AciC4 {plantecophys}

C4 Photosynthesis

Description

An implementation of the A-Ci curve for C4 plants, based on von Caemmerer et al. (2000)

Usage

AciC4(
  Ci,
  PPFD = 1500,
  Tleaf = 25,
  VPMAX25 = 120,
  JMAX25 = 400,
  Vcmax = 60,
  Vpr = 80,
  alpha = 0,
  gbs = 0.003,
  O2 = 210,
  x = 0.4,
  THETA = 0.7,
  Q10 = 2.3,
  RD0 = 1,
  RTEMP = 25,
  TBELOW = 0,
  DAYRESP = 1,
  Q10F = 2,
  FRM = 0.5,
  ...
)

Arguments

Ci

Intercellular CO2 concentration (ppm)

PPFD

Photosynthetic photon flux density (mu mol m-2 s-1)

Tleaf

Leaf temperature (C)

VPMAX25

The maximum rate of PEP carboxylation (mu mol m-2 s-1)

JMAX25

Maximum electron transport rate (at 25C)

Vcmax

Maximum rate of carboxylation (mu mol m-2 s-1) (at 25C)

Vpr

PEP regeneration (mu mol m-2 s-1)

alpha

Fraction of PSII activity in the bundle sheath (-)

gbs

Bundle sheath conductance (mol m-2 s-1)

O2

Mesophyll O2 concentration

x

Partitioning factor for electron transport

THETA

Shape parameter of the non-rectangular hyperbola

Q10

T-dependence parameter for Michaelis-Menten coefficients.

RD0

Respiration at base temperature (RTEMP) (mu mol m-2 s-1)

RTEMP

Base leaf temperature for respiration (C)

TBELOW

Below this T, respiration is zero.

DAYRESP

Fraction respiration in the light vs. that measured in the dark

Q10F

T-dependence parameter of respiration

FRM

Fraction of day respiration that is mesophyll respiration (Rm)

...

Further arguments (currently ignored).

Details

Note that the temperature response parameters have been hardwired in this function, and are based on von Caemmerer (2000).

Note that it is not (yet) possible to fit this curve to observations of photosynthesis (see fitaci to fit the C3 model of photosynthesis).

Author(s)

Rhys Whitley

References

Caemmerer, S.V., 2000. Biochemical Models of Leaf Photosynthesis. Csiro Publishing.

Examples

# Simulate a C4 A-Ci curve. 
aci <- AciC4(Ci=seq(5,600, length=101))
with(aci, plot(Ci, ALEAF, type='l', ylim=c(0,max(ALEAF))))