Compute the median germination time (\(t_{50}\)). Median germination time is the time to reach 50% of final/maximum germination.

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

- 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"`

.

The median germination time (\(t_{50}\)) value in the same unit
of time as specified in the argument `intervals`

.

With argument `method`

specified as `"coolbear"`

, median
germination time is computed according to the formula by
Coolbear et al. (1984)
as follows.

\[t_{50}=T_{i}+ \frac{(\frac{N+1}{2}-N_{i})(T_{j}-T_{i})}{N_{j}-N_{i}}\]

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 \(N_{i} < \frac{N + 1}{2} < N_{j}\).

Similarly with argument `method`

specified as `"farooq"`

, median
germination time is computed according to the formula by by
Farooq et al. (2005)
as follows.

\[t_{50}=T_{i}+ \frac{(\frac{N}{2}-N_{i})(T_{j}-T_{i})}{N_{j}-N_{i}}\]

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 \(N_{i} < \frac{N}{2} < N_{j}\).

Coolbear P, Francis A, Grierson D (1984).
“The effect of low temperature pre-sowing treatment on the germination performance and membrane integrity of artificially aged tomato seeds.”
*Journal of Experimental Botany*, **35**(11), 1609--1617.

Farooq M, Basra SMA, Ahmad N, Hafeez K (2005).
“Thermal hardening: A new seed vigor enhancement tool in rice.”
*Journal of Integrative Plant Biology*, **47**(2), 187--193.

```
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")
#> [1] 5.970588
t50(germ.counts = x, intervals = int, method = "farooq")
#> [1] 5.941176
# From cumulative germination counts
#----------------------------------------------------------------------------
t50(germ.counts = y, intervals = int, partial = FALSE, method = "coolbear")
#> [1] 5.970588
t50(germ.counts = y, intervals = int, partial = FALSE, method = "farooq")
#> [1] 5.941176
```