Towards a plant-based method of CO₂ management

Three plant-based approaches to greenhouse CO₂ management were explored in commercial and experimental tomato greenhouses. These were: (1) simulation modelling, (2) a non-destructive analysis of growth and (3) plant carbon status. A cost and benefit analysis using simulation modeling was carried out using grower-collected greenhouse environment and yield data. Simulation modelling was useful in a retrospective analysis for determining the costs and benefits of several CO₂ dosing scenarios. However, the analysis was hampered as a C0₂ management tool because key data relating CO ₂ production to the CO₂ concentration in the greenhouse was unavailable and also because the yield model was inaccurate. Nondestructive measures of growth are collected by growers and might be useful as plant-based indicators of CO₂ response. However, the measures investigated were deemed to be too sluggish to be used for CO₂ dosing decision-making. Finally, plants under CO₂ enrichment can accumulate substantial amounts of starch in their leaves and excess starch may indicate CO₂ over-dosing. Plant carbon status was investigated by determining the distribution of leaf starch in the canopy and diurnally. These profiles led to the identification of canopy strata that are under the influence of both source and sink. The carbon status of this region maybe useful for CO₂ dosing decisions and is worthy of further study.