THE MODEL OF WHEAT YIELD FORECAST BASED ON MODIS-NDVI – A CASE STUDY OF XINXIANG

The yield estimation models on a regional scale are generally constrained by the lack of spatially distributed information on major environmental. The utilization of remote sensing data with various spatial and temporal resolutions can settle this problem. The NDVI, which retrieved from satellite remote sensing, was adopted to forecast winter wheat yields in this paper. There are two key steps in the process of calculating. The first is the establishment of the relationship between NDVI and Above Ground Biomass (AGB). The second is the Harvest Index(HI) calculating based on the change of NDVI from the period of re-greening to maturity. The validation results showed that forecast accuracy is satisfied and can be applied in practice of winter wheat yield forecasting. However, the error will be increased in abnormal weather condition, for higher or lower value of NDVI is made than normal situation, (such as re-greening too early, overgrowth, and late-maturing, etc.). So the model amendment is required according to the status of crop and weather condition in the year