Estudo da fertilidade dos gomos em três castas brancas da Região Demarcada dos Vinhos Verdes
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2022-03-18
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A quantidade e qualidade de uvas são critérios de elevada importância para o setor vitivinícola, mas altamente variáveis de ano para ano. Neste âmbito, as condições ambientais e endógenas, desde a indução e diferenciação floral até à maturação têm um papel preponderante em todo processo reprodutivo e produtivo a ponto de comprometer a colheita. A fertilidade e a incidência de necroses nos gomos, associadas ao número de cachos por gomo e ao número e peso dos bagos, são parâmetros que contribuem para esta variação anual da produção. Conhecer estes fatores são importantes não só para a compreensão da variabilidade interanual como podem contribuir para uma melhoria da produção. Neste sentido, definiu-se como objetivo geral desta tese de doutoramento avaliar a fertilidade dos gomos antes do abrolhamento por diferentes técnicas de análise bem como conhecer as características morfológicas e biométricas de inflorescências e cachos ao longo do ciclo, a fim de encontrar as relações alométricas mais significativas no sentido de contribuir para uma estimativa mais robusta e focada nas características individuais de cada casta. Os estudos realizados incidiram sobre três castas brancas Alvarinho, Fernão-Pires e Loureiro, pelo potencial agronómico, e potencial enológicos para a produção de vinho Verde na Região Demarcada do Vinho Verde (RDVV). O ensaio foi conduzido em duas importantes parcelas da RDVV, localizadas em Celorico de Basto (Sub-região de Basto) e Penafiel (Sub-região do Sousa), ambas propriedade da empresa Aveleda SA. A fertilidade dos gomos foi avaliada por meio de análise anatómica ou através da forçagem do abrolhamento dos gomos dormentes, sendo cada um dos métodos caracterizado por diferentes equipamentos, reagentes e informações obtidas. Todas elas mostram que o número de inflorescências é diferente entre castas e ciclos produtivos (2016/2017 e 2017/2018). Assim, perante os resultados obtidos, verificamos que a casta Fernão-Pires foi a que apresentou maior fertilidade dos seus gomos, seguindo-se a casta Loureiro e por fim a Alvarinho, com menor número de inflorescências por gomo abrolhado. Embora a percentagem de incidência de necroses seja variável entre castas, não foram observadas diferenças estatisticamente significativas nos dois anos, com percentagens inferiores a 30%. No entanto, x foram evidentes as diferenças entre castas e anos quanto à concentração de açúcares solúveis e amido presentes nas zonas do nó e entrenó dos sarmentos. Observaram-se alterações bioquímicas entre a dormência e o abrolhamento dos gomos, com o conteúdo de malondialdeído (MDA) e prolina endógena a serem significativamente mais elevados no abrolhamento. Em termos de atividade das enzimas antioxidantes, observou-se um efeito da casta e do estágio fenológico, com a Ascorbato-Peroxidase (APX), Peroxidase (POX) e Superóxido Dismutase (SOD) a apresentarem maior atividade na dormência e menor no abrolhamento, contrariamente à Catalase (CAT) e Glutationa-s-transferase (GST), que foi significativamente maior no abrolhamento. Todas as castas apresentaram um aumento da concentração de açúcares solúveis totais e diminuição do amido nos gomos no abrolhamento. Quanto aos parâmetros morfológicos e biométricos observaram-se diferenças entre castas em relação ao peso, às dimensões das ráquis, número de botões florais e de bagos, desde o estado de inflorescência e até à maturação do cacho. Ainda que os valores sejam igualmente variáveis entre anos, a cada ciclo observou-se um comportamento padrão de cada uma das castas nos três estados fenológico (antes da floração, pintor e maturação). A casta Loureiro foi a que apresentou inflorescências e cachos mais pesados, mais compridos e com maior número de botões florais e bagos, assim como maior percentagem de vingamento, nos dois anos, o que contribuiu para o maior número de bagos. A casta Alvarinho caracteriza-se por inflorescências e cachos com menor dimensão e consequentemente menor número de botões florais. A obtenção de relações alométricas significativas entre o peso, as principais dimensões primárias da ráquis, entre dimensões secundárias na casta Alvarinho e Fernão-Pires indicam a possibilidade de utilização destas variáveis para uma estimativa de colheita mais robusta com base nas características das inflorescencias e cachos em cada casta. Considerando a variação da fertilidade, as mudanças bioquímicas que ocorrem nos gomos entre estados fenológicos, assim como as diferenças morfológicas e biométricas entre castas e anos, os resultados obtidos reforçam a importância do estudo destas variáveis para melhor perceber e ajustar o processo produtivo.
The quantity and quality are highly important criteria for the wine sector but are extremely variable from year to year. However, environmental, and endogenous conditions, from floral induction and differentiation to harvest, play a preponderant role in the entire reproductive and productive process and consequently comprise yield. Fruitfulness and incidence of necrotic buds, associated with the bunches number per bud, and number and weight of berries per bunch are parameters that contribute to these seasonal yield variations. Knowing how all these factors interact with each other, as well the determinant stages for yield are important not only for understanding the seasonal variation but also contributing to the improvement of the yield estimation models that one intends to make. Knowing all these factors, as well as all the determining stages of production, are important not only for understanding the seasonal yield variation but can also contribute to an improvement for vineyard yield estimation models. The present PhD thesis overall aims to provide practical information about bud fruitfulness during the successive growing season, as well as investigate allometric relations among morphological and biometric characteristics. The study focused on three Vitis vinifera L. white varieties, Alvarinho, Fernão-Pires, and Loureiro, which have phenological and oenological characteristics, the highly productive and commercial potential to produce Vinho Verde in the Vinho Verde Demarcated Region (VVDR). The trial was conducted in two important vineyards of the VVDR, located in Celorico de Basto (Sub-region of Basto) and Penafiel (Subregion of Sousa), both owned by Aveleda S.A Company. Bud fruitfulness was assessed by bud analysis and by forced bud growth under controlled environmental conditions, each of the techniques being characterized by different equipment, reagents and type of information obtained. Thus, all techniques showed that fruitfulness values varied greatly among the varieties and years analyzed. Fernão-Pires variety showed the highest bud fruitfulness, followed by the Loureiro, and finally Alvarinho with the lowest number of inflorescences per bud. No statistically significant differences were observed between varieties for bud necrosis percentage, with values less than 30% in both years. Furthermore, statistically, differences were observed between varieties and years regarding total soluble sugars and starch content present in the node and internode of wood canes. Malondialdehyde (MDA) and endogenous proline content were significantly higher in budburst. In terms of antioxidant enzymes activity, an effect of variety and the phenological stage are observed. With this respect, Ascorbate-Peroxidase (APX), Peroxidase (POX) and Superoxide Dismutase (SOD) showed higher activity in dormancy and lower in budburst, in opposition Catalase (CAT) and Glutathione-stransferase (GST) were higher in budburst. All varieties showed an increase in total soluble sugars and consequently a decrease in starch in the buds during budburst. Based on morphological and biometric parameters, we observed significant differences between grapevines as to brunch weight, rachis dimensions, flowers, and berries number per inflorescence /bunches. Although the values are equally variable between years, at each cycle there is the standard behaviour of each of the varieties in the three phenological states. With regard, Loureiro showed longer, heavier and more number of flowers and berries per inflorescences and bunch, as wells as the highest fruit set, in both years. In turn, Alvarinho was characterized by smaller inflorescences and bunch size, and consequently a lower number of flowers and berries. The allometric relationships between weight, as the main primary dimensions of the variety, between secondary dimensions in the Alvarinho and Fernão-Pires varieties indicate the possibility of using these variables for a more robust yield estimation based on the characteristics of each variety. Considering the variation in the bud fruitfulness, biochemical changes in buds that occur in the between phenological states, as well as the biometric and morphological differences between varieties and years, the results obtained reinforce the importance of studying these variables to better understand and adjust the production process.
The quantity and quality are highly important criteria for the wine sector but are extremely variable from year to year. However, environmental, and endogenous conditions, from floral induction and differentiation to harvest, play a preponderant role in the entire reproductive and productive process and consequently comprise yield. Fruitfulness and incidence of necrotic buds, associated with the bunches number per bud, and number and weight of berries per bunch are parameters that contribute to these seasonal yield variations. Knowing how all these factors interact with each other, as well the determinant stages for yield are important not only for understanding the seasonal variation but also contributing to the improvement of the yield estimation models that one intends to make. Knowing all these factors, as well as all the determining stages of production, are important not only for understanding the seasonal yield variation but can also contribute to an improvement for vineyard yield estimation models. The present PhD thesis overall aims to provide practical information about bud fruitfulness during the successive growing season, as well as investigate allometric relations among morphological and biometric characteristics. The study focused on three Vitis vinifera L. white varieties, Alvarinho, Fernão-Pires, and Loureiro, which have phenological and oenological characteristics, the highly productive and commercial potential to produce Vinho Verde in the Vinho Verde Demarcated Region (VVDR). The trial was conducted in two important vineyards of the VVDR, located in Celorico de Basto (Sub-region of Basto) and Penafiel (Subregion of Sousa), both owned by Aveleda S.A Company. Bud fruitfulness was assessed by bud analysis and by forced bud growth under controlled environmental conditions, each of the techniques being characterized by different equipment, reagents and type of information obtained. Thus, all techniques showed that fruitfulness values varied greatly among the varieties and years analyzed. Fernão-Pires variety showed the highest bud fruitfulness, followed by the Loureiro, and finally Alvarinho with the lowest number of inflorescences per bud. No statistically significant differences were observed between varieties for bud necrosis percentage, with values less than 30% in both years. Furthermore, statistically, differences were observed between varieties and years regarding total soluble sugars and starch content present in the node and internode of wood canes. Malondialdehyde (MDA) and endogenous proline content were significantly higher in budburst. In terms of antioxidant enzymes activity, an effect of variety and the phenological stage are observed. With this respect, Ascorbate-Peroxidase (APX), Peroxidase (POX) and Superoxide Dismutase (SOD) showed higher activity in dormancy and lower in budburst, in opposition Catalase (CAT) and Glutathione-stransferase (GST) were higher in budburst. All varieties showed an increase in total soluble sugars and consequently a decrease in starch in the buds during budburst. Based on morphological and biometric parameters, we observed significant differences between grapevines as to brunch weight, rachis dimensions, flowers, and berries number per inflorescence /bunches. Although the values are equally variable between years, at each cycle there is the standard behaviour of each of the varieties in the three phenological states. With regard, Loureiro showed longer, heavier and more number of flowers and berries per inflorescences and bunch, as wells as the highest fruit set, in both years. In turn, Alvarinho was characterized by smaller inflorescences and bunch size, and consequently a lower number of flowers and berries. The allometric relationships between weight, as the main primary dimensions of the variety, between secondary dimensions in the Alvarinho and Fernão-Pires varieties indicate the possibility of using these variables for a more robust yield estimation based on the characteristics of each variety. Considering the variation in the bud fruitfulness, biochemical changes in buds that occur in the between phenological states, as well as the biometric and morphological differences between varieties and years, the results obtained reinforce the importance of studying these variables to better understand and adjust the production process.
Descrição
Tese de Doutoramento submetida para a obtenção do grau de Doutor em Ciências Agronómicas e Florestais, pela Universidade de Trás-os-Montes e Alto Douro
Palavras-chave
Vitis vinifera L. , inflorescências e cachos