Selection for Early Heading and Correlated Response in Grain Yield and its Components in Durum Wheat

Two cycles of selection were applied to the F₃ generation of a cross between Bani Sweif 1/3/STJ3 and Bani Sweif 1/3/LKS4 lines to evaluate the effect of direct selection for heading date and correlated response in grain yield and its components. Significant differences among F₃ families were found for heading date, plant height, no. of kernels/spike, spikes/plant, 100-kernel weight and grain yield/plant. Estimates of the phenotypic and genotypic coefficients of variation indicated the presence of sufficient variability for heading date and other studied traits. Phenotypic and genotypic variances expressed as PCV% and GCV% decreased rapidly after two cycles of selection for early heading. The results indicate that the two cycles of selection were enough to identify the early genotypes. Flowering time was reduced by 3.53 and 7.45 days after two cycles of selection compared to the earliest parent and the bulk of the F₃-families, respectively. The results indicated that five out of the ten early selected families were significantly or highly significantly earlier than the earlier parent. Direct selection for early heading was accompanied by average decrease of 3.17, 3.76, 0.26 and 1.95% for plant height, no. of kernels/spike, 100 kernels weight and grain yield/plant, respectively, after two cycles of selection compared to the best parent. Direct selection for early heading significantly reduced grain yield/plant by 2.31, 2.45, 3.20, 5.72 and 6.98% for family no. 54, 76, 77, 68 and 50, respectively, compared with the best parent. The results should be indicated to the promising family no. 29 which was earlier and significantly increased in no. of kernels/spike, 100 grain weight and grain yield/plant.