Sangwan, R.S.Lingaraja L.2017-10-042017-10-042017http://krishikosh.egranth.ac.in/handle/1/5810032236The present investigation was carried out with the aim to estimate the heterosis, combining ability and molecular diversity. The GCA of the parents and SCA of hybrids considered for the development of high yielding and better quality cultivars. 19 parents and 60 F1 hybrids obtained by crossing 15 lines and 4 testers in line x tester mating design during kharif 2014. These materials were sown in randomized block design in kharif 2015 at Cotton Research area, Department of Genetics and Plant Breeding, CCS HAU, Hisar, India. Combining ability analysis indicated that both additive and non-additive gene effects were important in the inheritance of all the traits. The studies on GCA of parents revealed that the lines H1442 was a good general combiner for seed cotton yield, number of bolls per plant, boll weight, number of monopodia per plant, plant height, 2.5% span length and fibre strength. Among the testers, H1098-i was a good general combiner for seed cotton yield, number of bolls per plant and boll weight, number of seeds/boll, 2.5% span length, fibre strength and micronaire value. The crosses RS875 x H1098-i, H1316 x H1236 and LH2306 X H1098-i exhibited positive significant SCA effects for number of bolls per plant, boll weight and seed cotton yield per plant. The heterosis revealed that the better performing hybrids, H1316 X H1236, H1442 X H1226 and H1316 X H1098-i for seed cotton yield and its components traits like number of bolls, boll weight, number of monopods. So these crosses could be exploited to improve the yield along with one or more yield contributing traits through heterosis breeding. The Diversity analysis revealed that among parents was estimated through molecular approach. The 19 parents altogether shared 57% similarity on the basis of simple matching coefficient. Among parents H1226 was the most diverse followed by H1200, H1117 and RS875. maximum similarity coefficient of 0.93 was observed between H1442 and H1442-1 which indicated these genotypes derived from same parent.ennullThesis