Introduction of pasture mycorrhizal fungi affects multiple above- and below-ground biotic interactions

LANATI M; OMACINI M; GRIMOLDI AA; GARCÍA-PARISI PA

Mérida

Simposio; III International Symposium on Mycorrhizal Symbiosis in South America; 2023

South American Mycorrhizal Research Network

Arbuscular mycorrhizal fungi (AMF) play a key role determining the structure and functioning ofagroecosystems, but agricultural intensification challenges their effectiveness. Our aim was toevaluate the impact of a prolonged and intensive agricultural management on the establishmentof a pasture focusing on its effect on the AMF community. We hypothesized that introducingthe AMF community from a pasture soil favors the success of forage plants through modifyingmultiple biotic interactions. We conducted a mesocosms experiment filled with a pampean soilwith 20 years of intensive agriculture. Half of the mesocosms were inoculated with sporesextracted from a neighboring system where agricultural activities ceased 5 years ago with agrass-legume pasture. All mesocosms received a suspension of pasture-soil microorganismswithout spores. A similar combination of grasses and legumes was sown in each mesocosm. Wemeasured the presence, incidence and damage by plant enemies, plant productivity and rootcolonization by rhizobia or AMF. Restoring the mycorrhizal community increased herbivoredamage in Trifolium pratense but reduced aphid incidence in the grasses Bromus catharticus andLolium multiflorum. It also increased pathogen incidence in B. catharticus and T. pratense,nematode incidence and weed emergence. The restored mycorrhizal community decreasedgrasses biomass production, shifting towards a legume dominated system. Although the AMFcommunity addition slightly increased mycorrhizal colonization, it did not correlate with damage levels or pest and disease incidence. In conclusion, the AMF community provides a range of benefits beyond host´s nutrient supply, emphasizing the importance of considering them in themanagement of crop-livestock systems.