Characterizing and Estimating Fungal Disease Severity of Rice Brown Spot with Hyperspectral Reflectance Data

作     者：LIU Zhan-yu HUANG Jing-feng TAO Rong-xiang LIU Zhan-yu1, HUANG Jing-feng1, TAO Rong-xiang2 (1Institute of Agricultural Remote Sensing & Information System Application, Zhejiang University, Hangzhou 310029, China;2Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China)

作者机构：Institute of Agricultural Remote Sensing ＆ Information System Application Zhejiang University Hangzhou 310029 China Institute of Plant Protection and Microbiology Zhejiang Academy of Agricultural Sciences Hangzhou 310021 China 

出 版 物：《Rice science》 (水稻科学（英文版）)

年 卷 期：2008年第15卷第3期

页      面：232-242页

学科分类：0710[理学-生物学] 0831[工学-生物医学工程（可授工学、理学、医学学位）] 09[农学] 0901[农学-作物学] 0836[工学-生物工程] 0902[农学-园艺学] 

基　　金：supported by the National High Technology Research and Development Program of China (Grant No. 2006AA10Z203) the National Natural Science Foundation of China (Grant No. 40571115). 

主　　题：derivative spectrum hyperspectral reflectance ratio of spectral reflectance rice brown spot disease severity Bipolaris oryzae （ Helminthosporium oryzae） sensitivity analysis remote sensing 

摘      要：Large-scale farming of agriculture crops requires real-time detection of disease for field pest management. Hyperspectral remote sensing data generally have high spectral resolution, which could be very useful for detecting disease stress in green vegetation at the leaf and canopy levels. In this study, hyperspectral reflectances of rice in the laboratory and field were measured to characterize the spectral regions and wavebands, which were the most sensitive to rice brown spot infected by Bipolaris oryzae （Helminthosporium oryzae Breda. de Hann）. Leaf reflectance increased at the ranges of 450 to 500 nm and 630 to 680 nm with the increasing percentage of infected leaf surface, and decreased at the ranges of 520 to 580 nm, 760 to 790 nm, 1550 to 1750 nm, and 2080 to 2350 nm with the increasing percentage of infected leaf surface respectively. The sensitivity analysis and derivative technique were used to select the sensitive wavebands for the detection of rice brown spot infected by B. oryzae. Ratios of rice leaf reflectance were evaluated as indicators of brown spot. R669/R746 （the reflectance at 669 nm divided by the reflectance at 746 nm, the following ratios may be deduced by analogy）, R702/R718, R692/R530, R692/R732, R535/R746, R521/R718, and R569/R718 increased significantly as the incidence of rice brown spot increased regardless of whether it＇s at the leaf or canopy level. R702/R718, R692/R530, R692/R732 were the best three ratios for estimating the disease severity of rice brown spot at the leaf and canopy levels. This result not only confirms the capability of hyperspectral remote sensing data in characterizing crop disease for precision pest management in the real world, but also testifies that the ratios of crop reflectance is a useful method to estimate crop disease severity.