Nodulation of Legumes in the Sudan: Cross-Inoculation Groups and the Associated Rhizobium Strains

Summary Cross-inoculation tests, based on nodule formation and nitrogen fixation, were made on 21 species of legumes commonly found in the Sudan. The results showed that they may be grouped according to the accepted system of classification, but there were some important inconsistencies in the cowpea group. For instance,Arachis hypogaeaandAcacia spp.have their own strains of Rhizobium. The cultural and physiological characters of the rhizobia studied were generally similar to those known for other species of the organisms.