Winegrape phenology and temperature relationships in the Lisbon wine region, Portugal

Aim: To investigate the characteristics, relationships and trends in the phenology of four winegrape varieties and associated temperature relationships in the Lisbon wine region (LWR), between 1990 and 2011. Methods and results: Budburst, flowering and véraison dates of red (Castelão and Aragonez, syn. Tempranillo) and white (Chasselas and Fernão Pires) varieties were taken from an experimental vineyard in the LWR. Harvest dates were determined based on a similar maturity level for all varieties. From these data, varietal characteristics, temporal trends as well as relationships between phenology and temperature were assessed through stepwise multivariate linear regressions. Flowering was the most sensitive to temperature in the preceding months (March-April). Differences/similarities between the phenological timing of the different varieties are presented. With few exceptions, no trends were found in phenophases over the 1990-2011 period, whereas several significant negative slopes were displayed for phenological intervals, suggesting a role for accumulated thermal effects in phenological timing. Strong correlations were observed between phenophases, especially between flowering and véraison. Conclusion: The study highlights the key role played by temperature on phenology, particularly during springtime. Furthermore, an increase in temperature during that period will cause an advance in the timing of the following phenological events. Given the significant trends found, phenological shifts may occur in the long term, emphasizing the need to assess varietal characteristics and responses to regional climate. Significance and impact of the study: The present work is the first attempt to systematically examine temporal trends in phenology and corresponding relationships with temperature in a Portuguese viticultural area, providing valuable information on the development and suitability of grapevine varieties, which determine viticultural practices and winegrower’s income.