Saturation Kinetics of the Velocity of Stomatal Closing in Response to CO21

AUTOR(ES)

Raschke, Klaus

RESUMO

Stomatal closing movements in response to changes from CO2-free to CO2-containing air were recorded in leaf sections of Zea mays using air flow porometers. The response to CO2 was fast; the shortest lag between the application of 300 microliters CO2 per liter of air and the beginning of a stomatal response was 3 seconds. The velocity of stomatal closing increased with CO2 concentration and approached its maximal value between 103 and 104 microliters CO2 per liter of air. The CO2 concentration at which the closing velocity reached half its maximal value was approximately 200 microliters CO2 per liter of air, both in the light and in darkness. This indicates that the mechanism of stomatal responses to CO2 is the same in both light regimes and that the range of stomatal sensitivity to changes in CO2 concentration coincides with the range of CO2 concentrations known to occur in the intercellular spaces of illuminated leaves.

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