Hawkesbury Institute for the Environment, University of Western Sydney, Penrith, NSW 2751, Australia.
Plant Cell Environ. 2013 Feb;36(2):262-74. doi: 10.1111/j.1365-3040.2012.02570.x. Epub 2012 Aug 7.
Models of stomatal conductance (g(s)) are based on coupling between g(s) and CO(2) assimilation (A(net)), and it is often assumed that the slope of this relationship ('g(1) ') is constant across species. However, if different plant species have adapted to different access costs of water, then there will be differences in g(1) among species. We hypothesized that g(1) should vary among species adapted to different climates, and tested the theory and its linkage to plant hydraulics using four Eucalyptus species from different climatic origins in a common garden. Optimal stomatal theory predicts that species from sub-humid zones have a lower marginal water cost of C gain, hence lower g(1) than humid-zone species. In agreement with the theory that g(1) is related to tissue carbon costs for water supply, we found a relationship between wood density and g(1) across Eucalyptus species of contrasting climatic origins. There were significant reductions in the parameter g(1) during drought in humid but not sub-humid species, with the latter group maintaining g(1) in drought. There are strong differences in stomatal behaviour among related tree species in agreement with optimal stomatal theory, and these differences are consistent with the economics involved in water uptake and transport for carbon gain.
气孔导度（g(s)）模型基于 g(s) 和 CO₂同化（A(net)）之间的耦合，通常假设这种关系的斜率（'g(1) '）在物种间是恒定的。然而，如果不同的植物物种已经适应了不同的水分获取成本，那么物种间的 g(1) 就会存在差异。我们假设 g(1) 应该在适应不同气候的物种之间存在差异，并使用来自不同起源气候的四个桉树物种在一个共同的花园中检验了这一理论及其与植物水力学的联系。最佳气孔理论预测，来自半湿润区的物种在获得碳的边际水分成本较低，因此比湿润区的物种具有较低的 g(1)。与 g(1) 与组织供水碳成本相关的理论一致，我们发现了在具有不同起源气候的桉树物种之间存在木质密度与 g(1) 的关系。在湿润但不是半湿润物种中，干旱期间 g(1) 参数显著降低，而后者在干旱期间保持 g(1)。与最佳气孔理论一致，相关树种的气孔行为存在很大差异，这些差异与水分获取和运输的经济成本有关。
