Functions of the root are to support stems and leaves
of a plant above the ground, absorb water and
nutrients from the surrounding soil and convey some
hormones secreted as a result of interactions with
ambient natural environment (Tatsumi, 1994). In a
preparatory stage of root growth, the radicle is formed
inside the seed, which becomes the main root after its
germination. The main root consists of a root cap,
meristem, elongation zone and mature zone, where
lateral roots sprout. Moreover, a root is sometimes
regarded as either a sink or a source of chemical and
biological reactions, where essential nutrients flow
from the root to leaves and stems, and vice versa, as
shown in Figure 1.