Researchers at the University of Bath have developed a new spray coating for greenhouses to improve plant growth and help extend the growing seasons in less sunny countries like the UK in a more sustainable way.
The technology, which can be applied like a varnish to existing greenhouses, works by optimising the wavelength of light shining onto the plants. As a result, it will enable farmers to produce more crops in the future using the same or less energy.
With a relatively short growing season in the UK due to its climate and latitude, retailers rely on European imports for most of fruit and vegetables. These tend to be grown in vast artificially lit greenhouses thaat use huge amounts of electricity.
The Bath researchers, working with a team from the University of Cambridge and commercial partner Lambda Agri, also based in Cambridge, are backed by two government grants, including a DEFRA project worth £500,000 and a second project worth £750,000 within the Department for Energy Security and Net Zero’s innovation portfolio.
While US researchers have previously achieved an increase in growth using similar technologies, they use rare earth materials such as indium – the metal used in phone screens which is very expensive and difficult to recycle.
The Bath/Cambridge collaboration with Lambda Agri deploys a patent-pending lower-cost and more abundant material.
In addition, they can make the materials using a chemical flow reactor, speeding up the manufacturing process and making it more easily scalable.
The coating works by absorbing blue light from sunlight and converting it to red light, increasing the fraction of red light that can be used by the plants, which increases the crop yield.
Prof Petra Cameron, from the University of Bath’s Institute of Sustainability and Climate Change (ISCC), explains this by describing how UV light in a night club will make a gin and tonic drink glow – the quinine chemical in the tonic water is absorbing the UV and re-emitting it as visible light.
“Our coating contains molecules that absorb UV light from the sun and converts around 80-90% of it into red light, making photosynthesis more efficient, meaning we can grow more with less light,” she added.
“In field trials we’ve seen a 9% increase in crop yield when growing basil in treated greenhouses.
“This means our technology could in the future be used to extend the growing seasons for produce and use less artificial light to get the same results, saving money and reducing the associated carbon emissions."
As well as changing the wavelength of the light coming into the greenhouse, the coating also scatters the light, which increases the yield.
There is even some evidence that suggests it improves the taste by raising the sugar content in the fruit.
Prof Dominic Wright from the University of Cambridge, Inorganic and Materials Section in Chemistry, said: “This is a nice application of fundamental molecular science to an important, real-world problem, one that is particularly important in regards to the backdrop of food security and global warming.
“There is a very real prospect of this having a significant impact on the availability and cost of soft fruit and salad vegetables for consumers in the future, especially in northern European countries like the UK, where the weather conditions are far from ideal.”
The team has submitted a patent for the technology and have published their research in the journal Advanced Materials Technologies. They hope to make the technology commercially available for growers in a few years.
