Impact of Wheat Leaf Rust Severity on Grain Yield Losses in Relation to Host Resistance for Some Egyptian Wheat Cultivars

Abstract

Leaf rust (Puccinia triticina) is a vital disease that cause significant yield losses in wheat fields. The relation between yield losses due to leaf rust disease and host resistance was studied in nine bread wheat cultivars through the two successive growing seasons 2014/2015 and 2015/016. Experiments were conducted in Sids Agricultural Research Station (Middle Egypt) under high disease pressure. Yield losses were determined under field conditions for infected and fungicide protected plants. Rust incidence was also recorded as final rust severity % (FRS %) and area under disease progress curve (AUDPC). In general, yield losses were parallel to leaf rust severity and area under disease progress curve in both of the two growing seasons. Wheat cultivars which revealed high leaf rust severity exhibited maximum values of area under disease progress curve (AUDPC) and yield loss%. However, the wheat cultivars revealed lower leaf rust severity exhibited minimum values of area under disease progress curve (AUDPC) and yield loss%. Leaf rust triggered losses irrespective of the level of resistance obsessed by the cultivars. Giza-168, Sids-13 and Sakha-94 cultivars showed lower levels of both FRS % and AUDPC which exhibited lower levels of losses (2.72% to 5.90%) as compared to the highly susceptible cultivar Gimmeza-7 in which grain reduction reached 12.29% to 18.23%. On the other hand, losses in yield per plot in Giza-168, Sids-13 and Sakha-94 cultivars ranged from 4.09% to 5.72% compared to cultivar Gimmeza-7 ranged from 16.45% to 20.12%. The yield losses were significantly correlated with AUDPC. The cultivars Sids-1 and Gimmeza-9 had great values for susceptibility to leaf rust incidence while, the average grain yield potential for both cultivars was similar to the highest yield commercial cultivars. This indicated that Sids-1 and Gimmeza-9 cultivars have high level of tolerance to leaf rust infection under the Egyptian field condition.