近30年吴桥县冬小麦生育期水分亏缺变化趋势分析

为了给地处黑龙港地区的河北省吴桥县制定冬小麦稳产灌溉制度提供理论依据,本文利用1981—2013年吴桥县的气象数据和SIMETAW模型,分析了冬小麦全生育期及播种—返青期、返青—拔节期、拔节—开花期、开花—成熟期4个生育阶段的降水量、需水量、耗水强度及水分亏缺指数(CWDI)的变化趋势;同时利用5年滑动平均法将分析年份冬小麦实际产量分为趋势产量和气象产量,计算了不同降雨年型下冬小麦减产率的变异系数。结果表明,近30年河北省吴桥县冬小麦生育时期的水分亏缺指数和需水量均呈现轻微的上升趋势;冬小麦发生干旱的概率为93.75%,其中,中旱和重旱发生概率为65.52%。冬小麦生育时期的平均日降雨量呈现从冬小麦生育中期向后期转移的趋势,日耗水强度表现为从生育后期向生育中期移动的趋势,这是导致返青—拔节期和拔节—开花期水分亏缺指数较大的重要原因。冬小麦减产率的变异系数的绝对值在缺水年最大,为154.241;在丰水年最小,为1.999;正常年份为24.776。因此,冬小麦拔节—开花期的及时灌溉对于保障冬小麦的稳产增产具有重要作用。建议在缺水年份调整冬小麦的水分管理制度,在冬小麦拔节初期一次性充分灌溉或在拔节初期和中后期分次进行少量灌溉。

Study on water deficit trend in the recent 30 years in Wuqiao County, Hebei Province

Water is in severe shortage in Heilonggang region, a region where insufficient and uneven precipitation are the main limiting factors to stable production of winter wheat. Thus to lay the theoretical basis for stable winter wheat production in the region under optimal irrigation, a study was conducted on the trends in water deficit in recent 30 years in Wuqiao County, Heibei Province. Based on observed daily meteorological data in Wuqiao County, we analyzed the dynamics of precipitation, crop water requirement, crop water consumption intensity and crop water deficit index (CWDI) for the whole growth period and the individual growth stages of winter wheat from 1981 to 2013 using SIMETAW model. To calculate the coefficient of variation of winter wheat yield reduction in different precipitation years, we divided winter wheat yield into trend yield and meteorological yield using linear moving average. The results of the study showed that CWDI and crop water requirement for the whole growth period of winter wheat gradually increased with time. The probability of the occurrence of drought in the whole growth period of winter wheat was 93.75% in the analyzed 32 years. Of this, the probability of both moderate drought and severe drought was 65.52%. Precipitation decreased in the middle stages of winter wheat growth while it increased in the late stages of winter wheat growth. The trend in daily crop water consumption intensity was the reverse of that of precipitation. The trends in both precipitation and crop water consumption intensity resulted in higher CWDI during greening to jointing and then jointing to flowering stages than in the other growth stages of winter wheat. The absolute value of coefficient of variation of yield reduction of winter wheat was highest (154.241) for dry years, lowest (1.999) for humid years and average (24.776) for normal years. Timing irrigation at jointing through flowering stage was critical for ensuring a stable increase in winter wheat production. Thus to ensure stable yield production in the study area, an adequately irrigation at the beginning of jointing stage or twice irrigations at the early and late jointing stage of winter wheat were required.