论文题目: Changes in evapotranspiration over irrigated winter wheat and maize in North China Plain over three decades

论文编号:
作者: Xiying Zhang（张喜英）,Suying Chen（陈素英）, Hongyong Sun（孙宏勇）, Liwei Shao（邵立威） and Yanzhe Wang（王艳哲）
刊物名称: Agricultural Water Management
卷期页码: Available online, ,
发表年度: 2011
DOI: http://dx.doi.org/10.1016/j.agwat.2011.02.003
摘要:
Evapotranspiration (ET) is an important component of the water cycle at field, regional and global scales. This study used measured data from a 30-year irrigation experiment (1979–2009) in the North China Plain (NCP) on winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) to analyze the impacts of climatic factors and crop yield on ET. The results showed that grass reference evapotranspiration (ETo, calculated by FAO Penmen–Monteith method) was relatively constant from 1979 to 2009. However, the actual seasonal ET of winter wheat and maize under well-watered condition gradually increased from the 1980s to the 2000s. The mean seasonal ET was 401.4 mm, 417.3 mm and 458.6 mm for winter wheat, and 375.7 mm, 381.1 mm and 396.2 mm for maize in 1980s, 1990s and 2000s, respectively. The crop coefficient (Kc) was not constant and changed with the yield of the crops. The seasonal average Kc of winter wheat was 0.75 in the 1980s, 0.81 in the 1990s and 0.85 in the 2000s, and the corresponding average grain yield (GY) was 4790 kg ha?1, 5501 kg ha?1 and 6685 kg ha?1. The average Kc of maize was 0.88 in the 1980s, 0.88 in the 1990s and 0.94 in the 2000s, with a GY of 5054 kg ha^-1, 7041 kg ha^-1 and 7874 kg ha^-1, respectively, for the three decades. The increase in ET was not in proportion to the increase in GY, resulting improved water use efficiency (WUE). The increase in ET was possibly related to the increase in leaf stomatal conductance with renewing in cultivars. The less increase in water use with more increase in grain production could be partly attributed to the significant increase in harvest index. The results showed that with new cultivars and improved management practices it was possible to further increase grain production without much increase in water use.