Journal of Advances in Biology & Biotechnology

Genetic variability among tomato genotypes provides a basis for evaluating traits potentially useful in breeding. The present investigation was conducted at the experimental farm of the Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj. The experiment was conducted in a randomised complete block design with 30 diverse genotypes and three replications. The mean performance of the genotypes ranged from 2.35 for mean fruit yield per plant (MFYP) to 81.94 for mean fruit per cluster (MFPC), with an overall mean of 47.18 for total yield (TY). The highest genotypic variance was recorded for average fruit weight (AFW; 7.343), followed by total yield (1.175) and days to first flowering (DFF; 0.644), whereas the lowest was observed for fruit yield per plant (FYP; 0.004). Phenotypic variance was highest for AFW (13.340) and lowest for FYP (0.015). GCV ranged from 1.023% for MFPC to 3.574% for AFW, while PCV ranged from 2.150% for MFPC to 4.817% for AFW. Broad-sense heritability ranged from 9.637% for days to first fruit set (DFFS) to 56.003% for DFF. The highest heritability was recorded for DFF (56.003%), followed by AFW (55.043%) and MFYP (43.799%). Genetic advance ranged from 0.071 for FYP to 4.141 for AFW, while genetic advance as a percentage of the mean was highest for AFW (5.462%), followed by MFYP (3.748%) and DFF (3.263%). Phenotypic correlation analysis revealed predominantly positive associations among the traits. Total yield showed significant positive associations with TSP (r = 0.4024**), AFW (r = 0.3445**), FD (r = 0.3030**), MFYP (r = 0.2873**), DFF (r = 0.2824**), FYP (r = 0.2276*), NFP (r = 0.2136*) and FL (r = 0.2078*). At the phenotypic level, TSP exhibited the highest positive direct effect on TY (0.30387), followed by AFW (0.18593), MFPC (0.11895), FD (0.11793), MFYP (0.11144) and NFP (0.10083). At the genotypic level, strong positive direct effects were recorded for NFP (2.51975), MFYP (2.26081), AFW (1.10824), FYP (0.86300) and MFPC (0.43325). The genotypic association with TY was highest for NFT (1.0666**), followed by FYP (1.0061**), TSP (0.8859**), AFW (0.7793**), FL and MFYP (0.7569**). Cluster analysis grouped the 30 genotypes into three distinct clusters. Cluster I comprised 13 genotypes (43.3%), Cluster II contained 9 genotypes (30.0%), and Cluster III consisted of 8 genotypes (26.7%), indicating considerable genetic diversity among the genotypes. Overall, DFF and AFW showed comparatively high heritability coupled with higher genetic advance, while TSP, AFW, FD, NFP and MFYP exhibited important associations and/or direct effects on total yield. These traits, together with the genetically diverse genotypes identified through cluster analysis, may therefore be effectively utilized as selection criteria and parental material in future tomato breeding programmes aimed at improving yield and associated traits.