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首页> 外文会议>Agriculture and Hydrology Applications of Remote Sensing; Proceedings of SPIE-The International Society for Optical Engineering; vol.6411 >Spectral characteristics of peanut crop infected by late leafspot disease under rainfed conditions
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Spectral characteristics of peanut crop infected by late leafspot disease under rainfed conditions

机译：雨育条件下晚叶斑病侵染的花生作物的光谱特征

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摘要

A leafspot susceptible peanut cultivar (cv JL 24) was sown during kharif season of 2005 in rainfed region of Andhra Pradesh, India. Five disease levels (scale 0-4) were created in the field by differential fungicidal spray schedule, and each treatment was replicated four times. Spectral data was recorded at 2 nm intervals using a portable spectroradiometer within a spectral range of 300-1100 nm. The loss of leaf pigments (Chlorophyll a & b) due to diseases was quantified using spectrophotometer. The red and infrared reflectance values between 620- 680 and 770-860 nm, respectively were used for calculating Normalized Difference Vegetation Index (NDVI). Significant reduction in chlorophyll content was observed only when the disease reached a stage of scale 2 and above. The ratio of chlorophyll a to b showed a declining trend as the number of spots per leaf increased. From the spectral reflectance studies typical chlorophyll absorption bands (350 - 500 and 620-690 nm) of healthy and diseased plants could not be differentiated. However, the difference was evident in the chlorophyll reflection bands (522- 600 nm). The infrared spectral region between 700-850 nm was found to be sensitive to canopy disease stress. The reflectance (%) in this part of spectrum was higher for healthy plants compared to diseased plants. But, the low level of disease intensity (scale 1) was not differentiated by the spectral reflectance. The NDVI value for 82 days old healthy crop was in the range of 0.45 to 0.50, while the same for diseased plants was between 0.34 and 0.45. This study finds potential application of remote sensing techniques in detection of plant diseases.
机译：在印度安得拉邦的雨养地区，2005年的卡里夫季节播种了对叶斑敏感的花生品种（cv JL 24）。通过不同的杀真菌喷雾时间表，在田间产生了五个疾病等级（0-4级），每种处理重复四次。使用便携式分光光度计以2 nm的间隔记录光谱数据，光谱范围为300-1100 nm。使用分光光度计对由于疾病引起的叶片色素损失（叶绿素a和b）进行了定量。分别在620-680和770-860 nm之间的红色和红外反射率值用于计算归一化植被指数（NDVI）。仅当疾病达到2级及以上的阶段时，才观察到叶绿素含量的显着降低。叶绿素a与b的比例随着每片叶上斑点数的增加而呈下降趋势。根据光谱反射率研究，无法区分健康和患病植物的典型叶绿素吸收带（350-500和620-690 nm）。但是，在叶绿素反射带（522-600 nm）中差异明显。发现700-850nm之间的红外光谱区域对冠层疾病胁迫敏感。与患病植物相比，健康植物在这部分光谱中的反射率（％）更高。但是，低强度的疾病强度（等级1）无法通过光谱反射率来区分。 82日龄健康作物的NDVI值在0.45至0.50的范围内，而患病植物的NDVI值在0.34至0.45之间。这项研究发现了遥感技术在植物病害检测中的潜在应用。

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