The other major plant-breeding option has centred on the promiscuity of nodulation of the soybean cultivars. Two methods have emerged: (i) to breed for highly promiscuous lines that nodulate with rhizobia naturally present in the soil; and (ii) to breed for lines with limited nodulation ability that will select for better-quality soil rhizobia or may be artificially inoculated with matched efficient rhizobia that can overcome their non-nodulation phenotype.

Residual benefits of promiscuous soybean to maize (Zea mays L.) grown on farmers’ fields around Minna in the southern Guinea savanna zone of Nigeria.