drcSeedGerm (version 1.0.1)

hordeum: Germination of Hordeum spontaneum at different temperatures and water potentials

Description

This dataset was obtained from a germination assay with four replicated Petri dishes with 20 seeds, tested at six different water potential levels (0, -0.3, -0.6, -0.9, -1.2 and -1.5 MPa). Osmotic potentials were produced using variable amount of polyethylene glycol (PEG, molecular weight 8000) adjusted for the temperature level. Petri dishes were incubated at six constant temperature levels (8, 12, 16, 20, 24 and 28 °C), under a photoperiod of 12 h. Germinated seeds (radicle protrusion > 3 mm) were counted and removed daily for 20 days.

Usage

data("hordeum")

Format

A data frame with 3024 observations on the following 8 variables.

temp

a numeric vector: temperature level

water

a numeric vector: water potential level

Dish

a numeric vector: code for Petri dishes

timeBef

a numeric vector: beginning of scoring interval

timeAf

a numeric vector: end of scoring interval

nViable

a numeric vector: number of viable seeds at the beginning of assay, in each dish

nSeeds

a numeric vector: number of germinated seeds, between timeBef and timeAf

nCum

a numeric vector: cumulative number of germinated seeds at timeAf

Details

This dataset was analysed in the time-to-event framework in Onofri et al (2018). See Example 2.

References

Mesgaran, MB, A Onofri, HR Mashhadi, RD Cousens (2017) Water availability shifts the optimal temperatures for seed germination: A modelling approach. Ecological Modelling 351:87–95

Onofri, A, P Benincasa, MB Mesgaran, C Ritz (2018) Hydrothermal-time-to-event models for seed germination. European Journal of Agronomy 101:129–139

Examples

# Fitting a hydrotime model
data(rape)
gmod <- drmte(nSeeds ~ timeBef + timeAf + Psi,
              fct=HTnorm(), data=rape)
summary(gmod)
# \donttest{
jackGroupSE(gmod, rape, rape$Dish)
# }