Proportion of cross-bred and selfed seed obtained from successive generations of winter bean (Vicia faba L.) crops

Abstract

SummaryThe proportions of cross-bred and selfed seed were estimated in up to four consecutive generations of Throws MS winter beans on three farms where farm-saved seed was regularly used.Within one stock the percentage of cross-breds rose a significant amount from 31 to 46, whilst in another stock no change was detected over four consecutive generations. On the third farm a change of stock mid-way through the period of the survey was associated with a highly significant increase in proportion of cross-breds.In general a rise in outcrossing was not followed by a significant fall as would be expected if cross-breds have a greater tendency than inbreds to self pollinate, but the possible role of a regulatory mechanism is discussed as are implications of the range in outcrossing within stocks for variety trials and commercial production of winter beans.Estimates of outcrossing frequency made in two crops in 1983 were slightly lower than some obtained in 1974–6 but no lower than those reported in 1951 thus providing no evidence of any long-term change in levels of natural cross-breeding in field beans in England.