calc_gammastar | R Documentation |
Calculates the photorespiratory CO2 compensation point in absence of dark respiration, Γ* (Farquhar, 1980).
calc_gammastar(tc, patm)
tc |
Temperature, relevant for photosynthesis (degrees Celsius) |
patm |
Atmospheric pressure (Pa) |
The temperature and pressure-dependent photorespiratory compensation point in absence of dark respiration Γ* (T,p) is calculated from its value at standard temperature (T0 = 25 deg C) and atmospheric pressure (p0 = 101325 Pa), referred to as Γ*0, quantified by Bernacchi et al. (2001) to 4.332 Pa (their value in molar concentration units is multiplied here with 101325 Pa to yield 4.332 Pa). Γ*0 is modified by temperature following an Arrhenius-type temperature response function f(T, Δ Ha) (implemented by ftemp_arrh) with activation energy Δ Ha = 37830 J mol-1 and is corrected for atmospheric pressure p(z) (see calc_patm) at elevation z.
Γ* = Γ*0 f(T, Δ Ha) p(z) / p_0
p(z) is given by argument patm
.
A numeric value for Γ* (in Pa)
Farquhar, G. D., von Caemmerer, S., and Berry, J. A.: A biochemical model of photosynthetic CO2 assimilation in leaves of C 3 species, Planta, 149, 78–90, 1980.
Bernacchi, C. J., Singsaas, E. L., Pimentel, C., Portis, A. R. J., and Long, S. P.:Improved temperature response functions for models of Rubisco-limited photosyn-thesis, Plant, Cell and Environment, 24, 253–259, 2001
print("CO2 compensation point at 20 degrees Celsius and standard atmosphere (in Pa):") print(calc_gammastar(20, 101325))
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