INTEGRATED MORPHO-MOLECULAR AND GENETIC DISSECTION REVEALS NITROGEN-EFFICIENT PARENTAL LINES AND SUPERIOR HYBRIDS FOR SUSTAINABLE IMPROVEMENT OF INDIAN MUSTARD (BRASSICA JUNCEA L.)

Abstract

Aims: To evaluate genetic variability for NUE and yield traits under controlled N-levels (N0 and N40) followed by morpho molecular diversity in Indian mustard; selection of superior genotypes for hybridisation; to identify superior N-efficient parental lines and high-yielding hybrid combinations Methods: experiment conducted at Assam Agricultural University, Jorhat, during Rabi seasons (2021-22 to 2023-24). Evaluated 44 genotypes in a pot trial under two N-doses (0 and 40 kg N ha-1) using a completely randomized design (CRD). Mahalanobis D2 and SSR study revealed genetic diversity among the genotypes. Line × Tester design involved eight superior lines and three testers; field Evaluation of 24 hybrids hybrids and parents under recommended N levels (N40) using a randomized complete block design (RCBD). Results: ANOVA revealed significant differences for most traits; high heritability and GAM for NUE and yield was recorded. PIC revealed all markers were highly informative (0.63 to 0.95). ANOVA (LXT) revealed significant genotypic differences for most traits; Kranti, RRE 2012/14, PM25, and NRCHB101 emerged as superior combiners while superior hybrids with strong positive specific combining ability were Kranti × TM2, Kranti × PM25, Kranti × NRCHB-101, RRE2012/14 × PM25, RRE2012/14 × NRCHB-101, and JM13-4 × PM25. RRE2012/14 x PM25 and Kranti x NRCHB 101 revealed considerable positive specific combining ability and standard heterosis of up to 104% and 8.3%, respectively, over the check variety NRCHB-101 for seed production hectare-1. Conclusions: The study successfully identified genetically diverse, N-efficient parents and high-yielding hybrids. These genotypes provide valuable genetic resources for sustainable Indian mustard breeding programs.