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Plant Water Relations

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The transfer of water, nutrients, and other materials from one section of the plant to another is referred to as transport in plants. Plants rely on their transport system for growth, survival, and reproduction. Water transport in plants is critical for sustaining the turgor pressure required for cell structure and function.

What are Plant-water Relations?

Water is required for all physiological functions of the plant and is vital to all living species. It serves as a medium in which most compounds dissolve. The protoplasm of the cells is nothing more than water in which various molecules dissolve and (many particles) are suspended.

A watermelon has approximately 92% water, but most herbaceous plants contain about 10 to 15% of their fresh weight as dry matter. Of course, the distribution of water within a plant varies; woody regions have very little water, whereas soft parts have a lot. A seed may appear dry, yet it still contains water; otherwise, it would not be alive and breathing!

Terrestrial plants consume a large quantity of water each day, but the majority of it is lost to the atmosphere by evaporation from the leaves, also known as transpiration. A mature corn plant absorbs over three liters of water per day, whereas a mustard plant absorbs water equal to its own weight in approximately five hours. It is not unexpected, given the tremendous demand for water, that water is frequently the limiting factor for plant growth and productivity in both agricultural and natural situations

What is Water Potential?

Water molecules have a quantity of kinetic energy. The more water there is in a system, the greater it’s kinetic energy or water potential. When two water-containing systems come into contact, water molecules flow from the higher-energy system to the lower-energy system. The potential of water is measured in pascals. At standard temperature, the water potential of pure water is zero.

When a specific amount of solute is introduced to pure water, the concentration of water decreases, as does the water potential. The solute potential is the amount by which the water potential decreases. This is always negative, and the value of solute potential drops as the number of dissolved solutes increases. When pure water is subjected to pressures greater than atmospheric pressure, the value of water potential increases. When water enters a plant cell via diffusion and exerts pressure on the cell’s walls, the cell is said to be turgid. This raises the potential for pressure. This value is almost always positive. The sum of solute potential and pressure potential is water potential.


Osmosis is the process of the movement of water molecules from an area of higher water concentration to an area of lower water concentration, across a semi-permeable membrane. The semi-permeable membrane allows the passage of water molecules but not solute molecules. Thus, osmosis helps plants in the absorption of water from the soil. The water moves from a region of higher concentration (soil) to a region of lower concentration (root cells) through osmosis.


Plasmolysis is the shrinking of the protoplasm of a cell away from the cell wall due to the loss of water through osmosis. When a plant cell is placed in a hypertonic solution (higher solute concentration outside the cell), water moves out of the cell through osmosis, resulting in the shrinking of the cell. This can lead to wilting of the plant. Plasmolysis is a reversible process, and the cell can regain its shape and size when placed in a hypotonic solution (lower solute concentration outside the cell).


The process by which a substance absorbs water without generating a solution is known as imbibition (for example, a seed or a plant component). The water is absorbed by the substance’s surface, causing it to swell. Imbibition is vital for seed germination because it supplies the water required for embryo growth. Seed swelling during imbibition can also aid in seed coat shattering, allowing the embryo to stretch out.

FAQs on Plant water Relation

Question 1: What is the importance of Plant-water Relations?


Water is necessary for both plant and animal cells. A large amount of water is taken by plants for their basic requirements. So it is necessary to understand the creation between plants and water for between understanding.

Question 2: What is the role of water in plant physiology?


Water is required for all physiological functions of the plant and serves as a medium in which most compounds dissolve. It is essential for the proper functioning of plant cells and is vital to all living species.

Question 3: How much water do plants consume daily?


Terrestrial plants consume a large quantity of water each day, with a mature corn plant absorbing over three litres of water per day, and a mustard plant absorbing water equal to its own weight in approximately five hours.

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Last Updated : 15 Mar, 2023
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