germinationmetrics (version 0.1.9)

EmergenceRateIndex: Emergence Rate Index or Germination Rate Index

Description

Compute the Emergence rate index or Germination rate index according to

• shmueli_emergence_1971;textualgerminationmetrics and it's modification by de_santana_alise_2004;textualgerminationmetrics ranal_how_2006germinationmetrics;

• bilbro_soil_1982;textualgerminationmetrics; and

• fakorede_relation_1980;textualgerminationmetrics, fakorede_variability_1981;textualgerminationmetrics, and fakorede_heterotic_1983;textualgerminationmetrics.

Usage

EmergenceRateIndex(
  germ.counts,
  intervals,
  partial = TRUE,
  total.seeds = NULL,
  method = c("shmueligoldberg", "sgsantanaranal", "bilbrowanjura", "fakorede")
)

Value

The value of the Emergence rate index with the units according to

method as follows.

shmueligoldberg

count

sgsantanaranal

no \, unit

bilbrowanjura

count \, time^-1

fakorede

time \, count^-1

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.

total.seeds

Total number of seeds.

method

The method to be used. Either "shmueligoldberg", "sgsantanaranal", "bilbrowanjura" or "fakorede". Default is "shmueligoldberg" (see Details).

Details

Several germination indices are referred to as Emergence rate Index (ERI).

shmueli_emergence_1971;textualgerminationmetrics

With argument method specified as "shmueligoldberg" ERI is estimated as follows.

ERI = _i=i_0^k-1N_i(k-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), i_0 is the time interval when emergence/germination started, and k is the total number of time intervals.

A modification for the same was suggested by de_santana_alise_2004;textualgerminationmetrics ranal_how_2006germinationmetrics and is estimated by dividing Emergence rate index (ERI) by total number of emerged seedlings (or germinated seeds) as follows with argument method specified as "sgsantanaranal").

ERI_mod = _i=i_0^k-1N_i(k-i)N_g = ERIN_g

Where, N_g is the total number of germinated seeds at the end of the test, 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), i_0 is the time interval when emergence/germination started, and k is the total number of time intervals.

bilbro_soil_1982;textualgerminationmetrics

With argument method specified as "bilbrowanjura" ERI is the estimated as follows.

ERI = _i=1^kN_iT = N_gT

Where, N_g is the total number of germinated seeds at the end of the test, 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 T is the mean germination time or mean emergence time.

fakorede_relation_1980,fakorede_variability_1981,fakorede_heterotic_1983;textualgerminationmetrics

With argument method specified as "fakorede" ERI is the estimated as follows.

ERI = TFGP/100

Where, T is the Mean germination time and FGP is the final germination time.

Others

Apart from the above the above, the name Emergence rate index (ERI) has also been used to for the mathematical expressions for Speed of germination (GermSpeed) allan_seedling_1962,erbach_tillage_1982germinationmetrics, Timson's index (TimsonsIndex) chaudhary_effect_1970germinationmetrics, and George's index (GermRateGeorge) chopra_effect_1980germinationmetrics.

References

See Also

GermSpeed, TimsonsIndex, GermRateGeorge

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
#----------------------------------------------------------------------------
EmergenceRateIndex(germ.counts = x, intervals = int, total.seeds = 50)
EmergenceRateIndex(germ.counts = x, intervals = int, total.seeds = 50,
                   method = "shmueligoldberg")
EmergenceRateIndex(germ.counts = x, intervals = int, total.seeds = 50,
                   method = "sgsantanaranal")
EmergenceRateIndex(germ.counts = x, intervals = int, total.seeds = 50,
                   method = "bilbrowanjura")
EmergenceRateIndex(germ.counts = x, intervals = int, total.seeds = 50,
                   method = "fakorede")

# From cumulative germination counts
#----------------------------------------------------------------------------
EmergenceRateIndex(germ.counts = y, intervals = int, total.seeds = 50,
                   partial = FALSE)
EmergenceRateIndex(germ.counts = y, intervals = int, total.seeds = 50,
                   partial = FALSE,
                   method = "shmueligoldberg")
EmergenceRateIndex(germ.counts = y, intervals = int, total.seeds = 50,
                   partial = FALSE,
                   method = "sgsantanaranal")
EmergenceRateIndex(germ.counts = y, intervals = int, total.seeds = 50,
                   partial = FALSE,
                   method = "bilbrowanjura")
EmergenceRateIndex(germ.counts = y, intervals = int, total.seeds = 50,
                   partial = FALSE,
                   method = "fakorede")