Comparison of Macrobubbles, Microbubbles, and Ultrafine Bubbles Applications in Plant Factory on Lettuce Growth, Fertilizer Use, and Electricity Consumption

Abstract

　This comparative study investigated the effects of various aeration treatments on lettuce cultivation in a plant factory using artificial light (PFAL). A deep-water culture (DWC) hydroponic system was used in the present study. Three aeration treatments, namely macrobubbles (MA), microbubbles (MI), and ultrafine bubbles (UFB), were compared. We examined the influence of different aeration methods and fertilizer doses on lettuce growth and measured electricity consumption. The results showed that MI and UFB treatments significantly increased the yield and accelerated lettuce growth in PFAL. Relative to the MA treatment, the UFB treatment increase the SFW of lettuce by 1.5 times bigger in PFAL. Despite the increased energy consumption, UFB treatment demonstrated high energy efficiency compared to MA treatment. Notably, lettuce treated with UFB and 25% less fertilizer grew as well as lettuce given the full fertilizer dose without UFB. These findings suggest that UFB application has significant potential in PFAL. UFB enhances yield and accelerates lettuce growth.