Phosphate solubilization by microorganisms is an important process for increasing the bioavailability of phosphorus (P) to plants. This study aimed to: (a) in solid medium, isolate CaHPO4-solubilizing and non-P-solubilizing microorganisms from the rhizosphere of guanandi (Calophyllum brasiliensis) collected from a nursery and the field; (b) in liquid media, quantify the ability of CaHPO4-solubilizing isolates from the rhizosphere of guanandi to solubilize FePO4; and (c) quantify indoleacetic acid (IAA) production by FePO4-solubilizing rhizosphere microorganisms. Two guanandi plants, one cultivated in nursery and another from the field, were used for the isolation of FePO4 and CaHPO4-solubilizing bacteria and fungi. The largest population of P-solubilizing and non-P-solubilizing microorganisms was found in the rhizosphere of guanandi cuttings cultivated in the field. The abilities to solubilize FePO4 and produce IAA are variable among guanandi rhizosphere isolates, where bacterial isolates produce higher levels of IAA than fungal isolates.
Key words: Phosphorus, auxin, phosphate solubilization, seedlings.
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