Evaluation of Tolerance to Yellow Rust Disease in Some Selected Bread Wheat Cultivars

Tolerance to the disease is defined as the plant's ability to reduce damage caused by a pathogen attack and yield is good even when the plant is infected by pathogen. The concept of tolerance arises from the fact that in conditions of severe disease infection, in some cultivars, yield reduction is less than the other cultivars. In this study, the tolerance of 20 wheat cultivars was evaluated against yellow rust. The effect of stripe rust in Neishabour on grain yield under conditions of severe disease (stress) and protected from disease (non- stress) were analysed. The mean reduction (%) in grain yield in all cultivars infected by yellow rust was 18.2%. Damage by stripe rust varied from 3.5 to 57 percent. Based on the results of two years of disease stress, Kavir, Neishabour and Inia (with 16%, 14% and 13% yield loss, respectively) were more tolerant to yellow rust. In moderately susceptible cultivars, Tajan with 5.71% yield reduction was identifiect as the most tolerant cultivar. Sirvan among the cultivars with moderate infection (5MS) had highest resistance reaction. The average yield reduction of Sirvan in disease condition was about 15%, and its 1000 grain weight reduced by 9% as compared with protected condition.