EFFECT OF Penicillium bilaji ON THE SOLUBILITY AND UPTAKE OF P AND MICRONUTRIENTS FROM SOIL BY WHEAT

Abstract

Penicillium bilaji has previously been shown to increase wheat growth and P uptake by solubilizing phosphates under soil conditions. Laboratory experiments were conducted to determine if P. bilaji was able to solubilize inorganic compounds of copper, iron and zinc. Greenhouse and field experiments were also conducted to determine if P. bilaji had an effect on uptake of copper, iron and zinc by wheat. Under pure culture conditions, P. bilaji was able to solubilize cuprous and cupric oxide, cupric carbonate and zinc metal and, to a lesser extent, ferrous and ferric oxides and pyrite. The soil studies showed increased wheat dry matter production and seed and P yields in response to P. bilaji inoculation, which was related to increased incidence of P-solubilizing fungi in the wheat rhizospheres. Penicillium-inoculated plants contained greater quantities of Cu and Zn under greenhouse conditions and more Cu and Fe under field conditions than treatments not receiving Penicillium inoculum. Cu and Fe concentrations in the plants, in most cases, were not affected; however, Zn concentrations were increased by P. bilaji under greenhouse conditions. It was concluded that P. bilaji is able to cause solubilization of relatively insoluble forms of Cu, Fe and Zn. It did not directly affect the uptake of Fe and Cu by wheat in the soils used in these experiments, but may increase the uptake of Zn by plants. Key words: Penicillium bilaji, rock phosphate, copper, zinc, iron, wheat