What is the Difference Between Stomatal Conductance and Transpiration?

Stomatal conductance and transpiration are related but distinct processes involved in plant physiology. Here are the key differences between the two:

• Stomatal Conductance: This refers to the rate of CO2 entering or water exiting through the stomata of leaves, which are the small pores on the epidermis of plant leaves. Stomatal conductance is determined by the degree of stomatal aperture, which in turn affects the rate of gas exchange and water loss through the stomata. It is influenced by factors such as canopy temperature, relative humidity, and the supply of water to the leaves.
• Transpiration: This is the process of water movement through a plant and its evaporation from aerial parts of stems, flowers, or leaves. Transpiration is closely related to stomatal conductance, as water loss through stomata is directly related to the degree of stomatal opening, the supply of water to the leaves, and the evaporative demand of the atmosphere surrounding the leaf. Transpiration is ultimately regulated by the plant through stomatal adjustment and is driven by environmental factors.

In summary, stomatal conductance is the rate of gas exchange and water loss through the stomata, while transpiration is the broader process of water movement and evaporation within the plant. Stomatal conductance plays a significant role in regulating transpiration and can influence photosynthesis rates.

Comparative Table: Stomatal Conductance vs Transpiration

Here is a table comparing stomatal conductance and transpiration:

In summary, stomatal conductance refers to the exchange of gases and water vapor through the stomata of leaves, while transpiration involves the movement of water within the plant and its evaporation from aerial parts. These processes are interconnected, as stomatal conductance affects the rate of transpiration and, consequently, the water balance and photosynthetic efficiency of the plant.