Estimating carbon dioxide offtake by commercial UK tomato crops to optimize enrichment strategies

E. Gage, I. Corkley, C. Whiteside, B. Mulholland
Carbon dioxide (CO2) enrichment to a target concentration of 1000 ppm has become standard practice in the UK tomato industry to promote high yields in vented glasshouses. This requires CO2 dosage rates above 300 kg ha‑1 h‑1, representing a significant economic cost. The lack of standard practice to quantify crop CO2 uptake relative to venting losses has so far made growers cautious in any attempt to optimize the use of this resource at the potential risk of losing marketable yield. The objective of the work was to develop tools for the UK tomato industry to estimate crop CO2 usage efficiency (CO2 offtake) and to devise strategies for improved CO2 management in long season crops. Ambient crop CO2 usage was measured and used to generate a multivariate model for estimating crop CO2 uptake using environmental and non-destructive crop measurements over four seasons. Data from four commercial cultivars was used to refine the model by incorporating data from diverse growth habits to establish CO2 offtake in long season glasshouse grown crops. Supplementary interlighting was then trialed as a strategy for increasing CO2 offtake by driving lower canopy uptake by providing additional stimulus for photosynthesis and manipulating leaf ageing. A method for determining crop CO2 offtake was developed, which demonstrated that crop offtake varied between 5.3 and 19.6% depending on cultivar, season, glasshouse design and CO2 dosage rates. For conventional crops, supplementary interlighting was able to increase CO2 uptake up to 31%. Crop CO2 use can be improved by two approaches: 1) optimizing dosage rates relative to achieved concentrations and 2) enhancing light penetration/availability in the lower canopy. Improving the efficiency of CO2 assimilation by the crop represents additional route beyond engineering and energy market approaches to maximize returns on investment in CO2 provision.
Gage, E., Corkley, I., Whiteside, C. and Mulholland, B. (2020). Estimating carbon dioxide offtake by commercial UK tomato crops to optimize enrichment strategies. Acta Hortic. 1271, 185-192
DOI: 10.17660/ActaHortic.2020.1271.26
https://doi.org/10.17660/ActaHortic.2020.1271.26
tomato, CO2 enrichment, assimilation model, offtake
English

Acta Horticulturae