Genetic studies on stripe and leaf rusts of bread wheat under different sowing dates

Includes references.

The present experiment was conducted at Sakha Agric. Res. Sin. during 2007/2008 and 2008/2009 wheat growing seasons to estimate the combining ability, type of gene action, heterosis and simple correlation coefficient for some agronomic characters and reaction to wheat stripe and leaf rusts using a diallel cross mating design <)f eight wheat parental gerrotypes. These genotypes are P,- Attila-3, PzGemmiza g, p," Line 1, P₄ Sids 1, P5- Sakha 94, p.- Sakha 69, P7- Sids 12 and p.. Sakha 93. Days to heading, days to physiological maturity, plant height number of spikes I plant, number of kemels I spike, weight of kernels I spike, kernel weight, grain yield I plant and reaction to rust were estimated. Significant mean squares were obtained for genotypes, parents, crosses and parents vs. crosses in all studied characters except for days to heading and number of spikes I plant for parents vs. crosses. The mean squares associated with general combining ability (GCA) and specific combining ability (SeA) were significant for all studied characters, indicating the presence of both additive and dominance types of gene effects. The ratio of GCAI SCA was more than unity in all studied characters except for kernel weight, indicating the importance role of additive genetic effects. The crosses P₃x P₄ and P₃ x P₆ gave the most positive significant heterosis values for grain yield I plant relative to mid and better parents, respectively. Moreover, the cross P₁ x P₇gave the most negative significant heterosis values for leaf rust resistance relative to mid and better parents. The correlation coefficient between grain yieldJ plant wilh each of number of kernels I spike, kernel weight I spike and kernel weight were significantly positive. Meanwhile, the correlation coefficients between leaf rust with each of number of kernels I spike and kernel weight I spike were significanUy negative.

Summary in Arabic.

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