Intra-varietal diversity

Examples of gains in yield obtained without losing quality traits are presented in Table 8.2. Often, gains in quality in terms of sugar, acidity and anthocyanins are also obtained, although this occurs to a lesser extent because of the lower intra-varietal diversity of those traits. 

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. 

In the vine and wine area we observe today a marked confusion about the concepts of variety, clone, cultivar... This confusion comes mainly from insufficient knowledge about the reality of intra-varietal diversity and about differences in the amount of diversity among varieties very high in old varieties and zero (or near) in new varieties. And also the lack of a clear terminology to distinguish between those different situations and communicate about than. 

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