Exploring the diversity and use of native arbuscular mycorrhizal fungi for low-input agroecological weed menagement in European Living Labs

Arbuscular mycorrhizal fungi, key plant soil beneficial symbionts, play a fundamental role in the transition towards low-input, safe and resilient agroecosystems. In particular, they can contribute to the reduction of agrochemicals, together with other Agroecological Weed Management (AWM) strategies. This work within the framework of the Horizon Europe project GOOD (AGrOecOlogy for weeDs) investigated the diversity of native AMF communities of 14 European Living Labs (LLs) from 7 different EU countries (the Netherlands, Serbia, Italy, Greece, Portugal, Spain, and Cyprus) to be used as seed inocula to promote the competitive ability of cover crops against weeds. Such native AMF communities were massively reproduced in pot cultures, given their status of obligate biotrophic symbionts. Moreover, a protocol was developed and tested on seeds of 11 plant species varying in shape, size and weight, to use seed inoculation as a means of delivering native AMF communities to cover crops. Morphotypes richness differed among EU LLs: the highest (17 AMF species) was found in Spanish LLs, while the lowest was detected in Italy and Cyprus (4-5 AMF species). Some species, such as Entrophospora etunicata, Glomus badium, Pacispora sp. and Rhizoglomus spp. were retrieved in 3-5 LLs, while spores belonging to Ambisporaceae, Archaeosporaceae, Acaulosporaceae and Scutellosporacerae were found at very low density in many LLs. Seed inoculation protocol was set up using different quantities of AMF inoculum, a commercial liquid adhesive material and water, to ensure uniform coverage of seeds. The protocol was then scaled up for on-farm application. Future studies will be carried out in order to assess mycorrhizal inoculum potential of LLs soils, the changes in the native AMF communities after cover crop inoculation and weed reduction.