Table 1.
Description of the abbreviations, symbol, value (as in Evans and von Caemmerer, 2013), and unit of the environmental parameters and leaf variables used in this study
| Abbreviation | Description | |
|---|---|---|
| Gch | Growth chamber | |
| GDC | Glycine decarboxylase complex | |
| gdch-KD | Transgenic GDC H-subunit knockdown | |
| Lch | Leaf chamber | |
| LEDR | Light-enhanced dark respiration | |
| NH3 | Ammonia | |
| NH4+ | Ammonium cation | |
| PDH | Pyruvate dehydrogenase | |
| RuBP | Ribulose 1,5-bisphosphate | |
| TCA | Tricarboxylic acid | |
| 2-PG | 2-phosphoglycolate | |
| 3-PGA | 3-phosphoglycerate | |
| Symbol | Environmental parameters/leaf variables | Value and unit |
| A | Net CO2 assimilation rate per unit (one side) leaf surface area | µmol CO2 m−2 s−1 |
| a | 13C fractionation during CO2 diffusion (in air) through stomata | 4.4‰ |
| b 3 | Rubisco 13C fractionation | 29.0‰ |
| C a | CO2 mole fraction or CO2 partial pressure set in the leaf chamber | µmol mol−1; Pa |
| C c | CO2 mole fraction or CO2 partial pressure in the chloroplast | µmol mol−1; Pa |
| C i | CO2 mole fraction or CO2 partial pressure in the intercellular air space | µmol mol−1; Pa |
| C in | CO2 mole fraction entering the leaf chamber | µmol mol−1 |
| C out | CO2 mole fraction leaving the leaf chamber | µmol mol−1 |
| C s | CO2 mole fraction at the leaf surface | µmol mol−1 |
| f | Photorespiratory 13CO2 fractionation | ‰ |
| g m | Mesophyll conductance to CO2 diffusion from the substomatal cavity to the chloroplast stroma | µmol CO2 m−2 s−1 Pa−1 |
| g sC | Stomatal conductance to CO2 diffusion | µmol CO2 m−2 s−1 Pa−1 |
| LMA | Leaf dry mass per (one side) unit surface area | g m−2 |
| pCO2 | Partial pressure of CO2 | Pa |
| pO2 | Partial pressure of O2 | kPa |
| PPFD | Photosynthetic photon flux density | µmol photons m−2 s−1 |
| R d | Dark respiration rate per unit (one side) leaf surface area | µmol CO2 m−2 s-1 |
| R d(24h) | R d after 24 h dark | µmol CO2 m−2 s−1 |
| R d(30min) | R d after 30 min dark | µmol CO2 m−2 s−1 |
| R d(3h) | R d after 3 h dark | µmol CO2 m−2 s−1 |
| R d(6min) | R d after 6 min dark | µmol CO2 m−2 s−1 |
| R L | Light mitochondrial non-photorespiratoy respiration rate per unit (one side) leaf surface area | µmol CO2 m−2 s−1 |
| t | Correction factor for ternary effects | ‰ |
| t air | Air temperature | °C |
| t leaf | Leaf temperature | °C |
| VPD | Vapor pressure deficit | kPa |
| α | Moles of CO2 released in the photorespiratory pathway per mole of O2 reacting with RuBP | mol CO2 mol−1 O2 |
| Δe | 13C discrimination associated wtih mitochondrial non-photorespiratory respiration | ‰ |
| Δf | 13C discrimination associated with photorespiration | ‰ |
| Δgm | 13C discrimination associated with mesophyll conductance to CO2 diffusion | ‰ |
| Δi | 13C discrimination due to carboxylation, boundary layer and stomatal CO2 diffusion | ‰ |
| Δo | Observed (instantaneous) leaf net discrimination against 13CO2 in the light | ‰ |
| Γ | CO2 compensation point | µmol mol−1; Pa |
| Γ* | CO2 compensation point in absence of mitochondrial non-photorespiratory respiration | µmol mol−1; Pa |
| δin | δ13C of CO2 entering the leaf chamber | ‰ |
| δout | δ13C of CO2 leaving the leaf chamber | ‰ |
| δRdGch_substr | Fractional contribution of respiratory substrates from Gch carbon assimilates to δ13C of dark-evolved CO2 | ‰/‰ |
| δRdLch_substr | Fractional contribution of respiratory substrates from Lch carbon assimilates to δ13C of dark-evolved CO2 | ‰/‰ |
| δ13C | 13C composition of CO2 | ‰ |
| δ13Cdm | 13C signature of leaf dry matter | ‰ |
| δ13CGch | 13C composition of atmospheric CO2 in the growth chamber during the photoperiod | ‰ |
| δ13CLch_Ph | Representative δ13C of carbon assimilates produced in the Lch | ‰ |
| δ13CRd | δ13C of CO2 evolved by leaves in the dark | ‰ |
| δ13CRd(24h) | δ13C of CO2 evolved by leaves after 24 h dark | ‰ |
| δ13CRd(30min) | δ13C of CO2 evolved by leaves after 30 min dark | ‰ |
| δ13CRd(3h) | δ13C of CO2 evolved by leaves after 3 h dark | ‰ |
| δ13CRd(6min) | δ13C of CO2 evolved by leaves after 6 min dark | ‰ |