Inoculation with Pseudomonas fluorescens biocontrol strains does not affect the symbiosis between rhizobia and forage legumes

Pseudomonas fluorescens strains UP61, UP143 and UP148, isolated from Uruguayan soils, have shown the ability to control soil-borne fungal pathogens that cause damping-off in birdsfoot trefoil. In this communication, we study the effect of these strains on the symbiotic efficiency of rhizobia from commercial inoculants in birdsfoot trefoil, alfalfa and white clover. Shoot dry weights and the rate of nodulation by rhizobia were not modified by the presence of Pseudomonas strains, despite antagonistic activity against rhizobia in vitro. Survival of P. fluorescens UP61 and rhizobia on roots in non-sterile soil were not affected by co-inoculation of the selected forage legumes.