Solubilization of insoluble phosphates by some soil fungi isolated from nursery seedbeds

Phosphate (tricalcium phosphate, hydroxyapatite, and fluorapatite) solubilizing potential of several fungi, commonly encountered in forest tree seedbeds, was evaluated in vitro. Of the several fungi tested, Aspergillus niger, Aspergillus flavus, Fusarium oxysporum, Sclerotium rolfsii, Cylindrocladium sp., and Penicillium sp. showed significant solubilization of all three phosphatic compounds tested. Damping-off fungi, viz. species of Pythium and Rhizoctonia, failed to degrade any of the phosphatic compounds tested. Conversely, the antagonists of these fungi used most of the phosphate compounds and sporulated abundantly.Data from the present study support the hypothesis that liberation of organic acids in the culture media helps solubilize phosphates.