Factors affecting transpiration
The factors affecting transpiration can be classified into two groups:
- External factor:
a) Light: It is a very important factor of transpiration because most of the stomata open during the daytime. If light intensity is increased, it increases the rate of transpiration.
b) Temperature: The increase in temperature increases the rate of transpiration by increasing the rate of evaporation of water from the cell surface. It also causes the opening of stomata.
c) Wind velocity: The increase in the wind velocity normally increases the rate of transpiration by removing the moist air surrounding the leaves. The transpiration is faster in the mild wind but reduces in high velocity of wind due to the rapture of stomata.
d)Humidity: The increase in the RH rate of transpiration because it influences the DPD gradient between the inter-cellular space and outside the atmosphere.
e) Soil water: The water in the soil directly affects the rate of transpiration. The water reduction in the soil causes a decrease in the rate of transpiration because of minimized photosynthesis.
f) Atmospheric pressure: The low atmospheric pressure increases the rate of transpiration through a reaction of the density of the air.
g) Pollution, dust, and chemicals: The pollution, dust particles and deposition of materials over a leaf surface decrease the rate of transpiration because of reduced atmospheric pressure and intensity of light.
- Internal factor :
a) Leaf surface: Some factors that influence the rate of transpiration such as thick cuticle, less no. of stomata of leaves, sunken stomata, phyllode, phylloclade, etc. thus rreducingttheranspiration.
b) Plant age: As the plant becomes mature, the rate of transpiration is increased.
c) Root and shoot ratio: The high and-shoot ratio increases the rate of transpiration.
d) Leaf Leaf area directly affects the rate of transpiration because, in large leaf areas, there are more stomata.
