Abstract
With the rising pressures on food security, GREENBOX technology was developed as an avenue for fresh leafy vegetable crop production in urban settings. GREENBOX units were designed to be thermally insulated and climate controlled, with an artificial lighting source and soilless cultivation methods. Previous studies of GREENBOX units used the Nutrient Film Technique (NFT); however, various hydroponic methods exist, such as the Deep-Water Culture (DWC) method being the most commonly used. The APS Laboratory for Sustainable Food at Florida Gulf Coast University (FGCU) compared the crop growth performance between DWC and NFT systems using GREENBOX technology. The following study monitored environmental conditions and compared productivity and biomass data of lettuce crops between DWC and NFT systems. We assembled two GREENBOX units using commercially available materials and the standard nutrient solution for fertigation. The crops grown in DWC and NFT were in a 4x6 configuration. The DWC and NFT systems were implemented in the two GREENBOX units using commercially available equipment to grow 'Rex Butterhead' Lettuce (Lactuca sativa) over 30 days to full bloom from prepared plugs grown for 14 days. We collected lettuce crop growth data, which included wet weight (g), dry weight (g), leaf area (cm2), and chlorophyll concentration (µmol/m2). We derived data, including Specific Leaf Area (SLA, cm2/g) and biomass productivity (kg/m2), from previously collected data. We used descriptive statistics to present the collected data. We used a Paired t-test to understand the differences in biomass and productivity parameters between DWC and NFT grown lettuce crops. Both the DWC and NFT grown crops could grow lettuce crops to harvest weight at full bloom. The biomass parameters and productivity do not differ significantly between the two hydroponics techniques. Therefore, we determined both hydroponic methods may be similar in growth performance and may be used in future iterations of GREENBOX design.
