How does light intensity influence transpiration?

Light intensity increases the rate of transpiration by stimulating the opening of the stomata in plant leaves.

Transpiration is the process by which water is carried through plants from roots to small pores on the underside of leaves, where it changes to vapour and is released to the atmosphere. This process is significantly influenced by light intensity. During the day, when light intensity is high, the stomata (small openings on the leaf surface) open to allow for the exchange of gases. This opening of stomata facilitates transpiration as water vapour escapes from the leaf to the atmosphere.

The relationship between light intensity and transpiration can be explained through the process of photosynthesis. Photosynthesis, the process by which plants convert light energy into chemical energy, requires carbon dioxide from the atmosphere. The stomata, when open, allow for the intake of carbon dioxide. However, when these stomata open, water vapour within the plant also escapes, leading to transpiration. Therefore, during periods of high light intensity, when photosynthesis is at its peak, the rate of transpiration also increases.

Furthermore, light also influences the temperature and humidity within the plant's environment. High light intensity often correlates with increased temperatures, which can increase the rate of evaporation from the leaf surface, thereby increasing the rate of transpiration. Conversely, low light intensity often correlates with lower temperatures and higher humidity, which can reduce the rate of transpiration.

In summary, light intensity plays a crucial role in regulating the rate of transpiration in plants. It does this primarily by influencing the opening and closing of stomata, but also by affecting environmental factors such as temperature and humidity. Understanding this relationship is key to understanding the overall water balance within plants.