Assessing freeze injury to winter wheat with multi-temporal HJ-1 satellite imagery

The spatial distribution and severity level of freeze injury on winter wheat is of great importance to timely agriculture recovery. In this paper, taking central and southern Hebei province as study area, a rapid algorithm for assessing freeze injury on winter wheat was developed. Firstly, Enhanced Vegetation Index (EVI) was selected as the optimal vegetation index after sensitivity analysis of vegetation index to freeze injury. Secondly, a freeze injury assessing algorithm was developed based on multi-temporal HJ-1 satellite imagery without ground data. Thirdly, this algorithm was validated through ground survey points. It is shown that the relative change of pre- and post-frozen EVI is linearly related to the damage severity. The new approach is proved to be able to assess winter wheat injury spatial distribution and severity level rapidly and successfully.