Inorganic phosphate solubilization by two Penicillium species in solution culture and soil

Abstract

Two fungal isolates, Penicillium bilaji and Penicillium cf. fuscum were found to solubilize different amounts of rock phosphate in liquid culture. Inorganic P solubilization was directly related to the pH drop generated by each isolate. Nitrogen in the ammonium form in the medium was necessary for increased P solubilization by P. bilaji. Penicillium isolates and the form of nitrogen affected the duration of the lag before each isolate began to solubilize P, the rate at which inorganic P was solubilized and the net amount of P solubilized and maintained in solution. In a greenhouse experiment, wheat, Triticum aestivum L. cv. Neepawa, was grown in a calcareous Chernozemic soil which had low available P. When this soil was inoculated with P. bilaji, plant dry matter yield increased by 16%, and total plant P uptake by 14%. P. bilaji also increased the proportion of P derived from native P sources by 11% even in the presence of added rock phosphate.