Cuticular conductance to water (g cw) is difficult to quantify for stomatous surfaces due to the complexity of separating cuticular and stomatal transpiration, and additional complications arise for determining adaxial and abaxial g cw. This has led to the neglect of g cw as a separate parameter in most common gas exchange measurements. Here, we describe a simple technique to simultaneously estimate adaxial and abaxial values of g cw, tested in two amphistomatous plant species. What we term the ‘Red-Light method’ is used to estimate g cw from gas exchange measurements and a known CO 2 concentration inside the leaf during photosynthetic induction under red light. We provide an easy-to-use web application to assist with the calculation of g cw. While adaxial and abaxial g cw varies significantly between leaves of the same species we found that the ratio of adaxial/abaxial g cw (γ n) is stable within a plant species. This has implications for use of generic values of g cw when analysing gas exchange data. The Red-Light method can be used to estimate total cuticular conductance (g cw-T) accurately with the most common setup of gas exchange instruments, i.e. a chamber mixing the adaxial and abaxial gases, allowing for a wide application of this technique.
Bibliographical noteFunding Information:
The authors thank CONICYT, Doctorado Becas Chile/2015 Folio: 72160160 and the ARC Centre of Excellence for Translational Photosynthesis for funding part of the research; Suan Chin Wong for providing technical support; the Centre for Advanced Microscopy at the Australian National University (ANU) for instruments and technical assistance; ANU Plant Services for taking care of the plant material.
© 2021 The Authors New Phytologist © 2021 New Phytologist Foundation
- abaxial cuticular conductance
- adaxial cuticular conductance
- amphistomatous leaf
- cuticular conductance to water
- leaf gas exchange
- nocturnal conductance
- photosynthetic induction
ASJC Scopus subject areas
- Plant Science