Method Research Of Cold Damage Prediction For Cotton In Xinjiang Uygur Autonomous Region

Cold damage is the vital agro meteorological disaster affecting cotton production seriously in Xinjiang. It is significant to study in forecasting the cotton cold damage timely, in order to arrange the cotton varieties properly, make relevant agricultural precaution, and reduce the effects of cold disaster.Using the mean daily air temperature from 1961 to 2005 of the representative stations of the main cotton areas in Xinjiang, the data of cotton growth period and local yield in resent years, the studies below were mainly developed in this thesis.(1) The calculation scheme of cotton heat index was easy to computing and using with clear biological and physical meanings. Based on it, cool injury index was defined and was the key precondition of the further research in cotton cold damage prediction. According to cotton growth period, cotton heat indexes were calculated at every period of ten days, and then they were better than indexes calculated at every month to reflect accurately the sufficiency of heat in cotton growth period in major cotton areas in Xinjiang.(2) Considering the effects of weather system and general circulation background on the temperature during cotton growth stage, the annual change of heat condition itself, and other factors, cotton cool damage was forecasted accurately by stepwise regression models, gray forecasting models GM(1,1), mean generating function forecasting models separately. Through return-calculating and trial forecast for heat indexes and the types of years, the accuracy of every model was satisfied, about above 90% each. It was illustrated that the situations of cotton cool damage in main cotton areas in Xinjiang were predicted well by the three methods.(3) Using the method of rolling forecasting, models were built monthly from the cotton's seeding time to the end stage, to predict the heat index after the predicted month. Then occurrence status and severity of cool injury in predicted year in main cotton areas in Xinjiang were decided by adding the actual heat conditions and cool injury index before the predicted month. By the method of rolling forecasting monthly, the predicting accuracy of each model was increased month by month, and then the prediction of cotton cool damage has improved obviously.