Effect of an arbuscular mycorrhizal fungus, Glomus mosseae , and a rock‐phosphate‐solubilizing fungus, Penicillium thomii , on Mentha piperita growth in a soilless medium

Rock phosphate effect on English mint ( Mentha piperita L .) grown on steamed perlite:vermiculite (1:1, v:v) substrate, with and without rock phosphate, was evaluated in greenhouse experiments. Five treatments were carried out by inoculation with an arbuscular mycorrhizal fungus Glomus mosseae and a phosphorus solubilizing microorganism Penicillium thomii . Plant aerial biomass, phosphorus concentration in plant tissue, and P available in the substrate, were evaluated upon two harvests. After the first harvest, plant aerial biomass did not show significant differences between treatments using rock phosphate as fertilizer, although P content in plants inoculated with P. thomii was higher. The second harvest revealed a higher biomass and plant tissue P content in treatments inoculated with G. mosseae. P. thomii increased P available in the substrate, whereas in the absence of G. mosseae , it did not enhance plant tissue P content. Mycorrhizal colonization was not affected by P. thomii . Microbial inoculation effect on English mint growth was also evaluated. The microbial effect was positive in all treatments when compared with the control without rock phosphate. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)