Arbuscular mycorrhizal fungi in the rhizosphere of soybean in integrated crop livestock systems with intercropping in the pasture phase

Abstract

Arbuscular mycorrhizal fungi (AMF) are important microorganisms that act as sensitive soil quality indicators. The increase in plant diversity in Integrated Crop Livestock Systems under no-tillage (ICLS-NT) can also alter the diversity of species of fungi and bring benefits to the system. This study had the objective of evaluating the AMF diversity and its quantitative characteristics in ICLS-NT with intercrop in the pasture phase. The experiment was conducted in a dystrophic red latosol, with plots represented by the grasses Panicum maximun cv. BRS Tamani and Urochloa brizantha cv. Piatã, intercrop with the legumes (subplots): cowpea (Vigna unguiculata) cv. BRS Tumucumaque, pigeon pea (Cajanus cajan) cv. BRS Mandarim and single grass type only. The potential for inoculation was elevated in areas with legume intercrop, with either grass, and about 29% higher in areas with the C. cajan/P. maximun consortium. They may be associated with the benefits that the intercrop with legumes brings, through the relationship of rhizobia and AMF. The spore density and mycorrhizal colonization were higher with the use of grass from the genus Urochloa in relation to Panicum, reaching 92% and 88% higher, respectively, as well as an increase in species richness, being associated with a greater affinity of AMF with intercropped grasses. The insertion of the legumes into the intercrop with the grasses affected soybean productivity, positively correlating (74%) with mycorrhizal colonization. These results are related to the fact that intercrop promote the release of a high diversity of organic compounds, helping in the activity of soil microbiota, including AMF, increasing colonization and species diversity of these fungi. Thus, intercrops of grasses with legumes affected positively the activity and diversity of species of the AMF, reflecting in the increase in productivity of the soybean crop.