A Comparative Study Analyzing Light Durations for the Growth of ‘Rex Butterhead’ Lettuce Lactuca sativa Utilizing GREENBOX Technology

Abstract

Exponential population growth pressures the agriculture industry to provide fresh foods to both rural and urban areas. GREENBOX technology, based on Controlled Environment Agriculture (CEA) principles, addresses this challenge by optimizing conditions for leafy green crops. It integrates into urban infrastructure to mitigate the effects of urbanization on fresh food availability. GREENBOX controls environmental factors like temperature, humidity, light, and nutrient delivery to enhance crop growth. Given that artificial lighting is a major energy consumer in CEA, this study explored different photoperiods to improve energy efficiency. Lactuca sativa ‘Rex Butterhead’ lettuce was grown under three photoperiods: 16-hour light/8-hour dark (control), 14-hour light/10-hour dark, and 12-hour light/12-hour dark. Biomass parameters, including fresh and dry weight, leaf area, leaf count, and chlorophyll concentration, were measured. While all treatments produced viable crops above the expected harvest weight, the 16-hour photoperiod caused statistically significant (p, 0.001) differences in fresh weight, dry weight, leaf count, Specific Leaf Area (SLA), and Leaf Area Index (LAI) compared to the shorter photoperiods. No significant differences were found between the 12-hour and 14-hour treatments. These results suggest that photoperiod adjustments could enhance the efficiency and productivity of GREENBOX units for urban agriculture. Species used in this study: Rex ‘Butterhead’ lettuce, Latuca sativa L.