الفهرس Only 14 pages are availabe for public view
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Abstract
This study was carried out in 2004/05, 2005/06 and 2006/07 seasons at Sakha Res. Station, Agric. Res. Center, Egypt. The main objective was to study the mode of inheritance, combining ability and heritability for earliness, grain filling and agronomic and yield characteristics in some Egyptian bread wheat genotypes and their diallel F1 crosses under two irrigation regimes. Water stress caused significant reductions in all studied traits, except kernels/ spike (K/S)and 100 kernel weight (100KW) of F1’s; with grain yield of F1’s showing maximum reduction (22.3%). Genotypic differences were found in all traits under both irrigation treatments. Line-1 and Sakha-61 x Sids-4 were early heading and maturing as well as having high yielding ability. Line-1 x Line-3 had the best yield under both irrigation regimes and the lowest reduction due to drought besides heterobeltiosis for most studied traits under both conditions. Both general (GCA) and specific (SCA) combining ability variances were significant for all studied traits; with higher magnitude for GCA than SCA. The best general combiners were Sids-4, Line-1 and Line-2 for days to heading (DTH) and to maturity (DTM) and Sakha-61, Line-3 and Gemmeiza-10 for grain filling rate (GFR) and grain yield (GY). Additive and dominance variances were significant for all studied traits; with additive was more important than dominance for DTH, DTM, GFP, GFR and K/S under both environments and S/P and 100 KW under non-stress. While, dominance was more important than additive for GY, plant height (PH) and leaf area (LA). Degree of dominance was partial for DTH, DTM, GFP and K/S, complete for GFR, and over-dominance for GY and PH under both environments. Number of genes (gene groups) controlling inheritance was one for GFP, GFR, LA, S/P, K/S and GY; two for 100KW and DTM under both environments, three for DTH and PH under non-stress and four for DTM under water stress. Narrow-sense heritability estimates were very high for DTH and GFP, high for DTM, moderate for GFR, LA and S/P and low for PH and GY under both conditions. Results suggested that early heading genotypes showed longer GFP and that S/P and GFR were the most important factors for increasing GY.