Prediction of heterosis based on genetic divergence in tomato

Abstract

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 (rp = 0.4404) and ascorbic acid (rp = -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 (rp = 0.4548), days to first (rp = -0.4293) and days to fifty per cent flowering (rp = -0.4652), days to first fruit maturity (rp = -0.3878), polar (rp = -0.4794) and equatorial (rp = -0.5990) diameter of the fruit, number of fruits per plant (rp = -0.5156) and average fruit weight (rp = -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.