Abstract Understanding the key processes and potential mechanisms of crops in response to elevated atmospheric CO2 concentration and drought may further shed lights on the impacts of climate change on the global agriculture ecosystems. This study examined the effects of elevated atmospheric CO2 concentration on the growth of winter wheat under different soil water conditions (full irrigation, mild water stress, moderate water stress, and severe water stress) with growth chambers where the CO2 concentration was controlled at 400 and 800 µmol mol−1, respectively. We found a very strong CO2 fertilization effect on the growth of winter wheat under full irrigation condition, whereas this CO2 fertilization effect declined and eventually vanished with soil water stress, as evidenced by the decreased plant biomass and leaf photosynthesis of winter wheat independent of CO2 concentration. This adverse impact of water stress on the CO2 fertilization effect for plant growth may attribute to the changes in morphological characteristics of individual stoma and spatial distribution pattern of stomata as well as the non-structural carbohydrates of winter wheat. These results suggested that water stress may lower the CO2 fertilization effect on plant growth through altering stomatal traits, leaf photochemical processes, and biochemical compositions of winter wheat. Therefore, many current climate models based on earlier “double-CO2” experiment may overestimate the CO2 fertilization effect on crops, and meanwhile underestimate the impacts of climate change on global agriculture production when the elevated atmospheric CO2 concentration confounded with drought stress under future climate change.

中文翻译：

---

土壤水分状况触发 CO2 施肥对冬小麦（Triticum aestivum）生长的影响

摘要 了解作物响应大气 CO2 浓度升高和干旱的关键过程和潜在机制可能会进一步阐明气候变化对全球农业生态系统的影响。本研究通过将 CO2 浓度控制在 400 和分别为 800 µmol mol−1。我们发现在充分灌溉条件下，CO2 施肥对冬小麦的生长有很强的影响，而这种 CO2 施肥作用随着土壤水分胁迫而下降并最终消失，冬小麦植物生物量和叶片光合作用的减少与 CO2 浓度无关就证明了这一点。水分胁迫对植物生长的CO2施肥效应的这种不利影响可能归因于冬小麦个体气孔形态特征和气孔空间分布格局以及非结构性碳水化合物的变化。这些结果表明，水分胁迫可能通过改变冬小麦的气孔性状、叶片光化学过程和生化成分来降低 CO2 施肥对植物生长的影响。因此，目前许多基于早期“双 CO2”实验的气候模型可能高估了 CO2 施肥对作物的影响，