2019 ASHS Annual Conference

Historical experiments using monochromatic light from light-emitting diodes (LEDs) generally concluded that plants grown under red (R) or blue (B) light alone results in abnormal growth or decreased yield metrics. However, recent research focusing on applying monochromatic R or B as part of a dynamic lighting strategy has shown some promise by means of increasing leaf area and net assimilation rate to increase overall growth. Therefore, there is a potential to apply similar treatments as part of standard commercial lighting programs to increase early-phase canopy growth or total crop photosynthesis to achieve increased production. Applying academic research, especially sole-source experiments, to commercial applications does not necessarily yield projected results, either through influence of solar radiation in a greenhouse or limitations of lighting apparatus for delivering lighting treatments among other challenges. Compared to standard commercial lighting programs, applying monochromatic R or B light treatments as either end-of-day or alternating 12-hour periods showed variable results across multiple crops including Lactuca sativa, Solanum lycopersicum, and Cannabis sativa. Continued investigation of the underlying processes to increase plant production will be necessary at both the commercial and academic level.