Experiments testing the efficiency of arbuscular mycorrhizal fungi (AMF) originating from the same soil sample complement studies of taxonomic diversity by assessing functional relationships within mycorrhizal communities. In this study fungal isolates from three distinct communities were evaluated regarding their efficiency to increase dry biomass production and P content in two mycotrophic hosts. In the first experiment, the effect of 13 AMF isolates from the JA205, MN414, and VA105 communities were screened in order to test the hypothesis that at least one isolate of each mycorrhizal community was efficient for soybean. All three isolates from the JA205 community and Glomus clarum from the VA105 community increased the biomass production compared to non-mycorrhized plants. No isolate from the community MN414 had a significant effect compared to control plants. Phosporus content, however, was significantly increased by 7 out of 13 isolates compared to control plants. In the second experiment, it was evaluated the effect of single inoculation or co-inoculation using isolates from communities VA105 and MN414 in red clover. Colonizaton by 5 isolates from both communities significantly increased dry biomass production and P content in red clover, with exception of Scutellospora calospora MN414C that had an effect only on P content. Co-inoculation of isolates did not necessarily confer a higher benefit to plants than inoculation with a single isolate. Plants colonized by S. verrucosa VA105B + Glomus clarum VA105D produced significantly larger quantities of biomass than plants inoculated with only S. verrucosa, but dry biomass production and P content did not differ from those inoculated with G. clarum. Conversely, dry biomass production and P content of plants inoculated with Glomus sp. MN414B + Gigaspora gigantea MN414D were not significantly different from those inoculated with each isolate separately. Testing the relative efficiency of fungal isolates originating from the same community represents a first step to adopt strategies of management of native fungi versus inoculation with exotic fungi aiming to increase productivity in natural or agricultural ecosystems.
arbuscular mycorrhizal fungi; co-inoculation; mycorrhizal community; spores; root colonization; soybean; clover; efficiency
