Published b ~ Elsevier

ity) is not a measure of inter-strain competitive-ness, and Rhizobium strains used as inocula fre-quently compete poorly with indigenous rhizobia for nodulation of the host legume. Competition between rhizobia delimits the use of Rhizobium inoculum in agriculture. We therefore chose to investigate aspects of the gene pool represented by an indigenous population of R. meliloti selected for maximum diversity, particularly for evidence of competitive dominance. This unadapted popu-lation was very heterogeneous in terms of plasmid content, somatic antigens and intrinsic antibiotic resistance (IAR). Little tendency towards competi-tive dominance (measured in terms of nodule oc-cupancy) was observed. Classical methods (sero