Yellow Rust Effects on Grain Yield, and Yield Components of Some Spring Bread Wheat Cultivars under Rainfed Conditions

Stripe rust caused by Puccinia striiformis, is currently the major foliar disease of spring bread wheat (Triticum aestivum L.) in Tunisia, causing serious yield losses and affecting grain quality. Farmers often use foliar fungicide application or resistant cultivars to counter yield loss, however, this is hampered by a lack of resistant varieties. To investigate the effects of genetic resistance and foliar fungicide application on disease level and yield components, six improved varieties were evaluated at the regional experimental station in Beja during three consecutive growing seasons. Under natural stripe rust infection, three varieties were detected as completely resistant and the others are susceptible. The pathogen affected the leaf area in the susceptible varieties and reduces the above ground biomass at harvest, seed weight and grain yield. Fungicide application reduces the disease severity on the sensitive genotypes and improves biomass, seed weight, grain yield, and harvest index. Yield benefits were much greater in the use of resistant genotypes than fungicide application on the susceptible varieties; consequently the resistance to stripe rust can have more significant benefits to farmer and to the wheat industry.