Factors Affecting Transpiration - QS Study
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Affecting factors of transpiration are of two types; External and Internal.

(a) External Factors:

Light: Photosynthesis takes place in presence of light and as a result stomata opens. So light is the main factor, which influence transpiration

Temperature: With the increase of temperature water vapourises rapidly and increased the humidity in the atmosphere. So temperature controls the rate of transpiration.

Relative Humidity: If relative humidity is less the water vapour holding capacity of the air decreases, therefore rate or transpiration decreases.

  • Air Current: The air current disposes the saturated air (as a result of transpiration), away from the plant and thus increases the rate of transpiration.
  • Atmospheric pressure: Under low pressure water vapourise at low temperature. So if pressure decreases the rate of transpiration increases and if pressure increases the rate of transpiration will decrease.
  • Soil water: If availability of soil water is less the rate of transpiration will decrease.


(b) Internal Factors:

  • Root-Leaf Ratio: If the number and total surface area of leaves become much less in comparison with root region (absorption region) the rate of transpiration will reduce.
  • Leaf area: The greater the leaf area, greater will be the rate of transpiration, and lesser the leaf area the lesser the rate of transpiration.
  • Internal surface of leaf: Thin cuticle, thin cell walls, exposed stomata, and well-developed spongy parenchyma favour transpiration. On the other hand leaves those possesses thick cuticle, thick cell walls, well-developed palisade parenchyma, Sunken stomata etc. will reducd the rate of transpirations.