Abstract
Three experiments were conducted at the research farm of Energypac Agro Ltd. located in Gazipur, Bangladesh from Rabi 2011-12 to Rabi 2013-14 with a view to selecting superior parental lines for heterotic hybrid in tomato. Experiment conducted for diversity analysis on seventy germplasm to identify parental genotypes. Analyses of variance showed the presence of significant variation among the tested genotypes in respect to yield and yield contributing traits. Clustering pattern indicates that there was no association between geographical distribution of genotypes and genetic divergence. Genotypes were grouped into five clusters based on D2 values and cluster II was the biggest with 23 genotypes. The maximum inter cluster distance was recorded between cluster III and cluster V was 8.34 whereas maximum (0.061) intra cluster distance was recorded in cluster I. Characters like fruits per plant, pericarp thickness, days to 50% flowering and locule number per fruit are important to genetic divergence. Considering the magnitude of genetic distance, contribution of characters to the divergence, magnitude of cluster mean and per se performances, 20 parents were selected. Among these five were male parents including TM 409, TM 386, TM 528, TM 403 and TM 349 from cluster I & III, and 15 female parents from cluster II, IV & V including TM 356, TM 361, TM 368, TM 371, TM 377, TM 384, TM 422, TM 423 TMM 388, TM 390, TM 392 and TM 410, TM 382, TM 419, TM 360 were selected for hybridization program as line x tester analysis. The overall findings showed that both additive and non-additive gene action were predominant in the studied traits, but most of the traits were under control of non-additive gene action. The prevalence of non-additive gene action implies that all the characters could be improved through heterosis breeding. By analysis of combining ability lines TM 384, TM 410, TM 360 and TM 390 were selected as good general combiner for fruits per plant, days to flowering, plant height, fruit weight and fruit yield per plant. Tester TM 409 and TM 403 were found best general combiner for fruit weight, fruit length, fruit diameter and fruit yield per plant and TM 386 for fruits per plant. The hybrids TM 360/TM 528 followed by TM 356/TM 409, TM 410/TM 528 were the best specific combiners for fruit yield per plant. Hybrids TM 422/TM 403, TM 410/TM 386, TM 356/TM 528 and TM 371/TM 386 were considered as the best specific combiner for earliness. On the basis of per se performance, heterosis, GCA and SCA effects the crosses 384/TM 386 and TM 392/TM 386 could be selected as heteroric hybrid for higher yield. In case of tomato fruit quality traits line TM 382 was found best general combiner for fruit pH and beta carotene. The crosses TM 382/TM 386 and TM 388/TM 386 appear to be the most suitable for exploiting high beta carotene content. Two hybrids TM 388/TM 349 and TM 361/TM 403 were showed desirable heterobeltiosis for lycopene content.