Vol. 9, Special Issue 12, Part V (2025)

Combining ability analysis, primarily conducted through designs like the diallel cross, provides a genetic blueprint by elucidating the nature and magnitude of gene action involved in economically important traits in tomato. Significant GCA effects were found for each of the 22 traits, including yield, fruit weight, and shelf life, in the current 16 × 16 half-diallel cross population. The study also showed that no parent behaved as a good general combiner for all characters at a time. But there were parents with high GCA for specific traits: IIHR-2327-1 was found to be an excellent general combiner for yield per plant (0.933) and average fruit weight (37.166), whereas Pusa Early Dwarf was outstanding for earliness attributes like no of days taken to 50% flowering and fruit ripening. Genotypes IIHR-2957 for shelf life and TSS were also the superior parents, along with Arka Ashish for pulp recovery. The results of the present study revealed that the extent of SCA variance was greater than GCA variance for all the characters under study, indicating that non-additive gene action played a predominant role in the expression of yield and quality components. Some of the promising hybrids with high SCA effects were IIHR-2327-1 x IIHR-2955 for yield per plant (2.479), IIHR-2847 x IIHR-Sel 19 for shelf life (14.534) and Pusa Early Dwarf x Arka Ashish for earliness and fruit firmness. The non-additive traits need to be exploited/bred through heterosis breeding or selection in subsequent segregating generations in order to realize an economically significant improvement. The findings of this study indicate that while parental lines such as IIHR-2327-1 and IIHR-Sel. 41-1 are effective for improving morphological traits in general, the development of specialized F1 hybrids remains the most effective strategy for optimizing tomato productivity and processing quality.