| Soybean genotypes grown in Africa are presumed to nodulate effectively with indigenous Bradyrhizobium spp. populations. Many soybean growing fields, however, reveal the inadequacy of biological nitrogen fixation to support high soybean yields indicating the need to provide other management options. The sizes, nodulation and N;Bradyrhizobium sp. (TGx), and B. japonicum populations were detected in 72% and 37% of the soil samples, respectively. Bradyrhizobium sp. (TGx) populations were generally low, and significantly less than the total bradyrhizobia populations in 57% of the samples. Populations sizes of less than 10 cells g;On the basis of 16S rDNA-RFLP, many of the Bradyrhizobium sp. (TGx) strains were phylogenetically related to Bradyrhizobium spp. while only a few were closely related to B. japonicum. Similar relationships were identified based on randomly amplified polymorphic DNA, intrinsic antibiotic resistance patterns, and the genomic arrangement of nod and nifDH gene sequences. The sizes and N... |
