Unsaturation of vapour pressure inside leaves: fundamental, but unknown

该项目旨在确定树叶内部的空气何时变得不饱和，以及在多大程度上变得不饱和。目前对叶片气体交换的所有解释和模型在任何情况下都是饱和的。令人信服的证据表明，在适度的空气蒸气压力赤字下，情况并非如此。一种新的技术将被用来评估树叶内空气的水蒸气浓度，该技术基于二氧化碳和树叶与空气之间交换的水蒸气的稳定同位素分析。该项目预计将提供有关气孔如何调节光合作用和水分利用的基础知识，对建立植被功能模型和改善作物表现具有重要意义。

This project aims to determine when and to what extent the air inside leaves becomes unsaturated with water vapour. All current interpretation and modelling of leaf gas exchange assumes saturation under all circumstances. Compelling evidence has been obtained that suggests this is not true under moderate air vapour pressure deficits. A novel technique will be employed to assess the water vapour concentration of the air inside leaves based on stable isotope analysis of carbon dioxide and water vapour exchanged between leaves and air. The project is expected to provide fundamental knowledge about how stomata regulate photosynthesis and water use, with significant implications for modelling vegetation function and for improving the performance of crop plants.