Stomatal Sensitivity to Carbon Dioxide and Humidity

The sensitivity of stomatal conductance to changes of CO2 concentration and leaf-air vapor pressure difference (VPD) was compared between two C3 and two C4 grass species. There was no evidence that stomata of the C4 species were more sensitive to CO2 than stomata of the C3 species. The sensitivity of stomatal conductance to CO2 change was linearly proportional to the magnitude of stomatal conductance, as determined by the VPD, the same slope...