Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red light

IntroductionLow light intensity and far-red (FR) light act as shade signals to induce specific morphological changes mediated by plant photoreceptors phytochromes (PHYs). Applying FR light or lowering light intensity over a longer photoperiod at a constant daily light integral (DLI) can increase cro...

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Main Authors: Sang Jun Jeong, Shuyang Zhen, Qianwen Zhang, Genhua Niu
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-01-01
Series:Frontiers in Plant Science
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Online Access:https://www.frontiersin.org/articles/10.3389/fpls.2025.1529455/full
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author Sang Jun Jeong
Sang Jun Jeong
Shuyang Zhen
Qianwen Zhang
Qianwen Zhang
Genhua Niu
author_facet Sang Jun Jeong
Sang Jun Jeong
Shuyang Zhen
Qianwen Zhang
Qianwen Zhang
Genhua Niu
author_sort Sang Jun Jeong
collection DOAJ
description IntroductionLow light intensity and far-red (FR) light act as shade signals to induce specific morphological changes mediated by plant photoreceptors phytochromes (PHYs). Applying FR light or lowering light intensity over a longer photoperiod at a constant daily light integral (DLI) can increase crop yield by enhancing leaf expansion and photon capture. However, PHY activity is also dependent on temperature. We aimed to investigate the interactive effects of FR light, light intensity, photoperiod, and temperature on plant growth and morphology.MethodsLettuce (Lactuca sativa L.) ‘Rex’ was grown under three temperatures (20, 24, and 28 °C), each containing six light treatments [two levels of FR light (0 and 20% FR in total photon flux density from 400-800 nm) x three light intensities (150, 200, and 300 μmol m-2 s-1)]. As light intensity increased, photoperiod was reduced (150, 200, and 300 μmol m-2 s-1 with photoperiods of 24 h, 18 h, and 12 h, respectively) to maintain a constant DLI of 13 mol m-2 d-1.ResultsUnder 0% FR light, the combination of lower light intensity/longer photoperiod and warmer temperature synergistically enhanced leaf expansion and photon capture; however, this interactive effect disappeared under 20% FR light. Stem elongation exhibited an opposite response pattern to leaf expansion; lower light intensity and warm temperature had a synergistic enhancement on stem elongation under 20% FR light, but not under 0% FR light. Shoot dry weight responded to the light and temperature factors similarly to total leaf area. Our results showed that plant biomass accumulation depended primarily on photon capture (r2 = 0.93), rather than single-leaf photosynthetic efficiency. Antioxidant capacity was generally reduced by lower light intensity and FR light, but the reduction could be compensated by warmer temperatures.DiscussionThus, we concluded that applying lower light intensity over a longer photoperiod, combined with warm temperature, can effectively maximize leaf expansion and crop yield while maintaining nutritional quality in the absence of FR light. However, under strong shade signals composed of FR light, low light intensity, and warm temperature, lettuce prioritizes stem elongation at the expense of leaf expansion, leading to reduced crop yield.
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publishDate 2025-01-01
publisher Frontiers Media S.A.
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spelling doaj-art-30f1fec527bf403498c84ec0e2e425722025-01-24T11:40:54ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2025-01-011610.3389/fpls.2025.15294551529455Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red lightSang Jun Jeong0Sang Jun Jeong1Shuyang Zhen2Qianwen Zhang3Qianwen Zhang4Genhua Niu5Department of Horticultural Sciences, Texas A&M University, College Station, TX, United StatesTexas A&M AgriLife Research, Dallas, TX, United StatesDepartment of Horticultural Sciences, Texas A&M University, College Station, TX, United StatesTexas A&M AgriLife Research, Dallas, TX, United StatesTruck Crops Branch Experiment Station, Mississippi State University, Crystal Springs, MS, United StatesTexas A&M AgriLife Research, Dallas, TX, United StatesIntroductionLow light intensity and far-red (FR) light act as shade signals to induce specific morphological changes mediated by plant photoreceptors phytochromes (PHYs). Applying FR light or lowering light intensity over a longer photoperiod at a constant daily light integral (DLI) can increase crop yield by enhancing leaf expansion and photon capture. However, PHY activity is also dependent on temperature. We aimed to investigate the interactive effects of FR light, light intensity, photoperiod, and temperature on plant growth and morphology.MethodsLettuce (Lactuca sativa L.) ‘Rex’ was grown under three temperatures (20, 24, and 28 °C), each containing six light treatments [two levels of FR light (0 and 20% FR in total photon flux density from 400-800 nm) x three light intensities (150, 200, and 300 μmol m-2 s-1)]. As light intensity increased, photoperiod was reduced (150, 200, and 300 μmol m-2 s-1 with photoperiods of 24 h, 18 h, and 12 h, respectively) to maintain a constant DLI of 13 mol m-2 d-1.ResultsUnder 0% FR light, the combination of lower light intensity/longer photoperiod and warmer temperature synergistically enhanced leaf expansion and photon capture; however, this interactive effect disappeared under 20% FR light. Stem elongation exhibited an opposite response pattern to leaf expansion; lower light intensity and warm temperature had a synergistic enhancement on stem elongation under 20% FR light, but not under 0% FR light. Shoot dry weight responded to the light and temperature factors similarly to total leaf area. Our results showed that plant biomass accumulation depended primarily on photon capture (r2 = 0.93), rather than single-leaf photosynthetic efficiency. Antioxidant capacity was generally reduced by lower light intensity and FR light, but the reduction could be compensated by warmer temperatures.DiscussionThus, we concluded that applying lower light intensity over a longer photoperiod, combined with warm temperature, can effectively maximize leaf expansion and crop yield while maintaining nutritional quality in the absence of FR light. However, under strong shade signals composed of FR light, low light intensity, and warm temperature, lettuce prioritizes stem elongation at the expense of leaf expansion, leading to reduced crop yield.https://www.frontiersin.org/articles/10.3389/fpls.2025.1529455/fullindoor farmingphoton capturephytochrome photoequilibriumplant yieldantioxidant capacity
spellingShingle Sang Jun Jeong
Sang Jun Jeong
Shuyang Zhen
Qianwen Zhang
Qianwen Zhang
Genhua Niu
Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red light
Frontiers in Plant Science
indoor farming
photon capture
phytochrome photoequilibrium
plant yield
antioxidant capacity
title Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red light
title_full Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red light
title_fullStr Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red light
title_full_unstemmed Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red light
title_short Lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far-red light
title_sort lowering light intensity while extending photoperiod at a constant daily light integral synergistically interacts with warm temperature to enhance leaf expansion and crop yield in lettuce in the absence of far red light
topic indoor farming
photon capture
phytochrome photoequilibrium
plant yield
antioxidant capacity
url https://www.frontiersin.org/articles/10.3389/fpls.2025.1529455/full
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