Study On Corn Chilling Damage Index And Its Risk Factor In Northeast China

Various corn chilling damage indices were evaluated in northeast China based on the datafrom16representative weather stations including meteorological factors, maize growinginformation and the records of chilling damage during1992-2010, and the modified cornchilling damage indices suitable for corn in northeast China and corn risk factor would bestudied in this thesis. The main results included:(1) The temperature increased significantly in recent years in northeast China, climate andcorn varieties has also changed. As a result, the present corn chilling damage indices are notsuitable in northeast China.(2) Present corn chilling damage indices are not suitable in northeast China based on thedata during1992-2010. The heat index indicator and the accumulated temperature index havethe higher average accuracy. The heat index indicator is suitable to most parts of Heilongjiangprovince and Jilin province, while the accumulated temperature index is suitable in Liaoningprovince.(3) The modified average temperature departure index and the modified thermal index aresuggested for evaluating corn chilling damage in northeast China. The value of corn chillingdamage index become smaller for the modified average temperature departure index. During1992-2010, the value of generally chilling damage index reduced by1.3°C,1.2°C and1.0°C inthe area where average temperature sum is between80°C,90°C, between90°C and100°C, andmore than100°C during May to September due to climate warming, and the value of severechilling damage index reduced by2.8°C,2.3°C and1.4°C in the same region. The corn chillingdamage occurs when the modified thermal index F(T)＜0.89in Jilin province, F(T)＜0.91inLiaoning province, while the modified thermal index is not able to given due to the datalimitation in Heilongjiang province.(4)The study analyzes the temperature of1992-2010in of16research stations inNortheast China using the improved chilling damage index, and finds the frequency, risk indexand risk factor change of corn chilling damage in northeast China during1992–2010are givenbased on the modified average temperature departure index and the modified thermal index. The results show that the frequency of chilling damage is gradually increasing from South toNorth. The higher frequency of serious chilling damage appears in the southeast part ofHeilongjiang province and the northwest part of Jilin province, while lower frequency ofsevere chilling damage in the most part of Liaoning province. The region with the maximumvariation coefficient of the modified thermal index appears in the northern part of Heilongjiangprovince, where the thermal resources is so unstable and corn chilling damage happens easily.The frequency and strength of chilling damage appears in Haerbin station both increase. Thefrequency of chilling damage appears in Meihekou station increase, while the strength ofchilling damage appears is down. The frequency and strength of chilling damage appears inXinmin station are no change.