Tan et al. (2026) Divergent drivers of canopy and ecosystem water use efficiency in a drip-irrigated citrus orchard of a seasonal arid area in Southwest China

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-07-24
• Authors: Mingdong Tan, Ningbo Cui, Qingyan He, Zhihui Wang, Liwen Xing, Lu Zhao, Ziling He, Daozhi Gong, Yu Feng, Shouzheng Jiang
• DOI: 10.1016/j.agwat.2026.110649

Research Groups

• State Key Laboratory of Hydraulics and Mountain River Engineering & College of Water Resource and Hydropower, Sichuan University, Chengdu 610065, China
• Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China
• Ningbo Institute of Digital Twin, Eastern Institute of Technology, Ningbo 315200, China

Short Summary

This study analyzed four consecutive years of flux data from a subtropical drip-irrigated citrus orchard in Southwest China to quantify seasonal variations in ecosystem water use efficiency (eWUE) and canopy water use efficiency (cWUE), and identified their environmental controls during the growing and non-growing seasons. Results showed that eWUE exhibited pronounced seasonal dynamics, peaking in winter and declining to a minimum during summer, while cWUE remained relatively stable throughout the year.

Objective

• Investigate the seasonal patterns of eWUE and cWUE in citrus orchards
• Identify key environmental drivers governing eWUE and cWUE during both growing and non-growing seasons
• Quantify the relative contributions of carbon (GPP and NEP) and water fluxes (ET and T) on WUE during growing and non-growing seasons

Study Configuration

• Spatial Scale: Subtropical citrus orchard in Southwest China, with a row spacing of 3 × 4 m and average tree height of 1.8 m
• Temporal Scale: Four consecutive years from 2020 to 2023, covering both growing season (April to November) and non-growing season (December to March)

Methodology and Data

• Models used: Eddy covariance system (EC150, Campbell Scientific Inc., USA), three-dimensional sonic anemometer (CSAT3, Campbell Scientific Inc., USA)
• Data sources: Open-path infrared CO2/H2O gas analyzer, temperature and humidity sensor, net solar radiation monitor, precipitation gauge, soil moisture sensors

Main Results

• eWUE exhibited pronounced seasonal dynamics, peaking in winter and declining to a minimum during summer
• cWUE remained relatively stable throughout the year, with an overall mean of 2.58 g C kg−1 H2O
• The substantial reduction in soil E by 86% during the non-growing season drives a disproportional decrease in ET (62%) relative to GPP

Contributions

• This study provides a mechanistic understanding of carbon and water coupling in perennial orchard systems
• The findings highlight the importance of considering both growing and non-growing seasons when evaluating WUE in citrus orchards

Funding

• State Key Laboratory of Hydraulics and Mountain River Engineering & College of Water Resource and Hydropower, Sichuan University (project code: [insert project code])
• Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences (project code: [insert project code])

Citation

@article{Tan2026Divergent,
  author = {Tan, Mingdong and Cui, Ningbo and He, Qingyan and Wang, Zhihui and Xing, Liwen and Zhao, Lu and He, Ziling and Gong, Daozhi and Feng, Yu and Jiang, Shouzheng},
  title = {Divergent drivers of canopy and ecosystem water use efficiency in a drip-irrigated citrus orchard of a seasonal arid area in Southwest China},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110649},
  url = {https://doi.org/10.1016/j.agwat.2026.110649}
}