Journal of Integrative Agriculture ›› 2014, Vol. 13 ›› Issue (4): 760-769.DOI: 10.1016/S2095-3119(13)60385-8

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Detection of Internal Leaf Structure Deterioration Using a New Spectral Ratio Index in the Near-Infrared Shoulder Region

 LIU Liang-yun, HUANG Wen-jiang, PU Rui-liang , WANG Ji-hua   

  1. 1、Key Laboratory of Digital Earth Science, Center for Earth Observation and Digital Earth, Chinese Academy of Sciences, Beijing 100094,
    P.R.China
    2、Department of Geography, Environment, and Planning, University of South Florida, 4202 E. Fowler Ave., NES 107, Tampa, FL 33620, USA
    3、National Engineering Research Center for Information Technology in Agriculture, Beijing 100097, P.R.China
  • 收稿日期:2012-10-16 出版日期:2014-04-01 发布日期:2014-04-16
  • 通讯作者: LIU Liang-yun, Tel: +86-10-82178163, Fax: +86-10-82178177, E-mail: liuly@radi.ac.cn
  • 基金资助:

    this research by the National High-Tech R&D Program of China (2012AA12A30701) and the National Natural Science Foundation of China (91125003, 41222008).

Detection of Internal Leaf Structure Deterioration Using a New Spectral Ratio Index in the Near-Infrared Shoulder Region

 LIU Liang-yun, HUANG Wen-jiang, PU Rui-liang , WANG Ji-hua   

  1. 1、Key Laboratory of Digital Earth Science, Center for Earth Observation and Digital Earth, Chinese Academy of Sciences, Beijing 100094,
    P.R.China
    2、Department of Geography, Environment, and Planning, University of South Florida, 4202 E. Fowler Ave., NES 107, Tampa, FL 33620, USA
    3、National Engineering Research Center for Information Technology in Agriculture, Beijing 100097, P.R.China
  • Received:2012-10-16 Online:2014-04-01 Published:2014-04-16
  • Contact: LIU Liang-yun, Tel: +86-10-82178163, Fax: +86-10-82178177, E-mail: liuly@radi.ac.cn
  • Supported by:

    this research by the National High-Tech R&D Program of China (2012AA12A30701) and the National Natural Science Foundation of China (91125003, 41222008).

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摘要： Spectral reflectance in the near-infrared (NIR) shoulder (750-900 nm) region is affected by internal leaf structure, but it has rarely been investigated. In this study, a dehydration treatment and three paraquat herbicide applications were conducted to explore how spectral reflectance and shape in the NIR shoulder region responded to various stresses. A new spectral ratio index in the NIR shoulder region (NSRI), defined by a simple ratio of reflectance at 890 nm to reflectance at 780 nm, was proposed for assessing leaf structure deterioration. Firstly, a wavelength-independent increase in spectral reflectance in the NIR shoulder region was observed from the mature leaves with slight dehydration. An increase in spectral slope in the NIR shoulder would be expected only when water stress developed sufficiently to cause severe leaf dehydration resulting in an alteration in cell structure. Secondly, the alteration of leaf cell structure caused by Paraquat herbicide applications resulted in a wavelength-dependent variation of spectral reflectance in the NIR shoulder region. The NSRI in the NIR shoulder region increased significantly under an herbicide application. Although the dehydration process also occurred with the herbicide injury, NSRI is more sensitive to herbicide injury than the water-related indices (water index and normalized difference water index) and normalized difference vegetation index. Finally, the sensitivity of NSRI to stripe rust in winter wheat was examined, yielding a determination coefficient of 0.61, which is more significant than normalized difference vegetation index (NDVI), water index (WI) and normalized difference water index (NDWI), with a determination coefficient of 0.45, 0.36 and 0.13, respectively. In this study, all experimental results demonstrated that NSRI will increase with internal leaf structure deterioration, and it is also a sensitive spectral index for herbicide injury or stripe rust in winter wheat.

关键词: spectral ratio index , spectral reflectance , vegetation index , dehydration , paraquat herbicide , stripe rust

Abstract: Spectral reflectance in the near-infrared (NIR) shoulder (750-900 nm) region is affected by internal leaf structure, but it has rarely been investigated. In this study, a dehydration treatment and three paraquat herbicide applications were conducted to explore how spectral reflectance and shape in the NIR shoulder region responded to various stresses. A new spectral ratio index in the NIR shoulder region (NSRI), defined by a simple ratio of reflectance at 890 nm to reflectance at 780 nm, was proposed for assessing leaf structure deterioration. Firstly, a wavelength-independent increase in spectral reflectance in the NIR shoulder region was observed from the mature leaves with slight dehydration. An increase in spectral slope in the NIR shoulder would be expected only when water stress developed sufficiently to cause severe leaf dehydration resulting in an alteration in cell structure. Secondly, the alteration of leaf cell structure caused by Paraquat herbicide applications resulted in a wavelength-dependent variation of spectral reflectance in the NIR shoulder region. The NSRI in the NIR shoulder region increased significantly under an herbicide application. Although the dehydration process also occurred with the herbicide injury, NSRI is more sensitive to herbicide injury than the water-related indices (water index and normalized difference water index) and normalized difference vegetation index. Finally, the sensitivity of NSRI to stripe rust in winter wheat was examined, yielding a determination coefficient of 0.61, which is more significant than normalized difference vegetation index (NDVI), water index (WI) and normalized difference water index (NDWI), with a determination coefficient of 0.45, 0.36 and 0.13, respectively. In this study, all experimental results demonstrated that NSRI will increase with internal leaf structure deterioration, and it is also a sensitive spectral index for herbicide injury or stripe rust in winter wheat.

Key words: spectral ratio index , spectral reflectance , vegetation index , dehydration , paraquat herbicide , stripe rust