Comparative analysis of genetic diversity and its relation to heterosis in early and mid-maturity Indian cauliflower (Brassica oleracea var. botrytis L.)

Abstract

An experiment involving self-incompatible line based 80 F1 hybrids in early and 54 F1 hybrids in mid-maturity groups derived from line × tester design were studied with an aim of relating genetic divergence among the parents with the magnitude of heterosis in the F1 generations and to identify suitable hybrids. The significant improvements in mean of the hybrids were observed over the parents for all the traits in both maturity groups. Mean performance of all growth and yield contributing traits of parents and hybrids were higher in mid-maturity group over early maturity. Based on cluster analysis in early maturity group six (cc-13, cc-14, 14-4-17, 351aa, Pusa Deepali and SL-7) out of eighteen inbred lines were least diverse. Line vv of cluster VI was found most diverse from the lines xx-2-6, cc-32E and cc-12 of cluster VII with inter-cluster distance of 3.88. However, in mid-maturity group the most diverse lines were ccm-8 (II) and Palam Uphar (VI) with inter-cluster distance of 5.48. The combination of heterosis and diversity analysis indicated the higher fre quency and magnitude of heterosis of hybrids derived from the parental divergence class DC3 in early maturity and DC2 in mid-maturity group suggesting moderate genetic diversity is most desirable to produce highly heterotic hybrids in Indian cauliflower. The correlation between genetic distance and the level of mid-parent heterosis was not reliable for all the quantitative traits in both early and mid-maturity group of the cauliflower. Identified hybrids 395aa x Pusa Deepali and cc-32E × 23000 in early maturity and cc-22 × Sarju Maghi and cc-22 × Palam Uphar of mid-maturity group having higher magnitude of heterosis for maximum number of desirable traits may be selected for further evaluation and commercialization.