lotus {drcte}

Germination assay with Lotus ornithopodioides

Description

Seeds of L. ornithopodioides were harvested in three stages after anthesis and the time course of their germination was evaluated in Petri dishes. The dataset is organised as required by time-to-event analyses with the drc package.

Usage

data("lotus")

Format

A data frame with 192 observations on the following 7 variables.

Stage

a character vector coding for the maturation stage

Dish

a numeric vector coding for the Petri Dish

timeBef

a numeric vector: beginning of scoring interval

timeAf

a numeric vector: end of scoring interval

count

a numeric vector: count of germinated seeds in each scoring interval

nCum

a numeric vector: cumulative count of germinated seeds

propCum

a numeric vector: cumulative proportions of germinated seeds

Details

There were 25 seeds per Petri dish. Seeds of Lotus ornithopodioides were harvested at the following stages (A) Green fleshy pods with brilliant gree sedds (27 Days After Anthesis; DAA), (B) green pergamenous pods with brown soft seeds (35 DAA) and (C) green pergamenous pods with brown seeds and moderately hard (41 DAA).

Source

Data are kindly provided by Fabio Gresta (University of Reggio Calabria, Italy).

References

Gresta, F., Avola, G., Onofri, A., Anastasi, U., Cristaudo, A., 2011. When Does Hard Coat Impose Dormancy in Legume Seeds? Lotus and Scorpiurus Case Study. Crop Science 51, 1739–1747.

Examples

data(lotus)
library(drcte)
#A constraint was put on the second curve (Stage B), in order to avoid an estimate higher than 1.
mod <- drmte(count ~ timeBef + timeAf, data=lotus, fct=LL.3(),
           curveid=Stage, upperl = c(NA, 1, NA))
summary(mod)