Civil and Environmental Engineering Department, Duke University, Durham, NC 27708-0287, USA.
New Phytol. 2011 Nov;192(3):640-52. doi: 10.1111/j.1469-8137.2011.03847.x. Epub 2011 Aug 18.
• Understory plants are subjected to highly intermittent light availability and their leaf gas exchanges are mediated by delayed responses of stomata and leaf biochemistry to light fluctuations. In this article, the patterns in stomatal delays across biomes and plant functional types were studied and their effects on leaf carbon gains and water losses were quantified. • A database of more than 60 published datasets on stomatal responses to light fluctuations was assembled. To interpret these experimental observations, a leaf gas exchange model was developed and coupled to a novel formulation of stomatal movement energetics. The model was used to test whether stomatal delays optimize light capture for photosynthesis, whilst limiting transpiration and carbon costs for stomatal movement. • The data analysis showed that stomatal opening and closing delays occurred over a limited range of values and were strongly correlated. Plant functional type and climate were the most important drivers of stomatal delays, with faster responses in graminoids and species from dry climates. • Although perfectly tracking stomata would maximize photosynthesis and minimize transpiration at the expense of large opening costs, the observed combinations of opening and closure times appeared to be consistent with a near-optimal balance of carbon gain, water loss and movement costs.
• 林下植物的光照可用性高度间歇性，其叶片气体交换受气孔和叶片生物化学对光波动的延迟反应调节。本文研究了生物群落和植物功能类型中气孔延迟的模式，并量化了它们对叶片碳增益和水分损失的影响。
• 我们构建了一个包含 60 多个关于气孔对光波动响应的已发表数据集的数据库。为了解释这些实验观察结果，我们开发了一个叶片气体交换模型，并将其与气孔运动能量学的新公式耦合。该模型用于测试气孔延迟是否通过优化光合作用的光捕获来实现，同时限制蒸腾作用和气孔运动的碳成本。
• 数据分析表明，气孔的开闭延迟发生在有限的范围内，且具有很强的相关性。植物功能类型和气候是气孔延迟的最重要驱动因素，草本植物和干旱气候下的物种具有更快的响应速度。
• 虽然完全跟踪气孔可以在不考虑大的开启成本的情况下最大限度地提高光合作用和减少蒸腾作用，但观察到的开闭时间组合似乎与碳增益、水分损失和运动成本的近乎最佳平衡一致。
