Research on the Relationships among F_( APAR), LAI and VIs in the Winter Wheat Canopy

Based upon the observed data of the winter wheat canopy during April 2001 in Shunyi, Beijing, this paper studied the relationships among the fraction of absorbed photosynthetically active radiation (F APAR ), the leaf area index (LAI), and the vegetation indices (VIs). The results illustrate that there is a good linear correlation between F APAR and LAI, and the coefficient of the determination (R2) is approaching the value of 0.942 7. In addition, there is a good exponential correlation between F APAR and VIs, so does it with LAI and VIs. This coefficient of the determination is greater than 0.9. The relationships among them indicate the integrity and transmittability. Meanwhile, the conclusion is drawn that out of VIs, the Renormalized Difference Vegetation Index (RDVI) possesses the best correlation with LAI and F APAR respectively.