الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
The experiment was carried out at Gemmeiza Agricultural Research Station, Agriculture Research Center, Egypt, During the two successive season 2008/2009 and 2009/2010. Ten common wheat varieties and lines of wide divergent origins were used to establish the experimental materials for this investigation i.e. Gemmeiza 7, Sakha 93, Giza 168, Line 4, Line 5, Line 6, Line 7, Line 8, Line 9 and Sids 4. The obtained results can be summarized as follow: 1- Nitrogen fertilizer levels mean squares were found to be significant for all traits studied except plant height, number of spikelets per spike length and 1000-grain weight, with the mean values of the first nitrogen fertilizer level i.e. 20 kg (faddan) being higher than those of the second nitrogen fertilizer level i.e. 30 kg nitrogen per faddan, in the most cases. 2- Genotypes, parent and the resultant forty five crosses mean square estimates were found to be highly significant for all traits studied under the two nitrogen fertilizer levels and their combined data. 3- Parents vs crosses mean squares as an indication to average heterosis overall crosses, were found to be highly significant for heading data, plant height and 1000-grain weight under the two nitrogen fertilizer levels and their combined data. 4- The interaction of genotypes with the two nitrogen fertilizer levels were found to be significant for only heading data and maturity data. 5- The interactions of the two nitrogen levels with parents were found to be significant for heading data, maturity data, number of spikes per plant, spike weight and number of kernels per spike. 6- The interaction of parents vs crosses with the two nitrogen levels were found to be significant for plant height, number of spikes per plant, spike length and grain yield per plant. 7- The two crosses Gemmeiza 7 * Sakha 93 and Sakha93*Line 6 would of practical interest in hybrid breeding program because of their superiority in grain yield per plant and four traits contributing to yield, also heterosis for grain yield could be attributed to heterosis in number of spike weight. 8- General combining ability and specific combining ability were found to be highly significant for all characters under examination at the two nitrogen fertilizer levels and their combined data except number of spikelets per spike at both normal and stress nitrogen fertilizer levels and spike length under stress nitrogen level only. 9- The GCA / SCA ratios were found to be greater than unity, indicating that additive and additive * additive types of gene action were of greater importance in the in heritance of all traits. 10- The interactions of nitrogen fertilization with both types of combining ability were found to be significant for heading data and maturity data. 11- The parental variety Line 5 which possessed high general combining ability effects for grain yield per plant was found to be also good combiner for most of the attributes contributing to grain yield. 12- For grain yield per plant, the wheat cross Sakha 93* Line 4 showed highly significant specific combining ability effects under the normal nitrogen fertilizer level. 13- The additive genetic variance (D) was found to be highly significant for all traits studied under the two nitrogen fertilizer levels. 14- The dominance genetic variation H1 and H2 were found to be highly significant for all traits studied under the two nitrogen levels. 15- Correlation coefficients between (Yr) and (Wr+Vr) for maturity data under the stress nitrogen fertilizer level, spike length and kernels per spike under both normal and stress nitrogen fertilizer levels, spike weight and grain yield per plant under the normal nitrogen fertilizer level were found to be positive and significant. 16- The graphical analysis demonstrated the existence of the partial dominance in the inheritance of all traits studied except number of kernels per spike under the two nitrogen fertilizer levels and grain yield per plant at the stress nitrogen fertilizer level.