germinationmetrics (version 0.1.8)

FirstGermTime: Time for first, last and peak germination

Description

Compute the following metrics:

FirstGermTime

Time of first germination or Germination time lag (t_0) edwards_temperature_1932,czabator_germination_1962,goloff_germination_1975,labouriau_germinacao_1983,ranal_effects_1999,quintanilla_effect_2000germinationmetrics.

LastGermTime

Time of last germination (t_g) edwards_temperature_1932,labouriau_germinacao_1983,ranal_how_2006germinationmetrics.

TimeSpreadGerm

Time spread of germination al-mudaris_notes_1998,kader_comparison_2005germinationmetrics or Germination distribution schrader_seed_2000germinationmetrics.

PeakGermTime

Peak time of germination or Modal time of germination (t_peak) ranal_how_2006germinationmetrics.

Usage

FirstGermTime(germ.counts, intervals, partial = TRUE)
LastGermTime(germ.counts, intervals, partial = TRUE)
PeakGermTime(germ.counts, intervals, partial = TRUE)
TimeSpreadGerm(germ.counts, intervals, partial = TRUE)

Value

For FirstGermTime, the time of first germination value in the same unit of time as specified in the argument intervals.

For LastGermTime, the time of last germination value in the same unit of time as specified in the argument intervals.

For TimeSpreadGerm, the time spread of germination value in the same unit of time as specified in the argument intervals.

For PeakGermTime, the time(s) of peak germination value(s) as a numeric vector in the same unit of time as specified in the argument

intervals.

Arguments

germ.counts

Germination counts at each time interval. Can be partial or cumulative as specified in the argument partial.

intervals

The time intervals.

partial

logical. If TRUE, germ.counts is considered as partial and if FALSE, it is considered as cumulative. Default is TRUE.

Details

Time of first germination indicates time of germination of the faster seeds in a seedlot.

Lower value of time of first germination indicates faster initiation of germination and lower value of time of last germination indicates faster termination of germination.

t_0 = T_i : N_i 0

t_g = T_i : N_i 0

Where, T_i is the time from the start of the experiment to the ith interval and N_i is the number of seeds germinated in the ith time interval (not the accumulated number, but the number corresponding to the ith interval).

Time spread of germination (t_g-t_0) indicates difference between faster and slower germinating members of a sample.

Peak time of germination is the time in which highest frequency of germinated seeds are observed. Multiple peak times of germination are possible and if detected are indicated by a warning message.

t_peak = T_i : N_i = N_max

Where, N_max is the maximum number of seeds germinated per interval.

References

Examples

x <- c(0, 0, 0, 0, 4, 17, 10, 7, 1, 0, 1, 0, 0, 0)
y <- c(0, 0, 0, 0, 4, 21, 31, 38, 39, 39, 40, 40, 40, 40)
z <- c(0, 0, 0, 0, 11, 11, 9, 7, 1, 0, 1, 0, 0, 0)
int <- 1:length(x)

# From partial germination counts
#----------------------------------------------------------------------------
FirstGermTime(germ.counts = x, intervals = int)
LastGermTime(germ.counts = x, intervals = int)
TimeSpreadGerm(germ.counts = x, intervals = int)
PeakGermTime(germ.counts = x, intervals = int)
# For multiple peak germination times
PeakGermTime(germ.counts = z, intervals = int)

# From cumulative germination counts
#----------------------------------------------------------------------------
FirstGermTime(germ.counts = y, intervals = int, partial = FALSE)
LastGermTime(germ.counts = y, intervals = int, partial = FALSE)
TimeSpreadGerm(germ.counts = y, intervals = int, partial = FALSE)
PeakGermTime(germ.counts = y, intervals = int, partial = FALSE)
# For multiple peak germination time
PeakGermTime(germ.counts = cumsum(z), intervals = int, partial = FALSE)