Combining Ability in Tomato

The nature of combining ability in tomato was studied in a set of diallel crosses of ten varieties from diverse regions to characterise the genetic architecture of the population and to isolate best parents for hybridization. The variances due to general and specific combining ability were significant for all the characters, viz. locule number, plant length, fruit girth, number of fruits per bunch, number of primary branches per plant, number of fruits per plant, fruit weight and yield per plant. The higher magnitude for g.c.a. than s.c.a. variances indicated that inheritance of these characters is predominantly governed by additive and additive × additive epistatic components of genetic variance. The strains ‘K. Kuber,’ ‘Angoorlata,’ and ‘KT,’ are good general combiners for maximum desirable traits. The parent per se performance had high relationship with their general combining ability effects. A breeding plan which may mop up the additive gene effects effectively and can maintain certain degree of heterozygosity has been suggested for maximum exploitation. Large fruit size was observed to be positively associated with locule number, fruit length, fruit girth, fruit weight & yield per plant, irrespective of fruit shape. Small fruits, irrespective of fruit shape, were observed to be associated with number of fruits per bunch, number of primary branches and number of fruits per plant.