Effect of sowing density on tolerance of some susceptmle bread wheat cultivars to leaf rust disease [electronic resource].

Includes references.

Wheat leaf rust caused by Puccinia triticina Erikson is one of the most important diseases of wheat worldwide. Field experiment was carried out at Gemmeiza Research Station. Four wheat cvs. 8akha 93, Gemmeiza-7, Gemmeiza -10, and Gemmeiza -11 were Sown at two different densities (100 and 50 seed/ m2). Artificial inoculation was performed using spore suspension at flag leaf opening (growth stage - G8 53) as well as a mixture of uridia and talcum powder. The cultivars response to leaf rust showed the susceptible infection type and its disease severity was usually high. The tested four cultivars exhibited high disease severity, 70-80% on the flag and second leaves. High values of area under disease progress curve (AUDPC) were detected for Gemmeiza-l0 , Sakha-93, Gemmeiza-7 then Gemmeiza-ll ( 1405 ,1350, 1190 and 1165,respectively ). High correlation value was found between disease severities and values of AUDPC of the tested cultivars (r =0.99166). The effect of the disease on grain weight and grain yield/plant was studied to detect whether some form of incomplete resistance or tolerance was involved in the tested cultivars. In general, percentage losses in grain yield was low with the lower sowing density (50 seed!m2) than the high sowing density (100 seed/m2). Percentage losses varied from 4.17 to 18.41 % and from 5.39 to 21.20% for 1000 grain weight in 2009 and 2010 growing seasons, respectively .Percentage losses in grain yield I plant ranged from 14.78 to 21.70% in 2009 and from 13.01 to 26.53 % in 2010 growing seasons. Correlation analysis revealed a significant linear relationship (r = 0.56 & 0.55 P <0.05) between mean disease severity and mean percentage loss for 1000 kernel weight and grain yield/ plant. Keywords: Wheat, leaf rust, sowing density, tolerance, ADDC.

Summary in Arabic.

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