| Popis: |
the choice of low temperature disaster to th maize of three provinces in Northeast China was the study aresa,the crop growth model WOFOST was improved appropriately,analysed and tested in regional scale,and achieves the quantitative analysis and dynamic evaluation of low temperature disaster to th maize.The yields simulated under the condition of average temperatur 1961—2006 is the usual standard,the yields simulated under the condition of actual temperature in relevant year,by contrasting those two yields to decide the yield reduce rate.the yield reduce rate and meteorological condition were divided to the standard of serious degree for low temperature disaster.By experiment for numerical simulation,to determine the main meteorological factor and its value for causing the yield reduce,furthermore to determine the evaluation indexes of low temperature disaster.Based on the evaluation indexes,the impact evaluation was carried out in study area,the impact evaluation for disaster including typical years and ages.From the simulation results,the spatial distribution of low temperature disaster is decreasing by degrees from Northeast to Southwest in each decade in recent 50a,but it is different in the areas and grades of low temperature disaster.The evaluation results could be response the historical actual situation,and is consistent as the pre-production. |
