Mycorrhizal colonization, spore density and diversity of arbuscular mycorrhizal fungi in Cerrado soil under no-till and conventional tillage systems

Abstract

The quest for sustainability in agricultural production through conservation management practices such as no-tillage, has favored the biochemical processes of soil, such as soil arbuscular mycorrhizal fungi (AMFs), which promote a significant increase in specific surface absorption of the root system of plants. The objective of this study was to evaluate the root colonization, spore density and diversity of AMFs in rhizosphere of corn and soybean grown under no-tillage with different cover crops and compared an area conventional tillage and fallow, in Uberaba, state of Minas Gerais. The corn and soybeans were rotated with millet, crotalaria and brachiaria. The experimental design was randomized blocks, with split plots. The experiment was established in 2000, and in 2007 assessed the colonization (COL) and spore density (ESP) (0.0-0.05m and 0.05-0.10m). In the layer of 0.0-0.10m evaluated the diversity of AMFs. It was found that there was a strong effect of culture on COL and ESP. However, the effect of the covers and management was seen only in 0.0-0.05m. The roots of corn has a higher percentages of COL and ESP compared with soybeans, for the coverage Brachiaria and millet. The mycorrhizal colonization of soybean and maize in Cerrado area was up 80% for soybeans and up 95% for corn. Conventional tillage soil the lowest number of AMFs species in relation to the coverage of millet and Brachiaria in no-till corn and soybeans. The principal components analysis  with some chemical, physical and biological factors of soil shows the separation of the areas assessed, and the biological component (COL and ESP) in the efficient separation of the areas under cultivation,  for the conditions of this study.