Browsing by Author "Rodrigues, Manuel"
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- Effect of Foliar Application of Nitrogen-Fixing Microorganisms and Algae Extracts on Nutritional Status and Yield of Hazelnut and Walnut TreesPublication . Arrobas, Margarida; Roque, João; Martins, Sandra; Brito, Cátia; Correia, Carlos Manuel; Rodrigues, ManuelThis study presents the results of two on-farm trials evaluating the efficacy of a nitrogen (N)-fixing inoculant (Methylobacterium symbioticum) applied as a foliar spray to provide N to hazelnut (Corylus avellana L.) and walnut (Juglans regia L.) trees. In the hazelnut trial, a factorial design was employed with soil N application at three levels [0 (N0), 40 (N40), and 80 (N80) kg ha−1] and foliar application of the inoculant (Yes and No). The walnut trial was arranged as a completely randomized design with three treatments: the N-fixing microorganism, a seaweed extract, and a control. Soil N application significantly increased hazelnut yield in 2021 (1.99, 2.49, and 2.65 t ha−1 for N0, N40, and N80, respectively) but not in 2022 (average values ranging from 0.28 to 0.33 t ha−1). The inoculant application did not significantly affect hazelnut yield. In the walnut trial, no significant differences were observed among the treatments in either year. The average yields ranged from 1.72 to 2.38 t ha−1 in 2021 and 0.66 to 0.84 t ha−1 in 2022. Soil N application in hazelnuts tended to increase leaf N concentration and significantly increased kernel N concentration. The inoculant increased leaf N concentration in one of the three sampling dates but did not affect kernel N concentration. In walnuts, the inoculant did not increase leaf N concentration but significantly increased kernel N concentration in one of the two years. The seaweed extract did not influence walnut yield or leaf N concentration. None of the treatments in either trial consistently affected the concentration of other macronutrients and micronutrients in the leaves. Therefore, while the inoculant showed some potential to improve the N nutritional status of the trees, it did not affect the yield. Overall, the results of the inoculant application were not sufficiently compelling, indicating the need for further studies on these species before the commercial product can be confidently recommended to farmers.
- Fertilização do castanheiroPublication . Arrobas, Margarida; Rodrigues, ManuelA falência do setor dos cereais de inverno em todo o interior norte e centro de Portugal, fez do castanheiro (Castanea sativa Mill.) uma das únicas fontes de receita dos agricultores nas zonas de maior altitude onde o cultivo da vinha e do olival não são viáveis. O preço favorável da castanha dos últimos anos tem focado a atividade agrícola nesta espécie e levado a alguma intensificação cultural. Apesar dos problemas fitossanitários que enfrentam, os soutos são hoje cuidados, sendo a fertilização uma prática seguida pela generalidade dos produtores que, intuitivamente, entendem que dela depende, pelo menos em parte, a produtividade das árvores e o calibre dos frutos. Os castanheiros adultos são árvores enormes, com uma grande capacidade de regular internamente o fornecimento de nutrientes às folhas, e dispõem de um sistema radicular de grande expansão, o que lhes permite aceder a nutrientes que não estão ao alcance de outras culturas. Por outro lado, sabe-se que a generalidade das árvores se encontra micorrizada com fungos benéficos, o que também lhes facilita o acesso a nutrientes menos disponíveis no solo. A fertilização assume enorme importância para a generalidade das culturas e não o será menos para o castanheiro. No entanto, definir uma estratégia de fertilização coerente com as necessidades da espécie pode não ser tarefa fácil, sobretudo devido ao tamanho das árvores e ao facto de não haver investigação internacional sobre a temática. Ainda assim, alguns estudos realizados em Portugal apontam pistas, que serão discutidas neste documento, e que podem ajudar os produtores a orientar a fertilização do castanheiro.
- Revisão da avaliação pré-operatória da hemostase em 2838 criançasPublication . Costa, Elísio; Portal, Cristina; Rodrigues, Manuel; Barbot, JoséA avaliação pré-operatória da hemostase no Hospital de Crianças Maria Pia inclui uma história clínica protocolada dirigida à sintomatologia hemorrágica e exames analíticos de rastreio. Neste trabalho procurou-se avaliar esta metodologia no seu conjunto, assim como cada uma das suas duas vertentes isoladamente.
- Sewage sludge showed high agronomic value, releasing nitrogen faster than farmyard manurePublication . Dimande, Paulo; Arrobas, Margarida; Correia, Carlos Manuel; Rodrigues, ManuelThe use of fertilizers in agriculture, particularly organic fertilizers such as sewage sludge, is a key research priority due to its impacts on crop productivity, production costs, environmental risks and the push for a more circular economy. This study, conducted in Bragan & ccedil;a, northeastern Portugal, focused on forage maize during the 2022 and 2023 growing seasons. Eight fertilization treatments were established corresponding to the application of mineral nitrogen (N) at rates of 50 (N50), 100 (N100), 150 (N150) and 200 (N200) kg ha(-1), three organic amendments applied at a rate equivalent to 200 kg ha(-1) of N, namely sewage sludge (SS200), cow manure (CM200) and sheep manure (SM200), and a non-fertilized control (N0), with the aim of assessing the agronomic value of these treatments for forage maize (Zea mays L.). Maize dry matter yield (DMY) ranged from 10.8 to 20.3 t ha(-1) in 2022 and 13.7 to 23.6 t ha(-1) in 2023 for N0 and N200, respectively. Organic amendments produced 14.7-17.7 t ha(-1) in 2022 and 20.5-24.4 t ha(-1 )in 2023. Increased mineral N rates resulted in higher soil inorganic N content, N concentration in leaves and N recovery in tissues, with organic amendments showing lower values than crops fertilized with N200. However, due to cumulative nutrient release, organic amendments improved DMY and N use efficiency in the second year. Sewage sludge mineralized rapidly due to its low carbon (C)/N ratio and absence of hard-to-degrade compounds. It is also rich in phosphorus (P), enhancing its fertilizing value. Although nitrate leaching and denitrification potential appeared lower with organic amendments, long-term applications may increase risks, requiring careful monitoring to ensure sustainable and safe practices.
- A Spray Foliar Containing Methylobacterium symbioticum Did Not Increase Nitrogen Concentration in Leaves or Olive Yield Across Three Rainfed Olive OrchardsPublication . Rodrigues, Manuel Ângelo; Lopes, João Ilídio; Martins, Sandra; Brito, Cátia; Correia, Carlos Manuel; Arrobas, Margarida; Rodrigues, ManuelBiological nitrogen (N) fixation has been advocated in agricultural fields due to being considered a more sustainable way to introduce N into agrosystems than industrial N fertilizers. In this study, a foliar spray inoculant containing the microorganism Methylobacterium symbioticum was applied. This microorganism is known for fixing N in the phyllosphere, regardless of the cultivated species. This study was conducted in three rainfed olive orchards over three years. In two orchards managed according to European Union (EU) integrated production rules, the experiment was organized as a factorial design with inoculant (applied at two levels, yes and no) and N fertilization (applied to the soil at three levels, 0, 40, and 80 kg ha−1 of N). The third trial, managed according to EU organic farming rules, was organized in a completely randomized design with three treatments: with (yes) and without (no) inoculant and with a treatment involving a seaweed extract, also for foliar application. The microbiological inoculant did not consistently influence olive yield or N concentration in leaves across the three trials. Conversely, N application to the soil significantly influenced N concentration in leaves and olive yield. In one of the trials, in the third year of the study, soil N application (80 kg ha−1) resulted in an olive yield of ~eight times higher than the unfertilized control treatment. The seaweed extract also did not lead to significant differences in leaf mineral composition or olive yield compared with the other treatments. These findings from the on-farm research highlight the importance of accurately determining the conditions under which commercial products can deliver effective results. It is crucial to acknowledge that these products involve expenses not only in their acquisition but also in their application.