Single and three-way crosses for generating composite populations in rapeseed

Two unconventional systems of mating using inter- and intra-line variability generated by disruptive and directional selection were examined in Brassica campestris var. brown sarson in the context of breeding high yielding composite populations. Single crosses obtained by mating lines derived from disruptive with those from directional selection, and three-way crosses, using intra-line hybrids of disruptive selection as females with elite varieties as males, provided potential initial gene pools for generating composites, some of which were superior to checks and are being tested at national level. Parents were classified as high (H) and low (L) general combiners over a number of yield components. H × L and self-incompatible × self-compatible single crosses provided high frequency of heterotic crosses. Besides genetic divergence, compatibility divergence added another dimension for realising heterosis. Heterotic crosses with high specific combining ability were identified to be useful to constitute initial gene pools foi generating productive composite populations.