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"))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.countsis considered as partial and ifFALSE, it is considered as cumulative. Default isTRUE.- method
The method for computing median germination time. Either
"coolbear"or"farooq".
Value
The median germination time (\(t_{50}\)) value in the same unit
of time as specified in the argument intervals.
Details
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}
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}
References
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.
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")
#> [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