Application of ultraviolet a led as a disinfectant and morphological effects on indoor grown lettuce

Lettuce (Lactuca sativa 'Parris Island'), commonly grown in vertical farms for sustainable production, has been studied for its response to UVA LED light, but its disinfectant potential remains unexplored. Hence, the proposal intends to cover two important aspects, the development of the plant and its disinfection during cultivation, to obtain plants that are ready for consumption. Three LED light treatments were configured: Mode 1 (WBUVA-P) and Mode 2 (WBUVA-C) used White + Blue + UVA (395 nm), with intermittent and continuous application, respectively. The Control applied White + Blue (WB), denoted as Mode 3. A specific evaluation of different parameters, such as disinfection and identification of bacteria, biomass, chlorophyll content (SPAD units), and leaf area (LA), was conducted in the experiment. The most effective results were obtained with Mode 1 (WBUVA-P), achieving a 99.90% disinfection rate and promoting organic matter accumulation, as shown by increased leaf area, fresh weight, and dry weight. In contrast, Mode 2 (WBUVA-C) reached a 99.00% disinfection rate but did not significantly impact organic matter compared to the Control. These results suggest that UVA-LED radiation can be a valuable tool for food production, enhancing disinfection and organic matter content. However, further studies are needed to explore different intermittent UVA-LED emission durations and test other wavelengths.