Estratégias de rega deficitária na vinha em regiões de clima Mediterrânico

Nas regiões de clima mediterrânico, em que a cultura da vinha tem uma grande expressão em termos de área cultivada e importância económica, as secas sazonais que ocorrem durante parte do ciclo vegetativo da videira são frequentes e exercem um enorme constrangimento quer na produção quer na qualidade. Com o objectivo de contrariar as quebras de produção e da qualidade da uva, resultantes do decréscimo do teor de água disponível no solo, do aumento das temperaturas e do défice de pressão de vapor de água da atmosfera, que se acentuam ao longo do período estival, têm-se vindo a introduzir, na generalidade das regiões vitícolas mediterrânicas, a prática da rega na vinha. A videira responde muito marcadamente aos diferentes regimes hídricos em todas as etapas do seu ciclo vegetativo. Uma rega excessiva pode conduzir a um aumento do vigor e da densidade foliar com consequências ao nível das características da uva diminuindo o seu teor em açúcares, intensidade da cor e compostos fenólicos e aumentando a acidez. No entanto, a aplicação de regas moderadas pode conduzir a um aumento da produção mantendo a qualidade ou mesmo incrementando-a. Este compromisso entre a necessidade de assegurar o rendimento dos viticultores e manter ou melhorar a qualidade da produção, num contexto de escassez de água e da necessidade de a gerir de uma forma mais eficiente, tem levado à implementação de diferentes estratégias de rega deficitária na cultura da vinha. Neste trabalho descrevem-se as diferentes estratégias de rega deficitária que têm vindo a ser implementadas na cultura da vinha e apresentam-se os resultados de um caso de estudo sobre influência da aplicação de rega de deficitária no comportamento fisiológico e agronómico da variedade Tinta Roriz, levado a cabo na Região Demarcada do Douro durante os anos de 2006 a 2008

Response of grapevine CV. “Tinta roriz” (Vitis vinifera L.) to moderate irrigation in the Douro Region, Portugal

The behaviour of cv. “Tinta Roriz” (Vitis vinifera L.), was studied when moderate drip irrigation was applied from veraison to harvest. Field studies were conducted during three growing seasons (2006-2008) in a commercial vineyard located in the Douro region, Portugal. Experimental layout consisted in the measurement of physiological and agronomic parameters in vines submitted to three different irrigation treatments: 0R was non-irrigation, 2R and 4R were irrigated with a constant fraction of reference evapotranspiration of 0.2 and 0.4, respectively. The results showed that moderate irrigation improved plant water status, leaf photosynthesis and transpiration. Yield components and pruning weights had a significant increase, only in the 2008 growing season, in 4R irrigated treatment. There were no significant differences between treatments in the accumulation of sugar, titratable acidity and pH in berries. The total phenols and the colour intensity showed a tendency, not significant, to decrease in irrigated treatments

Response of grapevive CV. “Tinta Roriz (Vitis vinifera L. ) to moderate Irrigation in the Douro Region, Portugal

The behaviour of cv. “Tinta Roriz” (Vitis vinifera L.), was studied when moderate drip irrigation was applied from veraison to harvest. Field studies were conducted during three growing seasons (2006-2008) in a commercial vineyard located in the Douro region, Portugal. Experimental layout consisted in the measurement of physiological and agronomic parameters in vines submitted to three different irrigation treatments: 0R was non-irrigation, 2R and 4R were irrigated with a constant fraction of reference evapotranspiration of 0.2 and 0.4, respectively. The results showed that moderate irrigation improved plant water status, leaf photosynthesis and transpiration. Yield components and pruning weights had a significant increase, only in the 2008 growing season, in 4R irrigated treatment. There were no significant differences between treatments in the accumulation of sugar, titratable acidity and pH in berries. The total phenols and the colour intensity showed a tendency, not significant, to decrease in irrigated treatments

Lymphocyte population in the granulomatous lesions of wild-boars (Sus scrofa) suspected of tuberculosis

Só está disponível o resumoLymphocyte population in the granulomatous lesions of wild-boars (Sus scrofa) suspected of tuberculosis

Response of two grapevine (Vitis vinifera L.) Portuguese varieties Tinta Roriz and Touriga Nacional to different irrigation regimes in the Douro Region, Portugal

The effect of several deficit irrigation regimes on vine water status, grape yield and quality parameters were studied in two Portuguese cultivars, Tinta Roriz (2007 and 2008 growing seasons) and Touriga Nacional (2014 and 2015 growing seasons) (Vitis vinifera L.) grown in a commercial vineyards located in the Douro region, Portugal. Treatments consisted of non-irrigated vines and three deficit irrigation regimes with a constant fraction of reference evapotranspiration (ETo): 0.2, 0.4 and 0.6. The reference evapotranspiration was calculated using modified FAO Penman-Monteith equation and water was applied three times a week, from pre-veraison until one week before harvest, through a drip irrigation system. The results showed that moderate water supplies during ripening period, for the region where the study was conducted (severe water deficits), improved significantly the grapevine water status, leaf photosynthesis and transpiration in both cultivars. Yield components and pruning weights showed a significant increase in irrigated treatments with more water supplied. There were no significant differences in the majority of fruit quality parameters. However, the total phenols and the colour intensity showed a tendency to decrease in irrigated treatments with more water supplied.info:eu-repo/semantics/publishedVersio

Influência da rega deficitária na evolução da maturação da variedade Tinta Roriz (Vitis vinifera L.)

Na Região Demarcada do Douro, e em particular na sub-região do Douro Superior, a vinha é conduzida, durante uma parte significativa do seu ciclo vegetativo, em condições de défice hídrico acentuado associadas a altas temperaturas, elevado stresse radiativo e elevado défice de pressão de vapor. As práticas culturais implementadas para minimizar as condições adversas, e em particular o regime de rega, podem alterar substancialmente a fisiologia da videira afectando a produção e a composição do bago. O principal objectivo deste estudo foi o de avaliar o curso da maturação na variedade Tinta Roriz de Vitis vinífera L., através da monitorização dos principais parâmetros da maturação, quando submetida a dotações de rega moderadas

Avaliação do stresse hídrico em videiras submetidas a diferentes regimes hídricos

Nas regiões de clima mediterrânico onde as videiras são plantadas sem rega, verificam-se com frequência no Verão situações de elevado stresse hídrico para a planta. Estas surgem como consequência das baixas reservas hídricas do solo, devido às baixas precipitações estivais, elevada temperatura e elevado défice de pressão de vapor. A aplicação de diferentes regimes de rega pode alterar substancialmente a fisiologia da videira afectando desta forma a produção e a composição da uva, sendo, por isso, necessária a sua avaliação. Este estudo, enquadrado num projecto mais amplo de estudo das relações hídricas da vinha, teve como objectivo avaliar, em condições de stresse hídrico acentuado, duas metodologias indicadoras do estado hídrico de videiras submetidas a diferentes regimes hídricos: o potencial hídrico foliar e a temperatura da canópia. Os resultados mostram que potencial hídrico foliar mostrou ser o método mais fiável para avaliar o estado hídrico na videira em condições de stresse hídrico severo evidenciando uma melhor correlação com os parâmetros fisiológicos. A temperatura do copado tende a aumentar com o incremento do stresse hídrico em consequência do encerramento estomático mostrando uma correlação significativa com o potencial hídrico foliar mas correlações não significativas com os parâmetros fisiológicos.In regions with a Mediterranean type of climate, where grapevine is a traditionally non-irrigated crop, the periods of marked plant water stress are very common. Water deficits occurs as a consequence of low soil water content that usually develops gradually during summer, owing to low precipitation, and is normally associated with high temperature and high vapor pressure deficits. Different irrigation regimes can bring about substantial alteration in grapevine physiology, affecting yield and grape composition and thus need to be properly assessed. The objective of this study was to evaluate the leaf water potential and canopy temperature as grapevine water status indicators. The results shows that leaf water potential is the best reliable indicator of grapevine water status under severe water stress conditions, showing a good correlation with other physiological parameters. Canopy temperature have a tendency to increase due to stomata close showing a high correlation with leaf water potential but low correlations with physiological parameters

A viticultura das Arribas do Douro Internacional – uma história para contar, um futuro a reflectir

A actual Denominação de Origem (DO) Trás-os-Montes, sub-região Planalto Mirandês (PM) (Diário da República, 1ª série - Nº 216 – 9 de Novembro de 2006), situa-se no Nordeste de Portugal, distrito de Bragança, região natural Miranda- Mogadouro (Taborda, 1932). Inicialmente designada Ribadouro (1986) e posteriormente por Indicação de Proveniência Regulamentada do Planalto Mirandês (Decreto-Lei 341/89), a actual designação de sub-região Planalto Mirandês deve-se ao facto de grande parte da sua área estar incluída no conjunto dos planaltos de Miranda e de Mogadouro. Apesar de ser uma região relativamente pequena em termos de área de vinha (cerca de 4000 hectares), apresenta significativa diversidade mesoclimática, devida à fisiografia e hidrografia que determinam diversas exposições e declives e igualmente diversidade pedológica, em função dos materiais originários. Com efeito,é possível registar neste território diferentes origens e constituições, as quais se reflectem particularmente pela diversidade dos ecossistemas de vegetação natural: “O revestimento vegetal traz impressa a marca desta dupla natureza” (Taborda 1932)

ABC transporters and multidrug resistance in Aspergillus nidulans

The term multidrug resistance (MDR) stands for simultaneous cellular resistance to chemically unrelated toxicants and is often associated with overproduction of multidrug-efflux proteins of the A TP- b inding- c assette (ABC) superfamily. The ABC transporters comprise a large and multifunctional family of proteins. Besides multidrug transporters, the superfamily includes proteins involved in transmembrane transport of various substances such as ions, amino acids, peptides, sugars, vitamins, steroid hormones, bile acids, and phospholipids. An overview of the great variety of cellular functions that these proteins can perform in living cells is presented in Chapter 1.The aim of this thesis was to identify and characterize molecular mechanisms of drug resistance in Aspergillus nidulans , with special emphasis on drug-efflux proteins of the ABC-transporter superfamily. Using different approaches, we have identified seven A BC- tr ansporter genes ( atrA-G ) from A. nidulans . Heterologous screening of a genomic library from A. nidulans using a DNA probe from PDR5 , a well characterized multidrug transporter from Saccharomyces cerevisiae , yielded atrA and atrB , the first ABC-transporter genes isolated from a filamentous fungus (Chapter 2). The second approach, PCR with degenerate oligonucleotide primers based upon consensus sequences encoding ABC transporters from the subfamily of P-glycoproteins, resulted in the cloning of atrC and atrD (Chapter 3). The last approach, was based on a screening of an EST database of A. nidulans for sequences encoding proteins with homology to known fungal multidrug transporters, particularly involved in efflux of azole fungicides. With this approach, atrE , atrF and atrG were identified (Chapter 5). The proteins encoded by all seven atr genes isolated display high sequence homology to known multidrug-efflux proteins from other organisms.To investigate the role of the isolated atr genes from A. nidulans in multidrug transport, expression analysis of these genes in wild-type and MDR ( ima ) mutants of A. nidulans was performed, after treatment of germlings with toxicants. imaA and imaB are laboratory-generated mutants of A. nidulans selected for resistance to the azole fungicide imazalil and related compounds. In imaB mutants, resistance to the azole-like compound fenarimol is based on an increased energy-dependent efflux activity which results in decreased cytoplasmic drug accumulation. Therefore, these mutants were suitable to correlate azole resistance with expression levels of atr genes.Expression studies in a wild-type isolate demonstrated that the basal level of expression for most atr genes is low and can be strongly enhanced by treatment with unrelated toxicants (Chapters 2, 3, 5 and 6). Time course experiments indicated that within 5 min after treatment with a toxicant ( e.g. imazalil), enhanced transcript levels of atr genes can be observed (Chapter 2). Some compounds can specifically induce transcription of one particular atr gene while others may simultaneously affect transcription of several atr genes (Chapter 5). For instance, resveratrol specifically induces transcription of atrB , while treatment with fenarimol enhances transcription of several genes ( atrB-G ). Expression analyses in the ima mutants of A. nidulans shows that atrD , atrE , atrF , and atrG display a higher basal level of expression in imaB mutants than in the wild-type (Chapter 5). Treatment with fenarimol also enhances transcription of these atr genes in imaB mutants.Mutants in which atrB and atrD have been deleted display increased sensitivity to a number of unrelated toxicants. ∆ atrB mutants have increased sensitivity to different classes of fungicides, mutagens and natural toxic compounds.Δ atrD mutants display increased sensitivity to cycloheximide, the cyclosporin derivative PSC 833, nigericin and valinomycin. These results indicate that AtrBp and AtrDp from A. nidulans are multidrug transporters with different substrate specifities (Chapters 3 and 4).AtrBp has been further characterized by overexpression in A. nidulans and S. cerevisiae (Chapters 2, 4 and 6). Sensitivity to toxicants of a PDR5- deficient strain of S. cerevisiae was restored to wild-type levels, upon transformation with cDNA of atrB in a high copy number vector (Chapter 2). Mutants overexpressing atrB in A. nidulans also display decreased sensitivity to toxicants. These overexpression mutants display altered sensitivity to a wider range of compounds as compared to ∆atrB mutants (Chapter 4). These results indicate that the presence of additional drug-efflux pumps with affinity for the same compound prevent a change in phenotype of some deletion mutants. Redundancy of ABC transporters may explain, at least in part, the findings thatΔ atrA andΔ atrC mutants show no hypersensitive phenotype for any of the compounds tested (Chapters 3 and 5). However, the observation that atrA transcript levels were not influenced by any of the compounds tested and that atrA expression in S. cerevisiae does not confer drug resistance, suggest that AtrAp is not a multidrug transporter.ABC transporters which have overlapping substrate specificities may still have specific substrates. AtrBp has a distinctive specificity for the phenylpyrrole fungicide fludioxonil since both ∆ atrB and atrB overexpression mutants have altered sensitivity to this compound (Chapter 6). In addition, the increase in sensitivity to fludioxonil observed for ∆ atrB mutants correlates with the relatively high accumulation levels of this compund. This was not observed for fenarimol. Therefore, the ABC transporter AtrBp can be regarded as a major efflux pump of phenylpyrrole fungicides in A. nidulans .Unexpectedly, overexpression mutants of atrB displayed increased sensitivity to dithiocarbamate fungicides, chlorothalonil and the iron-activated antibiotic phleomycin (Chapter 4). This phenotype was most pronounced in the overexpression mutant with the highest levels of atrB expression. We hypothesize that this phenomenon could relate to involvement of AtrBp in iron metabolism.Δ atrD mutants display a decrease in penicillin production, indirectly measured as antimicrobial activity against Micrococcus luteus (Chapter 3). These results suggest that AtrDp has a role in penicillin production.In conclusion, data presented in this thesis demonstrated that some of the identified ABC transporters from A. nidulans function in protection against natural toxicants and xenobiotics. Deletion and overexpression mutants of specific atr genes display increased and decreased sensitivity to toxicants, respectively. A role for ABC transporters in production of fungal secondary metabolites has also been suggested. This may imply that strains overexpressing multidrug-transporter genes can show pleiotropic phenotypes with respect to production of secondary metabolites.</p