Factors Affecting Transpiration in Plants

Factors Affecting Transpiration in Plants

External Factors

(i) Atmospheric humidity: The rate of transpiration decreases with the increasing atmospheric humidity. Dry air favours vigorous transpiration. If the atmospheric humidity is more than the humidity present inside the stomatal pore then the atmosphere will not be able to accept more vapour.

(ii) Temperature: Increase in temperature increases the rate of
transpiration.

(iii) Light: Light is essential for the opening of stomata (due to photosynthesis) and for increasing the temperature.

(iv) Wind: The transpiring surface continuously receives water vapour and becomes saturated with it. If the wind does not remove the vapour from the transpiring surface the rate of transpiration will fall or it may be stopped. More transpiration occurs on windy days.

(v) Atmospheric pressure: Lowering of atmospheric pressure increases the rate of diffusion of water vapour into the
atmosphere.

(vi) Availability of water: If the water is not present sufficiently for absorption the rate of transpiration decreases.

Internal Factors

Morphological and anatomical adaptations are important factors that regulate transpiration. These are :
(i) reduction of the size of the leaves in xerophytic plants.
(ii) replacement of leaves by spines in xerophytic plants.
(iii) presence of sunken stomata.
(iv) development of thick cuticle, presence of wax, resin, suberin, hair coating on the leaf surface reduces the rate of transpiration.
(v) rate of transpiration is less in the seedling stage and in the aged plant.

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