The root of
plants must obtain sufficient water, oxygen and
nutrients from the surrounding environment.
The life processes of the root system excrete
CO2 and other gases that must disappear within
a certain time from the root environment. The
structure of the growing medium must be soft
and porous enough so that roots can easily
penetrate widely into the material and it must
also provide anchorage and support for the
plants. The well being of a plant is strongly
dependent on the correct functioning of the
root system. The physical, chemical and biological
properties of a growing medium can be used as
a basis of classifying the suitability of a growing
medium in relation to the needs of the roots.
Understanding the physical environment
surrounding roots in containers (relative volume
of air, water, and solid) is based on the relationship
between energy status and water content of the
medium