Sun Hong, Li Min-Zan, Zhou Zhi-Yan, Liu Gang, Luo Xi-Wen
Key Laboratory of Modern Precision Agriculture System Integration Research of Ministry of Education, China Agricultural University, Beijing 100083, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2010 Apr;30(4):1080-3.
The canopy reflectance of rice was measured in the filed in order to monitor the damaged region caused by Cnaphalocrocis medinalis Guenee. The characteristics of canopy spectral reflectance were analyzed in contrast region and damaged regions. When rice plant was damaged by Cnaphalocrocis medinalis Guenee, the chlorophyll absorption was decreased in the band of 600-700 nm. The canopy reflectance of moderate damage region was lower than that of the contrast region, while the reflectance of severe damage region rice was higher near 550 nm. The canopy reflectance of Cnaphalocrocis medinalis Guenee damaged rice was fluctuant and exhibited the significant peak in the NIR band of 750-770nm. Meanwhile, red edge inflection point as one of the most important spectral parameters was analyzed at different damage levels based on the first derivative of reflectance spectra. The analysis results indicated that red edge inflection position moved to direction of blue light (short wavelength) with the affection severity increasing. Then the modified reflectance of rice canopy was calculated based on zero-mean calculation and standard deviation. It was easy to find the degree of deviation from the average of samples and distinguish the damaged region from experiment plots. The canopy modified reflectance was gently in the contrast region, but changed violently in the affected regions in the band of 750-950 nm. The analysis of Cnaphalocrocis medinalis Guenee affected regions illustrated that the Cnaphalocrocis medinalis Guenee was increased with the increase in severity. The vegetation index was applied in detection of Cnaphalocrocis medinalis Guenee damaged regions because of the composition of multi-wavelength information. The wavelengths 762 and 774 nm were chosen to build detection parameters of Cnaphalocrocis medinalis Guenee such as NIR-RVI, NIR-DVI, NIR-NDVI and KI. The results indicated that the NIR-NDVI could be used to identify the damaged region with contrast region efficiently. The accurate rate of 25 verification samples selected randomly reached 70%. The preliminary studies on rice Cnaphalocrocis medinalis Guenee damaged regions provided a new method to detect the affected regions in the wide area.
为监测稻纵卷叶螟（Cnaphalocrocis medinalis Guenee）造成的受害区域，对稻田中水稻冠层反射率进行了测定。在对照区和受害区分析了冠层光谱反射率特征。当水稻植株受到稻纵卷叶螟为害时，600 - 700nm波段的叶绿素吸收减少。中度受害区的冠层反射率低于对照区，而重度受害区水稻在550nm附近的反射率较高。受稻纵卷叶螟为害水稻的冠层反射率呈波动状，在750 - 770nm的近红外波段出现明显峰值。同时，基于反射光谱的一阶导数，分析了不同受害程度下作为最重要光谱参数之一的红边拐点。分析结果表明，随着受害程度增加，红边拐点向蓝光（短波长）方向移动。然后基于零均值计算和标准差计算了水稻冠层的修正反射率。很容易发现与样本平均值的偏离程度，并从试验田中区分出受害区域。在750 - 950nm波段，冠层修正反射率在对照区变化平缓，但在受害区变化剧烈。对稻纵卷叶螟为害区域的分析表明，受害程度越高，稻纵卷叶螟数量越多。由于多波长信息的组成，植被指数被应用于稻纵卷叶螟受害区域的检测。选择762和774nm波长构建稻纵卷叶螟检测参数，如近红外比值植被指数（NIR - RVI）、近红外差值植被指数（NIR - DVI）、近红外归一化植被指数（NIR - NDVI）和K指数（KI）。结果表明，近红外归一化植被指数可有效区分受害区域和对照区。随机选取的25个验证样本的准确率达到70%。对水稻稻纵卷叶螟受害区域的初步研究为大面积受害区域的检测提供了一种新方法。
