GRTPsi_models function

Hydro-Thermal-time models based on the germination rate

These models are used to describe the germination rate of a seed, depending on the environmental temperature and water potential.

GRTPsi.M()
GRTPsi.M.fun(Temp, Psi, k, Tb, ThetaHT, Psib)
GRTPsi.BS()
GRTPsi.BS.fun(Temp, Psi, k, Tb, To, ThetaHT, Psib)

Details

The 'GRT.M.fun()' is a generic R function, while the GRT.M() function is meant to be used with the 'drm()' function, within the 'drc' package.

Arguments

• Temp: Temperature variable
• Psi: Water potential variable
• Psib: Base water potential variable
• k: regression parameter
• Tb: base temperature
• To: optimal temperature
• ThetaHT: Hydro-thermal-time parameter

Returns

The 'GRT.M.fun()' functions returns a vector of responses, for given values of temperature, Tc, Tb and ThetaH. The GRT.M() function returns a list containing the nonlinear function, the self starter function, the parameter names and other items which are internally used by the 'drm()' function.

References

https://www.statforbiology.com/2023/stat_drcte_12-htt2step/

Author(s)

Andrea Onofri

Examples

library(drcte)
Tval <- c(2, 5, 10, 15, 20, 25, 30, 35, 40)
GR <- c(0, 0, 0.209, 0.435, 0.759, 0.821, 0.417, 0.145, 0)
modM <- drm(GR ~ Tval, fct = GRT.M())
plot(modM, log="", xlim = c(0, 40), ylim=c(0,1.2),
     legendPos = c(5, 1.0), xlab = "Temperature (°C)")