Isolation of mutants of fast‐growing soybean strains that are effective on commercial soybean cultivars

Fast‐growing rhizobia that nodulate soybeans (Glycine max L. cvs Peking and Malayan) have been isolated. Initial inoculation of commercial cultivars of soybean with these strains results in the formation of a few pink nodules. Isoiates from these nodules form fully effective symbiosis with the soybean cultivar from which they were isolated. These results demonstrate that is is possible to isolate effective mutants of fast‐growing soybean strains by allowing the plants to select for effective mutants. These mutants are potentially valuable because, if their symbiotic properties can be improved, they could possibly be used as commercial soybean inoculants.