Microspore culture of swede (Brassica napus ssp. rapifera) and the effects of fresh and conditioned media.

Microspore culture was successfully carried out with four cultivars of swede (Brassica napus ssp. rapifera). Embryo yields increased markedly if the culture medium was replaced by fresh medium after a culture period of three days, with more than 200% increase with the highly responding cultivar Gry and more than 800% with the poorly responding cultivar Stenhaug. If the medium was changed at a later time, embryo production declined sharply. Transfer of microspores after 3 days of culture to a medium in which microspores of a different cultivar had been cultured for 3 days had no effect on embryogenesis. Bud size had a large effect on embryo production, particularly with the least responsive cultivar, Stenhaug.