A CO2 CONTROL SYSTEM FOR A GREENHOUSE WITH A HIGH VENTILATION RATE

K. Ohyama, T. Kozai, Y. Ishigami, Y. Ohno, H. Toida, Y. Ochi
2005 Acta Horticulturae  
A simple CO 2 control system was developed for a greenhouse with a high natural or forced ventilation rate. This CO 2 control system maintains the difference in CO 2 concentration between inside and outside the greenhouse, ∆C, during daytime being small (ca. 5 µmol mol -1 ), by supplying a variable amount of CO 2 gas with time. Results showed that this system worked satisfactorily, while the CO 2 concentration outside the greenhouse varied with time in a range between 350 and 450 µmol mol -1
more » ... 450 µmol mol -1 with an average of 380 µmol mol -1 . In this system, the CO 2 supply rate was determined based on the time course of ∆C only, and does not consider any physical or physiological mechanisms of CO 2 balance in the greenhouse. Theoretically, the CO 2 supply rate is equal to the net photosynthetic rate of greenhouse crops (Pn), if both rates of CO 2 emitted from the substrate/floor and CO 2 exchange between inside and outside the greenhouse are negligibly small. Hence, this CO 2 control system will be useful not only for monitoring and increasing the Pn in a greenhouse with a high ventilation rate, but also as a diagnosis tool for monitoring the physiological status of greenhouse crops.
doi:10.17660/actahortic.2005.691.79 fatcat:cmmu2ufuwfgt5ipfwdsqqfpnpq