Explain teanpiration and its importance for plants( long answer)
Answers
Answer:
This process of elimination of excess water from the plant body is known as transpiration. It is generally the evaporation of water from the surface of the leaves. During the process of transpiration, water molecules in the plant tissues are removed from the aerial parts of the plants.
Answer:
During the process of transpiration, water molecules in the plant tissues are removed from the aerial parts of the plants. Only a small amount of water absorbed by the plants is utilised in growth and development. The rest is eliminated in the form of transpiration.
Explanation:
Types of Transpiration
There are three different types of transpiration in plants:
Stomatal Transpiration
It is the evaporation of water from the stomata of the plants. Most of the water from the plants is transpired this way. The water near the surface of the leaves changes into vapour and evaporates when the stomata are open.
Lenticular Transpiration
Lenticels are minute openings in the bark of branches and twigs. Evaporation of water from the lenticels of the plants is known as lenticular transpiration.
Lenticels are not present in all the plants. A minimal amount of water is lost through lenticels.
Cuticular Transpiration
It is the evaporation of water from the cuticle of the plants. The cuticle is a waxy covering on the surface of the leaves of the plants. About 5-10% of the water from the leaves is lost through cuticular transpiration. During dry conditions when the stomata are closed, more water is transpired through the cuticles.
Factors Affecting Transpiration in Plants
Different factors affecting the rate of transpiration are:
Cellular Factors
The cellular factors affecting the rate of transpiration are:
The orientation of leaf,
The water status of the plant,
Structural Peculiarities of the leaf,
Total number and distribution of stomata in a leaf.
Environmental Factors
The environmental factors affecting the rate of transpiration are:
Light,
Humidity,
Temperature,
Atmospheric pressure,
Wind speed or velocity.
Relative Humidity
The amount of water vapour present in the air at a particular time and temperature is expressed as a percentage of the amount required for saturation at the same temperature. The rate of transpiration is inversely proportional to relative humidity. More the relative humidity less is the transpirate rate.
Temperature
A high temperature lowers the relative humidity and opens the stomata even in darkness. As a result, the rate of transpiration increases.
Light
The stomata open during the day and close in the dark. Presence of light is directly proportional to the rate of transpiration.
Air
If the air is still, the transpiration rate is low. This is because the water vapour accumulates around the transpiring organs and reduce the diffusion pressure deficit of the air.
If the air is moving, the saturated air around the leaves is removed and the transpiration rate increases.
Water Availability
The transpiration rate is directly proportional to the absorption of water by the roots from the soil. A decrease in water absorption causes the closure of stomata and wilting, thereby reducing the rate of transpiration.
Surface Area of the Leaves
A leaf having more surface area will show more transpiration rate than the leaf with a lesser surface area.
Also Read: Difference between Transpiration and Guttation
Ascent of Saps
When water evaporates through the leaves, a pull is created through the xylem, and water moves back to the leaves. This is known as the transpiration pull.
The ascent of sap that is driven by transpiration depends on the following properties of water:
Cohesion – This is the mutual attraction between molecules of water.
Adhesion – The attraction of water molecules towards polar surfaces.
Surface tension – The molecules of water are more attracted to each other in the liquid phase than in the gas phase.