drcSeedGerm (version 1.0.1)

GR_T_models: Thermal-time models based on the germination rate

Description

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

Usage

GRT.GH()
GRT.GH2()
GRT.YL()
GRT.BS()
GRT.BSb()
GRT.Ex()
GRT.Exb()
GRT.M()
GRT.Mb()
GRT.RF()
GRT.RFb()
GRT.GH.fun(Temp, Tb, ThetaT)
GRT.GH2.fun(Temp, Tb, beta)
GRT.YL.fun
GRT.BS.fun(Temp, k, Tb, To, ThetaT)
GRT.BSb.fun(Temp, Tc, Tb, To, ThetaT)
GRT.Ex.fun(Temp, k, Tb, Tc, ThetaT)
GRT.Exb.fun(Temp, k, Tb, Tc, ThetaT)
GRT.M.fun(Temp, k, Tb, ThetaT)
GRT.Mb.fun(Temp, Tb, Tc, ThetaT)
GRT.RF.fun(Temp, k, Tb, Td, ThetaT)
GRT.RFb.fun(Temp, Tc, Tb, Td, ThetaT)

Value

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

Arguments

The 'GR.funName()' functions have no arguments. The general purpose 'GR.funName.fun()' functions have some of the following arguments (depending on function):

Temp

Temperature variable

k

regression parameter

beta

regression parameter

Tc

ceiling temperature

Tb

base temperature

To

optimal temperature

Td

close-to-optimal temperature (Rowse-Fintch-Savage equation)

ThetaT

Hydro-time parameter

Author

Andrea Onofri

Details

All these functions are named according to this rule: 'GRT' (Germination Rate Temperature), followd by the 'function name' (e.g., BS, RF, M, Ex, YL). The R functions 'GR.funName().fun' are generic R function, that are meant to be used for general purposes, such as plotting or predicting. The corresponding 'GR.funName()' (without the '.fun' ending) are meant to be used for fitting with the 'drm()' function, within the 'drc' package.

References

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

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)")