Work

While end-of-production sole-source lighting at a moderate intensity increased nutrient, water-soluble vitamin, and carotenoid content, the anthocyanin concentration of red leaf lettuce decreased

Year: 2026

Type: article

Abstract: In controlled environments, light intensity and quality can be manipulated to enhance beneficial phytochemicals, vitamins, and foliage color by increasing anthocyanin levels before harvest. Our objectives were to quantify whether a 50% reduction in end-of-production (EOP) light intensity, enriched with blue (B) light alone or with red (R) light, would yield red leaf lettuce of comparable or higher quality than that grown under high-intensity white light. Seedlings of red leaf lettuce ( Lactuca sativa ) ‘Barlach’, ‘Rouxai’, and ‘Thurinus’ were grown under light-emitting diodes (LEDs) that provided a photosynthetic photon flux density (PPFD) of 300 µmol·m −2 ·s −1 with a ratio (%) of 19:39:39:3 B:green:R:far-red light. During the last 6–8 days of production, plants were either left in the same conditions or placed under LEDs providing a ratio (%) of 100:00, 75:25, or 50:50 B:R light and a PPFD of 150 µmol·m −2 ·s −1 . Compared to untreated plants, the shoot fresh mass of ‘Rouxai’ was 16%, 17%, and 21% lower, and the shoot dry mass was 25%, 27%, and 29% lower under 100:00, 75:25, and 50:50 B:R EOP treatments, respectively. ‘Thurinus’ exposed to 100:00 B:R EOP lighting contained 22%, 22%, 47%, 35%, 24%, 10%, 40%, 31%, 25%, 50%, and 38% greater N, P, Ca, Mg, S, B, Cu, Fe, Mn, Mo, and Zn concentrations, respectively, compared to the control. Plants exposed to EOP generally developed increased concentrations of water-soluble vitamins. Vitamin C of ‘Barlach’, ‘Rouxai’, and ‘Thurinus’ was between 37% and 42%, 36% and 45%, and 49% and 57% greater, respectively, when exposed to EOP B or B:R sole-source lighting. The carotenoid concentration of ‘Rouxai’ under 100:00 B:R was 29% greater than that of the control. Each cultivar developed the highest concentration of violaxanthin, neoxanthin, zeaxanthin, and α-carotene when not exposed to EOP lighting. Under EOP lighting, ‘Barlach’, ‘Rouxai’, and ‘Thurinus’ accumulated between 52% and 68%, 55% and 57%, and 33% and 43% lower anthocyanin concentrations, respectively, than the control plants. Our results indicate that maintaining a higher light intensity during the EOP phase was more effective at increasing anthocyanin production in red leaf lettuce than lowering light intensity and increasing the fraction of blue light.

Source: Frontiers in Plant Science

DOI: 10.3389/fpls.2026.1699278

Authors: Devin Brewer, Kellie J. Walters, Jennifer K. Boldt, Roberto G. Lopez

Institutions: Michigan State University, University of Tennessee at Knoxville, Agricultural Research Service, United States Department of Agriculture

Language: English

Topic: Light effects on plants

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: gold

Estimated APC paid: $3,801