Manifestation of heterosis and inbreeding depression in Indian mustard (Brassica juncea L.)

One of the most effective technical solutions for improving the quality and quantity of seed production as well as other yield-related parameters in the brassica variety is the heterosis breeding strategy. Ten different genotypes of Indian mustard were used in the current study to examine heterosis in the crop. These genotypes included NRCHB 101, DRMR-IJ-31, Kanti, Urvashi, Pusa mustard-25 (NPJ-112), Pusa mustard-26 (NPJ-113), Pusa mustard-27 (EJ-17), CS 54, RH 406, and RH 749. The pure lines were maintained through selfing over a number of generations. This produced 45 F1s and 45 F2s that were evaluated in a Randomized Block Design with three replications during the Rabi season of 2017–20 at the Agriculture Research Farm of School of Agricultural Sciences and Engineering, IFTM University, Moradabad (U.P.), India. These lines were crossed in a half-diallel fashion at Agriculture Research Farm of R. B. (PG) College, Agra, (U.P.), India. Quantitative character data was documented, and hybrid per se performance, heterosis, and inbreeding depression were identified. The crosses with the greatest levels of conventional heterosis and considerable negative heterobeltiosis were PM 27×RH 406, RGN-48 x Kranti, and Kanti×Urvashi. These crosses were also the first to mature. Based on the hybrid’s performance, it can be inferred that either parent’s dominant effect in expressing the trait during the F1 generation or high heterosis for the number of siliquae per plant contributed to the hybrid’s significant positive heterobeltiosis and standard heterosis for seed yield per plant, RH 406×RH 749. The lack of inbreeding depression for oil content in the hybrids resulting from the crossings NRCHB 101×DRMRIJ 31, NRCHB 101×PM-27, DRMRIJ 31×PM-27, and DRMRIJ 31×RH-749 may be caused by low heterosis and additive variance caused by the parents’ weak combining ability. These F1s may be exploited for obtaining transgressive segregants for the development of hybrid varieties in Indian mustard.