Optimised CO2 enrichment management for long-season tomato production in a UK tomato crop


PE 021a - Optimised CO2 enrichment management for long-season tomato production in a UK tomato crop

Start Date: 
Completion Date: 
Project Leader: 
Dr Ewan Gage, ADAS
PE 021a
Industry representativeDr Philip Morley
AHDB Horticulture Cost: £77,321
SummaryThis project directly builds on the outputs from the AHBD funded project PE 021 (Mulholland 2016 et al.), “Targeted enrichment management for long season crop production in the UK”.  This project discovered that biological demand for CO2 by the crop was dynamic and that there was potential to better meet CO2 demand through targeted enrichment dosing.  The project also developed a method to calculate CO2 offtake by the crop using non-destructive measurements and a photosynthesis-based model of crop CO2 uptake. By developing a biological approach to CO2 dosing, a variety of routes to enhanced CO2 efficiency were identified to complement other decision making processes relating to CO2 dosing, such as enrichment according to the economics of spark spread and CHP use.  There is a pressing need however to commercialise these findings to understand how to maximise offtake under fluctuating supply of CO2 and crop demand, and to use this knowledge to increase marketable yield above current standard tonnages per hectare.  A key next step will be to stimulate latent photosynthetic potential in the mid and lower canopy region to directly harness enhanced leaf CO2 assimilation for increased marketable yield with acceptable or enhanced fruit quality.
Aim: To drive increased marketable tomato crop yield through by enhanced CO2 use efficiency.
1. To maximise the impact of targeted CO2 enrichment by developing appropriate inter-lighting strategies at selected shoot densities for canopy photosynthesis, growth habit and yield output in a commercial tomato crop.
2. To quantify the effect of driving maximum CO2 use efficiency on carbon/nitrogen partitioning within the plant, and effects on marketable fruit characteristics e.g. proportion of in-spec produce, fruit flavour, texture and sugars. 
3. To generate and promote information that is directly relevant to the UK tomato industry which will be used to promote step change increases in commercial crop yield, including updates to agronomic practice and preliminary economic evaluations of using supplementary lighting provision to drive CO2 uptake. 
4. To integrate the outputs of Obj. 1 – 3 to understand the impact of targeted CO2 and supplementary lighting management for long season UK tomato crops. 
5. To use the outputs of PE 021 and combine with the current proposed project to develop grower-ready guidelines for integrated lighting and CO2 dosing in UK tomato production. 
6. To interact with industry representatives on a monthly basis to communicate outputs of the project in both verbal and written forms, and ensure outputs are best aligned to industry needs.
1) The UK tomato industry contributes £175m of product into a market worth £620m. The devaluation of the GBP as a result of “Brexit” has made tomato a key candidate for import substitution as home grown produce becomes increasingly competitive against the 72% of produce that is currently imported. To realise this potential in a timely fashion, yields from existing facilities must be maximised using optimum resource use efficiency to ensure that UK growers can meet rising demand. The outputs of the project are directly relevant to promoting yield increases, and a preliminary economic feasibility study of CO2 management enhanced with supplementary lighting will be included in the project to illustrate the economic benefits of this approach to growers along with its optimum integration with other resource provision. Conservative estimates of yield increases of 20% as a result of supplementary lighting are reported anecdotally in the UK industry. By providing an evidence base to support the use of supplementary lighting to drive enhanced CO2 use, there is potential for UK growers to add a further £35m to their annual outputs without investing in additional glasshouse facilities (based on a proportionate increase of 20% of current market value). Full realisation of this benefit can only occur if the industry is provided with sufficient evidence to support investment decisions, and methods of incorporating these into existing practice. 
2) Based on typical values, the UK tomato industry uses 360,000 tonnes of CO2 a year, at a cost of £29m (assuming £80/tonne of CO2, although this can reach £125/tonne based on conditions of use). If current practice only utilises 25% of this, annual wastage costs represent £23m to UK growers annually. The economic benefit of this project will be the provision of evidence to support growers in achieving the maximum return on the costs of CO2 and supplementary light provision from interlighting. If supplementary lighting is able to increase crop CO2 offtake by 50%, a reduction of £3.6m could be seen in wastage by the UK industry pa, which would of be of direct economic benefit in real terms by reduction in carbon tax levies. By fully quantifying the increases in CO2 uptake that can be achieved by supplementary lighting, and linking optimum crop management strategies that favour CO2 capture and partitioning of carbon into fruit (and ultimately marketable yield) growers will be able to derive direct economic benefit via maximised returns on the cost of CO2 provision.