EXTRACTING SPATIAL INFORMATION OF HARVEST INDEX FOR WINTER WHEAT BASED ON MODIS NDVI IN NORTH CHINA

In order to acquire the spatial information of winter wheat harvest index (HI), depending on the crop growth profile of time-series MODIS-NDVI to calculate mean slope of NDVI curve and accumulated NDVI at stage of before anthesis and after anthesis, the authors made full use of remote sensing information and structured two parameters HINDVI-k and HINDVI-SUM according to the definition of HI of crop. Then relationships between the two parameters and field measured HI of winter wheat were established respectively. After validation of retrieved winter wheat HI, it was shown that the accuracy of the retrieved HI of winter wheat was high and satisfied at large scale in study region of Huanghuaihai Plain in China. The mean relative errors of the retrieved HI were 3.60% and 2.40% and RMSE were 0.04 and 0.02 respectively. It was proved that the method of structuring parameters of HINDVI-k and HINDVI-SUM and extracting harvest index for winter wheat based on time-series MODIS-NDVI was reasonable and feasible.