Design and performance of unique field chamber and CO2 control system for the investigation of biological impacts on wheats grown under fluctuating CO2

Mahabubur Mollah1, Glenn Fitzgerald2

1 Agriculture Victoria Research, DJPR – Horsham, Vic, 3400, Email:

2 Agriculture Victoria Research, DJPR – Horsham, Vic, 3400


The CO2 concentration [CO2] in the atmosphere is increasing, affecting plant growth and development. Free Air CO2 Enrichment (FACE) technology is used for the study of plant development under elevated CO2. However, criticism of the FACE technology is that it underestimates plant and crop responses to elevated [CO2] because rapidly fluctuating [CO2] within the FACE rings may force stomata to close more often and for longer periods than would occur under non-FACE conditions. Therefore, data from FACE rings cannot be used as validation for plant and crop responses in crop modelling. This report focuses on the engineering of chamber design to test constant vs. variable changes in [CO2] levels on crops. Three chambers were built, and a non-replicated study was conducted during the 2015 and 2016 seasons to assess the methodology and chamber design. The chambers were set up to test the impacts of constant ambient [CO2], elevated [CO2] and variable [CO2] on wheat biomass, yield and water use efficiency. The chamber design and control system performed as expected keeping 1 min average CO2 concentration within 1.8 µmol/mol (insignificant variation) to the set point of 610 µmol/mol for elevated CO2 treatments (fluctuating and constant).


The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography Graham Centre for Agricultural Innovation, Charles Sturt University

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