Temporal and Spatial Variations of Agro-meteorological Disasters of Major Crops in China under the Background of Climate Change[I]: Delayed Chilling Damage of Spring Maize in Northeast China
Based on daily meteorological data from 65 meteorological stations from 1961 to 2010 in the potential areas of spring maize in Northeast China, the spatial and temporal distribution of chilling damage for spring maize was analyzed. The deviations of total monthly mean temperature from May to September were used as the chilling damage index, according to meteorological standard. Meanwhile, the highest risk of occurrence for chilling damage during entire growing season was also identified. The results showed that: (1) During the past 50 years (1961-2010), the area suffered chilling damage was severe> slight>moderate. The higher occurrence of slight chilling damage was in the west of Jilin province and the lower value located in the south of Liaoning province. The higher occurrence of moderate chilling damage distributed in several regions of Heilongjiang province and Jilin province, and the lower values located in Liaoning province. The higher occurrence (more than 25%) of severe chilling damage was in the north and south-east of Heilongjiang province and the east of Jilin province, and the lower values (less than 5%) located in the west and middle of Liaoning province. The frequency of all levels of chilling damage decreased during the past 5 decades. In recent 20 years (1991-2010), disaster occurred area decreased significantly. (2) All levels of chilling damage for spring maize mainly occurred in May and June in the study areas. Therefore, the temperature changes and the chilling damage in May and June should be paid more attentions in maize production.