CUGerm {germinationmetrics}

Coefficient of uniformity of germination

Description

Compute the Coefficient of uniformity of germination (CUG).

Usage

CUGerm(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

CUG is computed as follows (Heydecker 1972; Bewley and Black 1994).

\[CUG = \frac{\sum_{i=1}^{k}N_{i}}{\sum_{i=1}^{k}(\overline{T}-T_{i})^{2}N_{i}}\]

Where, \(\overline{T}\) is the the mean germination time, \(T_{i}\) is the time from the start of the experiment to the \(i\)th interval, \(N_{i}\) is the number of seeds germinated in the \(i\)th time interval (not the accumulated number, but the number corresponding to the \(i\)th interval), and \(k\) is the total number of time intervals.

Value

The value of the coefficient of uniformity of germination as \(\mathrm{time^{-2}}\).

References

Bewley JD, Black M (1994). Physiology of Development and Germination. Plenum Publishing Corporation, New York, USA. ISBN 0-306-44748-7, tex.ids= bewley_ seeds:_1994, bewley_ seeds:_1994-1, bewley_ seeds:_1994-2 googlebooksid: W6EbrewcpDwC.

Heydecker W (1972). Seed Ecology. Proceedings of the Nineteenth Easter School in Agricultural Science, University of Nottingham, 1972. Pennsylvania State University Press, University Park, USA.

See Also

GermSynchrony, MeanGermTime

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
#----------------------------------------------------------------------------
CUGerm(germ.counts = x, intervals = int)

# From cumulative germination counts
#----------------------------------------------------------------------------
CUGerm(germ.counts = y, intervals = int, partial = FALSE)