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What is transpiration in water cycle?

What are the factors affecting transpiration in plants?

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The process of transpiration is basically the process of water loss. In plants a large amount of water is absorbed by the root system and reaches to the leaves or the apical of plants.

From this large amount of absorbed water, very small amount is utilized in the physiological usage of plants.

The large amount of the lost water is in the form of vapour that is evaporated by the aerial parts of the plant into the atmosphere. The process of water loss is known as transpiration.

There are three types of transpiration:

  1. Cuticular transpiration: is the process where transpiration occurs at the aerial parts of the plant. In the plants the leaves are covered by cuticle which is impermeable to water. So the transpiration by the aerial parts is negligible.
  2. Lenticular transpiration: is the process where transpiration occurs through the lenticles on the stem of plants that is also takes place at very less amount.
  3. Stomatal transpiration: is the process where transpiration occurs by the stomata of the leaves. Large amount of transpiration takes place by this process. Stomata are the epidermal structure of plant that helps in the exchange of water vapour between the plant and the atmosphere.

There are four main factors that affect the process of transpiration. They are as follow:

  1. Humidity: This factor is correlated with the moisture of the atmosphere. The amount of the moisture in the atmosphere is inversely proportional to the process of transpiration. More the moisture, less transpiration and less the moisture, more the transpiration. It is the main factor that affects the process of transpiration.
  2. Temperature: The rate of the process of transpiration is directly proportional to the rate of the temperature. At the high temperature, the process of transpiration increases.
  3. Wind: is the stimulating factor that positively affects the process of transpiration. As, the wind helps in the replacement of moist air by the dry air that stimulates the process of transpiration.
  4. Light: is the main factor for plant. It helps in the photosynthesis but very small amount of light is used for this process whereas large amount of light is responsible for the generation for the heat at the aerial parts of the plant. This heat induces the process of transpiration.

There are some other factors that affect the process of transpiration:

  1. The capacity of water absorption by the roots from the soil.
  2. The process also depends on the structure and area of the leaf which is used for transpiration.
  3. Broder the lamina, higher the transpiration.
  4. More the stomata, higher the transpiration. It also depends upon the distribution of stomata on the leaves.
  5. Less the cuticle on the leaf surface, more the transpiration.

Signification of transpiration:

  1. It plays an important role in the ascent of sap process, where the water moves from the roots and stem towards the arial tip of the plant.
  2. Due to the process of transpiration, more amount of minerals are absorbed by the roots.
  3. This process creates cooling that maintains the temperature of the leaves, which produces heat during the process of the transpiration.
  4. The process of transpiration also has a side effect to the plant by which, more the transpiration, more the water loss. During this process if the water loss is more compare to the absorption of water by the roots, the plant develops the water-stress. Due to that the growth of plant gets retarded that is harmful for the plant survival.
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