Efficiency of some fungal species in phosphate solubilization and potassium and iron release from phlogopite and muscovite

Using efficient microorganisms can be beneficial for providing essential elements of phosphorus (P), potassium (K) and iron (Fe) to plants. In this study, the ability of some fungal species including Trichoderma asperellum, T. atroviride, T. brevicompactum, T. citrinoviride, T. harzianum, T. koningii, T. viridescens, Alternaria sp. and Aspergillus niger to release of these elements from insoluble minerals was evaluated. For this, the fungal species were added to Aleksandrov medium including tricalcium phosphate (P source) and muscovite or phlogopite (K and Fe source) and were incubated for 10-days under optimum conditions. The results showed that fungal species were able to release K from phlogopite by 103-389% and from muscovite by 21.5-178% compared to control. Among fungal species, the highest and lowest K release was observed by Aspergillus niger and T. koningii from phlogopite and by T. atroviride from muscovite, respectively. Also, the highest and lowest amount of soluble Fe was observed in medium with T. citrinoviride and Aspergillus niger in the presence of phlogopite and with T. atroviride in the presence of muscovite, respectively. The highest increase in soluble P was observed by Aspergillus niger (in the presence of both minerals), Alternaria sp., T. citrinoviride, T. coningii and T.viridescens in the presence of phlogopite compared to the control. Fungal species increased the electrical conductivity, indicating the release of elements from insoluble sources by the fungi species. There was also a significant negative relationship between P, K and Fe with pH, indicating that fungal species may have been able to release elements from the insoluble sources by producing organic and inorganic acids. In general, the fungal species have the ability to dissolve tricalcium phosphate and release more K and Fe from phlogopite than muscovite under in-vitro conditions. Thus, application of these microorganisms can be promising to provide the essential elements of plants.