{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T11:04:23Z","timestamp":1790593463257,"version":"4.1.0"},"reference-count":40,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T00:00:00Z","timestamp":1790553600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Key R&D Program of Shandong Province, China","award":["2025CXPT149"],"award-info":[{"award-number":["2025CXPT149"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["32372163"],"award-info":[{"award-number":["32372163"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["32372163"],"award-info":[{"award-number":["32372163"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>Whether photoinhibition occurs in tall trees of Pinus densiflora var. zhangwuensis and P. sylvestris var. mongolica in summer and their response mechanisms to strong midday light in sandy land are not yet clear. Therefore, three standard trees were selected for each species as biological replicates by randomly setting up standard plots. Daily changes in the chlorophyll a fluorescence parameter of current-year needles (CYNs) and one-year needles (OYNs) in different parts of the standard tree crowns (in sun branches and shade branches) of the two species were comparatively studied, and the potential hydraulic transport capacities of the sample branches were also evaluated. The results are as follows: (1) The daily changes in the maximal photochemical efficiency of PSII (Fv\/Fm) in the sun CYNs of P. sylvestris var. mongolica obviously presented a descending\u2013ascending trend, and its lowest value was observed at noon. The maximum non-photochemical quenching (NPQ) of the sun CYNs in this species was observed at noon, and an NPQ of greater than 1 lasted for 4\u20135 h. (2) The midday Fv\/Fm of the sun CYNs in P. densiflora var. zhangwuensis was close to the morning and shade CYN levels. Compared with P. sylvestris var. mongolica, the NPQ of the sun CYNs of P. densiflora var. zhangwuensis remained low under the condition of high light at noon, but the number of active reaction centers per unit cross-sectional area (RC\/CSm) and the electron transfer efficiency (Fm\/Fo) were higher. Further analysis of the variation in the light energy absorbed by each reaction center (ABS\/RC) showed that the variation in the NPQ in the sun CYNs of the two species was very similar to that of ABS\/RC, and the two indices had a very significant positive correlation (the correlation coefficients of P. sylvestris var. mongolica and P. densiflora var. zhangwuensis were 0.7535 and 0.7193, respectively, p &lt; 0.001). (3) Through the comparison of the tracheid morphologies, our study also found that the outer and inner diameters of the pit of P. densiflora var. zhangwuensis were 1.26 and 1.28 times those of the pit of P. sylvestris var. mongolica, respectively, and the theoretical hydraulic conductance (Kt) in the sun branches of the former was 6.32 times that of the latter. The above results suggested that photoinhibition might also be involved in the tall trees of P. sylvestris var. mongolica, while P. densiflora var. zhangwuensis had a more effective mechanism to avoid photoinhibition.<\/jats:p>","DOI":"10.3390\/plants15192953","type":"journal-article","created":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T10:00:34Z","timestamp":1790589634000},"page":"2953","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Comparative Study on Photoinhibition Characteristics and Adaptation Mechanisms of New Current-Year Needles of Pinus densiflora var. zhangwuensis and Pinus sylvestris var. mongolica in Sandy Land Environments"],"prefix":"10.3390","volume":"15","author":[{"given":"Peng","family":"Meng","sequence":"first","affiliation":[{"name":"School of Landscape Architecture and Forestry, Qingdao Agricultural University, Qingdao 266109, China"},{"name":"Shandong Key Laboratory for Germplasm Innovation of Saline-Alkaline Tolerant Grasses and Trees, Qingdao 266109, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mengyu","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Landscape Architecture and Forestry, Qingdao Agricultural University, Qingdao 266109, China"},{"name":"Shandong Key Laboratory for Germplasm Innovation of Saline-Alkaline Tolerant Grasses and Trees, Qingdao 266109, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoyun","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Landscape Architecture and Forestry, Qingdao Agricultural University, Qingdao 266109, China"},{"name":"Shandong Key Laboratory for Germplasm Innovation of Saline-Alkaline Tolerant Grasses and Trees, Qingdao 266109, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jing","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Civil Engineering & Architecture, Qingdao Agricultural University, Qingdao 266109, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,28]]},"reference":[{"key":"ref_1","first-page":"338","article-title":"A new variety of Pinus densiflora","volume":"15","author":"Zhang","year":"1995","journal-title":"Bull. Bot. Res."},{"key":"ref_2","first-page":"359","article-title":"Physiological characteristics of Pinus densiflora var. zhangwuensis and Pinus sylvestris var. mongolica seedlings on sandy lands under salt-alkali stresses","volume":"24","author":"Meng","year":"2013","journal-title":"Chin. J. Appl. Ecol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3050","DOI":"10.5846\/stxb201104260547","article-title":"Characteristics of photosynthetic productivity and water-consumption for transpiration in Pinus densiflora var. zhangwuensis and Pinus sylvestris var. mongolica","volume":"32","author":"Meng","year":"2012","journal-title":"Acta Ecol. Sin."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"105479","DOI":"10.1016\/j.gloplacha.2026.105479","article-title":"Spatiotemporal patterns and drivers of photoinhibition in terrestrial ecosystems revealed by eddy covariance fluxes","volume":"262","author":"Yi","year":"2026","journal-title":"Glob. Planet. Change"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1641\/0006-3568(2004)054[0041:PSOOE]2.0.CO;2","article-title":"Photoprotective strategies of overwintering evergreens","volume":"54","author":"Adams","year":"2004","journal-title":"BioScience"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1007\/BF00397440","article-title":"Changes in photosynthetic capacity, carboxylation efficiency, and CO2 compensation point associated with midday stomatal closure and midday depression of net CO2 exchange of leaves of Quercus suber","volume":"162","author":"Tenhunen","year":"1984","journal-title":"Planta"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"100421","DOI":"10.1016\/j.jphotochemrev.2021.100421","article-title":"Concepts of photochemical damage of Photosystem II and the role of excessive excitation","volume":"47","author":"Alonso","year":"2021","journal-title":"J. Photoch. Photobio."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1151","DOI":"10.1093\/treephys\/25.9.1151","article-title":"Susceptibility to low-temperature photoinhibition in three conifers differing in successional status","volume":"25","author":"Robakowski","year":"2005","journal-title":"Tree Physiol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1146\/annurev.pp.42.060191.001525","article-title":"Chlorophyll fluorescence and photosynthesis: The basics","volume":"42","author":"Krause","year":"1991","journal-title":"Annu. Rev. Plant Physiol. Plant Mol. Biol."},{"key":"ref_10","first-page":"31","article-title":"Photosynthetic acclimation to different growth light environments in seedlings of three tropical rainforest syzygium species","volume":"28","author":"Qi","year":"2004","journal-title":"Acta Phytoecol. Sin."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1016\/S0005-2728(98)00159-5","article-title":"The effect of excited state population in photosystem II on the photoinhibition-induced changes in chlorophyll fluorescence parameters","volume":"1409","author":"Santabarbara","year":"1999","journal-title":"Biochim. Biophys. Acta"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"510","DOI":"10.1111\/tpj.16241","article-title":"A desert Chlorella sp. that thrives at extreme high-light intensities using a unique photoinhibition protection mechanism","volume":"115","author":"Levin","year":"2023","journal-title":"Plant J."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1146\/annurev-arplant-071720-015522","article-title":"Dissipation of light energy absorbed in excess: The molecular mechanisms","volume":"72","author":"Bassi","year":"2021","journal-title":"Annu. Rev. Plant Biol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1023\/A:1024969518145","article-title":"Photoinhibition\u2014A historical perspective","volume":"76","author":"Adir","year":"2003","journal-title":"Photosynth. Res."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"5290","DOI":"10.3390\/ijms13055290","article-title":"Reduced photoinhibition under low irradiance enhanced kacip fatimah (Labisia pumila Benth) secondary metabolites, phenyl alanine lyase and antioxidant activity","volume":"13","author":"Ibrahim","year":"2012","journal-title":"Int. J. Mol. Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"671","DOI":"10.32615\/ps.2020.015","article-title":"Special issue in honour of Prof. Reto J. Strasser\u2014Phosphorus deficiency affects the I-step of chlorophyll a fluorescence induction curve of radish","volume":"58","author":"Cetner","year":"2020","journal-title":"Photosynthetica"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1180","DOI":"10.1016\/j.bbabio.2007.05.009","article-title":"Structural and functional self-organization of Photosystem II in grana thylakoids","volume":"1767","author":"Kirchhoff","year":"2007","journal-title":"Biochim. Biophys. Acta Bioenerg."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1007\/s11120-018-0498-8","article-title":"Site, trigger, quenching mechanism and recovery of non-photochemical quenching in cyanobacteria: Recent updates","volume":"137","author":"Sonani","year":"2018","journal-title":"Photosynth. Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"264","DOI":"10.1016\/j.tplants.2022.12.016","article-title":"Improving photosynthetic efficiency by modulating non-photochemical quenching","volume":"28","author":"Ghosh","year":"2022","journal-title":"Trends Plant Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1111\/j.1365-3040.1990.tb01311.x","article-title":"Photoinhibition in Vitis califomica interactive effects of sunlight, temperature and water status","volume":"13","author":"Gamon","year":"1990","journal-title":"Plant Cell Environ."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4989","DOI":"10.1002\/ece3.1766","article-title":"Effects of prolonged drought on the anatomy of sun and shade needles in young Norway spruce trees","volume":"5","author":"Gebauer","year":"2015","journal-title":"Ecol. Evol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1007\/BF00028752","article-title":"Photosynthetic activity, chloroplast ultrastructure, and leaf characteristics of high-light and low-light plants and of sun and shade leaves","volume":"2","author":"Lichtenthaler","year":"1981","journal-title":"Photosynth. Res."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1007\/BF00341354","article-title":"Determination of the quantum efficiency of photosystem II and of non- photochemical quenching of chlorophyll fluorescence in the field","volume":"102","author":"Bilger","year":"1995","journal-title":"Oecologia"},{"key":"ref_24","first-page":"23","article-title":"70 Years of introducing of Mongolian pine to sandy lands: History, progress, and perspectives","volume":"61","author":"Zhu","year":"2025","journal-title":"Sci. Silvae Sin."},{"key":"ref_25","first-page":"186","article-title":"Study on the effect of Trichoderma harziensis microcapsule on the prevention and treatment of P. sylvestris var. mongolica shoot blight","volume":"45","author":"Aierpani","year":"2025","journal-title":"J. Cent. South Univ. For. Technol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1260","DOI":"10.1111\/tpj.15232","article-title":"The desert green algae Chlorella ohadii thrives at excessively high light intensities by exceptionally enhancing the mechanisms that protect photosynthesis from photoinhibition","volume":"106","author":"Levin","year":"2021","journal-title":"Plant J."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1127","DOI":"10.1016\/j.bbabio.2012.02.020","article-title":"The mechanism of photoinhibition in vivo: Re-evaluation of the roles of catalase, \u03b1-tocopherol, non-photochemical quenching, and electron transport","volume":"1817","author":"Murata","year":"2012","journal-title":"Biochim. Biophys. Acta Bioenerg."},{"key":"ref_28","first-page":"3708","article-title":"Thermal dissipation and trigging depending on xanthophyll cycle in cucumber seedling under NO3- stress","volume":"41","author":"Su","year":"2008","journal-title":"Sci. Agric. Sin."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1093\/jxb\/eri056","article-title":"Is PsbS the site of non-photochemical quenching in photosynthesis?","volume":"56","author":"Niyogi","year":"2005","journal-title":"J. Exp. Bot."},{"key":"ref_30","first-page":"127","article-title":"Defense mechanisms of plants photosystem to heat stress","volume":"28","author":"Tang","year":"2012","journal-title":"Chin. J. Biochem. Mol. Biol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"111565","DOI":"10.1016\/j.scienta.2022.111565","article-title":"Physiological and proteomic analyses of Malus crabapples exposed to long-term warming and short-term heat shock treatments reveal the response characteristics of photosynthetic apparatus","volume":"308","author":"Wang","year":"2023","journal-title":"Sci. Hortic."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"361","DOI":"10.1146\/annurev.arplant.56.032604.144141","article-title":"Leaf hydraulics","volume":"57","author":"Sack","year":"2006","journal-title":"Annu. Rev. Plant Biol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"135327","DOI":"10.1016\/j.jhydrol.2026.135327","article-title":"Drought rather than nitrogen addition drives the coordination of hydraulic conductivity and photosynthesis in three coniferous tree species","volume":"672","author":"Tian","year":"2026","journal-title":"J. Hydrol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2705","DOI":"10.15666\/aeer\/2203_27052719","article-title":"Effect of Pinus densiflora var. zhangwuensis scion on root biomass and architecture of Pinus sylvestris var. mongolica rootstock after 25-year grafting","volume":"22","author":"Meng","year":"2024","journal-title":"Appl. Ecol. Env. Res."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"646","DOI":"10.1111\/j.1744-7909.2007.00443.x","article-title":"Quantitative trait loci mapping for chlorophyll fluorescence and associated traits in wheat (Triticum estivum)","volume":"49","author":"Yang","year":"2007","journal-title":"J. Integr. Plant Biol."},{"key":"ref_36","first-page":"65","article-title":"Effects of low temperature in winter on photoinhibition of sun leaves and shade leaves in three evergreen broad-leaved plants","volume":"32","author":"Hu","year":"2023","journal-title":"J. Plant Resour. Environ."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Zheng, B., Zhao, W., Ren, T.H., Zhang, X.H., Ning, T.Y., Liu, P., and Li, G. (2022). Low Light Increases the abundance of light reaction proteins: Proteomics analysis of maize (Zea mays L.) grown at high planting density. Int. J. Mol. Sci., 23.","DOI":"10.3390\/ijms23063015"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1007\/s00035-015-0146-2","article-title":"No evidence for photoinhibition of photosynthesis in alpine Caltha leptosepala DC","volume":"125","author":"Sanchez","year":"2015","journal-title":"Alp. Bot."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"659","DOI":"10.1093\/jexbot\/51.345.659","article-title":"Chlorophyll fluorescence\u2014A practical guide","volume":"51","author":"Maxwell","year":"2000","journal-title":"J. Exp. Bot."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Tyree, M.T., and Zimmermann, M.H. (2002). Xylem Structure and the Ascent of Sap, Springer.","DOI":"10.1007\/978-3-662-04931-0"}],"container-title":["Plants"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/19\/2953\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T10:28:18Z","timestamp":1790591298000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/19\/2953"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,28]]},"references-count":40,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["plants15192953"],"URL":"https:\/\/doi.org\/10.3390\/plants15192953","relation":{},"ISSN":["2223-7747"],"issn-type":[{"value":"2223-7747","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,28]]}}}