Photosynthesis and Photorespiration in Douglas-fir as Influenced by Irradiance, CO2 Concentration, and Temperature
Abstract:Gas exchange of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) was studied using an infrared gas analyzer with a closed system. Apparent photorespiration was estimated from the extrapolation of apparent photosynthesis to zero CO2 concentration and light respiration was derived from the post-illumination burst of CO2. Apparent photosynthesis increased with increasing irradiance and CO2 concentration and had a temperature optimum range of 10°-15°C. Apparent photorespiration increased with increasing irradiance and temperature. Light respiration increased with increasing irradiance, increasing temperature, and decreasing CO2 concentration. Values obtained from the difference between apparent photorespiration and light respiration suggest that photosynthetic refixation of photorespired CO2 increases with increasing temperature and that in the light at 5°C dark respiration contributes appreciable amounts of CO2, but this contribution decreases at higher temperatures. Forest Sci. 27:641-650.
Document Type: Journal Article
Affiliations: Professor of Botany, University of Washington, Seattle, Washington 98195
Publication date: December 1, 1981
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