Six population of brown sarson (Brassica campestris L.) which were complex multiple crosses in their second generation were selected on the basis of genetic, geographic and general combining ability divergence of their parents. In each population, early and late plants were selected and raised to their next generation. In the early and late progeny families, several plants were full-sibbed to produce early and late sib-populations, EE and LL. In addition, phenotypically superior (High) female plants were pollinated with mixed pollen from phenotypically superior (High) or inferior (Low) plants to produce 4 categories of intra-population crosses - Early high x Late high, Early high x Late low; Late high x Early high, Late high x Early low, EE and LL sib-populations registered significant yield advance compared to their original counterparts. But the yield advances recorded by intra-population selective mating were much higher and consistent. The extent of yield improvement was proportional to the initial genetic variability in the populations. The results suggest that disruption of mating between intermediate types even within a genetically broad-based population will be a potent method to breed for enhanced productivity
