Principal component analysis -based theory

The main techniqnes nsed to study GxE interaction generally include the classical analysis of variance with interaction, the coefficient of variation of different traits in distinct experimental enviromnents, regression analyses using environmental indices (Finlay and Wilkinson, 1963), non-parametric methods based on genotype ranking in different environments (Hiihn, 1990a,b), methods based on mixed-model theories (Smith et al., 2005) and principal components analyses (Kempton, 1984 Gauch, 2006). 

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