Calculate the rate of electron transport as a function of photosynthetic photon flux density (PPFD).
J(pars, unitless = FALSE)Concatenated parameters (leaf_par, enviro_par, and constants)
Logical. Should units be set? The function is faster when FALSE, but input must be in correct units or else results will be incorrect without any warning.
Value in \(\mu\)mol/ (m^2 s) of class units
\(J\) as a function of PPFD is the solution to the quadratic expression:
$$0 = \theta_J J ^ 2 - J (J_\mathrm{max} + \phi_J PPFD) + J_\mathrm{max} \phi_J PPFD$$
| Symbol | R | Description | Units | Default |
| \(J_\mathrm{max}\) | J_max | potential electron transport (T_leaf) | \(\mu\)mol CO2 / (m\(^2\) s) | calculated |
| \(\phi_J\) | phi_J | initial slope of the response of J to PPFD | none | 0.331 |
| PPFD | PPFD | photosynthetic photon flux density | \(\mu\)mol quanta / (m^2 s) | 1500 |
| \(\theta_J\) | theta_J | curvature factor for light-response curve | none | 0.825 |
library(magrittr)
library(photosynthesis)
bake_par = make_bakepar()
constants = make_constants(use_tealeaves = FALSE)
enviro_par = make_enviropar(use_tealeaves = FALSE)
leaf_par = make_leafpar(use_tealeaves = FALSE)
enviro_par$T_air = leaf_par$T_leaf
leaf_par %<>% bake(enviro_par, bake_par, constants)
pars = c(leaf_par, enviro_par, constants)
J(pars, FALSE)
#> 181.6577 [umol/m^2/s]