Effet des lombriciens sur l'absorption du potassium par le ray-grass dans des sols contaminés par CINQ elements traces

Abstract

My objective was to investigate, in a microcosm study, the effect of five trace elements (Cd, Cu, Fe, Pb and Zn) on the role of the anecic earthworm Lumbricus terrestris L. on the availability of K in soil, the K uptake by ryegrass Lolium perenne L. and its concentration in earthworm tissues. The microcosms contained soils with three different concentrations of trace elements and ryegrass plants. A week later, half of the microcosms received one adult earthworm and the whole was kept under controlled climatic conditions in the laboratory. In these experimental conditions, the presence of earthworms has little effect while the soil contamination by trace elements has a more important effect on the soil K availability. Earthworm biomass decreased and that of ryegrass increased with the soil contamination. Potassium content in earthworms and shoots and roots of ryegrass decreased while that of trace elements increased with soil contamination. However, K earthworm content varied very little with soil content indicating the possibility of biological regulation of this element by L. terrestris. Whether the earthworm was present or not, ryegrass took up more K and less trace elements in shoots than roots. An antagonistic interaction between K and trace elements absorption seems to be very likely.