Cultivar and Bradyrhizobium japonicum Strain Effects on the Performance of Promiscuously Nodulating Soyabeans (Glycine max(L.) Merr.) in the Nigerian Savanna

Abstract

ABSTRACT Field experiments were conducted on a leached ferruginous tropical soil (Haplustalf) in the Nigerian savanna to study the effects of inoculation with four different strains of Bradyrhizobium japonicum on the agronomic performance of five promiscuously nodulating soyabean cultivars during the 1985 and 1986 wet seasons. Nodulation was significantly increased by the Bradyrhizobium strains except IRj 2123. Inoculation had no effect on shoot dry matter yield and N content. At one of the two sites used in 1985, seed yields of inoculated treatments except strain IRj 2123 were significantly higher than the uninoculated control, and their yields were equivalent to that obtained from uninoculated plots which received 100 kg N ha−1. At the other site, only strains IRj 2114 and IRj 2133 gave higher seed yields than the uninoculated control. In 1986, although all inoculants except IRj 2123 improved yield over the control, the differences were not significant. Seed N was increased by strain IRj 2114. It is concluded that promiscuously nodulating soyabeans grown in Nigeria can benefit from inoculation with effective and adapted Bradyrhizobium japonicum strains such as IRj 2133 and IRj 2144, especially on soils having low populations of indigenous rhizobia.