NATURE OF GENE ACTION FOR EARLINESS AND YIELD IN BREAD WHEAT UNDER HEAT STRESS. | ||||
| Journal of Plant Production | ||||
| Article 5, Volume 29, Issue 11, November 2004, Page 6213-6224 PDF (3.28 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jpp.2004.238873 | ||||
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| Author | ||||
| G. A. R. EI-Sherbeny, | ||||
| Dept. of Agric. Botany (Genetics), Sohag Fac. of Agric., South Valley Univ., Egypt | ||||
| Abstract | ||||
| Five Egyptian and exotic wheat cultivars and their all half diallel possible cross combinations were used to generate combining ability information and identify suitable parents and cross combinations for further exploitation under normal (01) and late (02) planting dates. Mean squares of genotype x environment interactions were highly significant, suggesting a differential response of the genotypes under normal and stress environments. Heat stress conditions caused reduction about 7.69%, 5.84% and 19.37% in the F1 hybrids average for heading date, 1000 grain weight and grain yield per plant, res pectively. The results also revealed that all cross combinations including 00vin-2 (P3), Giza 164 (P4) and two out of four crosses including Sakha 69 (P1) gave susceptibility index (S) values less than the unity. This result that indicated that they transmitted their genes controlling heat tolerance. It was also noticed that the two crosses (P1XP3) and (P1XP4) gave the highest yield under both the two environments with susceptibility index less than unity. Correlation coefficients between stress susceptibility index (S) and each of grain yield per plant and heading date were - 0.34 and 0.84, respectively. Estimates of general combining ability of each parent revealed that the parents Sakha 69 (P1), Giza 164 (P4) and 00vin-2 (P3) possessed more desirable additive genes for all studied traits under each of the two environments and their combined data. whereas, Gemmeiza 5 (P2) and Bau'S' (Ps) were the poorest general combiners for the same traits. The results indicated that the cross combination (P1XP3) exhibited Significant SCA effects for earliness and high yielding ability under normal and stress conditions. While, the two crosses (P2XP4) and (P3XPS) revealed Significant SCA effects for grain yield per plant and 1000 grain weight, respectively, under each of the two environments and their combined data. The results also indicated that the non additive gene action including dominance (ifo) played a major role in the inheritance of days to heading. On the other hand, the estimates of additive variance (if A) were higher than those of non additive ones (ifo) for 1000 grain weight and grain yield per plant at optimum and stress conditions as well as their combined data, verifying by the ratios (rlrJifA)112 which were less than unity. The interaction if AxE variance was positive and lower than those of rloxE ones for heading date, verifying by the ratios ~oXElrlAXE)112 which were more than unity. In contrast, the ratio (ifoxElifAxE)1 were less than unity for 1000 grain weight and grain yield per plant. This finding indicated that the additive gene effects were more influenced by heat stress than non additive ones. The results showed that the largest values of broad sense heritability were observed for heading date (87.22% and 93.26%) under normal and stress conditions, respectively. While, the largest estimates of narrow sense heritability were obtained for 1000 grain weight (44.46% and 49.93%) and grain yield per plant ( 55.84% and 62.00%) under normal and stress conditions, respectively. Estimates of nature of gene action and narrow sense heritability in these promising populations proved that selection for heat tolerance could be effective in early segregating generations. | ||||
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