TY - JOUR

T1 - A new method to estimate photosynthetic parameters through net assimilation rate−intercellular space CO2 concentration (A−Ci) curve and chlorophyll fluorescence measurements

AU - Moualeu-Ngangue, Dany P.

AU - Chen, Tsu Wei

AU - Stützel, Hartmut

N1 - Publisher Copyright: © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust Copyright: Copyright 2017 Elsevier B.V., All rights reserved.

PY - 2017/2

Y1 - 2017/2

N2 - Gas exchange (GE) and chlorophyll fluorescence (CF) measurements are widely used to noninvasively study photosynthetic parameters, for example the rates of maximum Rubisco carboxylation (Vcmax), electron transport rate (J), daytime respiration (Rd) and mesophyll conductance (gm). Existing methods for fitting GE data (net assimilation rate−intercellular space CO2 concentration (A−Ci) curve) are based on two assumptions: gm is unvaried with CO2 concentration in the intercellular space (Ci); and light absorption (α) and the proportion of quanta absorbed by photosystem II (β) are constant in the data set. These may result in significant bias in estimating photosynthetic parameters. To avoid the above-mentioned hypotheses, we present a new method for fitting A−Ci curves and CF data simultaneously. This method was applied to a data set obtained from cucumber (Cucumis sativus) leaves of various leaf ages and grown under eight different light conditions. The new method had significantly lower root mean square error and a lower rate of failures compared with previously published methods (6.72% versus 24.1%, respectively) and the effect of light conditions on Vcmax and J was better observed. Furthermore, the new method allows the estimation of a new parameter, the fraction of incoming irradiance harvested by photosystem II, and the dependence of gm on Ci.

AB - Gas exchange (GE) and chlorophyll fluorescence (CF) measurements are widely used to noninvasively study photosynthetic parameters, for example the rates of maximum Rubisco carboxylation (Vcmax), electron transport rate (J), daytime respiration (Rd) and mesophyll conductance (gm). Existing methods for fitting GE data (net assimilation rate−intercellular space CO2 concentration (A−Ci) curve) are based on two assumptions: gm is unvaried with CO2 concentration in the intercellular space (Ci); and light absorption (α) and the proportion of quanta absorbed by photosystem II (β) are constant in the data set. These may result in significant bias in estimating photosynthetic parameters. To avoid the above-mentioned hypotheses, we present a new method for fitting A−Ci curves and CF data simultaneously. This method was applied to a data set obtained from cucumber (Cucumis sativus) leaves of various leaf ages and grown under eight different light conditions. The new method had significantly lower root mean square error and a lower rate of failures compared with previously published methods (6.72% versus 24.1%, respectively) and the effect of light conditions on Vcmax and J was better observed. Furthermore, the new method allows the estimation of a new parameter, the fraction of incoming irradiance harvested by photosystem II, and the dependence of gm on Ci.

KW - A–Ci curves

KW - chlorophyll fluorescence

KW - fitting method

KW - mesophyll conductance

KW - photosynthetic parameters

KW - A-Ci curves

UR - http://www.scopus.com/inward/record.url?scp=84992313130&partnerID=8YFLogxK

U2 - 10.1111/nph.14260

DO - 10.1111/nph.14260

M3 - Article

C2 - 27768807

AN - SCOPUS:84992313130

VL - 213

SP - 1543

EP - 1554

JO - New Phytologist

JF - New Phytologist

SN - 1469-8137

IS - 3

ER -