Heterosis and Gene Action in Some Genotypes of Tomato (Solanum Lycopersicum L.)

Abstract

The inheritance studies of some continuously variable characteristics of tomato were carried out using a half-diallel cross analysis among four parents. Important genetic variations were existed in all cases. Variance analysis showed highly significantce mean squares for the genotypes of all studied traits, indicating the wide diversity between the parents used in this study. Mean performance of the parental genotypes and their F₁ hybrids revealing that the parental genotype CastelRock had the heaviest yield/plant and the highest values of both fruit length & diameter. In the meantime, it had the lowest No. of locules. The highest fruit weight (91.92 g), No. of flower / cluster (7.2) & No. of locules (3.9) are obtained in Supermarmande. a greater ratio of GCA / SCA than one was determined for plant height and fruit weight; & the lower ratio of GCA / SCA than unit (<1) for No. of branch / plant, No. of flower / cluster; total yield / plant; fruit length; fruit diameter; fruit shape index; No. of locules and TSS%. Significant general combining ability effects for the individual parent in F₁ generation were found in the most studied traits. Both CastelRock and Supermarmande were the good general donors to the fruit weight. Also, they and Super Strain B appeared a good general donors for at least 3 yield components due for their highly significantace positive(+) values of GCA effects of these characters. Peto 86 was the best general donor parent for plant height, fruit diameter & TSS%. Five out of 6 crosses displayed significantce positive(+) SCA effects for the fruit yield per plant. Four of the five hybrids exhibited significantce desirable SCA effects to TSS%. Three hubrids of these four crosses: (CastelRock × Peto 86), (Supermarmande × Super Strain B) and (Supermarmande ×  Peto 86) exhibited significantce SCA effects for fruit weight & fruit shape index, indicated that the potential of collect with highly yield & good qualities. Fruit yield recorded the maximum significantce heterosis in desirable (+) direction (91.91%) followed by No. of locules (41.09%), shape index (27.96%), fruit weight (24.65%), No. of flowers (22.87%), TSS% (21.69%), fruit length (20.69%) and fruit diameter (19.16%).