الفهرس 
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Abstract
Eggplant (Solanum melongena L.), also known as Brinjal, Aubergine or Guinea squash, is an important vegetable crop cultivated worldwide, and is the second most important Solanaceous crop after tomato (S. lycopersicum L.). Other cultivated species of eggplant are known as (S. aethiopicum L.) and (S. macrocarpon ). Plant breeding has played an important role in Solanaceae improvement through the development of new hybrids with significantly increased quality and quantity. To improve any quantative trait, information about the mode of gene action of this trait is required. Additive and non-additive genetic variances could be determined from the estimates of general and specific combining ability, respectively.Tests of significance for mean squares revealed that all genotypes were highly significant for all studied traits with respect to the data from each year and the combined analysis over the two years. This finding indicated that these genotypes differed in their performance and further partition of this genetic variance to its components and the determination of heterosis estimates for these traits are valid. In addition, the result revealed that the mean squares of year by genotypes were highly significant for all studied traits. This finding indicated that these genotypes differed in their performance from one year to another with respect to the studied traits.The mean performances of all F1 hybrids and F1 reciprocal hybrids (F1r) indicated that there was no hybrid which gave the best results for all studied traits. In general, the hybrid (P3 x P1) was the best plant height, total fruits yield ton/fed, average fruit weight and fruit firmness, the hybrid (P1 x P3) for number of branches per plant, chlorophyll a, flowering time, early fruit yield per plot and anthocyanin content. However, the hybrid (P3 x P2) was the best for chlorophyll b, total chlorophyll, number of fruits per plant and fruit shape index, the hybrid (P4 x P2) was the best for TSS%, total nitrogen content and protein content %. On the other hand, the hybrids, (P2 x P1) and (P4 x P3) exhibited high values for leaf area and total phosphorus content, respectively.The results cleared that the mean squares of GCA, SCA and reciprocal effects were highly significant for most studied traits. Also, the results indicated that the mean squares of (GCA) were higher than those of the mean squares of (SCA) for all studied traits except leaf area, total nitrogen content and total phosphorus content. This finding revealed the importance of additive genetic variances in the inheritance of these traits. But the mean squares of (SCA) were higher than those of the mean squares of (GCA) for leaf area, total nitrogen content and total phosphorus content, which indicate the importance of non-additive genetic variances in the inheritance of these traitsThe best combination (P1xP2) obtained the highest values for improvement number of branches, leaf area, early fruit yield per plot, early fruit number per plot, average fruit weight and total iron. While, (P2 x P3) was the best combination for improvement plant height, chlorophyll b, number of fruits per plant, total fruits yield ton/fed ,fruit shape index and total phosphorus content. The interspecific hybrid (P1 x P4), which had the highest positive and significant specific combining ability effects for: chlorophyll a, total chlorophyll, TSS %, total carotene, total nitrogen content and protein content %. The hybrids (P1 x P3) was the best for days to the first flowering, fruit firmness and anthocyanin content; (P2 x P4) was the best combination and obtained the highest significant value for potassium content trait.In conclusion, the results of this investigation presented evidence about the probability of succeeded interspecific hybridization between local cultivates of eggplant and the wild relative (Solanum macrocarpon) and making in-depth studies on interspecific relation and hybridization are of great significance because sometimes interspecific hybridization may be necessary to incorporate desirable genes to cultivated species. Also, it introduces evidences about the presence of heterosis in eggplant. Additive and non-additive genetic variance in addition to cytoplasmic genetic factors contributed in the inheritance of the studied traits although, the predominant of additive genetic variance in the inheritance of all studied traits. Therefore, the plant breeder would design programs, which make use of these advantages to select superior lines from these advantages to select superior genotypes from the advanced segregating generations of the high yielding hybrids. Therefore, these results recommended the selection program to use additive gene action in the improvement of these traits.