ASHS 2024 Conference

Exponential population growth adds increasing pressure on the agriculture industry to grow and distribute fresh foods to rural and urban areas, leading to the development of GREENBOX technology, which utilizes Controlled Environment Agriculture (CEA) principles to optimize the desired conditions for growth of leafy green crops. Using commercially available equipment, GREENBOX technology has the capability to be integrated into existing urban infrastructure to help relieve the negative impact urbanization has on the availability of fresh foods. GREENBOX technology allows environmental variables, such as temperature, humidity, light intensity/ spectrum, and nutrient delivery, to be controlled to enhance the growth performance of leafy greens. Precursory experiments using GREENBOX Technology utilized the standard photoperiod of 16 hours of light, and 8 hours of dark for all crop production. The main objective of this study was to conduct a comparative analysis of Lactuca sativa Rex Butterhead Lettuce production grown under different photoperiods using GREENBOX technology. Using the standard 16 hours of light and 8 hours of dark as the control, two different photoperiod treatments were tested. Treatment one consisted of a 14-hour light period and a 10-hour dark period, while treatment two consisted of a 12-hour light period and a 12-hour dark period. The biomass and productivity of the crops were measured in addition to the environmental conditions for each lighting regimen to ascertain any significant differences. The biomass parameters included wet weight (g), dry weight (g), leaf area (cm2), leaf count (n), and chlorophyll concentration (mg/cm2). We derived additional data, including the Leaf Area Index (LAI, cm2/cm2), Specific Leaf Area (SLA, cm2/g), and biomass productivity (kg/m2). A statistical analysis of the biomass data was used to understand the differences in biomass parameters between crop growth and different light lengths. No statistically significant differences were found between the biomass and productivity parameters for the 12-hour and 14-hour photoperiods. However, the weight weights, dry weights, Leaf Count, SLA, and LAI from the 16-hour photoperiod showed statistically significant differences from the 12 and 14-hour photoperiods. All treatments still produced Rex Butterhead lettuce above the expected harvest weight of 180g and are viable for crop production in urban warehouse settings. The results of this experiment may help us understand the relationship between photoperiod and the biomass performance of leafy greens. Future GREENBOX experiments may use this information to increase the efficiency and productivity outputs of GREENBOX units. Keywords: CEA, Hydroponics, lettuce, soilless agriculture, urban agriculture