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In the present study, line× tester analysis was carried out at Castor-Mustard Research Station, S. D. Agricultural University, Sardarkrushinagar, Gujarat, India during rabi 2018–19 (October 2018 to February 2019) in order to estimate all three types of heterosis (relative heterosis, heterobeltiosis and economic heterosis) for identification of superior cross combinations of Indian mustard [Brassica juncea (L.) Czern&Coss]. Thirty-five hybrids along with five CMS lines, seven testers and check GDM 4 were evaluated for ten different traits. The F1 generation of all the crosses exhibited fertility restoration with pollen fertility except F1 crosses with Vardan, Rohini and SKM 319 fertile line (0%). The remaining crosses exhibited pollen fertility ranging from 68.26% (Kranti×SKM 303) to 85.17% (Kranti×Mori ‘R’ 1-18). The analysis of variance for parents, hybrids and parents vs. hybrids revealed that mean sum of squares of parents were highly significant for majority of the characters except days to maturity. Whereas, hybrids differed highly significant for all the characters. Comparison of mean squares due to parents vs. hybrids was found significant for almost all the characters except number of seeds siliqua-1 and oil content. This indicates that considerable amount of genetic variability present among the parents and hybrids for all the characters studied. On the basis of per se performance, three hybrids viz., Kranti×Mori ‘R’ 1-18, SKM 9928×PusaAgrani and SKM 9928×Mori ‘R’ 1-18 were foundpromising for seed yield plant-1 over the standard check GDM 4.With respect to heterosis, one of the hybrid Kranti×Mori ‘R’ 1-18 (17.85 %)manifested significant and positive standard heterosis for seed yield plant-1.

The phenomenon of heterosis has provided the most important genetic tools in improving yield of crop plants. Identification of specific parental combination capable of producing the highest level of heterotic effects in F1 has immense value for commercial exploitation of heterosis. The experimental material consisted of eight parents (including check G.TIL 4) and their 28 half-diallel crosses. The analysis of variance revealed highly significant differences due to genotypes for all the traits. On the basis of mean values, the parents G.TIL 10, G.TIL 4 and SKT 1607 recorded maximum seed yield per plant. G.TIL 10 was top ranking for number of effective branches per plant. This parental genotype also expressed good performance for various yield components, viz., number of seed per capsule, harvest index (%) and oil content (%).The parent SKT 1608 found better for earliness, dwarfness and 1000 seed weight (g). While in case of hybrids, SKT 1608 × SKT 12-2, SKT 1608 × G.TIL 2 and SKT 1607 × G.TIL 2 were the best for seed yield per plant. Among the 28 F1 hybrids, SKT 1608 × SKT 12-2 and SKT 1608 × G.TIL 2 manifested significant positive heterosis for seed yield per plant over better parent and standard check (G.TIL 4) These two crosses also exhibited either of the significant positive heterosis for various component traits viz., plant height (cm), capsule length (cm), number of seed per capsule, harvest index (%), 1000 seed weight (g), oil content (%) and leaf area per plant (cm2).

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