INRAE, UR P3F, F-86600 Lusignan, France.
Ann Bot. 2024 Nov 13;134(5):787-802. doi: 10.1093/aob/mcae114.
Leaf elongation is vital for productivity of Poaceae species, influenced by atmospheric CO2 concentration ([CO2]) and climate-induced water availability changes. Although [CO2] mitigates the effects of drought on reducing transpiration per unit leaf area, it also increases total leaf area and water use. These complex interactions associated with leaf growth pose challenges in anticipating climate change effects. This study aims to assess [CO2] effects on leaf growth response to drought in perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinacea) and wheat (Triticum aestivum).
Plants were cultivated in growth chambers with [CO2] at 200 or 800 ppm. At leaf six to seven unfolding, half of the plants were subjected to severe drought treatment. Leaf elongation rate (LER) was measured daily, whereas plant transpiration was continuously recorded gravimetrically. Additionally, water-soluble carbohydrate (WSC) content along with water and osmotic potentials in the leaf growing zone were measured at drought onset, mid-drought and leaf growth cessation.
Elevated [CO2] mitigated drought impacts on LER and delayed growth cessation across species. A positive correlation between LER and soil relative water content (SRWC) was observed. At the same SRWC, perennial grasses exhibited a higher LER with elevated [CO2], probably due to enhanced stomatal regulation. Despite stomatal closure and WSC accumulation, CO2 did not influence nighttime water potential or osmotic potential. The marked increase in leaf area across species resulted in similar (wheat and tall fescue) or higher (ryegrass) total water use by the end of the experiment, under both watered and unwatered conditions.
Elevated [CO2] mitigates the adverse effects of drought on leaf elongation in three Poaceae species, due to its impact on plant transpiration. Overall, these findings provide valuable insights into CO2 and drought interactions that may help anticipate plant responses to climate change.
叶片伸长对禾本科植物的生产力至关重要，受大气二氧化碳浓度 ([CO2]) 和气候诱导的水分可利用性变化的影响。尽管 [CO2] 减轻了干旱对降低单位叶面积蒸腾的影响，但它也增加了总叶片面积和耗水量。这些与叶片生长相关的复杂相互作用给预测气候变化的影响带来了挑战。本研究旨在评估 [CO2] 对多年生黑麦草 (Lolium perenne)、高羊茅 (Festuca arundinacea) 和小麦 (Triticum aestivum) 叶片生长对干旱响应的影响。
植物在生长室中用 200 或 800 ppm 的 [CO2] 进行培养。在叶片展开到第六到第七片时，将一半的植物置于严重干旱处理下。每天测量叶片伸长率 (LER)，同时连续称重记录植物蒸腾。此外，在干旱开始时、干旱中期和叶片生长停止时测量叶片生长区的水溶性碳水化合物 (WSC) 含量以及水和渗透势。
升高的 [CO2] 减轻了干旱对 LER 的影响，并延迟了物种的生长停止。LER 与土壤相对含水量 (SRWC) 呈正相关。在相同的 SRWC 下，多年生草具有更高的 LER，这可能是由于气孔调节增强所致。尽管气孔关闭和 WSC 积累，CO2 并未影响夜间水势或渗透势。由于叶片面积的显著增加，在浇水和不浇水条件下，三种禾本科植物的总耗水量相同（小麦和高羊茅）或更高（黑麦草）。
升高的 [CO2] 减轻了三种禾本科植物叶片伸长对干旱的不利影响，这是由于其对植物蒸腾的影响。总的来说，这些发现为 CO2 和干旱相互作用提供了有价值的见解，这可能有助于预测植物对气候变化的反应。
