Natural Resources Branch, Department of Environment and Conservation, Locked Bag 104, Bentley Delivery Centre, WA 6983, Australia.
J Exp Bot. 2013 Jan;64(2):495-505. doi: 10.1093/jxb/ers347. Epub 2012 Dec 21.
Maximum and minimum stomatal conductance, as well as stomatal size and rate of response, are known to vary widely across plant species, but the functional relationship between these static and dynamic stomatal properties is unknown. The objective of this study was to test three hypotheses: (i) operating stomatal conductance under standard conditions (g (op)) correlates with minimum stomatal conductance prior to morning light [g (min(dawn))]; (ii) stomatal size (S) is negatively correlated with g (op) and the maximum rate of stomatal opening in response to light, (dg/dt)(max); and (iii) g (op) correlates negatively with instantaneous water-use efficiency (WUE) despite positive correlations with maximum rate of carboxylation (Vc (max)) and light-saturated rate of electron transport (J (max)). Using five closely related species of the genus Banksia, the above variables were measured, and it was found that all three hypotheses were supported by the results. Overall, this indicates that leaves built for higher rates of gas exchange have smaller stomata and faster dynamic characteristics. With the aid of a stomatal control model, it is demonstrated that higher g (op) can potentially expose plants to larger tissue water potential gradients, and that faster stomatal response times can help offset this risk.
最大和最小气孔导度以及气孔大小和响应速率已知在植物物种间广泛变化，但这些静态和动态气孔特性之间的功能关系尚不清楚。本研究的目的是检验三个假设：（i）在标准条件下运行的气孔导度（g(op)）与清晨光前的最小气孔导度[g(min(dawn))]相关；（ii）气孔大小（S）与 g(op)和对光最大的气孔开度速率（dg/dt)(max)呈负相关；（iii）g(op)与瞬时水分利用效率（WUE）呈负相关，尽管与最大羧化速率（Vc(max)）和光饱和电子传递速率（J(max)）呈正相关。使用五组密切相关的 Banksia 属物种来测量上述变量，结果表明所有三个假设都得到了支持。总体而言，这表明叶片具有更高的气体交换速率，其气孔更小，动态特性更快。借助气孔控制模型，表明较高的 g(op)可能使植物暴露于更大的组织水势梯度中，而更快的气孔响应时间可以帮助抵消这种风险。
