MeanGermTime: Germination time

Description

Compute the following metrics:

MeanGermTime: Mean germination time (T) or Mean length of incubation time edmond_effects_1958,czabator_germination_1962,mockColdToleranceAdapted1972,ellis_improved_1980,labouriau_germinacao_1983,ranal_how_2006germinationmetrics.
VarGermTime: Variance of germination time (s_T^2) labouriau_germinacao_1983,ranal_how_2006germinationmetrics.
SEGermTime: Standard error of germination time (s_T) labouriau_germinacao_1983,ranal_how_2006germinationmetrics.
CVGermTime: Coefficient of variation of the germination time (CV_T) gomes_curso_1960,ranal_how_2006germinationmetrics.

Usage

MeanGermTime(germ.counts, intervals, partial = TRUE)
VarGermTime(germ.counts, intervals, partial = TRUE)
SEGermTime(germ.counts, intervals, partial = TRUE)
CVGermTime(germ.counts, intervals, partial = TRUE)

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.

Value

For MeanGermTime, the mean germination time value in the same unit of time as specified in the argument intervals.

For VarGermTime, the variance of germination time value as time^2.

For SEGermTime, the standard error of germination time in the same unit of time specified in the argument intervals.

For CVGermTime, the value of coefficient of variation of the germination time.

Details

MeanGermTime computes the mean germination time according to the following formula edmond_effects_1958,czabator_germination_1962,smith_germinating_1964,ellis_improved_1980,labouriau_germinacao_1983,ranal_how_2006germinationmetrics.

T = _i=1^kN_iT_i_i=1^kN_i

Where, T_i is the time from the start of the experiment to the ith interval, 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), and k is the total number of time intervals.

It is the same as Sprouting Index (SI) or Emergence Index (EI) described by smith_germinating_1964;textualgerminationmetrics and mockColdToleranceAdapted1972;textualgerminationmetrics as well as Germination Resistance (GR) described by gordon_observations_1969,gordon_germination_1971;textualgerminationmetrics.

It is the inverse of mean germination rate (V).

T = 1V

It indicates the average length of time required for maximum germination of a seed lot. Lower the T, faster the sample has germinated and reflects seed vigor.

VarGermTime computes the variance of germination time according to the following formula labouriau_germinacao_1983,ranal_how_2006germinationmetrics.

s_T^2 = _i=1^kN_i(T_i-T)^2_i=1^kN_i-1

SEGermTime computes the standard error of germination time (s_T) according to the following formula labouriau_germinacao_1983,ranal_how_2006germinationmetrics.

s_T = s_T^2_i=1^kN_i

Where, 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), and k is the total number of time intervals.

It signifies the accuracy of the calculation of the mean germination time.

CVGermTime computes the coefficient of variation of germination time (CV_T) according to the following formula gomes_curso_1960,ranal_how_2006germinationmetrics.

CV_T = s_T^2T

This indicates the uniformity of germination and permits comparisons irrespective of the magnitude of mean germination time (T).

References

Examples

Run this code

# NOT RUN {
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
#----------------------------------------------------------------------------
MeanGermTime(germ.counts = x, intervals = int)
VarGermTime(germ.counts = x, intervals = int)
SEGermTime(germ.counts = x, intervals = int)
CVGermTime(germ.counts = x, intervals = int)

# From cumulative germination counts
#----------------------------------------------------------------------------
MeanGermTime(germ.counts = y, intervals = int, partial = FALSE)
VarGermTime(germ.counts = y, intervals = int, partial = FALSE)
SEGermTime(germ.counts = y, intervals = int, partial = FALSE)
CVGermTime(germ.counts = y, intervals = int, partial = FALSE)

# }

Run the code above in your browser using DataLab

Get 50% off unlimited learning