NUTRIENT TRANSFER BETWEEN PLANTS THROUGH MYCORRHIZAL HYPHAE

Abstract

Soybean (Glycine ma × (L.) Merr.) and corn (Zea mays L.) plants were colonized by vesicular—arbuscular mycorrhizal (VAM) fungi and grown under controlled conditions. Three-part growth containers were used which separated the roots of N-donor (soybean) and N-receiver (corn) plants by screens (40 μm), permeable to VAM hyphae but not to roots. Significant, two-way nutrient transport occurred between plants connected only by the hyphae across a root-free soil bridge. Corn, when associated with nonnodulated, N-fertilized soybean, increased 19% in biomass and 67% in N content relative to similar, but N-deficient associations. Associated with nodulated soybean, there was a 16% decline in P content and a 22% increase in N content in corn. There was a large increase in N transport to the soil (VAM spores and soil mycelia) by the N-fertilized soybeans. If such nutrient fluxes between plants are controlled by source-sink effects, high N concentrations in soybean could account for the N fluxes to corn, and high module P requirement for the reverse flux of P. The results are of consequence for intercrop situations, especially under small-scale management conditions.