Root zones of plants. Division, suction, holding, growth zone

In this article, we will consider the zones of the structure of the root, which allow it to carry out the most important functions in the plant organism. The internal structure of this body is distinguished by a clear differentiation, thanks to which the coordinated work of the whole organism is carried out.

What is the root

The root is the axial underground organ of the plant. Depending on the peculiarities of the location, the main, lateral and accessory ones are distinguished. The first kind of definition is very simple. The main root of the plant is always one. On it there are lateral. Together they form the core root system. It is characteristic of all representatives of the Dicotyledon class, including the well-known families of Rosaceae, Nightshade, Astrope, Cabbage, Bean, and others. Straight from the escape of the subordinate roots. They grow in a bundle. Such a root system, which is called lobed, has Monocotyledon: Cereals, Onions and Liliaceae.

Functions of the root

The main task of the underground organ is to fix the plant in the soil, provide it with water and solutions of minerals. With the help of the root, nitrogen, potassium, iron, magnesium, phosphorus and other elements are absorbed from the soil. This process is called mineral nutrition. The obtained plant substances are used for self-synthesis of organic compounds.

Root and escape function in close relationship. The underground organ provides the plant with water with solutions of mineral substances. They come from the root to all parts of the escape. This is the ascending current of substances. In turn, as a result of photosynthesis, organic substances form in the leaves. They move from the shoot to the root, carrying a downward current.

In some cases, root zones of plants are modified to perform additional functions. For example, in radishes, turnips, carrots and beets, the underground organ thickens for a reserve of reserve substances. A ivy with the help of the roots of the trailer reliably clings to the support. Many parasitic plants are not capable of photosynthesis at all. Nutrition of such organisms occurs solely at the expense of the root system. An example of this will be a plant - a dodder parasite. Its roots penetrate the cells of the host organism, absorbing its juices.

Root Zones

If you cut an underground organ along its axis, you can easily notice the root zones. All of them are specialized, with a clear interrelation of the features of the structure and the functions performed. Zones are arranged in the following sequence: root cover, division, extension, suction, holding. It is already possible to guess by the names only from the elements of which tissues they are composed, and what is their role in the vital activity of plant organisms. Let's consider each of them in more detail.

Root cover

To penetrate deep into the soil, the root constantly grows its top. This function is carried out by the zone of division of the root, which is covered with a root sheath. It reliably protects the cells of the educational tissue from mechanical damage, prevents damage to the top of the underground organ during its penetration into the soil.

Root cover is formed by several layers of living cells of the integumentary tissue. They are not homogeneous in their structure. Thus, the cells of the outer layer are constantly destroyed when they come into contact with soil particles. Therefore, they require restoration. This process is due to the division of the cells of the educational tissue from the inside. Root cover also plays the role of a kind of "navigator" for the underground organ of plants. Since it has the ability to perceive the force of gravity, this zone determines the direction of root growth in depth.

Meristem

Then follows a part of the root, which combines two zones: division and extension. Due to these structures, its size increases. Therefore, it is called the root growth zone. What are the characteristics of the structure of each of them?

The zone of division of the root is located behind the root sheath. It is completely formed by an educational fabric - a meristem, whose length does not exceed 3 mm. Its cells are small, closely adjacent to each other, have thin walls. This zone has a unique ability. When it divides, cells of any other tissues are formed. This is very important for the restoration of lost or damaged parts of the organs of the plant organism.

Area of stretching

Behind the meristem the root growth zone continues with cells of a different type. They are constantly growing, lengthening, acquiring a fixed shape and dimensions. This is the stretch zone. Its dimensions are also insignificant: only a few mm. Increasing in size, her cells promote a meristem with a root sheath deeper. The stretch zone is also created by an educational tissue. Therefore, cells of any type can be formed here.

Suction area of the root

The following structure has larger dimensions, occupying a section from 5 to 20 mm. This is the root suction zone. Its main function is to absorb water with a solution of nutrients from the soil. This process is carried out with the help of root hairs, which are the outgrowths of the cells of the integumentary tissue. Their length varies from a few millimeters to one centimeter. Sometimes this figure exceeds the size of the cells themselves.

Root hairs are constantly renewing formations. They live up to 20 days, after which they die. New hairs are formed from cells that are located near the growth zone. At the same time, they disappear in the upper part. Therefore, it turns out that the suction zone plunges into the soil deeper as the root grows.

Root hairs are very easy to damage. Therefore, during the transplantation of plants it is recommended to carry it along with the soil in which it grew before that. These structures are quite numerous. At 1 square millimeter, several hundred root hairs are formed. This greatly increases the suction surface, which is several hundred times greater than the area of shoots of the plant.

Lateral roots

The area of the root, or lateral roots, is the largest. This is the site within which the subterranean organ thickens and branches. Here the lateral roots of the plant are formed. In the zone of carrying out there are no root hairs, therefore absorption of nutrients from the soil is not carried out. The root zone serves as a "transport route" from the suction zone to the ground part of the plant.

Features of the internal structure

As you can see, all the root zones are characterized by a clear specialization. This also applies to the internal structure of the subterranean organ. Several layers are clearly visible on the transverse section of the root in the suction zone. There is a cover cloth outside . It is represented by one layer of living skin cells. They form the new root hairs.

Under the skin is the bark. These are several layers of the underlying tissue. Through them, solutions of mineral substances from the root hairs to the elements of the conducting tissue move . The inner axial part of the root is occupied by the central cylinder. This structure consists of vessels and sieve tubes, as well as elements of mechanical and storage tissue. Around the central cylinder there is a layer of cells of the educational tissue, from which the lateral roots are formed.

Methods of forming the root system

Knowledge of the structure and physiology of the underground organ of plants man has long used in his economic activities. So, for the formation of additional roots developing in the surface layer of the soil, it is recommended to hill the site and pour the soil to the base of the shoots.

To increase the number of lateral roots, the pick method is used. It is carried out during transplantation of seedlings in the open ground. For this, the tip of the main root is plucked from the sprout, as a result of which the entire system becomes more branched. Lateral roots expand, which means that the soil nutrition of plants is more efficient. In addition, with hilling and picking, their predominant amount develops in the upper soil layer, which is more fertile.

So, the root zones are different parts of the axial underground organ of plants. All of them are distinguished by a narrow specialization, due to the peculiarities of their structure. Distinguish the following areas: a root cover, division, growth, including stretching and suction zones, and holding.