COMBINING ABILITY FOR EARLINESS AND YIELD AND SOME OF ITS COMPONENTS IN BREAD WHEAT UNDER FAVOURABLE AND DROUGHT STRESS CONDITIONS. | ||||
| Journal of Plant Production | ||||
| Article 5, Volume 31, Issue 2, February 2006, Page 723-734 PDF (1.74 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jpp.2006.235715 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| G. A.R. El-Sherbeny, | ||||
| Dept. of Agric. Botany (Genetics), Sohag Fac. of Agric., South Valley Univ., Egypt | ||||
| Abstract | ||||
| Six wheat cultivars and their all hall diallel possible cross combinations were used to estimate general and specific combining ability for earliness and yield components under favorable (F) and drought stress (8) conditions Drought stress conditions caused reduction in the F1 hybrids average about 5.56%; 17.12%; 7.16% and 16.71% for heading date; number of spikes per plant; 1000 grain weight and grain yield per plant, respectively. Estimates of drought susceptibility index (DSI) based on grain yield per plant showed that Giza 164(P5) and the cross combinations including (P1 x P5; P2 x P3; P3 x P5; P4 J: P5 and P5 x P5) gave susceptibility index ([351) values less than the unity, indicating that these genotypes were relatively tolerant to drought stress. Correlation coefficients between drought stress susceptibility index (BSD and each of grain yield per plant and heading date were - 0.15 and 0.16, respectively. The results showed that mean squares due to genotype x environment interaction were highly significant, suggesting a differential response of the genotypes under favorable (F) and drought stress (S) environments. The results indicated that GCA and SCA mean squares were highty significant for all studied traits under each environment and their combined data. The interactions of GCA x E and SCA x E mean squares were found to be highly significant for all studied traits except SCA x E in grain yield per plant, Moreover, the ratio of GCA x E iSCA x E was more than one I0r all studied traits, revealing that non additive genetic effects are more stable over the environments than additive ones. Estimates of general combining ability effects exhibited that Gemmeiza 3 (P1) was excellent generai combiner for earliness under the two environments. For yield components, Gemmeiza 3 (P1), Giza 164 (P5) and Gemmeiza 7 (P5) were considered the best parents under both environments. The results indicated that the crosses (P; x P5) and (P4 x P5) under favorable conditions as well as (P; at P2) and (P3 x P4) under stress conditions exhibited significant SCA effects for earliness. The crosses (P3 x P4) and (P4 x Fe) revealed significant SCA effects for number of spikes per plant under the two environments. Desirable SCA effects for 1000 grain weight were obtained by the cross (P; x P3) under each of the two environments. Concerning grain yield per plant. the cross (P1 x P3} was the most promising under the two environments. While. the cross (P5 x P5) exhibited desirable SCA effect for the same trait under drought stress conditions. It is interesting to note that the promising crosses which showed desirable SCA effects were also significantly earlier and higher yield than their mid and better parents under the two environments. Generaliy, estimates of GCA and SCA in these promising populations proved that selection for drought tolerance could be effective in early segregating generations. | ||||
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