ASSESSMENT OF SOME WHEAT GENOTYPES FOR RESISTANCE TO SOME DISEASES AND THEIR EFFECT ON YIELD AND YIELD COMPONENTS

Forty -five genotypes of wheat to determine the disease resistance of some wheat genotypes and to select disease resistant lines for future wheat breeding programs. The analysis of variance for 45 wheat genotypes revealed highly significant variation for all quantitative traits related parameters. Phenotypic coefficient of variance was slightly higher than the genotypic coefficient of variance for all studied traits, indicating presence of environmental influence on the expression of these characters. High heritability in broad sense was found in all studied traits. Highly positive significant correlation values between grain yield/plot and each of number of spikes/m2, number of kernels/spike and 1000-kernel weight. Highly positive significant correlations were detected between 1000- kernels weight and number of spikes/m2 and number of kernels/spike. Significant and high negative significant correlations between grain yield and each of yellow rust, leaf rust and powdery mildew. Yellow rust had negative correlations with number of spikes/m2, number of kernels/spike and 1000-kernel weight, respectively. Leaf rust had higher values of number of spikes/m2, number of kernels/spike in addition, 1000-kernel weight, respectively. Po Powdery mildew had negative effect on yield components with correlation values of the number of spikes/m2, number of kernels/spike and 1000-kernel weight. Disease severity response was variable among the tested genotypes. Eleven wheat genotypes have displayed high levels of adult plant resistance to diseases under study, they should be characterized as the completely resistant lines, Meanwhile, 8 genotypes exhibited susceptible disease reaction; on the other hand wheat genotypes 5-promissing lines and commercial variety Gemmiza-9 were moderately resistant to moderately susceptible or susceptible reactions but they can retard or delay the disease onset or development and show low to moderate levels of final rust severity (less than 30%) during the two growing seasons of the study. These wheat promising lines could be characterized or identified as partially resistant.