Male sterility in field beans (Vicia faba L.). III. Male sterility with a cytoplasmic type of inheritance

1. Male-sterile plants were discovered in the progeny of an open-pollinated plant which had undergone a much higher level of natural crossing than any of a group of fifty plants drawn from the same population. 2. Some male-sterile plants produced a few viable pollen grains under some conditions but these rarely permitted self-fertilization. A few plants had both sterile and fertile tillers. Male sterility was not transferred by grafting. No effect on the proportion of fertile plants could be found, when progenies were observed early and late in the season, sown in the autumn and spring or grown at contrasting plant densities. 3. Inbred lines, unrelated to the male-sterile plants and their derivatives, varied greatly in their ability to restore male fertility. Some lines maintained the sterility almost completely, two consistently gave all male-fertile offspring, but the majority were partial restorers.