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首页> 外文期刊>European Journal of Agronomy >Interactive effects of elevated atmospheric CO2 concentrations and plant available soil water content on canopy evapotranspiration and conductance of spring wheat.
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Interactive effects of elevated atmospheric CO2 concentrations and plant available soil water content on canopy evapotranspiration and conductance of spring wheat.

机译：大气CO2浓度升高和植物有效土壤水分对春小麦冠层蒸散和电导的交互作用。

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摘要

The present study was conducted to investigate the possible interactive effects of rising atmospheric CO2 concentration [CO2] and drought stress on water use of wheat. Spring wheat (Triticum aestivum cv. "Minaret") was grown either in 1 m diameter lysimeters with 0.4 m soil depth (1998) or in the field (1999) in open-top chambers under two CO2-concentrations (ambient, ambient+280 ppm) and two watering regimes (well-watered=WW with a plant available water content PAW>40 mm and drought stressed=DS, 10 mm < PAW < 30 mm) beginning after first node stage. Canopy evapotranspiration (EC) was measured continuously from first the node stage until the beginning of flag leaf senescence using four open-system canopy chambers (0.78 m3). Seasonal changes of the absorption of photosynthetically active radiation (APAR) of the canopy and root growth (1999) were also measured. In both growing seasons leaf area index increased in response to elevated [CO2] in both water treatments. The related effects of [CO2] on canopy radiation absorption (APAR) were, however, smaller. EC was linearily related to APAR in both growing seasons. While elevated [CO2] reduced the slope of this relation under WW conditions by ca. 20% in both growing seasons, it was not reduced (1998) and even increased (1999) under drought. Canopy conductance (GC) calculated as EC divided by vapour pressure deficit of air, showed a non-linear relationship to APAR that was best explained by saturation curves. Under WW conditions, elevated [CO2] reduced the initial slope of GC versus APAR as well as GC at saturating light conditions (ca. -30%), while under DS conditions no effect of elevated [CO2] could be detected. Under high light conditions (PAR>400 micro mol m-2 s-1) a critical "threshold value" of PAW (TPAW, ca. 40 mm) could be identified above which GC did not respond to PAW. While in 1998 GC did not respond to elevated [CO2] at PAW < TPAW, it was slightly increased at low PAW values in the field experiments of 1999. The reduction of TPAW by elevated [CO2] may be explained by enhanced root growth (1999) that would have given the plants better access to soil water resources. The present results suggest that below a critical soil water content elevated [CO2] will not reduce canopy water loss of wheat or may even enhance it.
机译：进行本研究以调查大气中CO2浓度[CO2]和干旱胁迫对小麦水分利用的可能的交互作用。春小麦（Triticum aestivum cv。“ Minaret”）在两个CO2浓度（环境温度，环境温度+280）下在直径为0.4 m深度的直径密耳式测厚仪中生长（1998年），或者在田间（1999年）中在敞顶箱中生长。 ppm）和两个灌溉制度（浇水充足= WW，植物可用水分PAW> 40 mm，干旱胁迫= DS，10 mm 400 micro mol m-2 s-1），可以确定PAW的临界“阈值”（TPAW，约40 mm），高于该阈值，GC对PAW无响应。尽管1998年GC对PAW

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