Growth, nutrient uptake and symbiosis with rhizobia and arbuscular mycorrhizal fungi in Lotus tenuis plants fertilized with different phosphate sources and inoculated with the phosphate-solubilizing bacterium Pantoea eucalypti M91

Background and aims The aim of this work was to evaluate the ability of P fertilization and phosphate-solubilizing bacteria (PSB) inoculation to promote the growth of L. tenuis in typical soils of the Salado River Basin (Argentina) with low P availability. Methods Aboveground biomass and P and N levels were evaluated in field-grown L. tenuis plants inoculated with Pantoea eucalypti M91, either without fertilization or in combination with phosphate rock and triple superphosphate (TSP). The impact of P fertilization and inoculation on the symbiotic interactions between L. tenuis and native rhizobia bacteria and arbuscular mycorrhizal fungi was also evaluated. Results Inoculation with M91 increased the L. tenuis biomass production and P concentration in shoots, at an early stage of plant growth. The combined treatment of inoculation with M91 and TSP significantly increased the P and N content in shoots compared to non-inoculated plants, fertilized or not. P. eucalypti M91 was found to endophytically colonize roots and leaves of L. tenuis plants grown in vitro and also under field conditions. Conclusions The results suggesting that inoculation of L. tenuis with the PSB such as P. eucalypti M91 strain might allow more efficient use of N and P and a more sustainable option for grasslands producers from the Salado River Basin, in order to reduce costs and avoid increased levels of P insoluble in soils.