Researchers have developed a spray coating for greenhouses that could optimise the wavelength of light shining onto plants, potentially improving their growth and yield.
The technology could help extend the growing seasons for fruit and vegetables in a more sustainable way.
Developed by team of scientists at the University of Bath, University of Cambridge and commercial partner Lambda Agri, the coating has the potential to help farmers to produce more crops while using the same or less energy.
Photosynthesis is most efficient at the wavelength of red light - green is the least efficient - but sunlight is a mixture of all the colour spectrum which means much of the light that shines on plants is not used. The spray coats greenhouse glass and absorbs blue light from sunlight, converting it to red light, increasing the fraction of red light that can be used by the plants.
The researchers said that other similar technologies have used expensive rare earth materials such as indium; this new spray replaces that with a patent-pending lower cost, more abundant material. In addition, the materials can be made using a chemical flow reactor, speeding up the manufacture process and making it more easily scalable.
Professor Petra Cameron, from the University of Bath’s Institute of Sustainability and Climate Change, said the coating contains molecules that absorb UV light and converts around 80-90% of it into red light, making photosynthesis more efficient. Cameron said that field trials have reported a nine per cent increase in crop yield when growing basil in treated greenhouses. As well as changing the wavelength of the light coming into the greenhouse, the coating also scatters the light, which increases the yield, and she said there is some evidence to suggests it improves the taste by raising the sugar content in the fruit.
Professor 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.”
The team has submitted a patent for the technology and published their research in the journal Advanced Materials Technologies.
The paper explains: “The coating reduces the amount of transmitted [photosynthetically active radiation] by 8% but has advantageous effects on diffuse radiation and in reducing the internal mean temperature.” It adds: “Although there is some uncertainty as to the contribution of down-shifting, with the bulk of the increase probably being due to higher diffused light and the reduction in maximum daily temperatures, this study establishes a model for the design of [luminescent down-shifting] paints for real-world agricultural applications.”
The researchers hope to make the technology commercially available for growers in a few years.
The development was backed by two UK government grants, including a DEFRA project worth £500,000 and a second £750,000 project within DESNZ’s Net Zero Innovation Portfolio.
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