germinationmetrics (version 0.1.8)

t50: Median germination time

Description

Compute the median germination time (t_50). Median germination time is the time to reach 50% of final/maximum germination.

Usage

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

Value

The median germination time (t_50) value 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.

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 coolbear_effect_1984;textualgerminationmetrics as follows.

t_50=T_i+ (N+12-N_i)(T_j-T_i)N_j-N_i

Where, t_50 is the median germination time, N is the final number of germinated seeds, and N_i and N_j are the total number of seeds germinated in adjacent counts at time T_i and T_j respectively, when N_i < N + 12 < N_j.

Similarly with argument method specified as "farooq", median germination time is computed according to the formula by by farooq_thermal_2005;textualgerminationmetrics as follows.

t_50=T_i+ (N2-N_i)(T_j-T_i)N_j-N_i

Where, t_50 is the median germination time, N is the final number of germinated seeds, and N_i and N_j are the total number of seeds germinated in adjacent counts at time T_i and T_j respectively, when N_i < N2 < N_j.

References

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")