Verma, S.S.Tripathi, Anurag2018-09-122018-09-122017-08http://krishikosh.egranth.ac.in/handle/1/5810072815The present investigation was carried out with half diallel mating design involving ten parents under two different plant densities (high plant density and optimum plant density) in kharif 2015, at N. E. Borlaug Crop Research Center, Pantnagar. Experimental material consisted of 10 parents, their 45 F1s and two checks, PSM1 and Vivek 43 were evaluated under RBD with three replications in two different plant density environment. Observations on grain yield and yield attributing traits were recorded and analyzed with analysis of variance. The analysis of variance for combining ability over two different plant density environments (OPD and HPD) indicated that mean sum of squares due to GCA was significant for all the characters in OPD and HPD environments. However, the mean sum squares due to SCA was found significant for all the characters in both the environments, except for ear diameter in OPD environment. This suggested that both additive and non additive gene action responsible for expression of traits. For all the traits ratio of variance GCA to SCA was lesser than unity that indicate the presence of non additive gene action. The GCA effects of parents in OPD, P1 for days to 50% tasselling, days to 50 % silking, ear height and in HPD P2 and P8 to be best general combiner for five traits as P2 for days to 50% tasselling, days to 50% silking, ear diameter, 100 kernel weight, grain yield and P8 for ear diameter, no of kernel rows per ear, grain yield. The promising cross combination for grain yield P1 X P10. For grain yield some promising crosses showing superiority over both mid parent and better parent. Crosses, P1 X P10, P4 X P9, P4 X P10, P5 X P7, P5 X P6, P2 X P9, P3 X P6, P3 X P8,, P4 X P10 showed high estimates of heterosis for grain yield. In the present investigation, the estimates of phenotypic coefficient of variation (PCV) were higher than that of genotypic coefficient of variation (GCV) and environmental coefficient of variation (ECV) for all the characters in both the environments. High level of broad sense heritability (h2) estimates (%) were observed for number of kernel rows/ear followed by days to 50% tasselling, days to 50% silking and plant height whereas moderate heritability estimates were recorded for anthesis- silking interval, ear length, grain yield ear height and ear length showed heritability in HPD. Molecular polymorphism indicated that average number of alleles were 7.24 per marker with a range from 4 to 10 alleles, in which, marker, K2T2 was least informative and marker, K1T5 was highest informative. The most similar parental lines were P2 and P3 (0.80) while least similar parents were P1 and P3 (0.13). Cluster diagram based on Jaccard’s similarity coefficients and UPGMA algorithm showed that major cluster B was having the nine parents while cluster A had only one parent. Clustering of parental lines indicate the presence of enough genetic diversity among the parents.ennullThesis