First characterization of Torrontés Riojano in la Rioja, Argentina: impact of pruning intensity on vine vigor and grape production 

Abstract

Context and purpose of the study – Pruning is one essential vineyard management activity whose main purpose is to regulate plant growth and vigour, modulating berry size, and consequently, wine quality. In Chilecito, La Rioja Province, Argentina, Torrontés Riojano stands as the only autochthonous variety for winemaking, yielding golden and aromatic berries and distinctive muscatel-tasting wines. This white cultivar, resulting from the natural cross between Moscatel de Alejandría x Criolla Chica, is traditionally trained in “parral” (horizontal trellis system), aimed to manage vigorous canopies.  This project constitutes the first study on the influence of pruning intensity on Torrontés Riojano growth habit and berry quality.

Material and methods – In Chilecito, Nonogasta and Colonias de Malligasta are two Torrontés Riojano growing sites with long productive traditions and contrasting edaphoclimatic conditions. In this context, three pruning intensities were tested in two vineyards per site, i.e. two properties in Nonogasta and two properties in Colonias de Malligasta. Treatments were: control (regular pruning), short (leaving 60% of buds with respect to control), and long (leaving 80% of buds with respect to control). Number of bunches, bunch weight, number of buds, pruning weight and yield were assessed in the 2021 and 2022 seasons. Preliminary data were analyzed by ANOVA and PCA. Berry and wine chemical and oenological analyses are still to be completed.

Results – Preliminary results from the 2021 season showed significant differences between sites and among pruning treatments for pruning weight. For number of bunches, significant differences were observed among long vs. short and long vs. control in one vineyard from Nonogasta. Average bunch weight and yield, showed no significant differences among pruning treatments. However, significant differences in yield were observed between sites. The second growing season and further analyses should confirm and complete our results. Berry and wine analyses will provide insight into metabolic, aromatic and oenological traits determining possible pruning and site effects on Torrontés Riojano. It might be possible that in Torrontés Riojano horizontally trained in “parral”, contrasting sites result in stronger effects than the tested pruning intensities.