Eight bread wheat cultivars were used to study some earliness and yield and its component traits. The parental cultivars were employed to produce 28 F 1 hybrids following 8 x 8 half Diallel crossing without reciprocals. The seeds of 28 F 1 hybrids and their parents were planted to estimate mean squares due to parents and their crosses which were significant for all studied traits. The parental variety P 3 was the best parent for earliness. However, P 8 was the best for remained traits. The crosses (P 1 x P 4) and (P 2 x P 4) were the best combinations for earliness traits, while the six crosses were the best for remained traits. Highly significant negative desirable heterotic effects were detected for earliness, on the contrary for remained traits relative to mid and better parent. The mean squares associated with general and specific combining abilities detected significant and highly significant estimates for all studied traits. Results indicated that P 4 (Sids12) was good combiner for earliness traits and most of yield and its component traits. The best cross combinations displayed fair amount of SCA effect were obtained from (P 2 x P 4) and (P 4 x P 5) for earliness traits, the six crosses for remained traits. The graphical analysis Wr/Vr indicated the importance of over dominance gene effects in controlling all traits. The results indicated the importance of additive and dominance genetic variances in controlling these traits. The "a" item was significant for most studied traits and more than "b" item. Narrow sense heritability was less than (0.50) for all traits except plant height trait (0.80). Positive alleles were not equally distributed among parents (H 2 /4H 1 ≠ 0.25) for all studied traits. The magnitude of dominance (H 1 /H 2) was significant or highly significant higher than additive components (D) for all traits, expect plant height trait. All estimates of environmental variance (E) were positive significant and highly significant for all studied traits indicating that all studied traits have greatly affected by environmental factors.

The present investigation used four bread wheat cultivars to study some earliness, yield and its components characters. The parental cultivars produced six F 1 hybrids following 4 x 4 half Diallel crossing without reciprocal. F 1 hybrids and their parents were evaluated via combined analysis to study mean squares due to the parents and their hybrids which showed significant values for all studied traits. The parental variety P 1 was the best for earliness. However, P 4 was the best for yield and its components. The crosses P 1 x P 4 and P 2 x P 4 were the best for earliness. However, four crosses were the best for yield components. The mean squares associated with general and specific combining ability appeared significant values for all studied traits in the both seasons. Gemmeiza 9 was the good parent for earliness traits; however, Gemmeiza 10 was the best parent for yield and its components in the two seasons. The graphical analysis Wr/Vr showed significance of over dominance gene effects, as well as, significance of additive and dominance genetic variance in controlling all traits. The additive components (A) were lower than dominance for all traits in both seasons. Heritability in narrow sense was low for all traits in both seasons. The magnitude of dominance (H 1 and H 2) was significant than additive for most traits in both seasons which reflected the presences of over dominance. The environmental variance (E) showed that all traits have been greatly affected by environmental factors.