GermValue: Peak value and germination value

Description Usage Arguments Details Value References Examples

View source: R/GermValue.R

Description

Compute the Peak value (\mjseqnPV) or Emergence Energy (\mjseqnEE) \insertCiteczabator_germination_1962,bonner_ideal_1967germinationmetrics and Germination value (\mjseqnGV) \insertCiteczabator_germination_1962,djavanshir_germination_1976,brown_representing_1988germinationmetrics. \loadmathjax

Usage

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PeakValue(germ.counts, intervals, total.seeds, partial = TRUE)

GermValue(
  germ.counts,
  intervals,
  total.seeds,
  partial = TRUE,
  method = c("czabator", "dp"),
  from.onset = TRUE,
  k = 10
)

Arguments

germ.counts

Germination counts at each time interval. Can be partial or cumulative as specified in the argument partial.

intervals

The time intervals.

total.seeds

Total number of seeds.

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 germination value. Either "czabator" or "dp".

from.onset

logical. If TRUE, duration is considered only from the onset of germination. If FALSE, full duration of germination test is considered. Default is TRUE.

k

Constant (See Details). Default is 10.

Details

Peak value (\mjseqnPV) is the maximum quotient obtained by dividing successive cumulative germination values by the relevant incubation time \insertCiteczabator_germination_1962germinationmetrics.

\mjsdeqn

PV = \max\left ( \fracG_1T_1,\fracG_2T_2,\cdots \fracG_kT_k \right )

Where, \mjseqnT_i is the time from the start of the experiment to the \mjseqnith interval, \mjseqnG_i is the cumulative germination percentage in the \mjseqnith time interval, and \mjseqnk is the total number of time intervals.

It represents the mean daily germination of the most vigorous component of the seed lot, and is a mathematical expression of the break, or shoulder, of a typical sigmoid germination curve \insertCitedjavanshir_germination_1976germinationmetrics. It is the accumulated number of seeds germinated at the point on the germination curve at which the rate of germination starts to decrease. It is also described as Emergence energy \insertCitebonner_ideal_1967germinationmetrics.

For daily germination counts, germination value (\mjseqnGV) is computed as follows \insertCiteczabator_germination_1962germinationmetrics.

\mjsdeqn

GV = PV \times MDG

Where, \mjseqnPV is the peak value, and \mjseqnMDG is the mean daily germination percentage from the onset of germination.

Germination value (\mjseqnGV) can also be computed for other time intervals of successive germination counts, by replacing \mjseqnMDG with the mean germination percentage per unit time (\mjseqn\overlineGP).

A new estimation of germination value was given by \insertCitedjavanshir_germination_1976;textualgerminationmetrics as follows.

\mjsdeqn

GV = \frac\sum DGSN \times GP \times c

Where, \mjseqnDGS is the daily germination speed computed by dividing cumulative germination percentage by the number of days since the onset of germination, \mjseqnN is the frequency or number of DGS calculated during the test, \mjseqnGP is the germination percentage expressed over 100, and \mjseqnc is a constant. The value of \mjseqnc is decided on the basis of average daily speed of germination (\mjseqn\frac\sum DGSN). If it is less than 10, then \mjseqnc value of 10 can be used and if it is more than 10, then value of 7 or 8 can be used for \mjseqnc.

For both methods of computing \mjseqnGV, only the duration from the onset of germination is considered by default. Alternatively, modified \mjseqnGV (\mjseqnGV_mod), where the entire duration from the beginning of the test is considered can be obtained by using the argument from.onset = FALSE \insertCitebrown_representing_1988germinationmetrics.

Value

A list with the following components:

Germination Value

The germination value

Calculations

The data frame of calculations.

testend

The end of test value (Only for method dp).

References

\insertAllCited

Examples

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x <- c(0, 0, 34, 40, 21, 10, 4, 5, 3, 5, 8, 7, 7, 6, 6, 4, 0, 2, 0, 2)
y <- c(0, 0, 34, 74, 95, 105, 109, 114, 117, 122, 130, 137, 144, 150,
      156, 160, 160, 162, 162, 164)
int <- 1:length(x)
total.seeds = 200

# From partial germination counts
#----------------------------------------------------------------------------
PeakValue(germ.counts = x, intervals = int, total.seeds = 200)
GermValue(germ.counts = x, intervals = int, total.seeds = 200,
          method = "czabator")
GermValue(germ.counts = x, intervals = int, total.seeds = 200,
          method = "dp", k = 10)
GermValue(germ.counts = x, intervals = int, total.seeds = 200,
          method = "czabator", from.onset = FALSE)
GermValue(germ.counts = x, intervals = int, total.seeds = 200,
          method = "dp", k = 10, from.onset = FALSE)

# From cumulative germination counts
#----------------------------------------------------------------------------
PeakValue(germ.counts = y, interval = int, total.seeds = 200,
          partial = FALSE)
GermValue(germ.counts = y, intervals = int, total.seeds = 200,
          partial = FALSE, method = "czabator")
GermValue(germ.counts = y, intervals = int, total.seeds = 200,
          partial = FALSE, method = "dp", k = 10)
GermValue(germ.counts = y, intervals = int, total.seeds = 200,
          partial = FALSE, method = "czabator", from.onset = FALSE)
GermValue(germ.counts = y, intervals = int, total.seeds = 200,
          partial = FALSE, method = "dp", k = 10, from.onset = FALSE)

germinationmetrics documentation built on Feb. 17, 2021, 5:09 p.m.