Predicting Nitrogen Concentrations from Hyperspectral Reflectance at Leaf and Canopy for Rape
WANG Yuan1,2,HUANG Jing-feng1,３*,WANG Fu-min1,2,LIU Zhan-yu1,2
1. Institute of Agricultural Remote Sensing and Information Application, Huajiachi Campus, Zhejiang University, Hangzhou 310029, China 2. Ministry of Education Key Laboratory of Environmental Remediation and Ecological, Health, Zhejiang University, Hangzhou310029, China 3. Key Laboratory of Agricultural Remote Sensing and Information System Application, Zhejiang Province, Hangzhou 310029, China
Abstract：An experiment was designed to determine whether nitrogen concentrations could be predicted from reflectance (R) spectra of rape leaves in laboratory, and, if so, whether the predictive spectral features could be correlated with nitrogen concentration of simple canopies of rape. The best predictors for nitrogen in leaves appeared with first-difference transformations of R, and the bands selected were similar to those found in other studies. Shortwave infrared bands were best predictors for nitrogen. In the shortwave infrared region, however, the absolute differences in reflectance at critical bands were extremely small, and the bands of high correlation were narrow. High spectral and radiance resolution are required to resolve these differences accurately. Variability in canopy reflectance in shortwave infrared region was at least an order of magnitude beyond that necessary to detect signals from chemicals. The variability in first-difference R and log 1/R on canopy scales were related to the arrangement of trees with respect to direct solar radiation, instrument noise, leaf fluttering, and small change in atmospheric moisture. The first-difference of reflectance R based regressions prediction of nitrogen concentration at canopy level gets a good fitness.
王渊1,2,黄敬峰1,3*,王福民1,2,刘占宇1,2. 油菜叶片和冠层水平氮素含量的高光谱反射率估算模型[J]. 光谱学与光谱分析, 2008, 28(02): 273-277.
WANG Yuan1,2,HUANG Jing-feng1,３*,WANG Fu-min1,2,LIU Zhan-yu1,2. Predicting Nitrogen Concentrations from Hyperspectral Reflectance at Leaf and Canopy for Rape. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2008, 28(02): 273-277.
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