EFFECT OF LEAF RUST INFECTION ON YIELD AND TECHNICAL PROPERTIES IN GRAINS OF SOME EGYPTIAN WHEAT CULTIVARS

Wheat leaf rust disease, caused by Puccinia triticina f. sp. tritici, is one of the most important wheat diseases in Egypt and worldwide. In the present study, Four epidemiological parameters; final rust severity (%), area under disease progress curve (AUDPC), relative area under disease progress curve (rAUDPC) and rate of disease increase (r-value) and technical properties were estimated for seven Egyptian bread wheat cultivars. The highest percentages of final rust severity (FRS), the highest values of area under disease progress curve (AUDPC), the highest values of relative area under disease progress curve (rAUDPC) and the highest rates of disease increase (r-value) were recorded with the cvs.; Gemmeiza-7, Gemmeiza-11 and Sids-1 during 2014/15 and 2015/16 growing seasons. Accordingly, they recorded high loss (%) in 1000 kernel weight, yield/feddan and Egyptian pound (LE). There were a positive relations between the four parameters under study and loss (%) of yield/feddan, where the relation between FRS (%) and loss (%) of yield/feddan was the strongest (R2 = 0.994).  Therefore, the loss (%) of yield/feddan could be predicted from FRS (%). Whereas, there were negative relations between FRS (%) and each of 1000 kernel weight and yield/feddan of the infected wheat cultivars during the two successive seasons. As for, the physical properties, the protected plots of wheat cultivars under study recorded the highest values in the hectoliter and flour extraction comparing to the infected plots of the same cultivars. On the other hand, protein and ash contents increased in the flour of infected wheat cultivars compared with the flour of the same protected ones. Also, farinograph parameters of dough improved slightly for infected cultivars, where values of water absorption and stability time showed little increase, compared with the same protected wheat cultivars. Accordingly, baking quality and sensory of balady bread made from the flour of protected and infected wheat cultivars were slightly increased in layers separation, crumb texture and odor bread. Thus, it could be concluded that the leaf rust infection, negatively affected both grain quality and quantity of wheat cultivars under study.