Maximising energy saving in the production of protected ornamentals using temperature integration: the conflict with humidity control and CO2 enrichment.

Good quality ornamental pot plants can be produced during the UK winter period under supplementary lighting using temperature integration.  Whilst high RH and low CO2 can be expected to coincide with periods when accumulated temperature credits are being used, in practise this had minimal impact on final quality of pot chrysanthemums for experiments carried out over the winter 2004/05 period. 

Climate change levy costs in addition with the escalating price of fuel, have resulted in the urgent need to provide protected crops growers with options to save energy whilst maintaining crop quality and scheduling.  Previous HDC funded projects have demonstrated how temperature integration can fulfil these requirements for different ornamental and edible crops.  

In spite of these developments, growers remained reluctant to fully adopt the technology.  This was apparently due to fears over how higher than usual humidities resulting from the lower than usual night temperatures associated with temperature integration might impact on disease incidence and plant quality.  This was coupled with concerns that where CO2 is harvested from boiler flue gasses, reduced boiler use during the day would lead to lower levels of CO2 availability and may therefore effect plant quality. 

The expected deliverables to growers from this work were to provide answers to the following quality related issues: 

• Do regular periods of higher than usual humidities (as a consequence of saving energy by relaxing humidity control) have deleterious effects on pot plant quality when disease risk is taken out of the equation? 

• Does reduced CO2 availability (as a consequence of temperature integration) have deleterious effects on perceived plant quality and longevity? 

Ultimately it was hoped that this would improve knowledge and therefore confidence in fully utilising temperature integration and allow growers to fully benefit from the energy savings possible.