河北省玉米生长季干旱特征及成因分析

干旱是影响河北省玉米生长的重要农业气象灾害。利用玉米种植区1971-2018年气象资料和1981-2018年玉米(Zea mays)生长观测资料,以有效降水量代替实际降水量计算水分亏缺指数,对河北省玉米生长季干旱分布特征、变化趋势和变化成因进行了分析。结果表明,(1)干旱概率和干旱强度分布特征基本一致,春玉米区由高到低依次为播种期>拔节-抽雄期>抽雄-乳熟期>出苗-拔节期>乳熟-成熟期,夏玉米区依次为播种期>抽雄-乳熟期>乳熟-成熟期>拔节-抽雄期>出苗-拔节期。(2)春玉米区4月下旬至5月上旬(播种期)和6月下旬至8月上旬(拔节-乳熟期)、夏玉米区6月上中旬(播种期)和8月上中旬(抽雄-乳熟期)受干旱影响较大,其中春玉米区以张家口和承德北部干旱最重,夏玉米区以石家庄东部、衡水西部和邢台东北部干旱最重。(3)春玉米区5月上中旬受需水量减少、降水量增加趋势影响,干旱强度和范围随年代显著下降,8月中下旬受需水量增加趋势影响,干旱强度和范围随年代显著上升;夏玉米区6月下旬受需水量减少趋势影响、9月下旬受需水量减少和降水量增加趋势影响,干旱强度均随年代显著下降。需水量减少与日照时数减少和风速减小密切相关,而需水量增加与气温上升、风速增大、空气湿度减少密切相关。

The Drought Characteristics of Maize in Hebei Province,China

Drought is an important natural disaster for maize production in Hebei province,China.Based on the observed meteorological(1971-2018)and maize growing data(1981-2018),and the CWDI(Crop Water Deficit Index)modified by replacing actual precipitation with effective precipitation,we analyzed the spatial and temporal variation characteristics of maize drought.The results showed that the drought probability was consistent with that of drought intensity.The probability and intensity of drought from high to low were sowing>jointing to tasseling>tasseling to milking>emerging to jointing>milking to maturity stage for spring maize,and sowing>tasseling to milking>milking to maturity>jointing to tasseling>emerging to jointing stage for summer maize.The droughts with high intensity and heavy impacts occurred mainly from late April to early May(sowing stage)and from late June to early August(jointing to milking)for spring maize,and in early-to-mid-June(sowing stage)and early-to-mid-August(tasseling to milking)for summer maize.And the worst-hit areas of drought were in Zhangjiakou,north of Chengde,east of Shijiazhuang,west of Hengshui and northeast of Xingtai.The drought intensity and spatial scale in early and middle May had a decreasing trend because of the water requirement decreasing and precipitation increasing,and these in middle and late August had an increasing trend because of the increasing of water requirement in spring maize zone.The drought intensity with a decreasing trend in late June was due to the decreasing of water requirement,and the same trend in late September was the decreasing of water requirement and increasing of precipitation in summer maize planted zone.The decreasing trend of water requirement was concerned with the decreasing of sunshine hours and wind speed,while the increasing trend of water requirement was related to the increasing of temperature and wind speed and decreasing of air humidity.The variations of climatic factors,such as temperature,sunshine hours,wind speed and humidity,are important to maize drought conditions.