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Search Results: 1 - 10 of 492446 matches for " Humberto M. F. Madeira "
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The type III secretion system is necessary for the development of a pathogenic and endophytic interaction between Herbaspirillum rubrisubalbicans and Poaceae
Maria A Schmidt, Eduardo Balsanelli, Helisson Faoro, Leonardo M Cruz, Roseli Wassem, Valter A de Baura, Vinicius Weiss, Marshall G Yates, Humberto M F Madeira, Lilian Pereira-Ferrari, Maria H P Fungaro, Francine M de Paula, Luiz F P Pereira, Luiz G E Vieira, Fábio L Olivares, Fábio O Pedrosa, Emanuel M de Souza, Rose A Monteiro
BMC Microbiology , 2012, DOI: 10.1186/1471-2180-12-98
Abstract: A 21?kb DNA region of the H. rubrisubalbicans genome contains a cluster of 26 hrp/hrc genes encoding for the type three secretion system (T3SS) proteins. To investigate the contribution of T3SS to the plant-bacterial interaction process we generated mutant strains of H. rubrisubalbicans M1 carrying a Tn5 insertion in both the hrcN and hrpE genes. H. rubrisulbalbicans hrpE and hrcN mutant strains of the T3SS system failed to cause the mottled stripe disease in the sugarcane susceptible variety B-4362. These mutant strains also did not produce lesions on Vigna unguiculata leaves. Oryza sativa and Zea mays colonization experiments showed that mutations in hrpE and hrcN genes reduced the capacity of H. rubrisulbalbicans to colonize these plants, suggesting that hrpE and hrcN genes are involved in the endophytic colonization.Our results indicate that the T3SS of H. rubrisubalbicans is necessary for the development of the mottled stripe disease and endophytic colonization of rice.
Influência de uma árvore isolada de freixo (Fraxinus angustifolia Vahl) no microclima num lameiro em Trás-os-Montes
Pereira,E.; Abreu,F. G.; Madeira,M.;
Revista de Ciências Agrárias , 2007,
Abstract: changes in microclimate caused by an isolated ash tree (fraxinus angustifolia vahl) were assessed in a pasture land close to bragan?a (41o 46? 55?? n; 6o 24? 51?? w; 510m de altitude), in northeastern portugal), where climate is csb according to k?ppen. the experimental site was located in the bottom of a small valley, and soils mostly fit the eutric fluvisols. solar radiation, rainfall, and air and soil temperature were measured during three years beneath the tree canopy and in the open. results showed that the microclimate conditions under the tree canopy were significantly different from those in the open. this is due to solar radiation interception (about 25 a 35% in winter and 55 a 65% in summer) and the interception of about 40% of the gross rainfall (52-56% during may- -october, and 35% when the foliage was absent). mean air temperatures under the canopy were higher than those in the open, with the differences being greater at nigth, reaching about 3oc in summer and 5oc in winter. compared to the open, mean soil temperatures in winter were higher (about 1oc at 20 cm depth) beneath the canopy, but were smaller (1oc at 2 cm depth) in summer. amplitudes of soil and air temperature were lower under the tree canopy than in the open. these microclimate conditions under the canopy may favour both the herbaceous biomass production and the earlier development of herbaceous at the end of winter.
Influência de diferentes sistemas de mobiliza??o do solo na decomposi??o de folhas e ouri?os de castanheiro
Raimundo,F.; Martins,A.; Madeira,M.;
Revista de Ciências Agrárias , 2007,
Abstract: decomposition of chestnut (castanea sativa mill.) leaves and burs, both incorporated into the soil and placed on its surface, were studied in a chestnut grove, in northeast portugal. the study was carried out during twenty-seven months, and the litterbag methodology was used. the mass loss and nutrient release (n, p, k, ca, and mg) showed by the buried organic residues was faster than that of those placed on the soil surface. the leaf litter placed beneath or beyond the influence of tree canopy did not show significant differences with regarding mass loss and nutrient release dynamics. for similar placement, decomposition and nutrient release from burs was slower than that observed for the leaf litter. substitution of the traditional soil management in chestnut groves by the zero tillage system will lead to the buildup of surface organic layers, and temporarily to the reduction of nutrient fluxes from organic residues to the soil.
Influência de uma árvore isolada de freixo (Fraxinus angustifolia Vahl) no microclima num lameiro em Trás-os-Montes Modification of microclimate by an isolated ash-tree (Fraxinus angustifolia Vahl) in natural pastures of Northeastern Portugal
E. Pereira,F. G. Abreu,M. Madeira
Revista de Ciências Agrárias , 2007,
Abstract: Estudaram-se as altera es microclimáticas decorrentes da presen a de árvores isoladas de freixo (Fraxinus angustifolia Vahl) num lameiro próximo de Alfai o (41o 46’ 55’’ N; 6o 24’ 51’’ W; 510m de altitude), no distrito de Bragan a (Nordeste de Portugal), em que o clima é do tipo Csb de K ppen. O lameiro localiza-se no fundo de um pequeno vale, cujos solos correspondem a Fluvissolos êutricos. Durante três anos mediu-se a radia o solar global incidente em campo aberto e a transmitida através da copa da árvore, a temperatura do ar e do solo sob e fora do coberto e a precipita o incidente sob a copa e em campo aberto. Em todas as esta es do ano a presen a da árvore alterou significativamente o microclima sob a mesma devido à intercep o de radia o solar (cerca de 25 a 35% no Inverno e de 55 a 65% no Ver o) e de cerca de 40% do total anual da precipita o bruta (52-56% no período de Maio-Setembro e 35% no período de ausência de folhagem). As temperaturas médias do ar sob a influência da copa (SIC) da árvore foram superiores às observadas fora da influência da copa (FIC), com as diferen as máximas ocorrendo durante o período nocturno e sendo da ordem de 3oC no Ver o e de 5oC no Inverno. Os valores médios da temperatura do solo foram superiores na área SIC durante o Inverno (1,1oC à profundidade de 20 cm) e no Ver o na área FIC (1oC à profundidade de 2 cm). As amplitudes térmicas no ar e no solo da área SIC foram inferiores às observadas na FIC. As condi es microclimáticas observadas sob coberto poder o favorecer o desenvolvimento da vegeta o herbácea no fim do Inverno, o que pode afectar a produ o de biomassa das herbáceas. Changes in microclimate caused by an isolated ash tree (Fraxinus angustifolia Vahl) were assessed in a pasture land close to Bragan a (41o 46’ 55’’ N; 6o 24’ 51’’ W; 510m de altitude), in Northeastern Portugal), where climate is Csb according to K ppen. The experimental site was located in the bottom of a small valley, and soils mostly fit the Eutric Fluvisols. Solar radiation, rainfall, and air and soil temperature were measured during three years beneath the tree canopy and in the open. Results showed that the microclimate conditions under the tree canopy were significantly different from those in the open. This is due to solar radiation interception (about 25 a 35% in winter and 55 a 65% in summer) and the interception of about 40% of the gross rainfall (52-56% during May- -October, and 35% when the foliage was absent). Mean air temperatures under the canopy were higher than those in the open, with the differences being greater
Influência de diferentes sistemas de mobiliza o do solo na decomposi o de folhas e ouri os de castanheiro Decomposition of chestnut leaves and burs under different soil management systems
F. Raimundo,A. Martins,M. Madeira
Revista de Ciências Agrárias , 2007,
Abstract: Estudou-se a decomposi o de folhas e ouri os de castanheiro (Castanea sativa Mill.), tanto incorporados no solo como colocados na superfície deste, sob e fora da influência da copa das árvores, num souto do Nordeste de Portugal. O estudo decorreu durante vinte e sete meses, utilizandose a metodologia das saquetas (litterbags). A perda de massa e a liberta o de nutrientes (N, P, K, Ca e Mg) foi mais rápida nos resíduos organicos incorporados no solo do que nos colocados na superfície do mesmo. As folhas colocadas sob ou fora da influência da copa n o apresentaram diferen as significativas no tocante à taxa de decomposi o e à dinamica de liberta o de nutrientes. Os ouri os decompuseram-se e libertaram os nutrientes mais lentamente do que as folhas, quando em semelhante posicionamento no solo. A substitui o da gest o tradicional do solo dos soutos pelo sistema de n o-mobiliza o traduzir-se-á pela acumula o de camadas organicas na superfície do solo e, temporariamente, pela redu o do fluxo de nutrientes dos resíduos organicos para o solo. Decomposition of chestnut (Castanea sativa Mill.) leaves and burs, both incorporated into the soil and placed on its surface, were studied in a chestnut grove, in Northeast Portugal. The study was carried out during twenty-seven months, and the litterbag methodology was used. The mass loss and nutrient release (N, P, K, Ca, and Mg) showed by the buried organic residues was faster than that of those placed on the soil surface. The leaf litter placed beneath or beyond the influence of tree canopy did not show significant differences with regarding mass loss and nutrient release dynamics. For similar placement, decomposition and nutrient release from burs was slower than that observed for the leaf litter. Substitution of the traditional soil management in chestnut groves by the zero tillage system will lead to the buildup of surface organic layers, and temporarily to the reduction of nutrient fluxes from organic residues to the soil.
Avalia??o das propriedades físicas e químicas do solo sujeito a diferentes sistemas de mobiliza??o em soutos do Nordeste Transmontano
Raimundo,F.; Fonseca,S.; Martins,A.; Madeira,M.;
Revista de Ciências Agrárias , 2007,
Abstract: several soil physical and chemical properties were evaluated in chestnut groves subjected to several soil management systems: chisel plow, that corresponds to the traditional tillage (mt), disc harrowing (gd), with rainfed seeded pasture (ps), and no-tillage with spontaneous herbaceous vegetation (nm). obtained results, between 1996 and 2004, showed that soil bulk density was significantly higher in treatments nm and ps than in mt, just after tillage; nevertheless, five months later, it did not show significant differences among treatments. in contrast to the traditional tillage, treatments gd and nm provoked an increment of the penetration resistance in the 0-12 cm soil layer; compaction in treatment gd was less than the treatments nm and ps in the 0-3 cm top soil layer only. n mineral concentration in the 0-15 cm soil layer was lowest in treatment nm, while in the treatment mt showed the highest values mostly in the period after soil tillage. contents of organic c, extractable p and k, exchangeable acidity and al, exchangeable bases (ca, mg, k), and ph values were not significantly affected by the treatments. nut production was smaller in mt treatment, mainly during the last three years of the experiment.
Decomposi??o de folhada de quatro espécies florestais no Norte de Portugal: Taxa de decomposi??o e evolu??o da composi??o estrutural e do teor em nutrientes
Martins,A.; Azevedo,S.; Raimundo,F.; Carvalho,L.; Madeira,M.;
Revista de Ciências Agrárias , 2009,
Abstract: decomposition of senescent leaves of castanea sativa (cs), and needles of pinus pinaster (pp), pinus nigra (pn) and pseudotsuga menziesii (pm) was studied during 3.1 to 3.5 years through weight loss and nutrient concentration evolution, using the litter bag technique, whereas the variation of chemical structural compounds was followed during 391 to 518 days. the highest contents of n were measured in pm and cs (respectively 14.5 and 12.1 g kg-1), which showed lower c/n ratio (39.0, 46.8) than pn and pp (122.2 and 147.7, respectively). highest contents of ca (9.1 g kg-1) and of alcohol and water soluble compounds (384 against 95 to 160 g kg-1 to other species) were measured in pm needles, which also showed the lowest contents of holocelulose (253 g kg-1 against about 500 g kg-1 in the other species). the lignin klason/n ratio decreased according to pp>pn>pm>cs, (71.2, 58.3, 20.5 and 20.3 respectively), and the holocelulose/lignin ratio ranged from 0.9 (pm) to 1.9-2.1 in the other species. annual decay rates, according to the negative exponential model, were ordered according to cs>pn>pm>pp (respectively -0.35, -0.27, -0.19 and -0.16), but with higher values during the first year for cs (-0.60) and pm (0.31). soluble compounds and hemicelulose strongly decreased during the decomposition period, while lignin and cellulose amounts showed a low variability, mainly in pp and pm needles. nutrient amounts decreased during the decomposition process, but remaining quantities for n (41 to 121 %) and p (33 to 104 %) were higher than those estimated for k, ca and mg (respectively 17 to 65%, 30 to 60 % and 18 to 59%). a strong decreasing of c/n ratio was observed especially for pp and pn, where reached 53.2 and 47.1.
Sistema de porosidade do solo numa topossequência Luvissolo-Solonetz no Sul de Portugal
Monteiro,F.; Madeira,M.; Marcelino,V.; Sousa,E.;
Revista de Ciências Agrárias , 2007,
Abstract: soils with stagnic properties occurring in alentejo commonly have low porosity. the study of a typical soil toposequence, showed that soil pore features were significantly different amongst summit and foot/toe slope pedons. in the summit pedon the ap1 horizon was more porous than the ap2, both exhibiting similar void distribution patterns. conversely, the ap1 and ap2 horizons of the footslope pedon had a similar pore space volume, but pores with diameter larger than 500 μm were less important in the later. pore space volume of bt horizons was low whatever the slope position of pedons. however, they differ significantly in terms of void type and orientation patterns. no preferred orientation patterns were found in soil voids that could be related with soil compaction, being their low porosity, namely their low ?conductive? porosity, not attributable to soil compaction. those features can instead be due to the sodicity and/or the low organic c of these soils.
A folhada de quatro povoamentos florestais no Norte de Portugal: Produ??o e concentra??o e quantidade de nutrientes devolvidos ao solo
Martins,A.; Coutinho,J.; Costa,S.; Fonseca,F.; Madeira,M.;
Revista de Ciências Agrárias , 2007,
Abstract: monthly litterfall production, nutrient concentration and nutrient devolution to the forest floor through litterfall were assessed in four forest stands of castanea sativa miller (cs), pseudotsuga menziesii (mirbel), franco var. menziesii (pm), pinus nigra arnold subsp. laricio (pn) and pinus pinaster aiton, (pp), located close to vila pouca de aguiar, northern portugal. mean annual amounts of litterfall measured during two years decreased in the order pn > pp > pm > cs respectively, 6910, 4115, 3934 and 2759 kg ha-1. values showed high inter-annual variation, which can be ascribed to the different climatic conditions during the study period. coniferous species showed a continuous litterfall production, with higher amounts in august and september for pp, september and october for pn and pm. in the case of the cs, there was not litterfall production during part of the year and the highest amounts were observed in october and november. concerning the proportion of the several components in the litterfall, needles and leaves were largely predominant in the following order pm > cs > pp > pn, respectively 83, 78, 68 and 55 %. concentration of nitrogen in the leaves of cs and needles of pm was higher (respectively 11.3 and 10.9 g kg-1) than in pn and pp needles (respectively 7,3 and 5,5 g kg-1). concentration of ca in pm (9,4 g kg-1) was also higher than in the other species, implying an higher amount of ca returned to the forest floor (34.5 kg ha-1 year-1) in the former than in the other species (9.3 to 14.4 kg ha-1 year-1), which positively favour soil surface layer chemical properties in stands of the first species.
Avalia o das propriedades físicas e químicas do solo sujeito a diferentes sistemas de mobiliza o em soutos do Nordeste Transmontano Effect of different soil management systems on soil physical and chemical properties in chestnut orchards of Northern Portugal
F. Raimundo,S. Fonseca,A. Martins,M. Madeira
Revista de Ciências Agrárias , 2007,
Abstract: Avaliaram-se várias propriedades físicas e químicas do solo de soutos do Nordeste de Portugal em que foram experimentados, a partir de 1996, quatro sistemas de prepara o do solo: (a) mobiliza o tradicional (MT) com escarificador, (b) mobiliza o com grade de discos (GD), (c) instala o de pastagem semeada de sequeiro (PS) e (d) n o-mobiliza o com vegeta o herbácea espontanea (NM). Até 2004 observou- -se que a massa volúmica aparente do solo foi significativamente superior nos tratamentos NM e PS do que no MT, imediatamente após as mobiliza es, pois poucos meses depois essa diferen a esbate-se. Os tratamentos GD, PS e NM induziram a um acréscimo da resistência à penetra o na camada superficial do solo (0-12 cm); comparativamente ao tratamento MT; o tratamento GD, por seu turno, determinou menor compacta o do solo do que os tratamentos NM e PS somente até 3 cm de profundidade. A concentra o de N mineral do solo, até 15 cm de profundidade, atingiu os menores valores no tratamento NM; o tratamento MT apresentou um forte aumento dessa concentra o no período posterior à execu o das mobiliza es. Os teores de C organico, P e K extraíveis, Ca, Mg, K, acidez e Al de troca e os valores de pH n o foram, na generalidade, influenciados significativamente pelos tratamentos, considerando o conjunto das varias camadas do solo analisadas. A produ o de fruto foi menor no tratamento MT, nomeadamente nos últimos três anos de estudo (2002-2004). Several soil physical and chemical properties were evaluated in chestnut groves subjected to several soil management systems: chisel plow, that corresponds to the traditional tillage (MT), disc harrowing (GD), with rainfed seeded pasture (PS), and no-tillage with spontaneous herbaceous vegetation (NM). Obtained results, between 1996 and 2004, showed that soil bulk density was significantly higher in treatments NM and PS than in MT, just after tillage; nevertheless, five months later, it did not show significant differences among treatments. In contrast to the traditional tillage, treatments GD and NM provoked an increment of the penetration resistance in the 0-12 cm soil layer; compaction in treatment GD was less than the treatments NM and PS in the 0-3 cm top soil layer only. N mineral concentration in the 0-15 cm soil layer was lowest in treatment NM, while in the treatment MT showed the highest values mostly in the period after soil tillage. Contents of organic C, extractable P and K, exchangeable acidity and Al, exchangeable bases (Ca, Mg, K), and pH values were not significantly affected by the treatments. Nut produc
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