Phosphate solubilizing microorganisms play an important role in supplying phosphorous to plants. This ability has stimulated research on plant inoculation. In our study, microorganisms were isolated from Pinus and Eucalyptus plantations and selected in culture medium. They were then employed in a series of 28 experiments under greenhouse conditions in substrate, forest or sterilized nursery soil, with or without phosphate fertilization, in one of the following P forms: calcium phosphate, Araxá, or Catalão phosphate. Three isolates promoted a higher dry matter production (isolates 177, 251 and 310A) in one of the experiments. However, in another experiment the isolates 177 and 261 had a negative effect on this parameter. The inoculation of 8 isolates (62, 177, 198, 251, 262, 310A and 310B) in seven of the experiments increased the P concentration in plant tissues. In two experiments, the isolates 177 and 198 presented a negative effect. Phosphorous uptake was increased by the isolates 62, 189, 198, 251 and 310A, in four experiments. Results on P nutrition and growth obtained with the isolates 62, 189, 251 and 310A indicate that these isolates possess a potential well worth of being applied in further inoculation programs aiming at inoculum production.
fertilization; biofertilizer; inoculant; phosphorus