Table III. Variables and parameters in the leaf model used in this study.
| Parameter/Variable Name | Symbol | Units | Baseline Value |
| Dynamic state variables | |||
| Epidermal volume | ve | m3 m−2leaf | – |
| Guard cell volume | vg | m3 m−2leaf | – |
| Mesophyll volume | vm | m3 m−2leaf | – |
| Bundle sheath volume | vb | m3 m−2leaf | – |
| Guard cell osmotic content | ng | mol m−2leaf | – |
| Calculated state variables (i = e, g, b, m) | |||
| Turgor pressure | Pi | MPa | – |
| Osmotic pressure | πi | MPa | – |
| Water potential | ψi | MPa | – |
| Stomatal conductance to water vapor | gs | mol air m−2 s−1 | – |
| Transpiration rate | E | mmol water m−2 s−1 | – |
| Parameters | |||
| Hydraulic resistances (leaf area basis) | |||
| Leaf | rleaf | MPa m2 s mmol−1 | 0.08 |
| Soil-leaf xylem | rsx | MPa m2 s mmol−1 | 0.232 or ∞a |
| Extraxylar | rox | MPa m2 s mmol−1 | 0.032 |
| Bundle sheath-mesophyll | rbm | MPa m2 s mmol−1 | 0.0116 |
| Xylem-bundle sheath | rxb | MPa m2 s mmol−1 | 0.0116 |
| Bundle sheath-epidermis | rbe | MPa m2 s mmol−1 | 0.0232 |
| Mesophyll-epidermis | rme | MPa m2 s mmol−1 | 0.0232 |
| Epidermis-guard cell | reg | MPa m2 s mmol−1 | 0.126 |
| Values at incipient plasmolysis | |||
| Leaf symplastic volume | vtotal | m3 m−2leaf | 1.3 × 10−4 |
| Epidermal volume fraction | veo/vtotal | – | 0.31 |
| Bundle sheath volume fraction | vbo/vtotal | – | 0.062 |
| Guard cell volume fraction | vgo/vtotal | – | 0.0085 |
| Mesophyll volume fraction | vmo/vtotal | – | 0.62 |
| Epidermal osmotic pressure | πeo | MPa | 0.6 |
| Mesophyll osmotic pressure | πmo | MPa | 0.6 |
| Bundle sheath osmotic pressure | πbo | MPa | 0.6 |
| Miscellaneous | |||
| Pressure-conductance scaling factor | χ | mol air m−2 s−1 MPa−1 | 0.11 |
| Guard cell pressure-volume coefficients | c1, c2 | MPa, – | 4.1, 6.7 |
| Epidermal pressure-volume coefficient | c3, c4 | MPa | −13.4, 7.4 |
| Maximum mesophyll elastic modulus | εm | MPa | 15.3 |
| Guard cell osmoregulatory rate constant | α | mol s−1 MPa−1 | 0.005 |
| Hydroactive sensitivity [∂(πg,ss − πe)/∂Pe] | B | – | 4 |
| Fraction of evaporation from epidermis | fe | – | 0.5 |
| Fraction of evaporation from mesophyll | fm | – | 0.5 |
| Fraction of evaporation from bundle sheath | fb | – | 0 |
| Fraction of evaporation from guard cells | fg | – | 0 |
| Leaf-air water mole fraction difference | Δw | mmol water mol−1 air | 15 or 25b |
a
rsx was changed to infinity to simulate leaf excision.
b
Δw was changed from 15 to 25 mmol mol−1 to simulate reduced humidity.