Correction of the Soil Adjusted Factors of Vegetation Indices for Monitoring Rice Leaf Index Zrea

The vegetation indices that take the soil adjustment factor into consideration can reduce the influence of soil background conditions and have been widely used in monitoring all kinds of vegetation.However，the rice has been planted in the soil covered by a certain thickness of layer of water，which is different with other various soil backgrounds.Therefore，in this paper，through two years of rice plot experiments，we obtained the rice canopy spectral data and the corresponding leaf area index (LAI) data，and then calculated a series of vegetation indices (EVI，SAVI，WDVI) by using different soil adjustment factors changing within a certain range.We compared the abilities of these vegetation indices for rice LAI estimation，and then determine the optimum soil adjustment factors of vegetation indices to adjust the background of rice.In the study，we found that the best soil adjustment factor L for EVI，L of SAVI，a of WDVI are 0.25，0.10 and 1.25 respectively，and we further compared the LAI estimation results of the best soil adjustment factor with those of the conventional soil adjustment factor.For the model taking EVI as an independent variable，the RMSE of LAI estimation using the best soil adjustment factor is 6.82 % lower than that using the conventional soil adjustment factor；In SAVI model，the RMSE using the best soil adjustment factor is 10.23% lower than that using the conventional soil adjustment factor .These results indicate that the corrected vegetation indices considering the background of rice can improve the accuracy of rice leaf area index using remotely sensed data.