chapter  1
22 Pages

Types, Amounts, and Possible Functions of Compounds Released into the Rhizosphere by Soil-Grown Plants

I. Introduction .................................................................................................................................1 II. Root Growth, the Rhizosphere, and Root Products ...................................................................4 III. Amounts Released.......................................................................................................................6 IV. Types of Root Products: Secretions and Their Roles ................................................................8 V. The Right Set of Circumstances...............................................................................................13 VI. Conclusions...............................................................................................................................14 Acknowledgment..............................................................................................................................15 References ........................................................................................................................................15

The rhizosphere is defined here as that volume of soil affected by the presence of the roots of growing plants. The overall change may be deemed biological, but chemical, biological, and physical properties of the soil in turn are affected to varying degrees. A multitude of compounds are released into the rhizosphere of soil-grown plants, most of which are organic compounds and are normal plant constituents derived from photosynthesis and other plant processes (Table 1.1). The relative and absolute amounts of these compounds produced by plant roots vary with the plant species, cultivars, plant’s age, and environmental conditions including soil properties, particularly, the level of physical, chemical, and biological stress and so on [1,2,15-18].