Impact of the earthworm Aporrectodea trapezoides and the arbuscular mycorrhizal fungus Glomus intraradices on 15N uptake by maize from wheat straw.

摘要

The interactive impacts of an arbuscular mycorrhizal fungus (AMF; Glomus intraradices) and an earthworm species (Aporrectodea trapezoides) on N uptake by maize growing during wheat straw decomposition was studied with a modified up-down two-compartment root containers incorporating an air gap system. Soil was sterilized and root compartments inoculated with AMF inoculum in each treatment. Treatments comprised hyphal compartments (HC) with or without AMF hyphae and with or without earthworms. Wheat straw labeled with 15N was added to the HC. We determined maize yield, 15N content of shoots and roots, concentration of inorganic 15N in soil, percent of 15N transfer, and soil microbial biomass and community composition as indicated by phospholipid fatty acid profiles of HC soil at harvest. Earthworms enhanced 15N mineralization by 47.7% from wheat straw compared to the control but did not directly increase N mineralization or transfer N from mycorrhizae to plant. AMF hyphae increased shoot and root 15N uptake by 117.9 and 87.4%, respectively. Interaction between the AMF and earthworms increased shoot and root 15N uptake by 22.0 and 36.2%, respectively, (compared to hyphae alone) and decreased soil 15N content by 28.9% (compared to earthworms alone). The AMF hyphae assisted maize in the uptake of 15N mineralized from wheat straw by earthworms. Interactions between earthworms and AMF may help plants to take up N mineralized from crop residues.