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Biblioteca Digital do IPB (53.442 recursos)

A Biblioteca Digital do IPB, tem por objectivo divulgar e permitir o livre acesso à produção científica produzida pela comunidade académica, promovendo a integração, partilha e a visibilidade da informação científica e garantindo a preservação da memória intelectual do Instituto Politécnico de Bragança.

CIMO - Artigos em Revistas Indexadas

Mostrando recursos 1 - 20 de 85

  1. Araneae communities associated with the canopies of chestnut trees

    Benhadi-Marín, Jacinto; Pereira, J.A.; Barrientos, José-Antonio; Bento, Albino; Santos, Sónia A.P.
    Chestnut (Castanea sativa Mill.) is one of the economically more important trees in the north of Portugal. Spiders, as generalist predators, are potential controlling agents of pests, yet the composition of the community of spiders associated with this crop is only poorly known. The objective of this study was to determine the spider communities in the canopies of chestnut trees subject to three different soil management practices in northeastern Portugal. Three chestnut groves each subject to a different agricultural practice (grazed, tilled or untilled) were studied in 2008 and 2009. The Araneae communities were sampled by beating the branches and the individuals collected were identified...

  2. Diversity of predaceous arthropods in the almond tree canopy in Northeastern Portugal: a methodological approach

    Benhadi-Marín, Jacinto; Pereira, J.A.; Barrientos, José-Antonio; Bento, Albino; Santos, Sónia A.P.
    The almond tree is an economically important crop in Mediterranean regions. However, knowledge about the biodiversity of natural enemies that may be useful as biocontrol agents, is scarce. The objectives of this work were (1) to study the diversity of predaceous arthropods and (2) establish a suitable sampling protocol for arthropods of the almond tree canopy. Between April and October of 2007-2008, 25 randomly selected trees were sampled in an organic almond grove located in the northeast of Portugal using the beating technique. The specimens collected were counted and identified and the sampling protocol was established by using the accumulation...

  3. Chemical, biochemical and electrochemical assays to evaluate phytochemicals and antioxidant activity of wild plants

    Barros, Lillian; Cabrita, Luís; Vilas-Boas, Miguel; Carvalho, Ana Maria; Ferreira, Isabel C.F.R.
    Plants are a source of compounds that may be used as pharmacologically active products. Cytisus multiflorus, Filipendula ulmaria and Sambucus nigra have been used as important medicinal plants in the Iberian Peninsula for many years, and are claimed to have various health benefits. Herein, the phytochemical composition and antioxidant activity of the mentioned wild medicinal plants were evaluated in vitro, based on chemical, biochemical and electrochemical methods. F. ulmaria was found to be richest in antioxidant phytochemicals, such as phenolics (228 mg GAE/g DW), flavonoids (62 mg CE/g DW), ascorbic acid (2700 lg/g DW) and tocopherols (497 lg/g DW). The...

  4. Anthocyanin-rich extract decreases indices of lipid peroxidation and DNA damage in vitamin E-depleted rats

    Ramirez-Tortosa, Carmen; Cabrita, Luís; Andersen, Øyvind M.; Gardner, P.T.; Morrice, P.C.; Wood, S.G.; Duthie, S.J.; Collins, A.R.; Garry, G.G.
    Anthocyanins are secondary plant metabolites responsible for the blue, purple, and red color of many plant tissues. The phenolic structure of anthocyanins conveys marked antioxidant activity in model systems via donation of electrons or hydrogen atoms from hydroxyl moieties to free radicals. Dietary intakes of anthocyanins may exceed 200 mg/day, however, little is known about their antioxidant potency in vivo. Consequently, the aim of this study was to establish whether anthocyanins could act as putative antioxidant micronutrients. Rats were maintained on vitamin E-deficient diets for 12 weeks in order to enhance susceptibility to oxidative damage and then repleted with rations containing a highly purified anthocyanin-rich...

  5. Anthocyanins in blue berries of Vaccinium padifolium

    Cabrita, Luís; Andersen, Øyvind M.
    Twenty anthocyanins were isolated from the extract of the edible blue berries of Vaccinium padifolium (Uveira) by a combination of chromatographic techniques. Mainly on the basis of nuclear magnetic resonance techniques (1H, COSY, TOCSY, HSQC, HMBC, SEFT) they were identified as the 3-O-beta-glucopyranosides, 3-O-beta-galactopyranosides, 3-O-beta-arabinopyranosides and 3-O-sambubiosides (2'-O-beta-xylopyranosyl-O-beta-glucopyranosides) of delphinidin, cyanidin, petunidin,malvidin and peonidin. Anthocyanidin disaccharides have not been identified in the genus Vaccinium previously, and the 3-sambubiosides of peonidin, petunidin and malvidin are novel compounds.

  6. Colour and stability of the six common anthocyanidin 3-glucosides

    Cabrita, Luís; Fossen, Torgils; Andersen, Øyvind M.
    This study on anthocyanin stability and colour variation (lambda max, absorptivity) in the pH range 1-12 during a period of 60 days storage at 10 and 23ºC, was conducted on the 3-glucosides of the six common anthocyanidins. It was mostly in the alkaline region that differences in colour and stability became significant. Although it has been generally accepted that anthocyanins are stable only at low pH values, this study revealed that, for some of the anthocyanin 3-glucosides (e.g. malvidin 3-glucoside), the bluish colours were rather intense and stability relatively high in the alkaline region. Thus, they can be regarded as potential colorants for...

  7. Colour and stability of pure anthocyanins influenced by pH including the alkaline region

    Fossen, Torgils; Cabrita, Luís; Andersen, Øyvind M.
    This study on anthocyanin colour variation (intensity, lambda max, absorptivity) over the pH range 1-9 during 60 days of storage, was conducted on petunidin 3-[6-O-(4-O-E-p- coumaroyl-O-alfa-L-rhamnopyranosyl)-beta-D-glucopyranoside]-5-O-beta-D-glucopyranoside (petanin) and cyanidin 3-O-beta-D-glucopyranoside (cy3glc) at 10 and 23ºC. Compared to cy3glc, petanin afforded higher colour intensity and higher or similar stability throughout the whole pH range. At pH 4.0, 84% of petanin was intact after 60 days storage at 10ºC, while the corresponding solution of cy3glc was totally degraded. At pH 8.1 the colour intensity of petanin was even higher than at the lowest pH values. The visible lambda max absorption of petanin after 5 days at pH 8.1 at...

  8. Anthocyanin trisaccharides in blue berries of Vaccinium padifolium

    Cabrita, Luís; Frøystein, Nils Åge; Andersen, Øyvind M.
    Delphinidin 3-O-alfa-rhamnoside, malvidin 3-O-(6''-O-alfa-rhamnopyranosyl-beta-glucopyranoside) and the 3-O-(6''-O-alfa-rhamnopyranosyl-2''-O-beta-xylopyranosyl-beta-glucopyranosides) of cyanidin, petunidin and peonidin were isolated by various chromatographic techniques from the edible berries of Vaccinium padifolium. Their complete structures were elucidated mainly by one- and two-dimensional nuclear magnetic resonance spectroscopy. Together they account for 7% of the anthocyanin content in this species. No anthocyanidin 3-triglycoside, 3-rutinoside or 3-rhamnoside had previously been found in the genus Vaccinium. The 3-O-(6''-O-alfa- rhamnopyranosyl-2''-O-beta-xylopyranosyl-beta-glucopyranosides) of petunidin and peonidin are novel compounds.

  9. Carbon allocation dynamics one decade after afforestation with Pinus radiata D. Don and Betula alba L. under two stand densities in NW Spain

    Fernández-Núñez, E.; Rigueiro-Rodríguez, A.; Mosquera-Losada, M.R.
    Silvopastoral systems can contribute to the mitigation of climate change by functioning as sinks for greenhouse gases better than exclusively agricultural systems. Tree species, density, and an adequate management of the pasture carrying capacity contribute to the capacity of carbon sequestration. In this study, the capacities for carbon sequestration in silvopastoral systems that were established with two different forest species (Pinus radiata D. Don and Betula alba L.) and at two distinct densities (833 and 2500 trees ha−1) were evaluated. Tree, litterfall, pasture and soil carbon storage determinations were carried out to deliver carbon sequestration in the different pools within...

  10. Voracity of coccinellid species on different phenological stages of the olive pest Saissetia oleae (Homoptera, Coccidae)

    Santos, Sónia A.P.; Pereira, J.A.; Torres, L.; Nogueira, A.J.A.
    Coccinellidae are well known predators in agroecosystems. In olive groves they may exert control against scales, such as the black scale, Saissetia oleae (Olivier, 1791). Laboratory studies on the consumption of three phenological stages (eggs, first and second instar nymphs) of S. oleae by four coccinellid species (Chilocorus bipustulatus, Scymnus (Pullus) subvillosus, Scymnus (Mimopullus) mediterraneus and Scymnus (Scymnus) interruptus) were carried out. C. bipustulatus presented a significantly high consumption of eggs, first and second instar nymphs compared with the other species. All coccinellids consumed eggs and first instar nymphs; however the second instar nymphs were only consumed by S. interruptus and C. bipustulatus. In a second...

  11. Establishment of continuous critical levels for indices of plant and presidedress soil nitrogen status in the potato crop

    Rodrigues, M.A.
    Critical levels for six plant and presidedress soil nitrogen (N) indices were established for the growing season, and their relative accuracy to diagnose the need for supplemental sidedress N was also compared. Field trials were conducted from 1996 to 1998 with irrigated potato in northeastern Portugal. Fertilizer treatments included several preplant and sidedress N rates. Petiole nitrate concentrations (determined by a standard laboratory method and with the portable RQflex reflectometer), leaf N content, leaf greenness (SPAD-502 chlorophyll meter), presidedress soil NO3-N and presidedress soil inorganic-N (NO3-N + NH4-N) were selected as N indicators. The Cate-Nelson graphical method and an analytical...

  12. An in situ incubation technique to measure the contribution of organic nitrogen to potatoes

    Rodrigues, M.A.
    The quantification of sidedress N rate from in-season information on crop N nutritional status is extremely important in order to use only the necessary amount of nutrient to achieve maximum yields without significant N losses from soil. During three consecutive years (1996, 1997 and 1998) field N fertilizer experiments with irrigated potato (Solanum tuberosum L., cv. Désirée) were conducted in Bragança (NE Portugal). Eight preplant treatments (0, 50, 100, 200 and 300 kg urea-N/ha and poultry manure, farmyard manure and municipal solid waste in rates equivalent to 100 kg organic-N/ha) were arranged as main plots and five sidedress N rates...

  13. Quantitative sidedress nitrogen recommendations for potatoes based upon crop nutritional indices

    Rodrigues, M.A.; Coutinho, João; Martins, Fernando; Arrobas, Margarida
    The quantification of sidedress N rate from in-season information on crop N nutritional status is extremely important in order to use only the necessary amount of nutrient to achieve maximum yields without significant N losses from soil. During three consecutive years (1996, 1997 and 1998) field N fertilizer experiments with irrigated potato (Solanum tuberosum L., cv. Désirée) were conducted in Bragança (NE Portugal). Eight preplant treatments (0, 50, 100, 200 and 300 kg urea-N/ha and poultry manure, farmyard manure and municipal solid waste in rates equivalent to 100 kg organic-N/ha) were arranged as main plots and five sidedress N rates...

  14. Rumex induratus leaves: interesting dietary source of potencial bioactive compounds

    Ferreres, F.; Ribeiro, Vitor; Gil Izquierdo, A.; Rodrigues, M.A.; Seabra, R.M.; Andrade, P.B.; Valentão, P.
    The phenolic compounds of Rumex induratus leaves were determined by HPLC-DAD-MS/MS-ESI. The results revealed a profile composed of 19 compounds: caffeoyl-hexoside, two p-coumaroyl-hexoside isomers, feruloyl-hexoside, sinapoyl-hexoside, 6-C-hexosyl-quercetin, 8-C-hexosyl-luteolin, 6-C-hexosyl-luteolin, 6-C-hexosyl-apigenin, 3-O-hexosyl-quercetin, 3-O-rutinosyl-quercetin, 7-O-hexosyl-diosmetin, 3-O-rutinosyl-isorhamnetin, 7-O-(acetyl)-pento-hexosyl-diosmetin, 6-C-hexosyl-genkwanin, and four unidentified O-glycosyl-C-glycosylflavones. The quantification of the identified phenolics by HPLC-DAD showed 6-C-hexosyl-luteolin as the main compound. Organic acid composition was determined by HPLC-UV, revealing a high content of oxalic acid. R. induratus was also investigated for its capacity to act as a scavenger of DPPH and superoxide radicals. Good antioxidative results were obtained against both radicals. Unlike other species of the genus...

  15. Tuber yield and leaf mineral composition of Jerusalem artichoke (Helianthus tuberosus L.) grown under different cropping practices

    Rodrigues, M.A.; Sousa, L.; Cabanas, J.E.; Arrobas, Margarida
    Jerusalem artichoke is commonly grown for its edible tubers, livestock feed and as an ornamental. The possibility of growing Jerusalem artichoke for energetic purposes has aroused scientific interest in this species. Despite several studies that have already been done in the last few decades, many aspects of the cropping practice are still relatively unknown. During the growing seasons of 2004-2006 field trials were carried out in NE Portugal. During the experimental period different cropping conditions were imposed, regarding irrigation, planting density, nitrogen fertilization and propagation method. The crop was irrigated in 2004 and 2005 and grown in rain-fed conditions in...

  16. Crops use-efficiency of nitrogen from manures permitted in organic farming

    Rodrigues, M.A.; Pereira, A.; Cabanas, J.E.; Dias, L.G.; Pires, Jaime; Arrobas, Margarida
    The current increase in the organic agriculture segment has created a new market for fertilisers permitted for use in organic farming. Off-farm N sources for organic farming are scarce, considering the restriction on the use of chemical fertilisers. Thus, when some products are permitted in organic agriculture, commercial opportunities become available. In this study we compare the performances of Vegethumus (Veg) and Phenix (Phe), two manures that are permitted in organic farming, with several other manures, ammonium nitrate (AN) and control treatments. A 3-year field trial and a pot experiment were carried out in order to estimate dry matter yield,...

  17. Targeted metabolite analysis and antioxidant potential of rumex induratus

    Guerra, Luís; Pereira, C.; Rodrigues, M.A.; Andrade, P.B.; Ferreres, F.
    Targeted metabolite analysis of aqueous extract of Rumex induratus leaves, in terms of phenolic compounds and organic acids, and the study of its antioxidant activity against the DPPH• radical, a reactive oxygen species, hypochlorous acid, and a reactive nitrogen species, nitric oxide (•NO), were performed. The samples were collected in several locations, spontaneously occurring or from greenhouse culture, at different stages of development and seasons. The phenolic composition was achieved by high-performance liquid chromatography (HPLC)-diode array detection, and four hydroxycinnamic acid derivatives and 10 flavonoid glycosides (C- and O-heterosides) were determined. Organic acids composition was established by HPLC-UV, revealing five compounds. The total amount of phenolic compounds...

  18. Effect of soil boron application on flower bud and leaf boron concentrations of olives

    Rodrigues, M.A.; Arrobas, Margarida
    In this work we report the effect of soil boron application on flower bud and leaf mineral composition of olives. Two field experiments were carried out. For experiment 1, we selected ten pairs of olive trees, chosen from ten different olive orchards, half being cv. Santulhana and the other cv. Madural. On each pair, one tree was B-fertilized (+B) on 29 March 2003 with 8.3 g of B (as Borax, 11% B) and the other pair kept as control (-B). On the experiment 2, three trees per treatment of cv. Cobrançosa were subjected to soil application of 0, 2.8, 5.5,...

  19. Slow-release N fertilisers are not an alternative to urea for fertilisation of autumn-grown tall cabbage

    Rodrigues, M.A.; Santos, H.; Ruivo, Sérgio; Arrobas, Margarida
    Tall cabbage (Brassica oleracea var. costata, cv. Penca de Mirandela) is grown in Portugal during autumn and winter months when heavy rains can be expected. In this agrosystem the management of N is a considerable challenge due to the risk of nitrate leaching. Field experiments with tall cabbage and rye were carried out during the growing seasons of 2007/2008 and 2008/2009. The experimental design included three fertilisers that delay N availability by different mechanisms [Floranid permanent, containing isobutylidene diurea (IBDU); Basacote, a polymer-coated fertiliser; and Entec 26, containing 3,4-dimethylpyrazole phosphate (DMPP) as nitrification inhibitor], two urea treatments (total N applied...

  20. Comparative boron nutritional diagnosis for olive based on July and January leaf samplings

    Arrobas, Margarida; Lopes, João; Pavão, Francisco; Cabanas, J.E.; Rodrigues, M.A.
    In this work, diagnosis of boron (B) nutritional status based on leaf B concentrations were compared for the most common leaf sampling times for olive trees, January and July. For this purpose field experiments were conducted over four years (2003-06) in two rainfed olive groves located in Mirandela and Bragança, in north-eastern Portugal. Leaf samples were collected in January and July and analysed for B by standard procedures. Fruit harvest occurred in December of each year. The crops followed typical alternate fruiting cycles. During the four years of the study, mean olive yields in the Bragança orchard, for instance, fluctuated, yielding...

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