Abstract
technology consists of individual climate-controlled units, including a thermally insulated growth apparatus, an artificial lighting source, a soilless cultivation method of hydroponics, and environmental controls. GREENBOX units may be integrated with existing urban infrastructure, such as buildings, garages, and warehouses. Previous studies have investigated the technical feasibility of lettuce Lactuca sativa ‘Rex Butterhead’ crop growth, which utilized white lighting elements. To our knowledge, no existing literature assessed the efficacy of supplementing red and blue light using GREENBOX technology. The APS Laboratory for Sustainable Agriculture aimed to fill this gap by assessing how different lighting element spectrums corresponding to red and blue colors affected the production of ‘Rex Butterhead’ lettuce using GREENBOX technology. We conducted comparative crop growth studies using three treatments: 1) supplemental blue light, 2) supplemental red light, and 3) no supplemental light for the white lighting element for control. The supplemental red light treatment produced the greatest average fresh weight plant‑1 of 218.36 g, which was 20.59 g heavier than the white light treatment and 75.8 g greater than the blue light treatment. Plants accumulated 1.27 mg g‑1 more nitrogen plant‑1 under the supplemental blue light treatment than the red light treatment. Similarly, the blue light treatment resulted in a 0.005 mg cm‑2 greater chlorophyll concentration plant‑1 than the red light treatment. An analysis of CIE-LAB correlations found that, as L (r=-0.526) and B (r=-0.608) increase, chlorophyll levels decrease (p<0.0001). Results from this study may inform the future iterations of GREENBOX design.