Stomatal conductance
A measure of how readily carbon dioxide and water vapor pass through a leaf's stomata, reflecting pore opening and the gas-exchange capacity of the leaf surface.
Conductance is the inverse of resistance. Higher stomatal conductance allows gases to move more readily between the leaf interior and the surrounding air; lower conductance restricts that movement.
Gas-exchange systems and porometers estimate stomatal conductance per unit leaf area. The value responds to light, carbon dioxide, humidity, temperature, water status, hormones, leaf age, and genetics.
Because carbon dioxide enters while water vapor exits through the same pores, a conductance change can affect photosynthesis and transpiration Transpiration Water moving up through the plant and evaporating out through the stomata. It drives nutrient uptake, and carries calcium, which moves almost entirely by that flow. together. Elevated carbon dioxide often reduces stomatal opening, but the size of the response varies among species, cultivars, and conditions.