Arie de Gelder, Mary Warmenhoven, Anja Dieleman, Peter Klapwijk and Piet Hein van Baar
Wageningen UR Greenhouse Horticulture developed a CO2 supply strategy in which slightly more CO2 is given than is taken up based on the amount of light. A test at GreenQ Improvement Centreresulted in a CO2 concentration in the greenhouse with open windows slightly above the outside value. With this supply strategy, 17 kg/m² CO2 supply resulted in a production level of 62.5 kg/m² tomato (cultivar Komeett). The energy consumption is 26 m3/m². When the stomata are open, the resistance of CO2 on the way from the environment into the chloroplast is for 40% determined by the transport of CO2 through the cell wall and the cytosol and for 60% by the diffusion resistance of greenhouse air to the intercellular space. A thin leaf with lots of spongy parenchym is therefore beneficial for CO2 binding. The number of stomata per cm2 leaf is therefore less important. Closing of the stomata inhibits photosynthesis within a minute because the CO2 in the leaf is then depleted. Comparison of the leaf structure at two heights in the crop with plants of the same variety in another compartment did not show differences, neither in height nor in treatment. This project was financed by Kas als Energiebron and Samenwerken aan Vaardigheden.