A new canopy photosynthesis and transpiration measurement system (CAPTS) for canopy gas exchange research

Accurate measurement of canopy gas exchange rates is crucial for studying canopy photosynthetic resource use efficiencies. We designed, created, and evaluated a new canopy photosynthesis and transpiration measurement system (CAPTS). The CAPTS included: (1) modular chamber sides, (2) sensors for temperature, CO2, air pressure and humidity that were integrated on a removable chamber cover, and (3) a user-friendly console for control of automatic opening and closing of the chamber cover for data recording, storage and analysis. The CAPTS can accurately measure canopy photosynthetic CO2 uptake rate, which was demonstrated with both rice and tobacco. The CAPTS provides a basic ability to measure rates of photosynthesis, respiration, and transpiration of plot-size canopies and other components of agro-ecosystems.