TRIFOLIUM AMBIGUUM AS A SOURCE OF VARIATION IN THE BREEDING OF WHITE CLOVER

Hybrids between T. ambiguum and T. repens were successfully establishe d after ovule culture. The hybrids were male sterile but one of the hy brids produced a single seed when backcrossed to T. repens, while the other produced a significantly greater number of seeds. The majority o f the backcross hybrids from the latter had 48 chromosomes, being prod uced from the fertilisation of unreduced gametes of the F1 hybrid by T . repens pollen. Regular meiosis in the BC1 hybrid resulted in the pro duction of balanced gametes containing the full complement of T. repen s chromosomes and the polyhaploid set of T. ambiguum chromosomes. Ther e was no difficulty in establishing a substantial population of BC2 hy brids. The meiotic behaviour of the BC1 hybrid indicated that it shoul d be possible to transfer genes from T. ambiguum into white clover T. repens. The significance of the results in terms of the use of alien v ariation in the improvement of white clover is discussed.