东北玉米低温冷害时空分布与多时间尺度变化规律分析

利用东北地区48个农业气象观测站1961-2010年逐日温度资料和近20多年玉米生育期资料,基于热量指数构建生育阶段冷害指数,采用EOF分析、Mann-Kendall法、子波变换等方法系统分析了近50年东北玉米4个生育阶段低温冷害时空分布及周期特征。结果表明:整个生育期全区平均冷害强度呈极显著的减弱趋势,地区间冷害变化趋势呈现差异化特征,冷害强度减弱趋势由西南向东北方向呈阶梯状递增;4个生育阶段冷害指数EOF第一模态均呈冷害空间变化趋势一致的特征;冷害强度呈较明显的减弱趋势,第1到第4生育阶段减弱趋势逐渐增大,突变均发生在1990年代中期;冷害强度具有较强的周期性,出苗—七叶、出苗—抽雄存在明显的23、25年周期,出苗—乳熟、出苗—成熟均具有较明显的3年周期振荡。

Spatial-temporal Distribution and Multiple-temporal Scale Variation Laws of Chilling Damage of Maize in Northeast China

By using daily temperature data of 48 agro-meteorological stations from 1961 to 2010 and the maize growth records over the recent 20 years in northeast China,a chilling damage index of growing stages of maize is defined on the basis of heat index.The temporal-spatial distribution and periodic features of chilling damage of maize during their 4 growing stages over the past 50 years are analyzed with the methods of EOF,Mann-Kendall,and wavelet analysis.The results show that the average chilling damage intensity of maize in the whole growing stage in all areas exhibits in a significant decreasing trend,but the chilling damage trend varying between the areas presents a character of differentiation and the decreasing trend displays a kind of stepladder increasing from southwest to northeast.As for the 4 growing stages,the chilling damage index’s EOF first mode shows the same tendency in the spatial change.The chilling damage intensity of 4 growing stages obviously drops,and the decreasing tendency increases gradually from the first growing stage to the forth growing stage.Sharp changes occurred all in the middle of 1990s.There is a 23 or 25-year periodic oscillation for emergence to seven-leaf stage and emergence to tasseling stage,and a 3-year oscillation for emergence to milky ripening and emergence to maturation.