Indoor vertical farming of leafy green vegetables is expanding due to its efficient use of land, water, and fertilizer, along with the absence of pesticides. Automation of cultivation practices and proximity to urban centers reduce labor and transportation costs compared to traditional field production. Despite the ability to control environmental factors like temperature, CO2 concentration, and light, indoor farms rely heavily on electricity. Electric lighting, particularly LEDs, is a significant expense and sustainability challenge. LEDs are preferred for their high efficacy, long lifespan, and precise light spectrum control, making them more effective than traditional lighting fixtures like high-pressure sodium or white fluorescent lamps.
Lettuce (Lactuca sativa) is the most grown species in indoor farms due to its compact size, short production cycle, high consumer demand, and versatility in culinary use. It is one of the most widely consumed vegetables in the United States, valued for its nutritional benefits. Lettuce serves as a model crop in horticultural lighting research because of its responsiveness to the light spectrum and intensity. Manipulating the light environment in controlled settings affects lettuce biomass, morphology, and bioactive compound concentrations.
Researchers at the Michigan State University, Controlled-Environment Lighting Lab have discovered that the application of UV-A and blue light during the final stages of lettuce growth leads to a more vibrant and appealing coloration. This is particularly beneficial for marketability, as visually attractive produce often commands higher consumer interest and better sales.
Both UV-A and blue light treatments were found to increase the levels of beneficial phytochemicals in lettuce. Phytochemicals are compounds that have numerous health benefits, including antioxidant properties and potential protective effects against various diseases. UV-A and blue light appear to have similar effects on the enhancement of lettuce characteristics, and since blue LEDs are much more economical to use, installation of UV-A light in an indoor farm is not necessarily needed.
By utilizing end-of-production light treatments, farmers can improve the quality and nutritional value of their crops without negatively impacting yield. This aligns with growing consumer demand for more natural and healthful food products. Improved coloration and nutritional content can lead to higher market prices and consumer preference, benefiting farmers economically.
Read the full story on the ASHS HortScience electronic journal website at: https://doi.org/10.21273/HORTSCI17108-23