Table 1.
Input parameter values for various parts of biochemical leaf photosynthesis models
| Category | Symbol | Definition (unit) | C3 | C4 | ||
|---|---|---|---|---|---|---|
| Value | Reference | Value | Reference | |||
| e− transport | Φ2LL | Quantum efficiency of PSII e− transport under limiting light (mol mol−1) at Topt | 0.78 | Yin et al., (2014) | 0.78 | Assumed to be the same as for C3 |
| r 2/1 | Ratio of Φ2LL to quantum efficiency of PSI e− transport under limiting light (–) | 0.85 | Genty and Harbinson (1996) | 0.85 | Assumed to be the same as for C3 | |
| θ | Convexity of irradiance response of PSII e− transport rate (–) | 0.8 | Yin et al., (2009) | 0.8 | Assumed to be the same as for C3 | |
| f cyc | Fraction of total PSI e− flux that follows cyclic e− transport (–) | 0.05 | Yin et al., (2006) | 0.45a | Yin and Struik (2012) | |
| f pseudo | Fraction of total PSI e− flux that follows pseudocyclic e− transport (–) | 0.10 | Yin et al., (2006) | 0.05 | Yin and Struik (2012) | |
| f Q | Fraction of total plastoquinone e− flux that follows the Q-cycle (–) | NU | NU | 1 | Furbank et al., (1990) | |
| h | H+ required per ATP production (mol mol−1) | NU | NU | 4 | Yin and Struik (2012) | |
| α | Fraction of O2 evolution in bundle-sheath cells (–) | NA | NA | 0.1 | Standard value for C4 species such as maize | |
| x | Fraction of ATP used for CCM (–) | NA | NA | 0.4a | von Caemmerer and Furbank (1999) | |
| φ | Extra ATP required for the CCM per CO2 fixed (mol mol−1) | NA | NA | 2a | von Caemmerer and Furbank (1999) | |
| T opt | Optimum temperature for Φ2LL (°C) | 23 | Data of Yin et al., (2014) | 34 | Data of Yin et al., (2016) | |
| Ω | Difference between Topt and the temperature at which Φ2LL falls to e−1 of its maximum (°C) | 36.8 | Data of Yin et al., (2014) | 38.4 | Data of Yin et al., (2016) | |
| Enzyme kinetics and activity | S c/o25 | Relative CO2/O2 specificity of Rubisco at 25 °C (mol mol−1) | 3022 | Cousins et al., (2010) | 2862 | Cousins et al., (2010) |
| γ*25 | Half the reciprocal of Sc/o25 (mol mol−1) | 0.5/Sc/o25 | By definition | 0.5/Sc/o25 | By definition | |
| K mC25 | Michaelis–Menten constant of Rubisco for CO2 at 25 °C (μmol mol−1) | 291 | Cousins et al., (2010) | 485 | Cousins et al., (2010) | |
| K mO25 | Michaelis–Menten constant of Rubisco for O2 at 25 °C (mmol mol−1) | 194 | Cousins et al., (2010) | 146 | Cousins et al., (2010) | |
| χVcmax25 | Linear slope of maximum Rubisco activity at 25°C (Vcmax25) versus (n–nb)b (μmol s−1 g−1) | 75 | Derived from data of Yin et al., (2009) | 93 | 1.24 times that for C3 (Cousins et al., 2010; Perdomo et al., 2015) | |
| χJmax25 | Linear slope of maximum PSII e− transport rate at 25 °C (Jmax25) versus (n–nb) (μmol s−1 g−1) | 100 | Harley et al., (1992); Yin et al., (2009) | 200 | Derived from data of Yin et al., (2011) | |
| χεp25 | Linear slope of PEP carboxylation efficiency at 25 °C (εp25) versus (n–nb) (mol s−1 g−1) | NA | NA | 0.791 | Derived from data of Yin et al., (2011) | |
| Leaf respiration | R d25 | Day respiration at 25 °C (μmol m−2 s−1) | 0.01Vcmax25 | Common assumption | 0.01Vcmax25 | Assumed to be the same as for C3 |
| R m | Respiration rate occurring in mesophyll cells (μmol m−2 s−1) | NA | NA | 0.5Rda | von Caemmerer and Furbank (1999) | |
| CO2 diffusion | g 0 | Empirical residual stomatal conductance if light approaches zero (mol m−2 s−1) | 0.01 | Leuning (1995) | 0.01 | Assumed to be the same as for C3 |
| a 1 | Empirical constant for gs response to VPD (–) | 0.9 | Derived from Morison and Gifford (1983) | 0.9 | Set the same as for C3 cropsc | |
| b 1 | Empirical constant for gs response to VPD (kPa−1) | 0.15 | Derived from Morison and Gifford (1983) | 0.15 | Set the same as for C3 cropsc | |
| χgm25 | Linear slope of mesophyll conductance at 25 °C (gm25) versus (n–nb) (mol s−1 g−1) | 0.125 | Derived from data of Yin et al., (2009); Gu et al., (2012) | NU | NU | |
| χgbs25 | Linear slope of bundle-sheath conductance at 25 °C (gbs25) versus (n–nb) (mol s−1 g−1) | NA | NA | 0.007a | Yin et al., (2011) | |
| u oc25 | Coefficient lumping diffusivities and solubilities of CO2 and O2 in H2O at 25 °C | NA | NA | 0.047 | von Caemmerer and Furbank (1999) | |
| Temperature response | Eγ* | Activation energy for γ* (J mol−1) | 24 460 | Bernacchi et al., (2002) | 27 417 | Yin et al., (2016) |
| E Vcmax | Activation energy for Vcmax (J mol−1) | 65 330 | Bernacchi et al., (2001) | 53 400 | Yin et al., (2016) | |
| E KmC | Activation energy for KmC (J mol−1) | 80 990 | Bernacchi et al., (2002) | 35 600 | Perdomo et al., (2015) | |
| E KmO | Activation energy for KmO (J mol−1) | 23 720 | Bernacchi et al., (2002) | 15 100 | Yin et al., (2016) | |
| E Rd | Activation energy for Rd (J mol−1) | 46 390 | Bernacchi et al., (2001) | 41 853 | Yin et al., (2016) | |
| E Jmax | Activation energy for Jmax (J mol−1) | 88 380d | Yin and van Laar (2005) | 116 439 | Yin et al., (2016) | |
| D Jmax | Deactivation energy for Jmax (J mol−1) | 200 000 | Harley et al., (1992) | 135 982 | Yin et al., (2016) | |
| S Jmax | Entropy term for Jmax (J K−1 mol−1) | 650 | Harley et al., (1992) | 458.7 | Yin et al., (2016) | |
| Eεp | Activation energy for εp (J mol−1) | NA | NA | 51 029 | Data of Yin et al., (2016) | |
| Dεp | Deactivation energy for εp (J mol−1) | NA | NA | 130 363 | Data of Yin et al., (2016) | |
| Sεp | Entropy term for εp (J K−1 mol−1) | NA | NA | 425.6 | Data of Yin et al., (2016) | |
| E gm | Activation energy for gm (J mol−1) | 49 600 | Bernacchi et al., (2001) | NU | NU | |
| D gm | Deactivation energy for gm (J mol−1) | 437 400 | Bernacchi et al., (2002) | NU | NU | |
| S gm | Entropy term for gm (J K−1 mol−1) | 1400 | Bernacchi et al., (2002) | NU | NU | |
| E gbs | Activation energy for gbs (J mol−1) | NA | NA | 116 767 | Yin et al., (2016) | |
| D gbs | Deactivation energy for gbs (J mol−1) | NA | NA | 264 604 | Yin et al., (2016) | |
| S gbs | Entropy term for gbs (J K−1 mol−1) | NA | NA | 860 | Yin et al., (2016) | |
| E uoc | Activation energy for uoc (J mol−1) | NA | NA | –1630 | Yin et al., (2016) | |
| Base leaf N | n b | Base leaf nitrogen, at and below which leaf photosynthesis is zero (g m−2) | 0.3 | Sinclair and Horie (1989) | 0.3 | Assumed to be the same as for C3 |
NA, not applicable; NU, not used by the model presented herein.
a These parameter values need to be adjusted if the C4 model is used for simulating the cyanobacterial CCM (see the text and Table 2).
b Where n is leaf nitrogen (g N m−2); and nb is the base leaf nitrogen, below which no leaf photosynthesis is observed.
c Data of Morison and Gifford (1983) showed that stomatal sensitivity to VPD could differ between C3 and C4; such a difference can be mimicked by our stomatal conductance model, Equation 2 for C3 and Equation 11 for C4 leaves, when using the same values of a1 and b1.
d Parameter set in GECROS to be dependent on crop species; the value 88 380 was set as default for rice (Yin and van Laar, 2005).