One of my favorite parts of attending the Cultivate conference every year is seeing the presentations from the AmericanHort HortScholars. Each year, six college students are chosen for this beyond-the-classroom experience, which gives them insight and awareness of the industry, its supply chain and where they might find a home for their passion.
Talking up his research on “Artificial Lighting in Controlled Environment Agriculture” this year was Samuel Mattia, a plant science graduate student at Cal Poly-Pomona. He called the topic “the most exciting advancement in agriculture in a long time.”
That may be a bit of hyperbole, but indoor farming (also known as controlled environment agriculture or CEA) continues to expand – as does the technology used to support it. With an ever-growing population and less space to grow crops, resource use efficiency for water, energy and land is crucial.
Right now, there is high electric energy demand for lighting and air conditioning for CEA. Mattia noted that lighting is the most critical “input” due to the need for the right intensity, length and quality to raise quality crops.
A total of 25% to 40% of the total energy consumed in indoor vertical farms and greenhouses is used by artificial lighting, per research from the University of Arizona, the University of Guelph and Wageningen University & Research.
“Of all the environmental parameters, light in the most complex because it must be controlled in three dimensions: quality (PAR), quantity (PPFD) and duration (photoperiod),” Mattia explained.
PAR is Photosynthetically Active Radiation, and it’s the range of light wavelength needed for photosynthesis. PPFD is Photosynthetic Photon Flux Density, and it is the number of photons within the PAR range that reach a defined area of a plant canopy every second. The photoperiod is the duration of light within a particular timeframe (usually 24 hours).
“An optimal combination of PAR, PPFD and photoperiod may increase plant biomass without a major impact on resource use efficiency,” Mattia explained. But that is also dependent on the lights being used.
He noted that many CEA operations still use high pressure sodium (HPS) lamps, but many are also switching to using light emitting diodes (LEDs) instead.
Mattia urged indoor farmers to make the transition from HPS lamps to LEDs for a very important reason. The latter save a lot of energy. He cited a 2019 study that found that LEDs are better than HPS lamps at converting electrical power to photosynthetic light. Another study noted from 2020 found that LEDs have 60% higher efficacy than traditional horticultural lamps.
Overall, light efficiency for HPS lamps averages 35.3%, while for LEDs it averages 52.3%.
Mattia plans to stay focused on this topic. He said he is currently studying how the switch from HPS lamps to LEDs impacts the quality and yield of plants grown under artificial lighting. As the horticulture industry continues to evolve in this area, I’m excited to see what he’ll discover.
