Roots of plants growing in their natural environment have evolved and live in close contact
with the solid phase of the soil; this interaction can determine changes both in root
physiology (l) and anatomy (2) and in the chemical, physical, and microbiological properties
of the soil. These phenomena occur in a limited area surrounding the root-the rhizosphere-
where nutrient, energy, and signal exchanges make this environment decisively different
from bulk soil, both from a chemical-physical and microbiological point of view.