Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman Spectra

Accurate diagnosis of crop nutritional status is critical for optimizing yield and quality in modern agriculture. This study enhances the accuracy of Raman spectroscopy-based nutrient diagnosis, improving its application in precision agriculture. We propose a method to identify optimal diagnostic po...

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Main Authors: Zhaolong Hou, Yaxuan Wang, Feng Tan, Jiaxin Gao, Feng Jiao, Chunjie Su, Xin Zheng
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/8/1199
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author Zhaolong Hou
Yaxuan Wang
Feng Tan
Jiaxin Gao
Feng Jiao
Chunjie Su
Xin Zheng
author_facet Zhaolong Hou
Yaxuan Wang
Feng Tan
Jiaxin Gao
Feng Jiao
Chunjie Su
Xin Zheng
author_sort Zhaolong Hou
collection DOAJ
description Accurate diagnosis of crop nutritional status is critical for optimizing yield and quality in modern agriculture. This study enhances the accuracy of Raman spectroscopy-based nutrient diagnosis, improving its application in precision agriculture. We propose a method to identify optimal diagnostic positions on cucumber leaves for early detection of nitrogen (N), phosphorus (P), and potassium (K) deficiencies, thereby providing a robust scientific basis for high-throughput phenotyping using Raman spectroscopy (RS). Using a dot-matrix approach, we collected RS data across different leaf positions and explored the selection of diagnostic positions through spectral cosine similarity analysis. These results provide critical insights for developing rapid, non-destructive methods for nutrient stress monitoring in crops. Results show that spectral similarity across positions exhibits higher instability during the early developmental stages of leaves or under short-term (24 h) nutrient stress, with significant differences in the stability of spectral data among treatment groups. However, visual analysis of the spatial distribution of positions with lower similarity values reveals consistent spectral similarity distribution patterns across different treatment groups, with the lower similarity values predominantly observed at the leaf margins, near the main veins, and at the leaf base. Excluding low-similarity data significantly improved model performance for early (24 h) nutrient deficiency diagnosis, resulting in higher precision, recall, and F1 scores. Based on these results, the efficacy of the proposed method for selecting diagnostic positions has been validated. It is recommended to avoid collecting RS data from areas near the leaf margins, main veins, and the leaf base when diagnosing early nutrient deficiencies in plants to enhance diagnostic accuracy.
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spelling doaj-art-7154976289bf4f25adb1fa2b75dc172c2025-08-20T02:18:10ZengMDPI AGPlants2223-77472025-04-01148119910.3390/plants14081199Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman SpectraZhaolong Hou0Yaxuan Wang1Feng Tan2Jiaxin Gao3Feng Jiao4Chunjie Su5Xin Zheng6College of Engineering, Heilongjiang Bayi Agricultural University, Daqing 163319, ChinaCollege of Civil Engineering and Water Conservancy, Heilongjiang Bayi Agricultural University, Daqing 163319, ChinaCollege of Information and Electrical Engineering, Heilongjiang Bayi Agricultural University, Daqing 163319, ChinaCollege of Engineering, Heilongjiang Bayi Agricultural University, Daqing 163319, ChinaCollege of Agriculture, Heilongjiang Bayi Agricultural University, Daqing 163319, ChinaCollege of Horticulture and Landscape Architecture, Heilongjiang Bayi Agricultural University, Daqing 163319, ChinaCollege of Civil Engineering and Water Conservancy, Heilongjiang Bayi Agricultural University, Daqing 163319, ChinaAccurate diagnosis of crop nutritional status is critical for optimizing yield and quality in modern agriculture. This study enhances the accuracy of Raman spectroscopy-based nutrient diagnosis, improving its application in precision agriculture. We propose a method to identify optimal diagnostic positions on cucumber leaves for early detection of nitrogen (N), phosphorus (P), and potassium (K) deficiencies, thereby providing a robust scientific basis for high-throughput phenotyping using Raman spectroscopy (RS). Using a dot-matrix approach, we collected RS data across different leaf positions and explored the selection of diagnostic positions through spectral cosine similarity analysis. These results provide critical insights for developing rapid, non-destructive methods for nutrient stress monitoring in crops. Results show that spectral similarity across positions exhibits higher instability during the early developmental stages of leaves or under short-term (24 h) nutrient stress, with significant differences in the stability of spectral data among treatment groups. However, visual analysis of the spatial distribution of positions with lower similarity values reveals consistent spectral similarity distribution patterns across different treatment groups, with the lower similarity values predominantly observed at the leaf margins, near the main veins, and at the leaf base. Excluding low-similarity data significantly improved model performance for early (24 h) nutrient deficiency diagnosis, resulting in higher precision, recall, and F1 scores. Based on these results, the efficacy of the proposed method for selecting diagnostic positions has been validated. It is recommended to avoid collecting RS data from areas near the leaf margins, main veins, and the leaf base when diagnosing early nutrient deficiencies in plants to enhance diagnostic accuracy.https://www.mdpi.com/2223-7747/14/8/1199nutrient deficiencycucumbersRaman spectroscopyprecision agricultureleaf positionnitrogen
spellingShingle Zhaolong Hou
Yaxuan Wang
Feng Tan
Jiaxin Gao
Feng Jiao
Chunjie Su
Xin Zheng
Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman Spectra
Plants
nutrient deficiency
cucumbers
Raman spectroscopy
precision agriculture
leaf position
nitrogen
title Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman Spectra
title_full Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman Spectra
title_fullStr Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman Spectra
title_full_unstemmed Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman Spectra
title_short Selection of Optimal Diagnostic Positions for Early Nutrient Deficiency in Cucumber Leaves Based on Spatial Distribution of Raman Spectra
title_sort selection of optimal diagnostic positions for early nutrient deficiency in cucumber leaves based on spatial distribution of raman spectra
topic nutrient deficiency
cucumbers
Raman spectroscopy
precision agriculture
leaf position
nitrogen
url https://www.mdpi.com/2223-7747/14/8/1199
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