Photosynthesis and conductance of spring-wheat leaves:: field response to continuous free-air atmospheric CO2 enrichment
Photosynthesis and conductance of spring-wheat leaves:: field response to continuous free-air atmospheric CO2 enrichment
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DOI：
10.1046/j.1365-3040.1998.00320.x
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发表时间：
1998-07-01
影响因子：
7.3
通讯作者：
Wechsung, F
中科院分区：
文献类型：
--
作者：
Garcia, RL;Long, SP;Wechsung, F
春小麦在两种CO2分压（pCO(2)）下生长，从萌芽到籽粒成熟：环境空气名义上为37 Pa，空气中富含CO2至55 Pa，使用自由空气CO2富集（FACE）装置。该实验首次在谷物田进行，没有改变或干扰小气候和生根环境，这为检验小麦持续暴露于高pCO(2)会导致光合能力同化性丧失的假设提供了独特的机会。在整个作物发育过程中，研究人员跟踪了冠层上部叶片的光合作用和电导的日变化过程，并与模型预测的光合作用速率进行了比较。暴露于高pCO(2)环境中的植物正午光合速率的季节平均值比对照高28%，高pCO(2)环境中光合作用日积分的季节平均值比环境空气中高21%。正午时的平均电导降低了36%。在高pCO(2)条件下观察到的光合作用的增强与假设光合能力没有驯化的机械生化模型的预测结果非常吻合。只有灌浆开始前的下午中段旗叶和灌浆结束后的全天测量值低于预测值。在这个最后阶段，增强的丧失归因于在pCO升高的情况下旗叶的早期衰老(2)。与一些受控环境和田间圈闭研究相比，这项利用自由空气CO2富集小麦的田间规模研究发现，在pCO(2)升高的环境中，光合能力的同化性丧失几乎没有证据，而在作物的整个生命周期中，叶片光合作用显著增加。
Spring wheat was grown from emergence to grain maturity in two partial pressures of CO2 (pCO(2)): ambient air of nominally 37 Pa and air enriched with CO2 to 55 Pa using a free-air CO2 enrichment (FACE) apparatus. This experiment was the first of its kind to be conducted within a cereal field without the modifications or disturbance of microclimate and rooting environment that accompanied previous studies, It provided a unique opportunity to examine the hypothesis that continuous exposure of wheat to elevated pCO(2) will lead to acclimatory loss of photosynthetic capacity. The diurnal courses of photosynthesis and conductance for upper canopy leaves were followed throughout the development of the crop and compared to model-predicted rates of photosynthesis. The seasonal average of midday photosynthesis rates was 28% greater in plants exposed to elevated pCO(2) than in contols and the seasonal average of the daily integrals of photosynthesis was 21% greater in elevated pCO(2) than in ambient air. The mean conductance at midday was reduced by 36%. The observed enhancement of photosynthesis in elevated pCO(2) agreed closely with that predicted from a mechanistic biochemical model that assumed no acclimation of photosynthetic capacity. Measured values fell below predicted only in the flag leaves in the mid afternoon before the onset of grain-filling and over the whole diurnal course at the end of grain-filling. The loss of enhancement at this final stage was attributed to the earlier senescence of flag leaves in elevated pCO(2). In contrast to some controlled-environment and field-enclosure studies, this field-scale study of wheat using free-air CO2 enrichment found little evidence of acclimatory loss of photosynthetic capacity with growth in elevated pCO(2) and a significant and substantial increase in leaf photosynthesis throughout the life of the crop.