Characteristics of Canopy Reflection Spectrum of Winter Wheat in Growth Period

The canopy spectral reflectance of winter wheat observed by mobile spectral radiometer in field survey was analyzed.The research result showed that,①the curve of wheat canopy spectral reflectance was similar with the normal spectral reflectance of healthy green plants.The growth conditions of wheat were all well.During 7 growth periods,the variation mainly occurred at flowering period and filling stage.②Comparing the reflectivity of different wave bands during the whole growing period,it was found out that the biggest change was in the yellow light wave band and green light wave band,followed by red light wave band and orange wave band,the variation in infrared band and blue wave band was little;the variation in ultraviolet wave band among different period was much less than that of other wave bands.The canopy spectral reflectivity was stable in visible light bands;the change mainly occurred in the red and near infrared bands.③The canopy spectral reflectivity of winter wheat increased with the increase of solar altitude angle,reached the highest reflectivity at 11∶20 am local time,and then decreased with the decrease of solar altitude angle.④The absorbing dust on leaf and plant density affected the canopy spectral reflectance of winter wheat,however,due to the research conditions and environment,the effective characteristic of the two factor was not clear.