ABSTRACT
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 tum, are affected. A multitude of compounds are released into the rhizosphere of plants grown in soil, most of which are organic compounds and are normal plant constituents derived from photosynthesis and other plant processes (Table 1). The relative and absolute amounts of these compounds produced by plant roots vary with the plant species, cultivars, the age of plant, the environmental conditions-including soil properties particularly, the level of physical, chemical, and biological stress, and so on (1,2,10-13).
