Feb 9, 2011

Glossary

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Exsudation

in plants: Secretion of substances via the roots

Various metabolites, most of them water-soluble, organic metabolites, like sugars and amino acids, are released into the soil via the roots. As a result of interactions with the micro-organisms in the root area of the soil (rhizosphere), substances including nutrients are released that are then more readily accessible to the plant. The root exudates also contain small quantities of organic acids, e.g. acetic acid, which regulate the pH value in the rhizosphere.

Exudates have a significant influence on the composition of micro-organisms in the rhizosphere, just as, conversely, the presence of micro-organisms stimulates exudation.

The composition and quantity of exudates depend on the species and age of the plant, but also on the soil composition and other environmental factors.