Absorption of Water in Plants

The absorption of water in plants is an essential process. It is vital because it plays a significant role in the development of the plant. Moreover, it also helps in other types of plant metabolic activities. When we observe lower plants, we notice that absorption in these plants occurs through osmosis and the whole body of the plant. On the other hand, the water gets absorbed via the root hairs in higher plants. Mostly, plants can absorb water from the soil via capillary action. Let’s learn about the process of water absorption in plants in detail.

Definition of Absorption of Water in Plants

It is a biological process that occurs when plants absorb capillary water from the soil. It goes on to the root xylem and through to the root hairs, thus ending with the absorption of water by roots. It happens during different plant processes such as osmosis, respiration, transpiration etc.

Thus, we see how the water supply plays an essential role as it has a direct and indirect influence on the activities of the plants including photosynthesis. If the plants start losing water, then it may lead to wilting of leaves, protoplasm disorganization, stomata closure and more.Water absorb by plant from soil through osmosis.Osmosis is a special type of diffusion of water that occurs through a semipermeable membrane. It occurs spontaneously in response to a driving force. The direction and rate of osmosis depended on both the pressure gradient and concentration gradient. Water will until equilibrium is reached. 

Types of Absorption of Water in Plants

There are mainly two ways in which the plants generally absorb water. They include active and passive absorption of water. Let’s learn about these two in detail.

Active Absorption of Water

In this kind of water absorption, metabolic energy is needed by the root cells to execute the activity relating to metabolism, such as respiration. This process takes place in two ways. They are osmotic absorption of water. Similarly, the second one is the non-osmotic absorption of water.

Active osmotic absorption of water, the absorption of water, takes place through osmosis. In non-osmotic absorption, the water is absorbed when it enters the cell through the soil against the cell’s concentration gradient.

Passive Absorption of Water

In this kind of water absorption in plants, no metabolic energy is needed. The absorption takes place by metabolic activity such as transpiration. In this type, the water is absorbed through the transpiration pull. As a result, tension has been produced that assists in moving the water upwards into the xylem sap. Thus, if the transpiration rate is higher, water absorption will also be higher.

The Function of Root Hairs in Absorption of Water in Plants

The root of the plant contains root hairs. They are tubular, hair-like structures that are unicellular. The root hair zone is the only area that partakes in water absorption. This zone is a water-permeable region.

The root hair’s cell wall includes a double-layer membrane. In the outer layer, there is pectin, and the inner layer of the cell wall has cellulose. Moreover, under this wall, there is a cytoplasmic membrane.

This membrane allows certain substances to pass across the cell concentration gradient. Inside the cytoplasmic membrane, the nucleus, vacuoles and root cells. Thus, the root hairs carry tiny water droplets into the root xylem through various mechanisms such as osmosis.

Process of Absorption of Water in Plants

The process of water moving from the soil to the root xylem happens in different stages. They begin with the root hairs of the plant absorbing water from the soil that surrounds it. This takes place via osmosis.

After the water enters the root hair, it crosses the epidermis layer of the root system. Following that, the water starts moving from the epidermis to the root cortex. From here, it travels through the endodermis.

Finally, the water starts moving from the pericycle to the root xylem. Thus, the xylem root system stores the water that is later used by the body of the plant to carry out several beneficial metabolic activities for its development.

Factors Affecting Absorption of Water in Plants

There are majorly two types of factors that have a direct or indirect influence on the activity of water absorption. They are extrinsic factors and intrinsic factors. The first one involves external factors or environmental factors.

The extrinsic factors include soil water, soil air, soil temperature and the concentration of the soil solution. In soil, five different kinds of water are present. Out of these five, capillary water comes in use to carry out the plant’s biological activities.

Further, soil air refers to the space between the soil particles. It helps in the proper supply of air in the soil. If the oxygen is less, the carbon dioxide quantity will increase. Thus, it results in anaerobic respiration.

Further, soil temperature refers to the optimum temperature of around 20 to 35°C. The concentration of soil solution is supposed to be less. If it is high, then the soil will be physiologically dry. Thus, dry soil is not suitable for water absorption.

The intrinsic factors include metabolic activities such as respiration, transcription, and the number of root hairs responsible for directly influencing the water absorption rate.

Conclusion

To sum it up, the absorption of water in plants takes place through the root hairs responsible for carrying the water found in the soil to create a zone. This zone is referred to as the root hair zone. The root hairs are responsible for absorbing water via their wall. The nature of it is hydrophilic, meaning it is attracted to water. As a result, the highly porous nature of the root hairs to the water is beneficial in absorbing water via osmosis or transpiration. Thus, water absorption takes place to help the plant carry out other significant activities.