Light quality is known to affect the growth and phytochemical content of numerous crops, including lettuce (Lactuca sativa L.). High tunnel production of lettuce provides many benefits to growers including increased yield due to higher soil temperatures and protection from abiotic stressors, such as strong wind and heavy rains. However, the use of UV-blocking polyethylene films can also result in lower antioxidant capacity and phenolic content, leading to a decrease in nutritional quality compared to lettuce grown in the open-field. Movable tunnels provide the ability to expose the crop to full-spectrum light once the crop has grown to full size. Our objective was to identify management strategies to optimize yield, phytochemical production, color, safety, and consumer acceptability of red-leaf cultivar (‘New Red Fire’). Lettuce was planted in a movable high tunnel April 2022 and exposed to 0, 2, 7, or 14 days of full sun prior to harvest. Total marketable yield, leaf color (L*a*b* color space), total phenolic content (TPC) and anthocyanin content were measured at harvest. Lettuce consumers (N=100) were asked to rate overall liking and various sensory attributes using continuous intensity scales, CATA, and open-ended comments. Total marketable yield and TPC were not affected. Leaf redness (a*) and anthocyanin content were significantly higher after 14, 7, and 2 days of full-sun exposure compared to 0 days. Significant differences were found in consumer liking for overall liking, color intensity, and ruffleness. The crop that was exposed to 14 days of full-spectrum light had a higher liking and more red color intensity. Using a movable tunnel system provides lettuce growers the ability to affect the color, phytochemical content, and consumer liking of their crop to varying degrees. This level of flexibility provides local, small-scale growers a crucial advantage in marketing their produce.
