CO2浓度、氮和水分对春小麦光合、蒸散及水分利用效率的影响

研究了不同土壤氮和土壤水分条件下，大气CO2浓度升高对春小麦光合作用、气孔导度、蒸散和水分利用效率的影响。结果表明，CO2浓度升高，干旱处理的春小麦（Triticum aestivum L.）叶片光合作用速率幅度增加大于湿润处理，随着氮肥用量增加光合速率相应增加，而不施氮脂增加有限；干旱处理气孔导度幅度减少大于湿润处理，不施氮肥的大于氮肥充足的CO2浓度升高，干旱处理的蒸散量减少比湿润处理多，不施氮肥的蒸散量减少较为明显；但干旱处理单叶WUE增加大于湿润处理；随着氮肥用量增加，冠层WUE提高，而不施氮肥的冠层WUE最低。因而CO2浓度升高、光合速率增加和蒸散量减少会减缓干旱的不利影响，增强作物对干旱胁迫的抵御能力。

Effects of CO2 enrichment, nitrogen and water on photosynthesis, evapotranspiration and water use efficiency of spring wheat

Spring wheat (Triticum aestivum L.) was treated with 2 atmospheric CO2 concentrations (350 and 700 mumol.mol-1), 2 levels of soil moisture (wet and drought), and 5 levels of nitrogen fertilizer (0, 50, 100, 150, 200 mg.kg-1 soil). The results showed that elevated atmospheric CO2 increased photosynthetic rate more in drought than in wet treatment. Photosynthetic rate increased with the increase of nitrogen fertilizer. Stomatal conductance decreased with CO2 enrichment, which was more in drought than in wet treatment. CO2 enrichment decreased more evapotranspiration in drought than in wet treatment. The decrease was more apparent with no fertilization. CO2 enrichment increased more leaf water use efficiency in drought than in wet treatment. Canopy WUE increased with CO2 enrichment and N fertilization. Thus, the increase in photosynthesis and the reduction in evapotranspiration due to elevated CO2 can ameliorate the negative effects of drought, and increase wheat resistance to water stress.