Research On Monitoring And Classifying Freeze Injury Of County Winter Wheat Based On 3S

Frequent occurring of freeze injury has effect on winter wheat which plays a very important role in food supply. Hence, probing some feasible and effective monitoring means of freeze injury is great significant for government at all levels to know the severity and distribution of freeze injury and to take effective measures to prevent freeze injury, and scientific command on agricultural production. The technology of 3S on monitoring freeze injury has its irreplaceable advantage.Therefore, this paper takes ecological area of winter wheat in Wenxi County as subject to study the monitoring effect of 3S. The image information was interpreted through visual interpretation based on field investigation and HJsatellite images. Types of crops wereidentified and winter wheat planting area was extracted through spatial analysis of GIS. Six vegetation indexes (RVI, DVI, NDVI, EVI, GRVI and SIPI) was extracted from the processed HJ image. Whether the winter wheat suffering from freeze injury or not, freezing injury severity and recovery degree were determined to classify the level by change vector analysis, vegetation indexes which can represent freeze injury and comprehensive methods on RS data with different phase. And the yield affected by freeze injury was quantitatively analyzed.The result shows:(1) Within the scope of Wenxi County, winter wheat suffering from freeze injury with different degree through change vector analysis. The percent of winter wheat suffering from severe freeze injury is 0.71%.Around the area, there are 5.93% suffering from moderate freeze injury. And the percent not suffering from freeze injury is 1.02%.The rest is suffering from slight freeze injury. There is good recovery region about 1.30% in not suffering from and slight freeze injury region, unrecovering region about 0.27% in slight freeze injury region, and poor recovery region about 14.64% around the area.(2) Based on the analysis of ΔNDVI, the percent of winter wheat suffering from severe freeze injury is 0.54%. Around the area, there are 9.48% suffering from moderate freeze injury. And the percent not suffering from freeze injury is3.46%.the rest are suffering slight freeze injury. There is unrecovering region about 0.20% in moderate freeze injury region, poor recovery region about 4.44% around the area, and good recovery region about 2.09% in not suffering from and slight freeze injury region.(3) Based on comprehensive methods analysis, the proportion of severe freeze injury region is minimum about 0.89%, following is untouched freeze injury region about 3.49%, moderate freeze injury region about 10.17%, and the rest is slight freeze injury region. There is unrecovering region about 0.20% in moderate freeze injury region, good recovery region about1.24%, and poor recovery region about 15.55%.(4) Winter wheat yield levels are corresponding to the freeze injury levels and restoringlevels, which verify the accuracy of freeze injury classification.