GRT_models: Thermal-time models based on the germination rate

In OnofriAndreaPG/drcSeedGerm: Utilities for Data Analyses in Seed Germination/Emergence Assays

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)

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

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.

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.

Author(s)

Andrea Onofri

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)")

OnofriAndreaPG/drcSeedGerm documentation built on Jan. 13, 2025, 5:53 a.m.