1Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
Plant Cell Environ. 2009 Dec;32(12):1737-1748. doi: 10.1111/j.1365-3040.2009.02031.x.
Maximum stomatal conductance to water vapour and CO2 (gwmax, gcmax, respectively), which are set at the time of leaf maturity, are determined predominantly by stomatal size (S) and density (D). In theory, many combinations of S and D yield the same gwmax and gcmax, so there is no inherent correlation between S and D, or between S, D and maximum stomatal conductance. However, using basic equations for gas diffusion through stomata of different sizes, we show that a negative correlation between S and D offers several advantages, including plasticity in gwmax and gcmax with minimal change in epidermal area allocation to stomata. Examination of the relationship between S and D in Eucalyptus globulus seedlings and coppice shoots growing in the field under high and low rainfall revealed a strong negative relationship between S and D, whereby S decreased with increasing D according to a negative power function. The results provide evidence that plasticity in maximum stomatal conductance may be constrained by a negative S versus D relationship, with higher maximum stomatal conductance characterized by smaller S and higher D, and a tendency to minimize change in epidermal space allocation to stomata as S and D vary.
最大水蒸气和二氧化碳气孔导度（分别为 gwmax 和 gcmax）在叶片成熟时确定，主要由气孔大小（S）和密度（D）决定。理论上，S 和 D 的许多组合都能产生相同的 gwmax 和 gcmax，因此 S 和 D 之间、S、D 和最大气孔导度之间没有内在相关性。然而，我们使用不同大小气孔气体扩散的基本方程表明，S 和 D 之间的负相关具有多个优势，包括 gwmax 和 gcmax 的可塑性，同时最小化表皮面积分配给气孔的变化。在高降雨和低降雨条件下生长的桉树幼苗和萌生枝中 S 和 D 之间的关系研究表明，S 和 D 之间存在很强的负相关关系，根据负幂函数，随着 D 的增加，S 减小。结果表明，最大气孔导度的可塑性可能受到 S 与 D 之间的负相关关系的限制，具有更高最大气孔导度的特征是 S 更小、D 更大，并且随着 S 和 D 的变化，表皮空间分配给气孔的变化趋势最小化。
