The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature Model

Transpiration is the dominant process driving water loss in crops, significantly influencing their growth, development, and yield. Efficient monitoring of transpiration rate (Tr) is crucial for evaluating crop physiological status and optimizing water management strategies. The three-temperature (3T...

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Main Authors: Xiaofei Yang, Zhitao Zhang, Qi Xu, Ning Dong, Xuqian Bai, Yanfu Liu
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/14/2209
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author Xiaofei Yang
Zhitao Zhang
Qi Xu
Ning Dong
Xuqian Bai
Yanfu Liu
author_facet Xiaofei Yang
Zhitao Zhang
Qi Xu
Ning Dong
Xuqian Bai
Yanfu Liu
author_sort Xiaofei Yang
collection DOAJ
description Transpiration is the dominant process driving water loss in crops, significantly influencing their growth, development, and yield. Efficient monitoring of transpiration rate (Tr) is crucial for evaluating crop physiological status and optimizing water management strategies. The three-temperature (3T) model has potential for rapid estimation of transpiration rates, but its application to low-altitude remote sensing has not yet been further investigated. To evaluate the performance of 3T model based on land surface temperature (LST) and canopy temperature (T<sub>C</sub>) in estimating transpiration rate, this study utilized an unmanned aerial vehicle (UAV) equipped with a thermal infrared (TIR) camera to capture TIR images of summer maize during the nodulation-irrigation stage under four different moisture treatments, from which LST was extracted. The Gaussian Hidden Markov Random Field (GHMRF) model was applied to segment the TIR images, facilitating the extraction of T<sub>C</sub>. Finally, an improved 3T model incorporating fractional vegetation coverage (FVC) was proposed. The findings of the study demonstrate that: (1) The GHMRF model offers an effective approach for TIR image segmentation. The mechanism of thermal TIR segmentation implemented by the GHMRF model is explored. The results indicate that when the potential energy function parameter β value is 0.1, the optimal performance is provided. (2) The feasibility of utilizing UAV-based TIR remote sensing in conjunction with the 3T model for estimating Tr has been demonstrated, showing a significant correlation between the measured and the estimated transpiration rate (T<sub>r</sub>-3T<sub>C</sub>), derived from T<sub>C</sub> data obtained through the segmentation and processing of TIR imagery. The correlation coefficients (r) were 0.946 in 2022 and 0.872 in 2023. (3) The improved 3T model has demonstrated its ability to enhance the estimation accuracy of crop Tr rapidly and effectively, exhibiting a robust correlation with T<sub>r</sub>-3T<sub>C</sub>. The correlation coefficients for the two observed years are 0.991 and 0.989, respectively, while the model maintains low RMSE of 0.756 mmol H<sub>2</sub>O m<sup>−2</sup> s<sup>−1</sup> and 0.555 mmol H<sub>2</sub>O m<sup>−2</sup> s<sup>−1</sup> for the respective years, indicating strong interannual stability.
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institution Kabale University
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publishDate 2025-07-01
publisher MDPI AG
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series Plants
spelling doaj-art-40415a1b904142b2bb01d4b5576d3dae2025-08-20T03:56:49ZengMDPI AGPlants2223-77472025-07-011414220910.3390/plants14142209The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature ModelXiaofei Yang0Zhitao Zhang1Qi Xu2Ning Dong3Xuqian Bai4Yanfu Liu5College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, ChinaCollege of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, ChinaCollege of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, ChinaCollege of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, ChinaCollege of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, ChinaCollege of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, ChinaTranspiration is the dominant process driving water loss in crops, significantly influencing their growth, development, and yield. Efficient monitoring of transpiration rate (Tr) is crucial for evaluating crop physiological status and optimizing water management strategies. The three-temperature (3T) model has potential for rapid estimation of transpiration rates, but its application to low-altitude remote sensing has not yet been further investigated. To evaluate the performance of 3T model based on land surface temperature (LST) and canopy temperature (T<sub>C</sub>) in estimating transpiration rate, this study utilized an unmanned aerial vehicle (UAV) equipped with a thermal infrared (TIR) camera to capture TIR images of summer maize during the nodulation-irrigation stage under four different moisture treatments, from which LST was extracted. The Gaussian Hidden Markov Random Field (GHMRF) model was applied to segment the TIR images, facilitating the extraction of T<sub>C</sub>. Finally, an improved 3T model incorporating fractional vegetation coverage (FVC) was proposed. The findings of the study demonstrate that: (1) The GHMRF model offers an effective approach for TIR image segmentation. The mechanism of thermal TIR segmentation implemented by the GHMRF model is explored. The results indicate that when the potential energy function parameter β value is 0.1, the optimal performance is provided. (2) The feasibility of utilizing UAV-based TIR remote sensing in conjunction with the 3T model for estimating Tr has been demonstrated, showing a significant correlation between the measured and the estimated transpiration rate (T<sub>r</sub>-3T<sub>C</sub>), derived from T<sub>C</sub> data obtained through the segmentation and processing of TIR imagery. The correlation coefficients (r) were 0.946 in 2022 and 0.872 in 2023. (3) The improved 3T model has demonstrated its ability to enhance the estimation accuracy of crop Tr rapidly and effectively, exhibiting a robust correlation with T<sub>r</sub>-3T<sub>C</sub>. The correlation coefficients for the two observed years are 0.991 and 0.989, respectively, while the model maintains low RMSE of 0.756 mmol H<sub>2</sub>O m<sup>−2</sup> s<sup>−1</sup> and 0.555 mmol H<sub>2</sub>O m<sup>−2</sup> s<sup>−1</sup> for the respective years, indicating strong interannual stability.https://www.mdpi.com/2223-7747/14/14/2209transpiration ratethree-temperature modelthermal infrared remote sensingunmanned aerial vehicleGHMRF model
spellingShingle Xiaofei Yang
Zhitao Zhang
Qi Xu
Ning Dong
Xuqian Bai
Yanfu Liu
The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature Model
Plants
transpiration rate
three-temperature model
thermal infrared remote sensing
unmanned aerial vehicle
GHMRF model
title The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature Model
title_full The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature Model
title_fullStr The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature Model
title_full_unstemmed The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature Model
title_short The Evaluation of Small-Scale Field Maize Transpiration Rate from UAV Thermal Infrared Images Using Improved Three-Temperature Model
title_sort evaluation of small scale field maize transpiration rate from uav thermal infrared images using improved three temperature model
topic transpiration rate
three-temperature model
thermal infrared remote sensing
unmanned aerial vehicle
GHMRF model
url https://www.mdpi.com/2223-7747/14/14/2209
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