Physiological modelling shows the options for a grower how to sustain high production levels with constrained supply of CO₂ fertilizer

In the coming years the supply of industrial CO₂ for greenhouse crop fertilization will decrease due to the measures to reduce fossil fuel use and the carbon footprint of industry. The limitation in CO₂ supply urges growers to dose CO₂ as efficient as possible. Using an extensive physiological model of tomato, we simulated the crop's adaptation to lower CO₂ concentrations while aiming at a similar production level as for high CO₂ supply. Despite a twofold decrease in CO₂ supply the modelled production was shown to hardly decrease as a result of a smart CO₂ dosage following crop demand and a constrained room opening without causing too high temperatures. The higher CO₂ utilization efficiency was also increased by simulating an increase in CO₂ assimilation of the leaves as observed in experiments on plant adaptation to lower CO₂ levels. A series of model scenarios were carried out to test the effects of air movement, humidity and timing of additional CO₂ supply on CO₂ utilization efficiency. The prospects of designing a feasible CO₂ constrained greenhouse system are discussed.