ANALYSIS AND EXTRACTION OF HYPERSPECTRAL INFORMATION FEATURE OF WINTER WHEAT UNDER N STRESS CONDITION
氮素胁迫下的冬小麦光谱特征提取与分析

Hyperspectral remote sensing is not only an important technical method in the study of global observation and the vegetation cover change, but also a main study aspect of precision agriculture. This paper first discusses sensors characteristics and image mechanisms of hyperspectral remote sensing data, its image processing, information extraction methodology, image analysis and model identification, as well as potential application of airborne and space borne hyperspectral remote sensing data. In order to monitor crop nutrient supply condition and to realize precision fertilization, different N nutrient stress condition is studies. A series of experiment have been arranged in Luancheng eco system experimental station, which concerns N, P, K stress, respectively. Rank difference of nitrogenous nutrition level is obtained by the man make style through 5 years' field experiment of winter wheat and summer corn. Canopy and plant spectral of different nitrogen application is measured by Analytical Spectral Devices (ASD Field Spec HH TM ) in different stage. The study has analyzed the variation of winter wheat canopy reflectance with wavelength and time, compared the reflectance spectra curves of difference growing stage and N stress condition. According to hyperspectral characteristic, reflectance and first order derivative spectra is determined by wheat biophysical parameters and agricultural properties. Three variables of hyperspectral in association of spectral position are used in the analysis. There are peak value of Near Infrared (NIR), green reflected peak value and red edge shift. The estimate models about biophysical parameters of winter wheat have been built on the basis of canopy reflectance data. The best parameter is chlorophyll density in estimated models of the biophysical parameters and best observational stage is pregnant period to winter wheat. The first derivative spectrum is more correlatively with the biophysical parameter including chlorophyll density and LAI.