ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Biophysics and Modeling
This article is part of the Research TopicStomatal Conductance in a Changing Climate: Mechanistic Insights and Ecosystem FeedbacksView all articles
Simulation of Citrus Foliar Gas Exchange Across Diverse Meteorological Conditions: Application of the Optimal Stomatal Regulation Method
Provisionally accepted
Mengying Fan1
Zhihui Wang1Xuelian Jiang2*
Ningbo Cui1*Jingtian Zhao3Shouzheng Jiang1Guoyu Zhu1Liwen Xing1
Xiaoxian Zhang4- 1Sichuan University, Chengdu, China
- 2Weifang University, Weifang, China
- 3Algoma University, Sault Ste. Marie, Canada
- 4Rothamsted Research, Harpenden, United Kingdom
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The optimal stomatal regulation theory provides an eco-evolutionary framework for interpreting the trade-off between CO2 uptake and water loss. This theory postulates that the marginal water cost of carbon gain (λ=∂E/∂A) remains approximately constant over short timescales, thereby offering a mechanistic basis for predicting stomatal behavior and gas exchange. In this study, leaf-level meteorological variables and gas exchange parameters of orchard citrus were measured throughout the entire phenological period during 2021–2022. We developed a family of optimal stomatal conductance-based models (OSCMs), comprising six forms: Rubisco-limited forms (OSCvc and OSCvcd), RuBP-regeneration-limited forms (OSCvj and OSCvjd), and combined forms that dynamically select the prevailing biochemical limitation (OSC and OSCd). The key parameter λ was estimated daily and averaged over the entire phenological period. Using daily λ inputs, the three models produced stomatal conductance (gs) with accuracies ranked as OSCvjd (R2 = 0.73) > OSCd (0.63) > OSCvcd (0.40). When a long-term constant λ was applied, model performance declined with accuracies ranked as OSCvj (0.66) > OSC (0.52) > OSCvc (0.38). The OSC model also produced intercellular CO2 concentration (ci) and photosynthesis (A) reasonably well (R2 = 0.78 and 0.48, respectively). Under moderate meteorological conditions (air temperature 30–40 ℃ and vapor pressure deficit 1–2 kPa), the OSC model showed its best performance with a mean absolute relative error of 35.2% for gs estimation. Overall, the OSCMs provided a mechanistic approach to simulate citrus leaf gas exchange requiring minimal species-specific traits and routine meteorological inputs. This modeling strategy supports rapid assessment of plant physiological status and estimation of foliar carbon-water fluxes in orchard management under subtropical climates.
Keywords: Citrus, Meteorological factors, Photosynthetic limitations, Stomatal conductance, the optimal stomatal regulation
Received: 03 Dec 2025; Accepted: 06 Feb 2026.
Copyright: © 2026 Fan, Wang, Jiang, Cui, Zhao, Jiang, Zhu, Xing and Zhang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Xuelian Jiang
Ningbo Cui
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