Uptake of phosphate and promotion of vegetative growth in glucose-exuding rice plants (Oryza sativa) inoculated with plant growth-promoting bacteria

Abstract

We measured phosphorus uptake by rice plants inoculated with plant growth-promoting bacteria (PGPB) using Pseudomonas sp. strain PAC, Serratia sp. strain CMR165, and Azospirillum brasilense strain FT326. We measured plant growth parameters and phosphate solubilization and uptake. Results show that the ability to solubilize phosphates varied among PGPB strains. Strain FT326 was unable to solubilize phosphates. In the presence of glucose, PAC and CMR165 can solubilize inorganic tricalcium phosphate and organic calcium magnesium inositol hexaphosphate. Phosphate solubilization by strains PAC and CMR165 was different over time; FT326 was similar to the untreated control. Plants inoculated with PAC or CMR165 had higher concentrations of phosphates than those inoculated with FT326 and plants that were not inoculated. Glucose was the only sugar identified in rice root exudates. PAC and CMR165 promoted plant growth and uptake of phosphate and could be used as biofertilizers to optimize phosphate fertilization.