environmental_variance is used to calculate variance of a genotype across environments.
environmental_variance(data, trait, genotype, unit.correct = FALSE)a dataframe containing trait, genotype and environment.
colname of a column containing a numeric vector of interested trait to be analysized.
colname of a column containing a character or factor vector labeling different genotypic varieties
logical, default is FALSE, returning the stability index with unit equals to squared unit of trait; when TRUE, returning stability index with the unit as same as unit of trait.'
a data table with environmental variance
Environmental variance (Roemer, 1917) is calculated by squared and suming up all deviation from genotypic mean for each genotype. The larger the environmental variance of one genotype is, the lower the stability. Equation of environmental variance can be found in vignette file.
R昼㸶mer T (1917). “Sind die ertragdreichen Sorten ertagissicherer?” Mitteilungen der Deutschen Landwirtschaftlichen Gesellschaft, 32(1), 87--89.
data(Data)
environmental.variance <- environmental_variance(
data = Data,
trait = "Yield",
genotype = "Genotype",
unit.correct = FALSE)