Shorting the metaphorical circuit: vascular partitioning and stomatal patchiness can create apparent unsaturation and CO 2 gradient inversion in the Ohmic analogy for leaf gas exchange.

Autor: Rockwell FE; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA.
Jazyk: angličtina
Zdroj: The New phytologist [New Phytol] 2024 Sep 05. Date of Electronic Publication: 2024 Sep 05.
DOI: 10.1111/nph.20106
Abstrakt: Analyses of leaf gas exchange rely on an Ohmic analogy that arrays single stomatal, internal air space, and mesophyll conductances in series. Such models underlie inferences of mesophyll conductance and the relative humidity of leaf airspaces, reported to fall as low as 80%. An unresolved question is whether such series models are biased with respect to real leaves, whose internal air spaces are chambered at various scales by vasculature. To test whether unsaturation could emerge from modeling artifacts, we compared series model estimates with true parameter values for a chambered leaf with varying distributions and magnitudes of leaf surface conductance ('patchiness'). Distributions of surface conductance can create large biases in gas exchange calculations. Both apparent unsaturation and internal CO 2 gradient inversion can be produced by the evolution of broader distributions of stomatal apertures consistent with a decrease in surface conductance, as might occur under increasing vapor pressure deficit. In gas exchange experiments, the behaviors of derived quantities defined by simple series models are highly sensitive to the true partitioning of flux and stomatal apertures across leaf surfaces. New methods are needed to disentangle model artifacts from real biological responses.
(© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)
Databáze: MEDLINE
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