Coefficient of genotypic variation

Estimates for the coefficient of genotypic variation and broad-sense heritability are then obtained. All analyses are guided by the objectives described in the following subsections. 

As previously mentioned, quantifying intra-varietal diversity is important because genetic diversity represents the raw material for selection and for conservation, and quantification of this diversity increases our knowledge of the origin and expansion of cultivars. Quantification of diversity can be performed for any quantitative nait. Yield is a suitable trait for this purpose because it is easy to evaluate and exhibits high relative diversity. There are various metrics to quantify diversity, and the coefficient of genotypic variation is a particularly objective one. As an example, the intra-varietal diversity of 42 varieties is shown in Table 8.3 expressed by the coefficient of genotypic variation of yield. 

Table 8.3 Intra-varietal genetic variability (CVg) of the yield expressed by the coefficient of genotypic variation evaluated in experimental populations of clones for 42 Portuguese grapevine varieties...

Table 8.4 Estimates of the overall mean (Ji), genotypic variance ( ) and coefficient of genotypic variation (CVg) of the yield (kg/plant) for variety Grenache, obtained with the fitting of two mixed models...

Coefficients of Variation and Phenotypic and Genotypic Variance, Heritability, and Genetic Gain Expected during Selection for 15 Traits in a Clonal Population... 

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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