RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern China

The context of global climate change, water stress has a significant impact on the ecological function and landscape value of urban greening shrubs. In this study, three typical greening shrubs (<i>Euonymus japonicus</i>, <i>Ligustrum</i> × <i>vicaryi</i>, and <...

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Main Authors: Yuan Niu, Xiaotian Xu, Wenxu Huang, Jiaying Li, Shaoning Li, Na Zhao, Bin Li, Chengyang Xu, Shaowei Lu
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/15/2253
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author Yuan Niu
Xiaotian Xu
Wenxu Huang
Jiaying Li
Shaoning Li
Na Zhao
Bin Li
Chengyang Xu
Shaowei Lu
author_facet Yuan Niu
Xiaotian Xu
Wenxu Huang
Jiaying Li
Shaoning Li
Na Zhao
Bin Li
Chengyang Xu
Shaowei Lu
author_sort Yuan Niu
collection DOAJ
description The context of global climate change, water stress has a significant impact on the ecological function and landscape value of urban greening shrubs. In this study, three typical greening shrubs (<i>Euonymus japonicus</i>, <i>Ligustrum</i> × <i>vicaryi</i>, and <i>Berberis thunbergii</i> var. <i>atropurpurea</i>) in North China were subjected to a two-year field-controlled experiment (2022–2023) with four water treatments: full irrigation, deficit irrigation, natural rainfall, and extreme drought. The key findings are as follows: (1) Extreme drought reduced the color indices substantially—the G<sub>CC</sub> of <i>E. japonicus</i> decreased by 40% (2023); the R<sub>CC</sub> of <i>B. thunbergii</i> var. <i>atropurpurea</i> declined by 35% (2022); and the color indices of <i>L.</i> × <i>vicaryi</i> remained stable (variation < 15%). (2) Early-season soil water content (SWC) strongly correlated with the color index of <i>E. japonicus</i> (r<sup>2</sup> = 0.42, <i>p</i> < 0.05) but weakly with <i>B. thunbergii</i> (r<sup>2</sup> = 0.28), suggesting species-specific drought-tolerance mechanisms like reduced leaf area. (3) Deficit irrigation (SWC ≈ 40%) maintained color indices between fully irrigated and drought-stressed levels. Notably, <i>B. thunbergii</i> retained high redness (R<sub>CC</sub> > 0.8) at an SWC ≈ 40%; <i>E. japonicus</i> required an SWC > 60% to preserve greenness (G<sub>CC</sub>). The research results provide a scientific basis for urban greening plant screening and water-saving irrigation strategies, and expand the application scenarios of color coordinates in plant physiological and ecological research.
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institution Kabale University
issn 2223-7747
language English
publishDate 2025-07-01
publisher MDPI AG
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series Plants
spelling doaj-art-ec80aa38f21c4684a12bbcb4fd7d4ae32025-08-20T03:36:22ZengMDPI AGPlants2223-77472025-07-011415225310.3390/plants14152253RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern ChinaYuan Niu0Xiaotian Xu1Wenxu Huang2Jiaying Li3Shaoning Li4Na Zhao5Bin Li6Chengyang Xu7Shaowei Lu8Urban Forestry Research Center, Beijing Forestry University, Beijing 100083, ChinaInstitute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, ChinaInstitute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, ChinaInstitute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, ChinaInstitute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, ChinaInstitute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, ChinaInstitute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, ChinaUrban Forestry Research Center, Beijing Forestry University, Beijing 100083, ChinaInstitute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, ChinaThe context of global climate change, water stress has a significant impact on the ecological function and landscape value of urban greening shrubs. In this study, three typical greening shrubs (<i>Euonymus japonicus</i>, <i>Ligustrum</i> × <i>vicaryi</i>, and <i>Berberis thunbergii</i> var. <i>atropurpurea</i>) in North China were subjected to a two-year field-controlled experiment (2022–2023) with four water treatments: full irrigation, deficit irrigation, natural rainfall, and extreme drought. The key findings are as follows: (1) Extreme drought reduced the color indices substantially—the G<sub>CC</sub> of <i>E. japonicus</i> decreased by 40% (2023); the R<sub>CC</sub> of <i>B. thunbergii</i> var. <i>atropurpurea</i> declined by 35% (2022); and the color indices of <i>L.</i> × <i>vicaryi</i> remained stable (variation < 15%). (2) Early-season soil water content (SWC) strongly correlated with the color index of <i>E. japonicus</i> (r<sup>2</sup> = 0.42, <i>p</i> < 0.05) but weakly with <i>B. thunbergii</i> (r<sup>2</sup> = 0.28), suggesting species-specific drought-tolerance mechanisms like reduced leaf area. (3) Deficit irrigation (SWC ≈ 40%) maintained color indices between fully irrigated and drought-stressed levels. Notably, <i>B. thunbergii</i> retained high redness (R<sub>CC</sub> > 0.8) at an SWC ≈ 40%; <i>E. japonicus</i> required an SWC > 60% to preserve greenness (G<sub>CC</sub>). The research results provide a scientific basis for urban greening plant screening and water-saving irrigation strategies, and expand the application scenarios of color coordinates in plant physiological and ecological research.https://www.mdpi.com/2223-7747/14/15/2253image processingcolor modedrought tolerancecolor index
spellingShingle Yuan Niu
Xiaotian Xu
Wenxu Huang
Jiaying Li
Shaoning Li
Na Zhao
Bin Li
Chengyang Xu
Shaowei Lu
RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern China
Plants
image processing
color mode
drought tolerance
color index
title RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern China
title_full RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern China
title_fullStr RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern China
title_full_unstemmed RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern China
title_short RGB Imaging and Irrigation Management Reveal Water Stress Thresholds in Three Urban Shrubs in Northern China
title_sort rgb imaging and irrigation management reveal water stress thresholds in three urban shrubs in northern china
topic image processing
color mode
drought tolerance
color index
url https://www.mdpi.com/2223-7747/14/15/2253
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