孔繁昌, 刘焕军, 于滋洋, 孟祥添, 韩雨, 张新乐, 宋少忠, 罗冲. 高寒地区粳稻穗颈瘟的无人机高光谱遥感识别[J]. 农业工程学报, 2020, 36(22): 68-75. DOI: 10.11975/j.issn.1002-6819.2020.22.008
    引用本文: 孔繁昌, 刘焕军, 于滋洋, 孟祥添, 韩雨, 张新乐, 宋少忠, 罗冲. 高寒地区粳稻穗颈瘟的无人机高光谱遥感识别[J]. 农业工程学报, 2020, 36(22): 68-75. DOI: 10.11975/j.issn.1002-6819.2020.22.008
    Kong Fanchang, Liu Huanjun, Yu Ziyang, Meng Xiangtian, Han Yu, Zhang Xinle, Song Shaozhong, Luo Chong. Identification of japonica rice panicle blast in alpine region by UAV hyperspectral remote sensing[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2020, 36(22): 68-75. DOI: 10.11975/j.issn.1002-6819.2020.22.008
    Citation: Kong Fanchang, Liu Huanjun, Yu Ziyang, Meng Xiangtian, Han Yu, Zhang Xinle, Song Shaozhong, Luo Chong. Identification of japonica rice panicle blast in alpine region by UAV hyperspectral remote sensing[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2020, 36(22): 68-75. DOI: 10.11975/j.issn.1002-6819.2020.22.008

    高寒地区粳稻穗颈瘟的无人机高光谱遥感识别

    Identification of japonica rice panicle blast in alpine region by UAV hyperspectral remote sensing

    • 摘要: 水稻穗颈瘟作为稻瘟病的一种发病形式常以褐色斑点性状出现在水稻穗颈节部位,对稻穗颈瘟病害快速、无损的识别与分级评估一直是备受关注的研究课题。该研究以高寒地区粳稻大田试验为基础,利用无人机高光谱平台获取不同病害等级的水稻穗颈瘟冠层数据;分别以不同处理的光谱数据作为输入量,使用随机森林(Random Forest,RF)的方法进行建模,并结合水稻生理对各输入量的特征关联加以解释。结果表明:随着穗颈瘟病害等级的提升,水稻冠层反射率整体呈现下降的趋势;植被指数组合(Combination of Vegetation Indices,CVIs)作为输入量建立起来的预测模型具有最高的精度,预测集精度达到90%,Kappa系数为0.86,能够解释穗颈瘟所引起的植株整体生理参数综合变化过程。该研究结果可为无人机高光谱遥感实现穗颈瘟病定量遥感监测与预警分级提供支持。

       

      Abstract: Abstract: Panicle blast is one of the most serious diseases in the rice production process. Because of its rapid transmission, difficult prevention and control, and strong destruction, it has the greatest impact on yield. The Unmanned Aerial Vehicle (UAV) hyperspectral remote sensing can not only realize the accurate monitoring of diseases and insect pests in a larger range and with higher spatial resolution but also promoted the application of the hyperspectral theory of rice blast. In this study, a field experiment on rice blast was conducted in Yongji, Jilin from April to September 2019. Jiyujing (code name: ji90-g4) was selected as the experimental variety. In order to maximally stimulate the natural onset of rice blast, Mongolian rice inoculated with Pyricularia oryzae was used as the inducing plant to infect healthy rice. The UAV hyperspectral remote sensing platform (UAV: DJI M600 Pro; Imaging spectrometer: Cubert S185) was used to collect hyperspectral image data of the entire experimental area. At the same time, plant protection experts were invited on the ground to classify the 30 sampling points according to the health, mild, moderate, and severe simultaneous disease severity. ENVI 5.3 was used for the geometric correction of the image. According to the GPS positioning points determined by ground sampling, each corresponding sampling area was extracted into a Region Of Interest (ROI) according to the 30 × 30(pixels) rectangular area, and the corresponding ground spatial resolution was 0.9 m × 0.9 m. The spectral data of all pixels in each ROI were averaged, and different spectral preprocessing and mathematical transformations were carried out as the input of the model. The samples were randomly divided into the modeling set and verification set according to the ratio of 2:1, and then Random Forest (RF) model was used for modeling. RF model avoided the overfitting problem when there were few sampling points. The overall reflectance of rice spectral curve with different panicle blast grades showed a downward trend, and change at 670 nm was the strongest correlation with the change of rice blast grade; Continuum Removal (CR) treatment further improved the spectral difference of target objects, and there were three obvious inflection points of reflection and absorption between 466 and 750 nm, with 498, 534, and 666 nm as the center points. Based on a variety of the Combination of Vegetation Indices (CVIs) which reflected the changes in rice physiological parameters, the best results were obtained in RF modeling. The highest accuracy of modeling was 90% and the Kappa coefficient was 0.86. At the same time, it explained the changes in plant physiological parameters such as chlorophyll, carotenoid, nitrogen content, cell structure, red edge, and so on. The relationship between the spectrum of panicle blast and the variation of plant parameters were established. The Principal Component Analysis (PCA) method for data processing and modeling, which was often used in previous studies on rice blast spectrum, did not achieve ideal results in this study, which might be due to the difference between field and laboratory environmental conditions. How to reduce environmental noise and extract more effective disease information would be the key to the next step of research. Compared with the indoor spectral theory research of rice blast, the UAV hyperspectral remote sensing monitoring experiment is the theoretical research, and it is the key link to the field rice blast quantitative remote sensing monitoring and early warning grading, filling the gap between the theory and practice of rice blast monitoring.

       

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