基于RZWQM2的黄土高原旱地冬小麦生长关键气象因子分析

Key meteorological factor analysis of dryland winter wheat growth on the Loess Plateau based on RZWQM2

利用根区水质模型(RZWQM2),结合过去56年(1956～2012年)基本气象因子的变化规律,研究黄土高原旱地冬小麦生长、产量和水分利用对气候变化的响应及其关键气象因子。结果表明:在过去56年中,冬小麦生育期内"暖干"趋势明显,冬小麦生育期内日平均气温和有效积温(GDD)均呈增加趋势,增幅每10年分别达0.2℃、44.5℃·d,1983年以后增加趋势更为显著,每10年分别达0.52℃、140.7℃·d,而降水量和太阳辐射整体随着时间变化呈缓慢减小趋势。冬小麦生育期内GDD的增加,显著缩短冬小麦生育期时间,1983年以后,冬小麦返青期、开花期和成熟期历时每10年分别缩短4.7、5.6和5.7d,出苗-越冬期缩短的时间占整个缩短时间的80.7%,返青-开花期缩短的时间占整个缩短时间的17.5%。冬小麦营养生长期缩短使得小麦植株干物质累积时间和累积量相应减少,进而影响冬小麦穗的形成和籽粒对氮素的吸收,导致冬小麦产量和水分利用效率均减小。降水资源是该区域冬小麦生长的决定性气象因子,同时太阳光热资源的变化则进一步限制冬小麦产量潜力和水分利用效率的提升。

In this study,a continuous crop rotation experiment of winter wheat(Triticum aestivum L.)and spring maize(Zea mays L.)from 2004 to 2011 was used to calibrated the Root Zone Water Quality Model(RZWQM2).We simulated winter wheat growth employing RZWQM2 based on the historical weather data on the Loess Plateau of China,and mainly aimed to(1)investigate the effect of climate change on winter wheat development,production and water use efficiency(WUE),and(2)find out the key meteorological factors impacting the dryland winter wheat growth and water use on the Loess Plateau,and then to select applicable measures to cope with climate change.Results showed that temperature and the available growing degree day(GDD)in the wheat growing season(from September through next June)increased significantly in the study site;the average temperature and the available GDD every decade increased by 0.2℃and 44.5℃·d from 1956 to 2012,respectively,even by 0.5℃and 140.7℃·d every decade since 1983,respectively;both the average precipitation and shortwave radiation decreased with time going.The results of this study indicate that climate change is likely to have strong environmental impacts in the Loess Plateau in the near future according to the existing trend.The duration of phase green-up,anthesis,and maturity of winter wheat were shortened by 4.6,5.6,and5.7 devery decade since the 1983 due to global warming,respectively;the shortened duration mainly happened from the phase emerge to green-up,which covered the 80.7% of the whole duration.Furthermore,the shortened duration reduced the dry matter accumulation during the vegetative phase,which limited the amount of photosynthates reallocating to the wheat grain,leading to a decreased grain yield.Due to the more significant decreasing trend of wheat yield than evapotranspiration,WUE showed a decreasing trend.Precipitation was the key meteorological factor for winter wheat growth because of water resources depletion on the Loess Plateau.The global warming also considerably limited the development of wheat yield potential.