Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/13/2014
Publication Date: 2/28/2014
Citation: Baker, J.T., Gitz, D.C., Payton, P.R., Broughton, K.J., Bange, M.P., Lascano, R.J. 2014. Carbon dioxide control in an open system that measures canopy gas exchanges. Agronomy Journal. 106(3):789-792. Interpretive Summary: Carbon dioxide in the Earth’s atmosphere is increasing mainly because humans burn fossil fuels for energy. The current level of carbon dioxide in the Earth’s atmosphere is expected to almost double by the end of this century. This carbon dioxide has large effects on plants, including crop plants that serve as food for humans. In order to develop crop varieties that can take advantage of high carbon dioxide levels, plant breeders need the ability to control atmospheric carbon dioxide levels. We have devised an outdoor, transparent chamber system that controls atmospheric carbon dioxide levels for this purpose.
Technical Abstract: Atmospheric carbon dioxide concentration ([CO2]) effects both C3 net assimilation (A) as well as crop water use. Methods for measuring whole canopy gas exchange responses under [CO2] enrichment are needed for breeding programs aiming to develop crop cultivars resistant to stresses like drought in a future higher CO2 world. In a previous study we developed and tested a portable, open transparent chamber system for measuring canopy gas exchanges. Here we describe further development of this system by adding the capability of controlling [CO2]. Pure CO2 injection into the system was accomplished with a data logger operated mass flow controller attached to a high pressure CO2 gas cylinder. Across the full range of chamber air flow rates, [CO2] enrichment controls were within ± 12 µmol mol-1 of the desired set point. Following an abrupt user-selected change in chamber air flow rate, [CO2] enrichment controls were reestablished within 3 to 5 minutes.