Integrating morphological and molecular diversity with heterosis and combining ability for seed yield improvement in mustard (Brassica spp.)

The 23 genotypes of mustard were evaluated for morphological genetic diversity using Mahalanobis D2 analysis reported five different clusters based of seed yield plant-1 and contributing traits. The maximum desirable inter-cluster distance observed between cluster I and IV (D2 =15.23), while the selected genotypes were grouped into five different clusters using Intron Polymorphic (IP) markers were used to assess molecular diversity among the selected genotypes, which also confirmed diversity among the genotypes. On confirming the variability among genotypes, these genotypes were intermated in line × tester mating design with 15 testers and 8 lines to study heterosis and combining ability between them. The heterosis analysis coupled with gene action revealed that seed yield exhibited high σ_SCA^2 effect. The crosses ACN-184 x DRMRMJB-35, CG-SARSON x LES-39, TAM 108-1 x RE-8, ACN-184 x RE-8 and CG-SARSON x DRMRIJ12-40 exhibited highly significant useful heterosis for seed yield plant-1 along with contributing characters. Additionally, the crosses CG-SARSON x RE-11 and NRCHB 101 x RE-11 showed superior performance over the check, possessing parents with significant variability that can be utilized in a hybridization program. The combining ability analysis indicated that among lines, CG-SARSON, ACN-184 and TAM 108-1, and among testers DRMRMJB-35, LES-39 and RE-11 were identified as good combiner parents. Among crosses, BHAWANI x DRMRMJB-35, ACN-184 x DRMRIJ-31, NRCHB 101 x LES-39, CG-SARSON x NPJ-112 and ACN-184 x RE-11 are recommended for further progression to the next generation, either through biparental mating, recurrent selection or diallel mating for further crop improvements.