中文摘要：

提高作物水分生产力（Water Poduetivity）是节水农业研究的最终目标,定量分析作物WP对干旱和半干旱地区水资源管理和决策制定具有重要意义。华北平原是我国重要的粮食生产基地,但水资源问题已成为制约该区可持续发展的瓶颈,明确该区作物WP时空变化特征及其与气候的关系,对指导该区农业生产和水资源高效利用具有重要作用。本文首先利用华北平原3个代表性试验站各连续3-4年的小麦-玉米轮作田间试验资料,校准验证澳大利亚开发的APSIM模型,然后利用校准后的APSIM模型和研究区域32个气象站1961年～2005年逐日气象数据,结合GIS技术,对华北平原不同供水情景下冬小麦、夏玉米WP空间分布特征进行了模拟研究。模拟结果表明：①当不考虑作物品种变化时,华北平原小麦、玉米WPET（产量与蒸散量比值）分布响应于该区平均气候状况,具有明显的空间分布特征;②充分供水情景下全区小麦WPET为（1.38～1.69）kg/m^3,平均值为1.53kg/m^3,玉米WPET为（1.69～2.05）kg/m^3,平均值为1.83kg/m^3;非充分供水情景（仅满足作物水分需求一半）下两作物WPET分布与充分供水情景下相似;雨养情景下小麦WPET为（0．29～1．57）kg／m^3，平均值为0．77kg／m^3，玉米WPET为（0．86～2．13）kg／m^3，平均值为1．47kg／m^3；③饱和水汽压差（VPD）是影响作物水分生产力的主要气象因子，研究区域小麦生长季VPD北高南低的趋势使得小麦WPET呈北低南高分布特征；而玉米生长季VPD西高东低，玉米WPET呈西低东高的趋势。改善灌溉管理可提高作物WP，减少由土壤蒸发损失的非生产性耗水对提高作物WP也具有重要意义。

英文摘要：

The North China Plain （NCP） is the largest agricultural production area in China with a dominant wheat-maize double cropping system. Excessive use of ground and surface water for irrigation has caused rapid decline in groundwater tables and surface water resources. Crop water productivity （WP） is the amount of water required per unit of yield, the increase of which is the ultimate objective of water-saving agriculture. In order to use water resources more efficiently, a better understanding of how WP responds to climate variations and irrigation strategies is required. This paper uses a modeling approach to investigate the responses in the NCP. The Agricultural Systems Model software APSIM is validated by using 14 years of experimental data at three sites. The validated model, together with long-term climate data from 32 weather stations are then used to simulate WP of wheat-maize double cropping system as it responds to climate variations and irrigation scenarios. The simulation results show that considerable spatial variations in WP values exit for both wheat and maize, which correspond to the average conditions in the NCP. WPET （the ratio of gain yield to evapotranspiration during crop growing season） for wheat rang from 1.38 to 1.69 kg/m^3 with an average of 1.53 kg/m^3 under full irrigation, decreasing from south to north of the NCP due to the increasing vapor press deficit （VPD）. Under this irrigation scenario, WPET for maize rang from 1.69 to 2.05 kg/m^3 with an average of 1.83 kg/m^3. Due to the relatively concentrated rainfall during the maize season, there are no significant differences in VPD and WP for maize has no great differences between south and north; however, it decreases from east to west as a result of the increasing VPD. WPET for wheat and maize under the irrigation scenario can partially meet crop water demand and is slightly higher than that under full irrigation. WPET for wheat under rain irrigation decreases from south to north, ranging from 0.29 to 1.57 kg/m^3 with an av