The root system in plants is a part which remains subterranean or underground the soil in the vascular plants. It provides strength and rigidity to the growing plant against adverse conditions. Some of the trees like a banyan tree, bonsai tree have their root system over the ground, which refers as “Aerial roots”. Unlike stems, roots are the irregularly branched structures which lack nodes and internodes. Plants like mosses and liverworts lack the presence of the root system.
Cellular processes like photosynthesis help in the functioning and metabolism of the root system. A root system lacks stomata which are present in leaves and stems. The root system consists of a thimble-like root cap and thread-like root hairs.
Content: Root System in Plants
Definition of Root System
The root system can define as the ramose structures that can form subterranean or superterranean to the earth surface. A root consists of the hard root cap, primary root meristem and root hairs. The growth of root system depends upon the soil composition, soil type, type of plant species and the growth conditions. Roots are such complex structures whose total dry weight may exceed the total weight of the plant body. A seed first develops a radicle which also refers as “Primary root” and later forms secondary, tertiary etc. roots.
Types of Root
Roots are of the following types:
Taproot system: A taproot is a primary root system which consists of lateral branched roots with the fine rootlets.
Example: Carrot, turnip etc.
Fibrous root system: It appears as a large number of roots of equal size arises from the base of the stem by replacing a primary root. Fibrous roots have a bushy appearance and consists of thin root fibres.
Example: Wheat, rice, maize grass etc.
A root system possesses the following key characteristics:
- It is mostly subterranean to the plant axis.
- A root system is:
- Positively geotropic.
- Negatively phototropic
- And, Positively hydrotropic.
- Root comprises of unicellular structures or root hairs which absorbs water from the soil.
- The cuticle or waxy coating that surrounds the epidermis is absent in the root system.
- Root system lacks chlorophyll and stomata.
- Unlike stems, it does not have nodes and internodes.
- Sometimes a root undergoes structural modification to perform functions like storage, respiration, physical support etc.
Parts of Root
A structure of root generally comprises of three parts:
It is found at the tip of the root system and has a thimble-like appearance. Root-cap is a multicellular structure present proximal to the primary meristem. It also secretes “Mucilage” which acts as a lubricating agent. A mucilage secreted by root cap protects the root system against the dryness. Few aquatic plants like Pistia, Ecchornia etc. have a root pocket instead of the root cap.
It is found 1mm above the root cap and also refers as “Zone of meristematic activity”. This region contains cells having a small size, thin-walled, dense protoplasm and undergoes repeated cell divisions. There are some cells proximal to the meristematic zone which enlarges rapidly and refers as “Zone of elongation”. The cells in the elongation zone extend the root length.
The cells in the zone of elongation undergo multiplication and differentiation into mature cells. The mature cells proximal to the area of elongation refers to a region of maturation. The epidermal cells of the maturation zone give rise to the fine, thread-like root-hairs. Root hairs perform a functional role in water and mineral absorption from the soil.
Five Functions of Root
The five primary roles in the root system include:
Anchorage and Physical support: A root system anchors the plant body or the shoot system to the soil. Roots that are dug into the ground helps in maintaining the plant’s posture by giving physical support. Taproots provide better attachment of the plant to the soil and make it resistant against the toppling during storms.
Absorption and Conduction: Roots help in absorption of water and dissolved minerals in the soil and conduction of the nutrients to the plant body. Root hairs are the fine structures that are in close vicinity to the ground and absorbs nutrients from the soil. The nutrient taken up by the root hairs is moved up to the shoot system via xylem through capillary action.
Therefore, the root system provides nourishment to the plant for growth or development. Fibrous roots are more efficient to absorb nutrients deep inside the soil.
Food Storage: Root system also acts as a storage organ of the plant, which mainly stores water and carbohydrates. The plant prepares its food during photosynthesis, stores in the specialized part of the plant like leaf, stem and roots. Taproots are more effective in food absorption than fibrous roots.
Role in Photosynthesis: Roots play an essential role in the process of photosynthesis. A plant gets water from the root system and releases excessive water through stomata, by a process refers as “Transpiration”. As the water vapours release out of the stomata, CO2 enters the plant cell that is required for the photosynthesis.
Ecological functions: Roots are the part of soil ecology, which helps in the soil aggregation and protects a plant from being carried away by wind or water.