# MeanGermTime: Germination time In germinationmetrics: Seed Germination Indices and Curve Fitting

## Description

Compute the following metrics:

MeanGermTime

Mean germination time (\mjseqn\overlineT) or Mean length of incubation time \insertCiteedmond_effects_1958,czabator_germination_1962,mockColdToleranceAdapted1972,ellis_improved_1980,labouriau_germinacao_1983,ranal_how_2006germinationmetrics.

VarGermTime

Variance of germination time (\mjseqns_T^2) \insertCitelabouriau_germinacao_1983,ranal_how_2006germinationmetrics.

SEGermTime

Standard error of germination time (\mjseqns_\overlineT) \insertCitelabouriau_germinacao_1983,ranal_how_2006germinationmetrics.

CVGermTime

Coefficient of variation of the germination time (\mjseqnCV_T) \insertCitegomes_curso_1960,ranal_how_2006germinationmetrics.

## Usage

 1 2 3 4 5 6 7 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.

## Details

MeanGermTime computes the mean germination time according to the following formula \insertCiteedmond_effects_1958,czabator_germination_1962,smith_germinating_1964,ellis_improved_1980,labouriau_germinacao_1983,ranal_how_2006germinationmetrics.

\mjsdeqn\overline

T = \frac\sum_i=1^kN_iT_i\sum_i=1^kN_i

Where, \mjseqnT_i is the time from the start of the experiment to the \mjseqnith interval, \mjseqnN_i is the number of seeds germinated in the \mjseqnith time interval (not the accumulated number, but the number corresponding to the \mjseqnith interval), and \mjseqnk is the total number of time intervals.

It is the same as Sprouting Index (\mjseqnSI) or Emergence Index (\mjseqnEI) described by \insertCitesmith_germinating_1964;textualgerminationmetrics and \insertCitemockColdToleranceAdapted1972;textualgerminationmetrics as well as Germination Resistance (\mjseqnGR) described by \insertCitegordon_observations_1969,gordon_germination_1971;textualgerminationmetrics.

It is the inverse of mean germination rate (\mjseqn\overlineV).

\mjsdeqn\overline

T = \frac1\overlineV

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

VarGermTime computes the variance of germination time according to the following formula \insertCitelabouriau_germinacao_1983,ranal_how_2006germinationmetrics.

\mjsdeqn

s_T^2 = \frac\sum_i=1^kN_i(T_i-\overlineT)^2\sum_i=1^kN_i-1

Where, \mjseqnT_i is the time from the start of the experiment to the \mjseqnith interval, \mjseqnN_i is the number of seeds germinated in the \mjseqnith time interval (not the accumulated number, but the number corresponding to the \mjseqnith interval), and \mjseqnk is the total number of time intervals.

SEGermTime computes the standard error of germination time (\mjseqns_\overlineT) according to the following formula \insertCitelabouriau_germinacao_1983,ranal_how_2006germinationmetrics.

\mjsdeqn

s_\overlineT = \sqrt\fracs_T^2\sum_i=1^kN_i

Where, \mjseqnN_i is the number of seeds germinated in the \mjseqnith time interval (not the accumulated number, but the number corresponding to the \mjseqnith interval), and \mjseqnk 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 (\mjseqnCV_T) according to the following formula \insertCitegomes_curso_1960,ranal_how_2006germinationmetrics.

\mjsdeqn

CV_T = \frac\sqrts_T^2\overlineT

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

## 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 \mjseqn\mathrmtime^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.

## References

\insertAllCited

MeanGermRate
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 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)