Publicação
Assessing the role of climate variability on grape berry quality parameters in Portugal
| Resumo: | Climate is a strong modulator of grape berry composition. Over the last decades, model projections have shown that ongoing climate changes are to continue in the future, but the direction and degree of climate change impact on fruit composition of winegrape cultivars is puzzling. Thus, the study how climatic variables, namely temperature and precipitation, have impacted berry composition during the last decades is of utmost importance to understand future scenarios. This was the main idea of the present study that was carried out in three Portuguese wine regions – Douro, Dão and Alentejo – and targeted two varieties with a strong national importance (Touriga Nacional and Aragonez). Berry weight, titratable acidity (TA), pH, probable alcohol (PA), anthocyanins and total phenols index (TPI) data, which were collected two to three weeks after the end of the véraison until technological maturity for > 10 years, since 1991 in Douro, 2004 in Alentejo and 2008 in Dão, were collected and compiled into a database. Climatic data were obtained from automatic weather stations (owned by Sogrape Vinhos S.A.) and from an estimated climatic database (provided by UTAD) at a very-high resolution grid (<1 Km). The influence of climate variables - monthly average (TG), maximum (TX) and minimum (TN) air temperature (November-October) and precipitation totals (April to June and July to September) – on the above-mentioned berry quality parameters was explored through correlation analyses. This approach was a starting point to identify the months/periods more influential in grape berry composition, as well as the most affect vineyards. Next, different statistical approaches were carried out to explore in detail the influence of climate variables in the vineyards identified as most affected previously. Results showed that, at technological maturity, temperature was negatively correlated to berry weight, TA, anthocyanins and TPI, but was positively correlated to pH and PA. Moreover, in warmer regions the berry weight was lower, and TA, anthocyanins and TPI followed the same trend, while in colder regions, pH and PA were lower than in warmer regions. Besides, a clustering analysis showed significant temperature differences between years where the quality parameter was higher (cluster 1) and years where it was lower (cluster 2). Additionally, results showed that the temperature differences between clusters resulted from differences between warmer and colder years. Moreover, we showed that temperatures at véraison and maturation periods (namely June to August) are more influential in determining grape berry composition at maturity. Regarding precipitation, its influence was dependent on vineyard and variety. Results also suggested that the berry composition from Alentejo vines is more affected by inter-annual climate variability than Douro vines. Furthermore, Aragonez variety seems more resistant to climatic variations than Touriga Nacional. The obtained results about the role of climate variability on grape berry quality parameters presented here provided important knowledge for the development of forecasting models. These models can predict changes in berry composition in response to changing climate. |
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| Autores principais: | Costa, Cátia Andreia Leal da |
| Assunto: | Climate Variability Maturation Grape berry Quality Touriga Nacional Aragonez Clima Variabilidade Maturação Bago da uva Qualidade Ciências Naturais::Ciências Biológicas |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Climate is a strong modulator of grape berry composition. Over the last decades, model projections have shown that ongoing climate changes are to continue in the future, but the direction and degree of climate change impact on fruit composition of winegrape cultivars is puzzling. Thus, the study how climatic variables, namely temperature and precipitation, have impacted berry composition during the last decades is of utmost importance to understand future scenarios. This was the main idea of the present study that was carried out in three Portuguese wine regions – Douro, Dão and Alentejo – and targeted two varieties with a strong national importance (Touriga Nacional and Aragonez). Berry weight, titratable acidity (TA), pH, probable alcohol (PA), anthocyanins and total phenols index (TPI) data, which were collected two to three weeks after the end of the véraison until technological maturity for > 10 years, since 1991 in Douro, 2004 in Alentejo and 2008 in Dão, were collected and compiled into a database. Climatic data were obtained from automatic weather stations (owned by Sogrape Vinhos S.A.) and from an estimated climatic database (provided by UTAD) at a very-high resolution grid (<1 Km). The influence of climate variables - monthly average (TG), maximum (TX) and minimum (TN) air temperature (November-October) and precipitation totals (April to June and July to September) – on the above-mentioned berry quality parameters was explored through correlation analyses. This approach was a starting point to identify the months/periods more influential in grape berry composition, as well as the most affect vineyards. Next, different statistical approaches were carried out to explore in detail the influence of climate variables in the vineyards identified as most affected previously. Results showed that, at technological maturity, temperature was negatively correlated to berry weight, TA, anthocyanins and TPI, but was positively correlated to pH and PA. Moreover, in warmer regions the berry weight was lower, and TA, anthocyanins and TPI followed the same trend, while in colder regions, pH and PA were lower than in warmer regions. Besides, a clustering analysis showed significant temperature differences between years where the quality parameter was higher (cluster 1) and years where it was lower (cluster 2). Additionally, results showed that the temperature differences between clusters resulted from differences between warmer and colder years. Moreover, we showed that temperatures at véraison and maturation periods (namely June to August) are more influential in determining grape berry composition at maturity. Regarding precipitation, its influence was dependent on vineyard and variety. Results also suggested that the berry composition from Alentejo vines is more affected by inter-annual climate variability than Douro vines. Furthermore, Aragonez variety seems more resistant to climatic variations than Touriga Nacional. The obtained results about the role of climate variability on grape berry quality parameters presented here provided important knowledge for the development of forecasting models. These models can predict changes in berry composition in response to changing climate. |
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