Outcrossing Rates of Six Common Bean Lines

The outcrossing rate of a species is an important parameter to consider when making a decision on the method to improve the species. Outcrossing rates were estimated for six white‐seeded common bean (Phaseolus vulgarisL.) lines sown in May and July 1985, at Irvine, CA. Estimates were based upon the proportion of black‐seeded (dominant) progeny from white‐seeded parents. Genetic variation for outcrossing rates among the six lines studied was suggested by the large difference between the mean estimate for ‘FM 53’ (66.8%) and the combined mean estimate for the other five lines (19.3%). Outcrosses occurred less frequently at the early planting date (18.8%) than at the late‐planting date (47.0%). Further studies on the outcrossing in the common bean and its application to recurrent selection are warranted in light of the reported results.