Competitive interaction among strains ofRhizobium leguminosarumbv.phaseoliin the nodulation of kidney beans (Phaseolus vulgarisL.)

摘要

We examined the competitiveness of five effectiveRhizobium leguminosarumbiovarphaseolistrains in the nodulation of kidney beans (Phaseolus vulgarisL.), either alone or in pairwise combination, against the indigenous strains. The results showed that the introducedRhizobiumsp. strains (B2, B17, B36, T2, or CIAT 652) occupying 64–79 of the total nodules (as single inocula) were more competitive in nodulation than the native rhizobia. However, the competitiveness of the individualRhizobium sp.strain either increased or decreased when used in a pairwise combination of double-strain inocula. For example, strain B17, although quite competitive against the indigenous population (68 nodule occupancy), became poorly competitive in the presence of strain B2 (reduced from 68 to 2.5). A similar reduction in nodule occupancy by strain B17 was observed in the presence of B36 or CIAT 652, indicating that two competitive strains may not always be compatible. These results suggest that it is important to co-select competitive as well as compatible rhizobia for multistrain inoculant formulatio