A root is an underground organ through which a plant obtains nutrients from the soil solution. The apical meristem, covered by the root sheath, allows the root to grow longitudinally. The root differs from the shoot in that it does not form leaves.

Functions:

Fortifying the plant in the soil layer (“anchoring”);
To enable growth deep in the soil;
ability to synthesize new chemical compounds in root tissues, which are then supplied to other plant organs;
ability to accumulate various substances;
interaction with root systems of other crops, representatives of microflora, fungal organisms in the soil layer.

Root types:

The main root, developed from the germinal root of the plant;
Lateral roots;
adventitious roots.

In terms of form, the classification distinguishes two varieties:

tap root – one main root, distinguished by length and diameter;
Ligamentous, characterized by a large number of adventitious roots without a main root.

By its nature, the root has no limitation in growth. But root growth is influenced by environmental factors, soil composition and structure, and the number of other roots nearby.

Division into zones

The growing root is divided into zones that differ in size, morphological and physiological features, and functional characteristics:

• The root sheath, containing a large number of starch grains, composed of living cells, continuously renewed, covering the root termination and thus protecting the apical meristem; having the ability to peel off living cells that create a mucilage mass to facilitate root movement in the soil layer;
• division zone – apical meristem, located under the root sheath, responsible for the formation of root tissues; consists of small cells with a large nucleus and dense cytoplasm, has a total thickness of not more than one millimeter;
• the growth (stretching) zone, located after the division zone, reaching the size of several millimeters, distinguished by the fact that its cells do not divide, but stretch lengthwise, absorbing water
• suction (absorption) zone, located behind the stretching zone, reaching a length of several centimeters, having a covering tissue with tiny hairs covering soil particles and absorbing microelements and water from them; in the absorption zone root tissues are formed and differentiated
• conduction zone, located above the absorption zone, necessary for transportation of water and microelements from root hairs to plant organs, as well as necessary for formation of lateral roots.

The absorption and conduction zones do not have the ability to change their position in relation to the soil zones. In most cases, other root zones are identified conventionally, since they tend to change their position as the root apex grows.

For example, new cells of the growth zone move to the suction zone, and old cells of the suction zone move to the conduction zone. Root tissues continually form and move around, providing nutrition and growth for the plant.