By Ian Ashdown, P. Eng. (Ret.), FIES
Senior Scientist, SunTracker Technologies

Marc Descoteaux
Senior Software Engineer, SunTracker Technologies

Written in 2015, “Greenhouse Design and Control” (Ponce et al. 2015) is extraordinarily comprehensive in its coverage of greenhouse design issues, from site selection through structural load bearing analysis and ventilation technologies to greenhouse automation using adaptive neural fuzzy inference systems. On the topic of greenhouse lighting, however, it has only this to say: “The light level in the greenhouse should be adequate and uniform for crop growth.”

By Ian Ashdown, P. Eng. (Ret.), FIES Senior Scientist, SunTracker Technologies The phrase déjà vu translates from French as “already seen,” which nicely describes a current issue with horticultural lighting design.

By Ian Ashdown, Senior Scientist SunTracker Technologies Whereas human vision relies on five opsins as photoreceptors, most plants have a wide variety of photopigments that are responsive to optical radiation from 280 nm to 800 nm. Beyond photosynthesis, plants rely on this radiation to control photomorphogenesis, phototropism, shade avoidance, and both circadian and circannual rhythm entrainment.