t50: Median germination time

In germinationmetrics: Seed Germination Indices and Curve Fitting

Median germination time

Description

Compute the median germination time (\mjseqnt_50). Median germination time is the time to reach 50% of final/maximum germination. \loadmathjax

Usage

t50(germ.counts, intervals, partial = TRUE, method = c("coolbear", "farooq"))

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.
method	The method for computing median germination time. Either "coolbear" or "farooq".

Details

With argument method specified as "coolbear", median germination time is computed according to the formula by \insertCitecoolbear_effect_1984;textualgerminationmetrics as follows.

\mjsdeqn

t_50=T_i+ \frac(\fracN+12-N_i)(T_j-T_i)N_j-N_i

Where, \mjseqnt_50 is the median germination time, \mjseqnN is the final number of germinated seeds, and \mjseqnN_i and \mjseqnN_j are the total number of seeds germinated in adjacent counts at time \mjseqnT_i and \mjseqnT_j respectively, when \mjseqnN_i < \fracN + 12 < N_j.

Similarly with argument method specified as "farooq", median germination time is computed according to the formula by by \insertCitefarooq_thermal_2005;textualgerminationmetrics as follows.

\mjsdeqn

t_50=T_i+ \frac(\fracN2-N_i)(T_j-T_i)N_j-N_i

Where, \mjseqnt_50 is the median germination time, \mjseqnN is the final number of germinated seeds, and \mjseqnN_i and \mjseqnN_j are the total number of seeds germinated in adjacent counts at time \mjseqnT_i and \mjseqnT_j respectively, when \mjseqnN_i < \fracN2 < N_j.

Value

The median germination time (\mjseqnt_50) value in the same unit of time as specified in the argument intervals.

References

\insertAllCited

See Also

MeanGermRate

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)
int <- 1:length(x)

# From partial germination counts
#----------------------------------------------------------------------------
t50(germ.counts = x, intervals = int, method = "coolbear")
t50(germ.counts = x, intervals = int, method = "farooq")

# From cumulative germination counts
#----------------------------------------------------------------------------
t50(germ.counts = y, intervals = int, partial = FALSE, method = "coolbear")
t50(germ.counts = y, intervals = int, partial = FALSE, method = "farooq")

germinationmetrics documentation built on Aug. 19, 2023, 1:07 a.m.