Heritability And Combining Ability Of Latent Period Of Puccinia Striiformis In Four Winter Wheat Cultivars

Wheat yellow rust (Puccinia striiformis) is one of the most important fungal diseases of wheat in Iran. Identification of resistance genes and their mode of action is important in utilization of resistance sources and the breeding strategy adopted in a breeding program. In this study, four resistant parents and one susceptible cultivar were used in a diallel fashion excluding reciprocals. Parents and the Fl progenies were inoculated at seedling stage (First leaf) with pathotype 230E245A+ of Puccinia striiformis. Latent period, defined as days from inoculation to first pustule appearance was daily recorded from the first appearance of pustules up to 25 days after inoculation. Entries without pustule formations were given a score of 25. Results of inheritance studies using Hayman and Griffing methods indicated that addative components and complete dominance played major roles in conditioning latent period in these ten crosses. Broad-sense and narrow-sense heritability estimates for latent period were 0.99 and 0.88, respectively. The results suggested that considerable progress may be expected for latent period in a breeding program.