Farquhar-Wheat User Guide#

Introduction#

This is the documentation for Farquhar-Wheat, a model of leaf photosynthesis based on Farquhar’s approach. The models computes C assimilation, stomatal conductance and organ temperature for individual shoot organs. The model also provides an option to calculate the photosynthesis at an infra-leaf scale (scene primitive).

  • Calculation of C assimilation was adapted from the Farquhar model proposed by Müller et al. (2005) and Braune et al. (2009) for wheat. The model was adapted to account for the metabolic contents provided by CN-Wheat model : (i) the actual surfacic N amount (stimulation of the assimilation rates) and (ii) the actual non-structural carbohydrate content (TPU limitation).

  • Calculation of the stomatal conductance is obtained from the BWB model

  • Leaf erergy balance is computed from the weather data inputs, C assimilation and stomatal conductance in order to simulate organ temperature.

The 3 processes described above are therefore coupled and iteratively computed until internal CO2 (Ci) and leaf temperature converge at each time step.

Inputs of Farquhar-Wheat#

  • ambient_CO2: atmospheric CO2 concentration (ppm)

  • RH : relative air humidity (decimal fraction)

  • Ur : wind speed at 2m height above canopy (m s-1)

  • height_canopy (m)

  • height : organ height (m)

  • width : lamina width or sheath diamter (m)

  • PARa : PAR absorbed (µmol m-2 s-1)

  • nitrates : amount of nitrates (µmol N)

  • amino_acids : amount of amino acids (µmol N)

  • proteins : amount of proteins (µmol N)

  • Nstruct : structural N (g)

  • sucrose : amount of sucrose (µmol C)

  • starch : amount of starch (µmol C)

  • fructan : amount of fructan (µmol C)

  • PARa_prim: PAR absorbed by the primitive (µmol m-2 s-1)

  • area_prim: area of the primitive (m²)

  • organ_label

Outputs of Farquhar-Wheat#

  • Ag: gross C assimilation (µmol m-2 s-1)

  • An : Net C assimilation (µmol m-2 s-1)

  • Rd : respiration (µmol m-2 s-1)

  • Tr : transpiration (mmol m-2 s-1)

  • Ts : organ surface temperature (°C)

  • gs : stomatal conductance for water (mol m-2 s-1)

Package architecture#

Farquhar-Wheat is a Python package which consists of several Python modules: