Question

Name the factors that affect the rate of transpiration. State their role in each case.

Answer 1

The factors that affect the rate of transpiration includes :

Sunlight:

• During daytime the rate of transpiration is faster.
• This is because the stomata remain open to allow inward diffusion of carbon dioxide for the process of photosynthesis.
• During night time the stomata remain closed and thus transpiration hardly occurs.

Temperature:

• Transpiration is faster on hot summer days due to faster evaporation of water.
• Similarly on cold winter days, when the temperature is low the rate of transpiration reduces.

Wind:

• Transpiration is more when the wind is blowing faster as the water vapour moves away from the leaf surface.
• This allows diffusion of water vapour into the atmosphere easily.

Humidity:

• Humid air cannot hold moisture and as it is already laden with water vapours.
• Thus, in high humidity condition, transpiration is reduced.