Investigate and describe the effects of variation of temperature and wind speed on transpiration rate

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Sourav · Answer

The effects of temperature and wind speed on the rate of transpiration in plants are significant and can be summarized as follows:

Effects of Temperature on Transpiration Rate

Increased Temperature:
- As temperature rises, the rate of transpiration increases. This is primarily due to the following reasons:
  - Increased Kinetic Energy: Higher temperatures provide water molecules with more kinetic energy, causing them to evaporate more quickly from the surfaces of mesophyll cells into the air spaces within the leaf.
  - Enhanced Diffusion: Warmer air can hold more water vapor, which creates a steeper concentration gradient between the inside of the leaf (where water vapor concentration is higher) and the outside atmosphere (where it is lower). This gradient promotes faster diffusion of water vapor out of the stomata.
  - Stomatal Opening: Higher temperatures often coincide with increased light intensity, leading to stomatal opening for gas exchange during photosynthesis, which further facilitates water loss through transpiration .
Optimal Range:
- While increased temperature generally enhances transpiration rates, extremely high temperatures can lead to stress in plants, potentially causing stomata to close to conserve water, which may reduce transpiration rates if prolonged .

Increased Wind Speed:
- As wind speed increases, the rate of transpiration also increases. This occurs due to several factors:
  - Removal of Water Vapor: Wind helps to quickly disperse water vapor that accumulates around the leaf surface. When water vapor is removed from the vicinity of the stomata, it maintains a steep concentration gradient, allowing more water vapor to diffuse out of the leaf.
  - Enhanced Evaporation: Increased air movement enhances the evaporation rate from the leaf surfaces by replacing humid air with drier air, which encourages further evaporation .
Impact on Humidity:
- Wind can also reduce local humidity levels around plants. In still air, humidity can build up around leaves due to transpiration, which may slow down further water loss. However, windy conditions prevent this buildup and promote continuous transpiration