Effect of climate and soil on phenology and ripening of Vitis vinifera cv Touriga acional in the Dão region

Abstract

Context and purpose of the study – “Terroir” has been acknowledged as an important factor in wine quality and style. It can be defined as an interaction between climate, soil, vine (cultivar, rootstock) and human factors such as viticultural and enological techniques. Soil and climate are the two components of the “Terroir” with an important role on the vine development and berries ripening. The present study is focused on the effects of the weather conditions and the soil characteristics on the phenological and berries ripening dynamics of the “Touriga Nacional” in Dão region.

Material and methods – This assay was carried out during 2017 and 2018 in four commercial vineyards at different places at Dão Region, centre of Portugal, with red grapevine variety Touriga Nacional. For each field were defined 3 plots were defined, and the observations were carried out in 10 plants per plot. Meteorological data was recorded at automatic stations localized next each vineyard. For the soil characterization, soil samples were taken in three layers until the 200 cm depths. Between budburst and veraison, the phenological stages were monitored using the E-L modify scale. During the ripening period, weekly, samples with 200 berries per plot were taken, determined their weights and juice volumes, and analysed their sugar contents, total acidity and pH. The anthocyanins accumulation was indirectly monitored, using the fluorescence optical sensor Multiplex, on six clusters per plot.

Results – The results showed similar characteristics of soils at the different vineyard, but different weather condition between places and years. The lag of the chronological evolution of the phenology and ripening between places and years was mainly due to the different thermal conditions of each place in each year.