Life processes in plants are a complex, highly developed and perfectly coordinated set of progressions by which the plants grows, absorbs nutrients, prepares food materials and reproduces.
Plants have a fascinating system of absorption, nutrition, excretion and growth. One such system is the system of transpiration.
What is Transpiration?
Plants absorb water through their roots which is necessary for photosynthesis. But, only some amount of water is utilized in photosynthesis and another small part of it gets retained in the plant.
As for the remaining amount of water, which is quite large, it is excreted by plants just like humans excrete excess water.
It is necessary for the plants to remove the excess water so that it can make space and provide suction for more water to be pulled up from the roots to the rest of the plant.
Stomata are small pores present on the leaves. Leaves remove extra water through stomata and other parts that are exposed to air, into the atmosphere in the form of water vapour.
The loss of water in the form of water vapour from the aerial parts of the plant is called transpiration.
Water molecules have a tendency of remaining joined which causes them to be pulled up when water is being transpired from the plant. This is very important in tall trees as it helps water to reach great heights of 100m.
Factors That Affect Transpiration-
Many factors affect the rate of transpiration. Not only do internal factors like amount of water present in the plant play a role, but external factors do too! Factors affecting the rate of transpiration:
1. Sunlight: During daytime, the stomata remain open which helps facilitate more transpiration from them and thereby increases the general rate of transpiration. At night, stomata remain closed and thus no transpiration occurs through them.
2. Temperature: Transpiration is faster on hot days as compared to cold days.
3. Humidity: Transpiration is reduced if the air is humid and saturated. It prevents more water from entering the air and stops transpiration altogether. Thus, more the humidity, lower is the transpiration.
4. Wind: The wind helps move the air around the plants and thus prevents the air around it from being saturated. Thus, transpiration is more when wind is blowing.
Importance of Transpiration-
Transpiration is important to plants just like excretion is important for the human body. The following are the important effects of transpiration-
1. Cooling Effect:
Humans have a tendency to sweat in order to cool their bodies. The same way, plants transpire to cool themselves. In transpiration, water gets evaporated from the plant. Heat is required for evaporation. This required heat is provided by the plant itself (latent heat) which results in the lowering of the temperature of the plant.
2. Maintaining the Concentration of the Sap inside the Plant:
If the plants continue to absorb water from the roots without any outlet for removal of excess water, the concentration of water in the plant body will increase causing the sap to become dilute. The sap of the plant should be more concentrated than the particles of the surrounding soil otherwise all absorption will come to a stop, not only preventing the intake of water but also minerals. By transpiring excess water, the balance of water, minerals and continuous absorption is maintained.
Thus, we can see that transpiration is of a lot of importance in a plant. It holds a high significance and a plant cannot do without it.