 3، SERI/KAUZ، KAUZ//KAUZ/PVZ as well as a susceptible cv. Bolani were crossed using half diallel 7  7 design. Evaluation of F1s and parents were carried out using a randomized complete blocks design with three replications. Plants were inoculated with 134E134A+ race using talk powder. Four resistance components latent period، infection type، pustule density and size were measured. Analysis of variance for combining ability using Griffing method showed that general combining ability (GCA) and specific combining ability (SCA) for four were significant which implies the additive and non-additive effects in genetic control of these components. Among parents cv. MV17 with high GCA for all four traits was identified as suitable parent to be used in breeding programs for enhancement of resistance to yellow rust. Bolani had the highest GCA next to MV17 but for susceptibility. Crosses of MV17 with Bolani، Pishtaz، Kauz//Kauz/PVZ had higher SCA (-) for infection type، number of pustules and pustule size، and the highest SCA (+) for latent period in enhancement of resistance which implies non-additive (dominance and epitasis) gene effects in these crosses. Graphic analysis of Vr and Wr indicated that latent period، infection type، pustule size، and number of pustules were recessive in some genotypes but dominant in some others. Broad and narrow sense heritabilities for all four traits were relatively high، therefore، selection based on these traits for enhancement of resistance to this race is useful.