Pant, UshaAdhikari, Sneha2018-04-192018-04-192016-06http://krishikosh.egranth.ac.in/handle/1/5810044053The present investigation was carried out with the aim to study selection parameters, combining ability, extent of heterosis for various quantitative characters in Brassica juncea (L.) Czern & Coss. The experimental material for present study comprised of a set of 10 genotypes of Indian mustard (Brassica juncea L.) of diverse origin involving two genotypes suitable for early sown (PRE-2011-15, PM-2), six for timely sown (Divya-55, Maya, DRMR-675-39, RRN-778, RB-57 and RMM-09-4 ) and two for late sown (PRL-2012-13, NRC-HB-101) situations. Crosses were made between these genotypes in all possible combinations excluding reciprocals during rabi 2014-15. The parents and their 45 F1‟s along with one standard variety (Kranti) were evaluated in a randomized block design with three replications during rabi 2015-16 at N. E. B. C. R. C., GBPUA& T, Pantnagar. The combining ability analysis was performed by following Griffing‟s (1956) method 2, model I. Results of ANOVA showed that the mean squares due to gca and sca were highly significant for all the characters. The magnitude of later being higher than former except for length of main raceme, seed yield per plant and glucosinolate content indicating predominance of non-additive gene action for the expression of the all the characters whereas, additive gene action was predominant for length of main raceme, seed yield per plant and glucosinolate content. The broad sense heritability h2b was high (>0.50) for glucosinolate content followed by seed yield/ plant, number of siliquae on main raceme, days to maturity, number of secondary branches/plant, number of primary branches/plant, siliqua density on main raceme, oil content and test weight and, medium (0.25 to 0.50 ) for rest of the characters. Genetic advance (GA) ranged from 0.043 for siliqua density to 4.929 for plant height. Higher heritability was associated with higher genetic advance under selection for glucosinolate content, seed yield/ plant (g) , number of siliquae on main raceme, number of secondary branches/plant and days to maturity. Predictability ratio was lower than unity for all the character under study, it represented the involvement of non-fixable type of variance so in such characters the heterosis breeding appears to be the best option. Average degree of dominance showed over dominance for all the character under study The estimates of 2s were found to be higher than the 2g for all characters. The estimates of 2 A and 2D indicated that the magnitude of later was higher than farmers indicating the presence of non-fixable type of gene action. The narrow sense heritability h2n was medium (0.30-0.10) for seed yield/ plant, length of main raceme, glucosinolate content, test weight, oil content, days to maturity, number of primary branches/plant, length of siliqua and number of siliquae on main raceme and low (<0.10) for remaining characters. Moderate to low h2n was due to low estimate of additive genetic variance. Based on significant GCA effects in desirable direction, the parents PM-25(-3.04**) for early maturity; Maya (- 7.25**) for dwarf plant height; PRL-2012-13 (1.703**) for seed yield per plant; RRN-778 (1.007**), for oil content and Divya-55 (-32.604**) for low glucosinolate content were found the best parents for respective traits. The study revealed that crosses PRL-2012-13×Divya-55 (-19.33**) for early maturity; RRN-778×PM-25 (-33.11**) for dwarf plant height; Divya-55×RRN-778 (4.14**), for seed yield, PRE-2011-15×RMM-09-4 (3.82**) for oil content and RRN-778×RMM-09-4 (-69.01**) for low glucosinolate content were the most outstanding crosses based on SCA effects. The evaluation of heterosis revealed that heterotic combinations RRN-778×Maya (-5.660*), RRN-778×Maya (7.41**), RB-57×Maya (-20.741**) for early maturity; Maya×RMM-09-4 (24.48**), RB-57×PM-25 (43.64**) and PRL2012-13xDRMR-675-39 (142.57**) for seed yield, PRL-2012-13×RRN-778 (3.22**), PRL-2012-13×RRN-778 (3.58**), DRMR-675-39×Maya (6.28**) for oil content showed maximum relative, better and economic heterosis respectively. Overall results indicated the advantage of heterozygosity perhaps due to predominance of non-additive gene effects. Promising parents have been identified based on GCA effects for different characters and outstanding crosses were identified based on SCA effects as well as expression of heterosis.ennullThesis