{ "abstract": "Leaf day respiratory rate (Rd), a pivotal component of plant carbon metabolism that directly modulates net photosynthetic carbon gain and plant fitness, has long been challenging to accurately quantify due to overlapping CO2 fluxes with photosynthesis and photorespiration (Rp). This study aimed to disentangle Rd from Rp in C3 crops using a high-CO2/low-O2 (>1200 μmol mol–1 CO2 + 2% O2) An/Ca (net photosynthetic rate-ambient CO2 concentration) model. We integrated two datasets: An/Ca curve data of four C3 species (Trifolium pratense, Silphium perfoliatum, Lolium perenne, Triticum aestivum) under ambient O2 (21% O2) from Ye et al. (2025) and newly collected data under low O2 (2% O2) for the same species. A dedicated model (Eqn 1) was developed to extract key parameters [e.g., the maximum net photosynthetic rate (Anmax), CO2 compensation point (Γ) in the presence of Rd, photorespiratory rate at Ca = 0 μmol mol–1 (RC0)] from An/Ca curves, with ANOVA confirming no significant differences between calculated and observed parameter values (p > 0.05). Under 2% O2, Rp was strongly suppressed, making the gross photorespiratory rate (RC = Rp + Rd) a reliable proxy for approximate Rd. Results showed that Rd estimates from the high-CO2/low-O2 approach (0.74–1.12 μmol m–2 s–1) were consistent with literature ranges (0.74–2.89 μmol m–2 s–1) for four C3 crops. Interspecific differences in Rd were observed: L. perenne had the highest Rd, while T. aestivum had the lowest, which correlated with species-specific photosynthetic traits (e.g., carboxylation efficiency). Rd remained stable across O2 levels (21% vs. 2%), indicating independence from short-term photorespiratory flux changes. The RC ≈ Rd assumption is supported by the substantial decrease in Γ (50–67%) and RCO (40–55%) under 2% O2, and by the consistency of Rd estimates with literature ranges, although independent ground-truth measurements remain to be conducted. This study suggests the high-CO2/low-O2 An/Ca model as a new tool for Rd quantification in C3 crops. The findings enhance understanding of non-photosynthetic carbon flux dynamics and provide critical parameters for refining crop carbon cycling models to predict growth and yield under current and future atmospheric conditions.", "abstract_shown": true, "affiliations": [ "Photosynthesis Research Institute, Nanchang Institute of Technology, Nanchang, Jiangxi, P.R. China.", "New Quality Productivity Research Center, Guangdong ATV College of Performing Arts, Deqing, P. R. China.", "Wenzhou Academy of Agricultural Sciences, Wenzhou, Zhejiang, P. R. China.", "School of Life Sciences, Nantong University, Nantong, China.", "State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.", "Key Laboratory of Crop Breeding in South Zhejiang, Wenzhou Academy of Agricultural Sciences, Wenzhou, China.", "Institute of Biophysics, Math & Physics College, Jinggangshan University, Ji'an, P. R. of China." ], "article_type": "Research Article", "arxiv": null, "author_total": 8, "authors": [ { "affs": [ 0, 1, 2 ], "name": "Zipiao Ye" }, { "affs": [ 3, 4 ], "name": "Xiaolong Yang" }, { "affs": [ 1 ], "name": "Ting An" }, { "affs": [ 2, 5 ], "name": "Zhengwen Niu" }, { "affs": [ 2, 5 ], "name": "Qi Huang" }, { "affs": [ 2, 5 ], "name": "Chunju Peng" }, { "affs": [ 6 ], "name": "Fubiao Wang", "orcid": "0000-0001-8596-7664" }, { "affs": [ 2, 5 ], "name": "Huajing Kang" } ], "bibtex": "https://research.draconitic.com/paper/9f529y0aewb26.bib", "cited_by": 0, "doi": "10.1371/journal.pone.0361238", "fulltext_url": "https://europepmc.org/articles/PMC13693880", "id": "9f529y0aewb26", "issns": [ "1932-6203" ], "landing_url": "https://doi.org/10.1371/journal.pone.0361238", "language": "eng", "licence": "CC-BY", "licence_label": "CC BY", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "1312|Photosynthetic Processes and Mechanisms" ], [ "plos", "/Biology and life sciences/Agriculture/Crop science/Crops" ], [ "plos", "/Biology and life sciences/Biochemistry/Plant biochemistry/Photosynthesis" ], [ "plos", "/Biology and life sciences/Biochemistry/Plant biochemistry/Photosynthesis/C3 photosynthesis" ], [ "plos", "/Biology and life sciences/Biochemistry/Proteins/Post-translational modification/Carboxylation" ], [ "plos", "/Biology and life sciences/Organisms/Eukaryota/Plants" ], [ "plos", "/Biology and life sciences/Organisms/Eukaryota/Plants/Grasses/Wheat/Common wheat" ], [ "plos", "/Biology and life sciences/Plant science/Plant anatomy/Leaves" ], [ "plos", "/Biology and life sciences/Plant science/Plant biochemistry/Photosynthesis" ], [ "plos", "/Biology and life sciences/Plant science/Plant biochemistry/Photosynthesis/C3 photosynthesis" ], [ "plos", "/Physical sciences/Chemistry/Chemical compounds/Carbon dioxide" ] ], "openalex": "W7223342152", "pdf_url": "https://europepmc.org/articles/PMC13693880?pdf=render", "pmcid": "PMC13693880", "pmid": "42912688", "published": "2026-10-23", "publisher": "Public Library of Science", "ris": "https://research.draconitic.com/paper/9f529y0aewb26.ris", "sources": [ { "first_seen": "2026-10-30T12:17:17Z", "native_id": "10.1371/journal.pone.0361238", "source": "plos", "url": "https://doi.org/10.1371/journal.pone.0361238" }, { "first_seen": "2026-10-30T12:20:03Z", "native_id": "MED:42912688", "source": "europepmc", "url": "https://europepmc.org/article/MED/42912688" } ], "subjects": [ { "field": "biology", "origin": "plos:plant science", "subfield": "plant-biology" } ], "title": "Disentangling leaf day respiration from photorespiration in C₃ leaves: A single-curve An/Ca approach validated under photorespiration-suppressed conditions", "title_text": "Disentangling leaf day respiration from photorespiration in C₃ leaves: A single-curve An/Ca approach validated under photorespiration-suppressed conditions", "type": "peer-reviewed", "updated_at": "2026-10-30T12:20:03Z", "url": "https://research.draconitic.com/paper/9f529y0aewb26", "venue": "PLOS One", "versions": [] }