Improved strategies for controlling CO2 enrichment in tomato greenhouses

A simulation analysis using biological models of photosynthesis, photosynthate partitioning to tomato fruit, fruit growth, and a seasonal fruit price model was undertaken to predict the increase in fruit value obtained by increased CO2 concentrations. Physical models were used to predict the losses of CO2 by leakage and by ventilation, and using the CO2 price enabled the costs of enrichment to be determined. By running the simulation over the tomato season with suitable meteorological data, it was possible to determine the economic performance of specific CO2 enrichment strategies. These showed that, for UK conditions in winter when the ventilators were closed, the concentration which gave the greatest financial margin of fruit value over cost of CO2 was summer, the constant concentration which gave the greatest margin when the ventilators were more than 5% open was 500 vpm. The simulation was used to evaluate a number of other CO2 enrichment strategies.