Militating selection indices in some bread wheat crosses

This study was carried out at El-Giza Agric. Res. Station during four seasons from 2005/2006 to 2008/2009 to evaluate the effect of eight methods of selection indices on grain yield per plant , number of spikes per plant , number of kernels per spike and 100kernel weight of three bread wheat crosses. Selection indices were 1- Bulk method as a control, 2- Number of spikes per plant (S.I1), 3- Number of kernels per spike (S.I2), 4- 100-kernel weight ( SI3) , 5- Number of spikes per plant and number of kernels per spike withholding 100 kernel weight (S.I12.3) , 6-Number of spikes per plant and 100-kernel weight withholding number of kernels per spike (S.I13.2) , 7- Number of kernels per spike and 100-kernel weight withholding number of spikes per plant (S.I23.1), 8- Number of spikes per plant, number of kernels per spike and 100-kernel weight (S.I123). After three cycles of selection in F2,F3 and F4, six genotypes from each selection indices were selected from each cross. A total number of 42 selected genotypes resulting from seven selection indices and six bulk populations were evaluated for grain yield and yield components. Single analysis of variance demonstrated significant differences between selection indices in all crosses. Genotypes significantly differed for all characters except number of spikes per plant, 100 kernel weight and kernel weight per spike in cross No. 1. The interaction between genotypes x indices had significantly effected all characters except 100-kernel weight in cross No.1 and 2 . Analysis of variance of selection indices M, crosses C and genotypes or lines G showed significant differences except grain yield per plant. The interactions between (C x M) , (C x G) , (M x G) and (M x C xG) had significant effect. Results also, showed that the best selection indices for number of spikes per plant was S.I13.2 , for number of kernels per spike was S.I123, for 100 kernel weight S.I3 , for kernel weight spike S.I3 , and for grain yield per plant were S.I 123 and S.I1 . Results also showed that the three crosses significantly differed in all characters except grain yield per plant . Cross No.3 had the highest number of spikes per plant , cross No.2 had the highest number of kernels per spike, and cross No.1 had the highest 100 kernel weight , kernels spike weight and grain yield per plant