Biologia das culturas mediterrânicas num contexto de alterações climáticas: estudo de caso em Vitis vinifera L.
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2017-11-23
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Decorrente da mudança climática global, é cada vez mais consensual que num futuro
próximo o clima das mais importantes regiões vitícolas do mundo será cada vez mais quente
e seco, o que poderá comprometer a viabilidade económica das vinhas (Vitis vinifera L.).
A vinha é tradicionalmente uma cultura de sequeiro, especialmente na Europa e
espalha-se por vastas regiões semiáridas, sendo exploradas fundamentalmente pela
indústria do vinho. A qualidade da produção e das uvas depende fortemente da capacidade
de adaptação da vinha à seca. Compreender e controlar as relações hídricas da planta e a
sua resistência ao stresse hídrico por meios fisiológicos e moleculares pode melhorar
significativamente a produtividade da planta e a qualidade ambiental. Sem desmerecer a
utilidade que a rega pode ter no crescimento e desenvolvimento das culturas é crucial a
implementação de medidas de mitigação alternativas/complementares, não só em termos
económicos mas também em termos de qualidade das produções e de sustentabilidade
ambiental. Entre essas medidas, tem havido um grande esforço por parte da comunidade
científica para estudar o efeito da aplicação de substâncias, na otimização do microclima
luminoso, nas relações hídricas das folhas, na produção, nas uvas e na qualidade do vinho.
O ensaio foi realizado entre 2011 e 2012 com videiras envasadas, localizadas em Vila
Real (Campus da Universidade de Trás-os-Montes e Alto Douro, 41°17’N, 7°44’W, 470 m de
altitude, na sub-região Baixo Corgo da Região Demarcada do Douro, Norte de Portugal). As
videiras do mesmo clone da espécie Vitis vinifera L. cultivar (cv) Touriga Nacional foram
instaladas em vasos, num total de 100 videiras em 2011 e 60 em 2012. As videiras foram
sujeitas a dois tipos de rega: I-capacidade de campo (CH) e II-1/3 da capacidade de campo
(SH). O sistema de irrigação foi instalado em todos os vasos e controlado. Os tratamentos
foram aplicados nas folhas, por pulverização e foram o ácido salicílico, calda bordalesa,
caulino em duas concentrações (3% e 6%) e silício no primeiro ano (2011). No segundo ano
(2012) foram aplicados o caulino a 5% e calda bordalesa. Em ambos os anos existe um
grupo controlo para cada condição hídrica. Cada tratamento era composto por um grupo de
10 plantas.
O ácido salicílico provou ter um efeito benéfico em muitos dos parâmetros, incluindo a
melhoria das trocas gasosas, a eficiência fotoquímica do PSII, o aumento da concentração
dos pigmentos fotossintéticos e açúcares solúveis e a redução da concentração de
substâncias reativas ao ácido tiobarbitúrico (TBARS). Registou-se um aumento no conteúdo
relativo de água (RWC) e massa por unidade de área foliar (LMA), no final do ciclo
vegetativo, tendo-se refletido num maior desenvolvimento vegetativo das videiras a todos os
níveis. A calda bordalesa não teve um efeito tão acentuado, mas mostrou uma melhoria na
eficiência fotoquímica do PSII, na concentração de pigmentos fotossintéticos e açúcares
solúveis e diminuiu os compostos fenólicos totais (CFT) e TBARS. Em alguns dos tecidos foliares, verificou-se um aumento da sua espessura e do desenvolvimento vegetativo,
embora essa diferença só foi reportada no maior comprimento dos lançamentos nas videiras
tratadas (devido às grandes restrições hídricas). O tratamento com caulino mostrou
melhorias na fisiologia das videiras, principalmente na eficiência fotoquímica do fotossistema
II (PSII), na concentração dos pigmentos fotossintéticos e açúcares solúveis; diminuindo a
concentração de CFT e da perda de eletrólitos. A nível histológico, as videiras tratadas
evidenciaram uma maior concentração de ceras cuticulares solúveis foliares e com caulino a
3% as videiras apresentaram lançamentos mais compridos, maior área foliar estimada e
peso seco por videira. O tratamento com silício foi o menos eficaz, uma vez que na maioria
dos parâmetros avaliados apresentou resultados inferiores que as videiras controlo. No
ensaio de 2012, a tendência observada no ano anterior manteve-se, com exceção da
concentração das clorofilas que diminuíram nas videiras tratadas. A aplicação de calda
bordalesa destacou-se pela positiva em quase todos os parâmetros.
Foi desenvolvido o Curso de Formação Contínua de Professores “Será que as plantas
também sofrem de stresse?”, tendo por base o tema e as metodologias deste trabalho de
investigação. A aplicação prática deste trabalho pretende sensibilizar professores e alunos
para esta problemática das alterações climáticas, com destaque da importância das plantas
e de como elas se comportam perante o meio mais ou menos adverso.
In a near future, as a result of global climate change, it is increasingly accepted that the climate of the most important world viticultural areas will become significantly warmer and dryer, which may result in decreased economic viability of grapevine (Vitis vinifera L.) cultivation. Vineyards are traditionally non-irrigated, especially in Europe, and widely spread across dry and semidry regions, being mostly explored by winemaking industry. Yield and berry quality strongly depend on vine adaptability to drought. Understanding and controlling plant-water relationships and water-stress resistance by means of physiology and molecular biology can significantly improve plant productivity and environmental quality. Therefore, not disregarding the usefulness that irrigation may have in grapevine growth and development, the implementation of mitigation strategies is crucial, not only in economic terms, but also in terms of yield, quality attributes and environmental sustainability. Among these measures, a great effort has been carried out by the scientific community to study the application of substances in optimizing light microclimate, leaf water relations, yield, grape and wine quality. The trial was carried out from 2011 to 2012 with grapevines located in Vila Real (Campus of UTAD, 41°17’N, 7°44’W, 470 m asl, Baixo Corgo sub-region of Demarcated Douro Region, Northern Portugal). Grapevines from the same clone of Vitis vinifera L. cv. Touriga Nacional were installed in pots, on a total of 100 pots in 2011 e 60 in 2012. The plants were conditioned to two types of irrigation: I-field capacity (CH), and II- 1/3 field capacity (SH). The irrigation system was installed and controlled in all pots. The treatments were applied on the leaves by pulverization, and were salicylic acid, bordeaux mixture, kaolin in two different concentrations (3% and 6%) and silicon in the first year (2011). In the second year were applied kaolin at 5% concentration and bordeaux mixture. In both years there was a control group in each irrigation condition. Each group of treatment consisted of ten plants. Salicylic acid has proved his beneficial effect in many parameters, including the improvement of gas exchanges, the photochemical efficiency of PSII, the increase in concentration of photosynthetic pigments and soluble sugars and the reduction of thiobarbituric acid reactive substances (TBARS) concentration. An increase in the relative water content (RWC) and the leaf mass per area (LMA), at the end of vegetative cycle, was reflected in higher vegetative growth of the grapevines at all levels. Bordeaux mixture had a less intense effect, however showed an improvement in the photochemical efficiency of photosystem II, chlorophyll content, soluble sugars, and decreased phenolic compounds and TBARS. In some leaf tissues, there was an increase in thickness and in growth development of grapevines, although that difference was only reported in bigger branches of the treated grapevines (largely due to water restrictions). Kaolin treatment showed improvements in the physiology of grapevines, specially in photochemical efficiency of photosystem II, in the concentration of chlorophyll and soluble sugars; there were lower phenolic compounds and lower loss of electrolytes. At histological level, the treated grapevines evidenced a higher concentration of leaf waxes, and grapevines with 3% kaolin had bigger branches, estimated leaf area and higher dry weight per grapevine. The treatment with silicon was the least effective treatment, since the majority of indices had lower values than the control grapevines. In the 2012 trial, the trend observed was similar to the year before, except for the chlorophyll concentrations that had decreased in the treated grapevines. The application of Bordeaux mixture stood out in almost all parameters. It was developed the Teacher Training Course "Do plants also suffer from stress?”, based on the theme and methodologies of this research work. The practical application of this work intends to sensitize teachers and students to this problem of climate change, highlighting the importance of plants and how they behave in multiple adverse environments.
In a near future, as a result of global climate change, it is increasingly accepted that the climate of the most important world viticultural areas will become significantly warmer and dryer, which may result in decreased economic viability of grapevine (Vitis vinifera L.) cultivation. Vineyards are traditionally non-irrigated, especially in Europe, and widely spread across dry and semidry regions, being mostly explored by winemaking industry. Yield and berry quality strongly depend on vine adaptability to drought. Understanding and controlling plant-water relationships and water-stress resistance by means of physiology and molecular biology can significantly improve plant productivity and environmental quality. Therefore, not disregarding the usefulness that irrigation may have in grapevine growth and development, the implementation of mitigation strategies is crucial, not only in economic terms, but also in terms of yield, quality attributes and environmental sustainability. Among these measures, a great effort has been carried out by the scientific community to study the application of substances in optimizing light microclimate, leaf water relations, yield, grape and wine quality. The trial was carried out from 2011 to 2012 with grapevines located in Vila Real (Campus of UTAD, 41°17’N, 7°44’W, 470 m asl, Baixo Corgo sub-region of Demarcated Douro Region, Northern Portugal). Grapevines from the same clone of Vitis vinifera L. cv. Touriga Nacional were installed in pots, on a total of 100 pots in 2011 e 60 in 2012. The plants were conditioned to two types of irrigation: I-field capacity (CH), and II- 1/3 field capacity (SH). The irrigation system was installed and controlled in all pots. The treatments were applied on the leaves by pulverization, and were salicylic acid, bordeaux mixture, kaolin in two different concentrations (3% and 6%) and silicon in the first year (2011). In the second year were applied kaolin at 5% concentration and bordeaux mixture. In both years there was a control group in each irrigation condition. Each group of treatment consisted of ten plants. Salicylic acid has proved his beneficial effect in many parameters, including the improvement of gas exchanges, the photochemical efficiency of PSII, the increase in concentration of photosynthetic pigments and soluble sugars and the reduction of thiobarbituric acid reactive substances (TBARS) concentration. An increase in the relative water content (RWC) and the leaf mass per area (LMA), at the end of vegetative cycle, was reflected in higher vegetative growth of the grapevines at all levels. Bordeaux mixture had a less intense effect, however showed an improvement in the photochemical efficiency of photosystem II, chlorophyll content, soluble sugars, and decreased phenolic compounds and TBARS. In some leaf tissues, there was an increase in thickness and in growth development of grapevines, although that difference was only reported in bigger branches of the treated grapevines (largely due to water restrictions). Kaolin treatment showed improvements in the physiology of grapevines, specially in photochemical efficiency of photosystem II, in the concentration of chlorophyll and soluble sugars; there were lower phenolic compounds and lower loss of electrolytes. At histological level, the treated grapevines evidenced a higher concentration of leaf waxes, and grapevines with 3% kaolin had bigger branches, estimated leaf area and higher dry weight per grapevine. The treatment with silicon was the least effective treatment, since the majority of indices had lower values than the control grapevines. In the 2012 trial, the trend observed was similar to the year before, except for the chlorophyll concentrations that had decreased in the treated grapevines. The application of Bordeaux mixture stood out in almost all parameters. It was developed the Teacher Training Course "Do plants also suffer from stress?”, based on the theme and methodologies of this research work. The practical application of this work intends to sensitize teachers and students to this problem of climate change, highlighting the importance of plants and how they behave in multiple adverse environments.
Descrição
Tese de Doutoramento em Ciências da Terra e da Vida
Palavras-chave
Caulino , Silício , Vitis vinifera , Stresse hídrico , Ácido salicílico , Calda Bordalesa