The Response of Canopy Direction Reflectance Spectrum for the Wheat Vertical Leaf Distributing

摘要

The accurate information access and analysis of crop canopy are the basis of quantitative research on crop information. This experiment was conducted using two winter-wheat (Triticum aestivum) cultivars P7 (leaf erect) and ZY9844 (leaf horizontal). The wheat canopy direction spectral reflectance over 350-2500 nm with view angles of 0°, 30°, 60°, 90°, 120°, 150° and 180° to the vertical line to wheat row were measured, using delamination slice method from underlayer of the wheat canopy to upside, and compared the direction spectral characteristic of removing difference leaf layer. The result showed that the spectral characteristics were varied in 300-700, 800-1300, 1400-1800 nm wave bands because of wiping off leaves layers and different view angle, the change of visible wave bands was less near infrared wave bands. Compared with the traditional 90° view angle measured, the spectral information of under leaves were more at 30° and 60° view angle than that of angles, that of upper leaves at 0° view angle were more. For two wheat, the spectral influence of ZY9844 upper leaves at 0° view angle were less than that of P7. The upper leaves of lax leaves plant-type wheat capture much radiation because the upper leaves were horizontal, the proportion of upwards lay was bigger than that of downwards; the erect leaves plant-type was opposite. The canopy spectral information was effected by the observation angles. It is a method to improve crop canopy spectral estimation precision that changed the measured angle for different canopy structure.