Development of dwarf B. carinata genotype employing inter-specific hybridization between B. juncea and B. carinata and cyto-morphological studies for patterns of variation

Abstract

Successful inter-speciûc hybrid plants were obtained through sexual hybridization between Brassica juncea cv. NRCDR2 (2n=4x=36, AABB), and B. carinata, NRCKR-304 (2n=4x=34, BBCC) using the latter as a pollen parent. Morphological and cytological analyses were carried out to conûrm the hybrid nature of F1 plants. The F1 plants (2n=35) were intermediate for most of the morphological attributes. Although, the F1s showed poor pollen fertility, nevertheless, few seeds were obtained from open pollination. Meiotic analysis of F1 plants showed a predominance of univalents, a typical feature of wide hybrids. The occurrence of chromosome association ranging from bivalents (0–16), trivalent (0–1) and quadrivalent (0–1) in the F1s indicated homeologous pairing between the AB and BC genomes.  The study suggests that B. carinata has partial genome homeology with B. juncea. Patterns of variations in F2 progenies of the cross were estimated. In the F2 generation, more number of plants resembling B. juncea was observed indicating transgressive segregation. Present study also indicated that inter-speciûc hybridization in Brassica could be a potential source for generating variability besides broadening the genetic base and segregants with desirable agro-economical characteristics were selected for further advancement and evaluation.