Prediction of heterosis based on genetic divergence in tomato

Tomato germplasm collected from different sources and lines developed through pedigree method of breeding were assessed and based on Mahalanobis D² analysis totally 67 genotypes were grouped in to 7 clusters where, maximum of 44 genotypes entered in cluster I, followed by 11 genotypes in cluster II, 7 genotypes in cluster IV, two genotypes in cluster III and the clusters V, VI and VII had solitary genotype each. Totally 14 lines and 2 testers representing three clusters were selected and crossed to get 28 hybrids. After evaluating the hybrids and parents, D² values of respective crosses (d² values between parents of the cross) were correlated with heterosis values for various traits. Heterosis over better parent was positively and significantly associated with D² values for only β-carotene (r_p = 0.4404) and ascorbic acid (r_p = -0.438) content of fruit. Heterosis over the best parent was significantly correlated with D² values (Table 2) for number of primary branches at 30 DAT (r_p = 0.4548), days to first (r_p= -0.4293) and days to fifty per cent flowering (r_p= -0.4652), days to first fruit maturity (r_p= -0.3878), polar (r_p= -0.4794) and equatorial (r_p= -0.5990) diameter of the fruit, number of fruits per plant (r_p= -0.5156) and average fruit weight (r_p = -0.5690) indicating the possibility of prediction of heterosis based on D² values and D² values can be useful in at least rejection of inferior combinations in tomato.