Field functional diversity of arbuscular mycorrhizal fungi in a crop rotation of Trifolium alexandrinum and Zea mays.

Soil microbes play a major role in the functioning of agroecosystems. Arbuscular mycorrhizal fungi (AMF) are beneficial microbes fundamental in soil fertility and plant nutrition, enhancing plant P and N uptake by means of their extraradical mycelium (ERM) spreading from mycorrhizal roots into the surrounding soil (Smith and Read, 2008). Many studies have been carried out with plants grown in sterile soil with or without AMF inoculation (Avio et al., 2006), while little is known about mycorrhizal symbiosis in nonsterile soils, which can contain diverse microorganisms differently influencing plant growth. Furthermore, the impact of agricultural practices on mycorrhizal colonization and host plant response in the field is not yet clearly understood. Greenhouse and field studies were performed in order to assess inter- and intraspecific functional diversity of geographically different isolates of the AMF species Glomus intraradices and Glomus mosseae, and of indigenous isolates inoculated on Trifolium alexandrinum and Zea mays, in a 2-year crop rotation.