Cropping Beyond the Visible; Innovative, UV-Emitting LED Applications for the Horticultural Industry

The estimated increase in the world population to 9.7 billion by 2050 and the increased frequency of extreme weather events caused by climate change will put further pressure on world food supply. This emphasises the need to optimise all agricultural techniques. Indoor farming provides novel opportunities to efficiently manipulate crop production by the control of key environmental parameters such as light, temperature, and water availability, which normally vary depending on the local weather and season. While there is extensive information concerning the manipulation of visible wavelengths and the consequent effects on growth and crop quality, there is less practical information on the exploitation of UV wavelengths for crop manipulation. Recent advances in UV Light Emitting Diodes (LEDs) technology have further expanded these possibilities, providing innovative tools for precise spectral control of plant architecture, flavour, and stress resistance. By using appropriate UV-LEDs and optical components, a homogenously illuminated area of the desired size can be obtained, while avoiding light pollution and increasing LED energy efficiency further. This review explores the emerging potential of UV-LEDs but also serves as a practical guide to the different UV sources that can be employed in controlled-environment agriculture. It discusses important technical considerations for selecting single-wavelength LEDs, along with current limitations in LED performance.