El potencial de colonización micorrícico-arbuscular varía entre prácticas agrícolas y sitios en diferentes áreas geográficas de la Región Pampeana

The evaluation of the fungal communities requires the identification of the present species, the quantification of the density of propagules and also the determination of their infectivity. In this study, arbuscular mycorrhizal colonization potential (MCP) was evaluated through an experimental trial. Three soils with different land uses (natural grassland, crop rotation and soybean monoculture in direct seeding) from four sites located in different geographical areas of the Pampas Region (Bengolea, Monte Buey, Pergamino and Viale) were used as inoculum using Vicia villosa Roth. as a control plant. The land uses and geographical areas had an effect on the PCM. Monoculture, as rotation scheme, showed greater potential to colonize the roots of Vicia villosa , with respect to natural grassland and crop rotation in most of the proposed combinations, although in previous work we had found that monoculture reduces the richness of the same mycorrhizal communities determined by density and diversity of spores in these soils. These results suggest the limitations of the paradigms of interpretation of the symbiotic systems generated from trials under controlled conditions and a great lack of knowledge of the functioning of plant-microorganism interactions in the soil. Alternatively, the result could be the consequence of an inhibitory effect of the greater fertility N-P in the soils with crop rotation with respect to the soils under monoculture due to a management of historical replenishment of nutrients by fertilization, absent in the cases of monoculture. The use of a single plant species in infectivity assays could also be biasing the results and limiting the expression thereof, by host specificity, in the entire soil mycorrhizal community.