The Beneficial Rhizosphere: a dynamic entity

This introductory paper attempts to put into perspective the papers given at the Inter-COST meeting on the Establishment of the Beneficial Rhizosphere. Although the rhizosphere concept is now relatively well understood, it is too frequently viewed as a static entity. An awareness of the short longevity of the roots of many common crop species, less than 7 days for half of the new roots of oats, and of the hyphae of arbuscular mycorrhizal fungi (AMF) bring a dynamic imperative to the rhizosphere concept. This actuality means that rhizosphere conditions need to be established and maintained on an almost continuous basis. A dynamic perspective of the rhizosphere changes views on thr: targets for microbial inoculation for both field grown and micropropagated plants. At the time when the concept was introduced, the rhizosphere was commonly regarded as an add-on to the normal plant. We are now aware that it is the "rhizosphere" condition which is normal. These concepts and their implications are the subjects of the papers in this special issue of Applied Soil Ecology. (C) 2000 Elsevier Science B.V. All rights reserved.