Assessment of quality parameters and phytochemical content of thirty ‘Tempranillo’ grape clones for varietal improvement in two distinct sub-regions of Douro

Abstract

Genetic improvement in grapevine (Vitis vinifera L.) is performed mainly through clonal selection processes. This procedure takes advantage of the intra-varietal genetic variability existing in ancient varieties. It focuses on the selection of the most promising genotypes for certain quantitative characteristics, such as yield, soluble solids content, acidity, anthocyanins, tannins, among others, always preserving the intra-varietal diversity. In the present work, we evaluated the performance of 30 clones of 'Tempranillo' grape in two distinct trial sites at the Douro Demarcated Region (DDR), Cavernelho and São Luiz, during two consecutive years, measuring phytochemical content and oenological potential parameters.Significant differences between clones related to phytochemical content and antiradical activity, were observed in the Cavernelho and São Luiz fields, besides some oenological parameters in São Luiz. Among years, significant differences for clones, in total phenols and antiradical activity by the DPPH method were observed in both fields. In São Luiz, such differences were also found for the contents in anthocyanins, flavonoids and ortho-diphenols. Concerning the differences between samples from the same clone in the two fields, the greatest number of significant differences was observed for the anthocyanins content in 2016.A set of ten 'Tempranillo' grape clones displayed behavioral stability associated with appropriate values of soluble solids, titratable acidity and phytochemical content.