Accessibility of Inorganic and Organic Nutrients for Mycorrhizas

Different mycorrhizal associations are dominant under different soil conditions. This has naturally placed emphasis on the ability of the fungal partner to supply the key limiting nutrient specific to that particular environment and the associated host plant. For the most widespread mycorrhizal association, the arbuscular mycorrhiza, the acquisition of poorly mobile phosphate ions has been the main research focus. In contrast, for the ectomycorrhizal association, emphasis has been placed upon nitrogen (N) acquisition, predominately from complex organic forms. However, the fungal mycobiont will in both cases also be able to acquire N and phosphorus (P) for its own nutritional needs. This gives rise to the possibility that both N and P may be exchanged for host carbon, depending on the nutritional status of the fungus and host. The interactions among various soil nutrient pools and their relative biotic availability therefore merits greater priority.