Abstract
Nitrogen fixation studies were made on genge-, Sesbania- and Mimosa- group to determine whether there exits any difference in the effectiveness to host among the classified strains of rhizobia in each group, respectively. The result on Sesbania shows that some differences may be found botween types A and B of Sesbania bacteria, though both are effective to host. The meaning of classification of rhizobial strains is also recognized in the results on Mimosa and Leucaena. The type E of cowpea bacteria which showed no effective association with three hosts of cowpea group is markedly effective to Mimosa. The result that the strain from Dalea is effective to Leucaena in summer, while ineffective in autumn, seems to suggest that whether or not the association between macro-and micro-symbiont is effective may be influenced by the environmental condition.
