Asymmetrical effects of mesophyll conductance on fundamental photosynthetic parameters and their relationships estimated from leaf gas exchange measurements

Worldwide measurements of nearly 130 C3 species covering all major plant functional types are analysed in conjunction with model simulations to determine the effects of mesophyll conductance (gm) on photosynthetic parameters and their relationships estimated fromA/Ci curves. We find that an assumption of infinite gm results in up to 75% underestimation for maximum carboxylation rate Vcmax, 60% for maximum electron transport rate Jmax, and 40% for triose phosphate utilization rate Tu. Vcmax is most sensitive, Jmax is less sensitive, and Tuhas the least sensitivity to the variation of gm. Because of this asymmetrical effect of gm, the ratios of Jmax to Vcmax, Tu to Vcmax and Tu toJmax are all overestimated. An infinite gm assumption also limits the freedom of variation of estimated parameters and artificially constrains parameter relationships to stronger shapes. These findings suggest the importance of quantifying gm for understanding in situphotosynthetic machinery functioning. We show that a nonzero resistance to CO2 movement in chloroplasts has small effects on estimated parameters. A non-linear function with gm as input is developed to convert the parameters estimated under an assumption of infinite gm to proper values. This function will facilitate gm representation in global carbon cycle models.

Gu, LianhongOak Ridge National Laboratory, USA (författare)
Dickinson, Robert E.University of Texas at Austin, USA (författare)
Pallardy, Stephen G.University of Missouri, USA (författare)
Baker, JohnUniversity of Minnesota, USA (författare)
Cao, YonghuiChinese Academy of Forestry, China (författare)
Damatta, Fábio MuriloUniversidade Federal de Viçosa, Brazil (författare)
Dong, XuejunNorth Dakota State University, USA (författare)
Ellsworth, DavidUniversity of Western Sydney, Australia (författare)
Van Goethem, DavinaUniversity of Antwerp, Belgium (författare)
Jensen, Anna M.Oak Ridge National Laboratory, USA(Swepub:lnu)anjeaa (författare)
Law, Beverly E.Oregon State University, USA (författare)
Loos, RodolfoTechnology Center, Fibria Celulose S.A, Aracruz, Brazil (författare)
Martins, Samuel C. VitorUniversidade Federal de Viçosa, Brazil (författare)
Norby, Richard J.Oak Ridge National Laboratory, USA (författare)
Warren, Jeffrey M.Oak Ridge National Laboratory, USA (författare)
Weston, DavidOak Ridge National Laboratory, USA (författare)
Winter, KlausSmithsonian Tropical Research Institute, Republic of Panama (författare)
University of Texas at Austin, Austin, USAOak Ridge National Laboratory, USA (creator_code:org_t)

Ingår i:Plant, Cell and Environment: John Wiley & Sons37:4, s. 978-9940140-77911365-3040

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