Crop Production Systems Research Unit,Agricultural Research Service,United States Department of Agriculture,MS 38776,USA;
Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agricultural Sciences,Beijing 100081,P.R.China;
Institute of Remote Sensing and Digital Earth,Chinese Academy of Sciences,Beijing 100094,P.R.China;
Institute of Remote Sensing and Digital Earth,Chinese Academy of Sciences,Beijing 100094,P.R.China;
Institute of Remote Sensing and Digital Earth,Chinese Academy of Sciences,Beijing 100094,P.R.China;