Five Egyptian parental genotypes of Faba bean were used for carrying out half diallel design to study
heterosis and nature of gene action for earliness, vegetative, yield and yield components traits. Mean
squares of genotypes were found to be highly significant for all studied traits. The results showed that
the majority of crosses exhibited significant heterosis estimates for better parent for all studied traits.
General combining ability (GCA) and specific combining ability (SCA) mean squares were highly
significant for all studied traits. The results indicated that the magnitude of additive genetic variance

2A) were positive and lower than those of non additive (σ
2D) one for all the studied traits, indicating
that non additive gene action played a major role in the inheritance of different traits under study. The
broad sense heritability estimates (H2
b %) were more than their corresponding narrow sense heritability
n %) for all studied traits. However, estimates of narrow sense heritability were 34.2 and 14.8% for
earliness traits and ranged from 15.2 to 29.8% for number of branches per plant and plant height,
respectively. Respecting to yield components, the estimates of narrow sense heritability ranged from
8.8 to 70.9% for number of pod per plant and weight of 100 seed (g), respectively. The results showed
that the two cultivar, Giza 843 (P4) and Misr 2 (P1) was good general combiner for earliness, yield and
yield components, respectively. The cross (P1xP5) showed desirable SCA effects and significant
heterosis values for earliness, and yield components. While, the two crosses, (P1xP3) and (P3xP4)
exhibited desirable SCA effects for vegetative traits. These promising crosses could be used for
breeding programs to produce pure lines.