2026/01/27 by Fatemeh Sheibani, Celina Gómez, Erik S. Runkle +1 · 1 voice
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · #Light effects on plants #Greenhouse Technology and Climate Control #Photosynthetic Processes and Mechanisms
paper · doi:10.21273/jashs05550-25
openalex publication_date 2026/01/27 · openalex created_date 2026/01/28 · openalex updated_date 2026/06/11
Multifactor optimization is a critical consideration needed to enhance resource-use efficiency and improve profitability of indoor crop production. This study investigated potential interactive effects of far-red (FR; 700–750 nm) radiation substitution for red (R; 600–700 nm) light and varying carbon dioxide (CO 2 ) concentrations on growth, morphology, and leaf gas exchange of ‘Rouxai’ young red oakleaf lettuce. Experiments were conducted under a moderate total photon flux density (TPFD) of 400 µmol·m −2 ·s −1 , including 60 µmol·m −2 ·s −1 of blue light (400-500 nm), and an 18-h photoperiod across three developmental stages of young lettuce: small baby (14-day cropping cycle), standard baby (18-day cropping cycle), and teen (22-day cropping cycle) stages. Building on prior work conducted under a lower TPFD (200 µmol·m −2 ·s −1 ), this study aimed to determine how a higher TPFD would influence crop response to FR and CO 2 enrichment during early crop stages. Plants were grown under four FR substitution levels for R (0, 20, 40, or 60 µmol·m −2 ·s −1 ) combined with three CO 2 concentrations (400, 800, or 1200 µmol·mol −1 ). The FR substitution significantly increased shoot biomass accumulation across all developmental stages. Significant interaction occurred between the two environmental variables. Thus, effects of FR depended on the CO 2 concentration. Lack of leaf photosynthetic stimulation in response to FR substitution for R indicated that morphological changes triggered by FR indirectly increased biomass accumulation at higher FR substitution levels. The moderate TPFD used mitigated the tendency of FR to decrease foliar pigmentation, and subjective product quality remained acceptable at all FR levels tested. These findings affirm that partial substitution of R with FR in sole-source lighting increases yield during early stages of lettuce crop production. Strategic FR use in combination with CO 2 management and stage-specific lighting offers a promising approach to improve productivity and profitability of indoor crop production when TPFD is adequately high.