Light-changing greenhouse paint could help extend UK fruit growing season

Because the UK’s growing season is relatively short due to its climate and latitude, we rely on European imports for most of our fruit and vegetables, grown in huge greenhouses with artificial lighting that consume huge amounts of electricity.

Now scientists from the Universities of Bath and Cambridge, in collaboration with commercial partner Lambda Agri, have developed a spray-on greenhouse coating that could help UK farmers produce more crops in the future using the same or less energy.

The development is actively supported by two UK Government grants, including a £500,000 DEFRA project and a second £750,000 project as part of the DESNZ Net Zero Innovation Portfolio.

Photosynthesis—the process plants use to capture sunlight and use energy to convert carbon dioxide and water into sugars—is most efficient at red light wavelengths. Green light is the least effective, so plants do not absorb it and therefore appear green.

Sunlight is a mixture of the entire color spectrum, so most of the light that hits plants is not used.

The new spray coats existing greenhouse glass like a varnish; this layer absorbs blue light from sunlight and converts it into red light, increasing the proportion of red light that can be used by plants, which increases crop yield.

More sustainable technologies

Although other researchers in the US have previously achieved growth enhancements using similar technologies, they use rare earth materials such as indium. This metal is used in phone screens, but is very expensive and difficult to recycle.

As a result of Bath and Cambridge’s collaboration with Lambda Agri, indium was replaced by a patented material that was cheaper and more abundant.

They can also produce materials using a chemical flow reactor, which speeds up the production process and makes it easier to scale up.

Sweet fruits

Professor Petra Cameron, from the Institute of Sustainability and Climate Change (ISCC) at the University of Bath, said: “The way our coating works is similar to when you go to a nightclub and your gin and tonic glows under an ultraviolet light – the chemical quinine in the tonic Absorbs ultraviolet light and re-emits it as visible light.

“Our coating contains molecules that absorb ultraviolet light from the sun and convert about 80-90% of it into red light, which makes photosynthesis more efficient, meaning we can grow better with less light.

“In field trials, we observed a nine percent increase in yield when basil was grown in treated greenhouses.

“This means that in the future our technology could be used to extend the growing season of production and use less artificial light to achieve the same results, saving money and reducing associated carbon emissions.

“In addition to changing the wavelength of light entering the greenhouse, the coating also diffuses the light, which also increases yield.

“There is even some evidence that it improves flavor by increasing the sugar content of fruit.”

Professor Dominic Wright, from the University of Cambridge’s Inorganic and Materials Chemistry Section, said: “This is a good application of basic molecular science to an important, real-world problem that is particularly important in the context of food security. and global warming.

“There is a very real prospect that this will have a significant impact on the availability and price of soft fruit and salad vegetables for consumers in the future, particularly in northern European countries such as the UK where weather conditions are less than ideal.”

Dr Monica Saavedra from Lambda Agri said: “Lambda stands for the sustainable fight against food poverty. The UK is already suffering from climate change, so the UK Government is actively funding and supporting our mission. Both the University of Cambridge, where we are currently based, and the University of Bath work closely together and share our vision.”

The team filed a patent for the technology and published their research in a journal. Advanced Materials Technology. They hope to make the technology commercially available to manufacturers in a few years.