Microbial-faunal interactions in the rhizosphere and effects on plant growth

Nutrient acquisition by plants occurs in an environment characterized by complex interactions between roots, micro-organisms and animals, termed the rhizosphere. Competition for mineral elements in this sphere is high. The rhizosphere processes are driven by photosynthetically fixed carbon released by roots either directly to myconhizal fungal symbionts or as exudates fuelling a wider spectrum of organisms, mainly bacteria. In particular, the role of the soil fauna interacting with rhizosphere micro-organisms and plant roots has so far found little attention. We present evidence that the interaction between plant roots, root exudates and micro-organisms can only be understood in relation to soil faunal activity, indicating that the soil fauna has an important function in regulating rhizosphere microbial processes and therefore significantly affects plant growth. (C) 2000 Editions scientifiques et medicales Elsevier SAS.