Rhizosphère

The rhizosphère is the area of the ground directly formed and influenced by the root S and the associated Micro-organisme S. It is a place of intense exchanges between the plant and the mineral substrate, which can be affected by the compressing of the ground, ennoiement durable, its Salinisation, its Eutrophisation or pollution, or by phenomena of aridification.

The rhizosphère is rich in micro-organisms, and in particular in Bactérie S (PGPR) and microscopic Champignon S which nourishes cell S and substances rejected by the plant in a process called rhizodéposition , including a great quantity of Protéine S, Sucre S and other secretions racinaires. Many symbioses and synergies are observed between plants, bacteria and virus of the ground, doping the biological activity of the ground: In this zone sometimes reduced to a few centimetres thickness under the lawns, but thicker in the moderated forests, up to 30% of the photosynthetized biomass is quickly réoxydée out of CO2. the rhizosphère receives part of the evapotranspiration of the plant (a plant perspires each day more than 5 times its biomass, that is to say nearly 500 times its biomass each year, playing for example a part in the dissolution of almost 30% of the limestone of the substrate; it would be necessary to pour 500 liters of acid chloridric concentrated on each cubic meter of ground to have a purely chemical equivalent!

The Protozoon S and Nématode S which nourishes Bactérie S are also concentrated around the roots. Thus, the majority of the cycle of the Nutriment S and the suppression of the diseases proceed in the immediately adjacent zone with the roots, which makes it essential for the Phytoremédiation, in particular by the Mycorrhizosphère.

The microbial activity in the rhizosphère is governed:

  • by factors of the climatic environment, in particular moisture of the air, temperature, solar radiation, content CO2,
  • by factors of the edaphic environment, in particular: content of oxygen and water the ground, temperature of the ground, content of the ground of assimilable elements by the plants, presence of compounds phytotoxic.

Etymology

The word " Rhizosphère" was introduced in 1904 by Lorenz Hiltner, Bactériologiste for the grounds and professor of Agronomie to the Technical school of Munich. “Rhizo” comes from the Greek “rhiza,” meaning “root”. “Sphere” is the influence or sphere of activity, here natural environment. It was also called the hidden half of the hidden half .

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