Abstract
Just when you thought illumination engineering was dead and that lighting design, with its emphasis on perceptions, was the future, the knowledge of the illuminating engineer has become important again. True, this is not for humans but for plants. Lighting for horticultural products has become a subject of serious research, for a number of reasons. The first is that the production of high-value horticultural products close to where they are to be sold is becoming economically and environmentally attractive, and not just for countries at extreme latitudes. The second is that light can now be used not just to enhance photosynthesis but also to control the growth, fruition, and nutritional value of plants. What delivers these benefits is the same light source that has caused so many changes in lighting practice for humans, the LED. The ability to manipulate the amount of light and the emitted spectrum easily and quickly makes the LED an ideal light source for manipulating plant growth. Further, because of its small size, the LED can be placed very close to the plant, even within the canopy of tall, leafy plants, such as tomatoes. This increases the efficiency of light delivery. As a result of these possibilities it is predicted that the horticultural lighting market will increase from the $2.43 billion it was in 2018 to $6.21 billion in 2023. This is why some major light source manufacturers are partnering with universities to develop flexible lighting systems for horticulture.
This expansion of the world of lighting is exciting but also represents a challenge. The principles of illuminating engineering are well established but it has always been a means to an end, namely the delivery of the required stimulus to a system. For many years, the only system of interest was the visual system with the result that all the familiar photometric and colorimetric quantities are based on the response of the visual system. Today, the circadian system is of interest and in the near future horticultural systems will be too. These two systems have very different characteristics from the visual system so anyone exploring the impact of light, or more correctly, radiation, in these areas will have a lot to learn. Much more research will certainly be needed.
The Society of Light and Lighting is pleased to make the following awards for papers published in Lighting Research and Technology in 2018. The Walsh-Weston Award goes to M Stokkermans, I Vogels, Y de Kort and I Heynderickx for their paper “Relation between the perceived atmosphere of a lit environment and perceptual attributes of light”. The Leon Gaster Award goes to MG Figueiro, R Nagare and LLA Price for their paper “Non-visual effects of light: How to use light to promote circadian entrainment and elicit alertness”. Congratulations to all authors.