Nitrogen supply – A determinant in water use efficiency of winter wheat grown under free air CO2 enrichment
Nitrogen supply – A determinant in water use efficiency of winter wheat grown under free air CO2 enrichment
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DOI：
10.1016/j.agwat.2018.07.034
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发表时间：
2018-11
影响因子：
6.7
通讯作者：
R. Manderscheid;Markus Dier;M. Erbs;Jan Sickora;H. Weigel
中科院分区：
文献类型：
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作者：
R. Manderscheid;Markus Dier;M. Erbs;Jan Sickora;H. Weigel
全球变暖和相关的夏季降水减少将加剧欧洲因缺水而对作物生长的限制。同时，大气CO2浓度（[CO2]）的升高降低了气孔导度，从而降低了叶片水平的蒸腾作用。然而，关于[CO2]（[eCO 2]）升高对作物季节性用水的影响的知识相当贫乏。在为期两年的田间试验中，采用自由空气CO2增浓（FACE）技术，在大气CO2浓度为393 ppm和eCO 2浓度为600 ppm的条件下，研究了冬小麦的生长状况。此外，还建立了具有三个氮（N）供应水平（35、190、320 kg N ha−1）的子区。连续测量土壤湿度，必要时灌溉小麦，以保持田间持水量在50%至90%之间。采用土壤水分平衡法计算了从茎伸长到成熟的蒸散量。水分利用效率（WUE）由地上生物量与蒸散量的比值决定，增加供氮量可增加冠层面积，减少辐射向土壤表面的传输。此外，增加氮供应使生物量产量从771-1569 g m−2增加，ET从227增加到336 mm，WUE从4.07增加到6.20 g kg−1。在所有N水平下，生物量在[eCO 2]下增加了17%。[eCO 2]增加了土壤水分，尤其是在土壤上层（0-20 cm），因此与[aCO 2]相比，[eCO 2]下的灌溉量减少。增加氮素供应可增强CO2×N交互作用对ET和WUE的影响。因此，在35、190、320 kg N ha-1条件下，[eCO 2]效应分别为ET −2、−9和−10%以及WUE + 20、+ 30和+29%。同时，似乎有一个更大的增加蒸发[eCO 2]下低比高N供应。
Global warming and associated decrease of summer precipitation will intensify the limitation of crop growth through water unavailability in Europe. Concomitantly, the rise of atmospheric CO2concentration ([CO2]) decreases stomatal conductance and thus transpiration as evident at the leaf level. However, knowledge about the effect of elevated [CO2] ([eCO2]) on seasonal water use of crops is rather poor. In a two year field study, winter wheat was grown under ambient [CO2] (393 ppm) and [eCO2] (600 ppm) using free air CO2enrichment (FACE). In addition, subplots were established with three levels of nitrogen (N) supply (35, 190, 320 kg N ha−1). Soil moisture was continuously measured and wheat was irrigated when necessary to keep field capacity at between 50% to 90%. Evapotranspiration (ET) from stem elongation until maturity was calculated using a soil water balance approach. Water use efficiency (WUE) was determined from the ratio of aboveground biomass production and ET during this period.Increasing N supply increased canopy size and decreased radiation transmission to the soil surface. Moreover increasing N supply enhanced biomass production from 771–1569 g m−2, ET from 227 to 336 mm and WUE from 4.07 to 6.20 g kg−1. Biomass was increased under [eCO2] by 17% among all N levels. [eCO2] increased soil moisture especially in the upper soil layer (0–20 cm) and thus irrigation was reduced under [eCO2] compared to [aCO2]. This effect was intensified by rising N supply leading to a significant CO2×N interaction on ET and WUE. Thus, the [eCO2] effect was for ET −2, −9 and −10% and for WUE + 20,+ 30 and +29% under 35, 190, 320 kg N ha-1, respectively. Simultaneously, there seems to be a greater increase of evaporation by [eCO2] under low than high N supply.