Sensing of atmospheric CO₂ by plants

Abstract

Abstract. Despite recent interest in the effects of high CO 2 on plant growth and physiology, very little is known about the mechanisms by which plants sense changes in the concentration of this gas. Because atmospheric CO 2 concentration is relatively constant and because the conductance of the cuticle to CO 2 is low, sensory mechanisms are likely to exist only for intercellular CO 2 concentration. Therefore, responses of plants to changes in atmospheric CO 2 will depend on the effect of these changes on intercellular CO 2 concentration. Although a variety of plant responses to atmospheric CO 2 concentration have been reported, most of these can be attributed to the effects of intercellular CO 2 on photosynthesis or stomatal conductance. Short‐term and long‐term effects of CO 2 on photosynthesis and stomatal conductance are discussed as sensory mechanisms for responses of plants to atmospheric CO 2 . Available data suggest that plants do not fully realize the potential increases in productivity associated with increased atmospheric CO 2 . This may be because of genetic and environmental limitations to productivity or because plant responses to CO 2 have evolved to cope with variations in intercellular CO 2 caused by factors other than changes in atmospheric CO 2 .