How does light intensity affect the rate of transpiration?

Light intensity significantly influences the rate of transpiration in plants primarily through its effect on stomatal opening. When light levels are high, plants undergo photosynthesis more effectively. To facilitate this process, stomata, which are small openings on the surface of leaves, open wider to allow carbon dioxide in for photosynthesis.

As the stomata open, water vapor escapes from the plant into the atmosphere, increasing the rate of transpiration. Therefore, in bright light conditions, the increased opening of stomata leads to a higher rate of water loss through transpiration.

In contrast, in low light conditions, stomata tend to close to conserve water, resulting in reduced transpiration rates. Thus, the relationship between light intensity and transpiration is directly proportional; as light intensity increases, so does the rate of transpiration.