Abstract
Cytology of three interspecific F1 hybrids in Brassica referred to in the text as Hl, H2 and H3 obtained by crossing B. napUs var. oleifera (n=19), B. campestris var. oleifera (n=10) and B. chinensis var. communis (n=10) was studied. The associations formed by the chromosomes of the genomes ‘a’ and ‘c’ were sorted out and the homologies have been assessed on the basis of their pairing at pachytene. The chromosomes of the ‘a’ genome contained in the three diploid species involved in the crosses are found to be homeologous from their complete pairing at pachytene. The affinities of the genomes ‘a’ and ‘c’ are found to be very feeble in terms of their synaptic relationships. The conclusion is arrived at by using information regarding the bivalents observed in the F1 hybrids of the present study together with those observed in amphidiploids and F1 ‘ac’ hybrids obtained by earlier workers.
