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

Nutrient acquisition by plants occurs in an environment characterized by co mplex interactions between roots, micro-organisms and animals, termed the r hizosphere. Competition for mineral elements in this sphere is high. The rh izosphere processes are driven by photosynthetically fixed carbon released by roots either directly to myconhizal fungal symbionts or as exudates fuel ling a wider spectrum of organisms, mainly bacteria. In particular, the rol e of the soil fauna interacting with rhizosphere micro-organisms and plant roots has so far found little attention. We present evidence that the inter action between plant roots, root exudates and micro-organisms can only be u nderstood in relation to soil faunal activity, indicating that the soil fau na has an important function in regulating rhizosphere microbial processes and therefore significantly affects plant growth. (C) 2000 Editions scienti fiques et medicales Elsevier SAS.