El-Malky MM and Al-Daej M
General combining ability (GCA), specific combining ability, (SCA) and genetic analysis were used in this study for F1 generation obtained from half diall cross among six rice parents namely; Toride1, Fuknishiki Giza172, Sakha101, IR83526-38-3-3-1, and Sakha105. The results showed that both (GCA) and (SCA) variances were found to be highly significant for all nine characters studied in F1 generations. This would indicate the importance of both additive and non-additive genetic variance in determining the performance of these nine characters. The best cross combinations for earliness were (IR 83526-38-3-3-1 x Sakha105), (Giza172 x Fuknishiki), (IR 83526-38-3-3-1 x Toride1), (IR 83526-38-3-3-1 x Fuknishiki), and (Sakha101 x Fuknishiki) for earliness and grain yield per plant, it could be used in breeding program. Analysis by components of variation showed that additive (D) genetic variances were significant for all characters in F1 generation except number of panicle/plant, grain yield/plant, and 1000-grain weight. The two dominant components H1 and H2 were found to be highly significant for all traits studied in the F1 generations. Also, the magnitudes of these components were found to be larger than those of the additive genetic variance. These results indicated that the dominance genetic variation had greater role in the inheritance of these traits, F value was positive in F1 for all traits except for number of panicles/plant and grain yield/plant. This indicates more dominant alleles present in the parental lines than recessive alleles in the F1 generation. Dominance variation overall heterozygous loci (h2) was significant in the 1000-grain weight and panicle weight in the F1 generation. The estimates of average degree of dominance (H1/D)1/2 were found to be higher than unity for all traits under investigation in the F1, indicating the presence of over dominance for these traits at F1 generations. Clustering varieties, based on similarity of quantitative characters, produced two broad groups. The first one included IR83526-38-3-3-1 alone in one branch due to the highest value in plant height, the number of field grains per panicle and this variety from Indica types. While, the second group was divided into two sub-groups, the first sub-group included Giza172 and Sakha 101, which were similar in the number of tiller per plant and number of panicles per plant. The second sub group including Fuknishiki in one branch, while, Toride1 and Sakha 105 varieties were very near due to similarity in grain yield/plant, number of field grains per panicle and 1000-grain weight.
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