Effect of Yellow Rust Disease on Quantitative and Qualitative Traits of Some Wheat Genotypes Under Rain-fed Conditions

Yellow rust incited by Puccinia striiformis Westend, is one of the most important fungal disease of wheat in the north of Iraq including Kurdistan region. The study was conducted to determine effect of yellow rust disease on grain yield and yield component of seven wheat genotypes with diverse levels of resistance and susceptibility under natural epidemics of the disease during 2011 at Bakrajo Experimental Station, Sulaimani. Two treatments applied for each genotype, the first one protected from the disease using Bayfidan 250EC while the second one exposed to the disease. Results revealed that yellow rust disease significantly decrease grain yield of the tested genotypes by 3.5 to 35% under natural epidemic of the disease at Bakrajo. Yield losses were mainly attributed to significant effect of the disease in reduction of grain weight by 1.6- 17.7% and number of grain per spike by 2.3-13%. Positive correlation between the Areas under Disease Progress Curve (AUDPC) values and the amount of grain yield loss in wheat genotypes were detected. Furthermore, the disease significantly affects qualitative characters of wheat grains by decreasing Protein and gluten content of the genotypes.