亚洲一区欧美在线,日韩欧美视频免费观看,色戒的三场床戏分别是在几段,欧美日韩国产在线人成

By field trials, the canopy hyperspectral reflectance and percentage vegetation cover (PVC) for winter wheat during 2010 and 2011 growth periods were measured. The canopy spectral characteristic of different PVC and the relationship between canopy reflectance and PVC were analyzed in different growth periods. The winter wheat PVC estimation models based on normalized difference vegetation index (NDVI), ratio vegetation index (RVI), wavelet energy coefficients were established in different growth periods. The results showed that the spectral reflectance of winter wheat decreased in visible bands, however, increased in near infrared bands following the PVC increased. The spectral reflectance was negatively correlated with the PVC in visible bands, but the correlation coefficient turned to positive correlation near the red edge. The PVC estimation models based on NDVI was performed better at the regreening stage and elongation stage with determination of coefficient (R2) 0.8359 and 0.8057, respectively. However, the PVC estimation models based on RVI was better at the heading stage, filling stage with R2 0.8031 and 0.8294, respectively.R2 of the PVC estimation models based on high frequency energy coefficient and low frequency energy coefficient were 0.9112, 0.8954, 0.8802, and 0.9275 at the regreening stage, elongation stage, heading stage and filling stage, respectively.