571 research outputs found

    Dynamic of Native Pasture Influenced by Deferment of Grazing and Fertilization

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    Native pastures of southern Brazil cover 12 million ha and are the main forage feed resource for most domestic livestock. However, their heavy and continuous use has reduced standing biomass and the presence of good forage species, reducing animal performance and jeopardizing the ecosystem sustainability. An alternative for better use of these pastures and their preservation is grazing deferment that allow natural reseeding. The objective of this research was evaluate native pasture dynamic after six years of grazing deferments (GD) periods and soil fertilization effects by point-quadrat method every season. All pasture components were affected by GD, with prostrate grasses increasing their frequency (P \u3c 0.05) under continuous grazing while periods of rest encouraged erect plants. Fertilization improved pasture condition by reducing frequencies of no forage species, litter and bare soil, and increasing frequencies and dry matter contribution of good ones like native legumes, especially Desmodium incanum

    Herbaceous Vegetation Dynamic after Cut and Burn Shrub Plants in Southern Brazil

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    A savanna area at Serra do Sudeste in southern Brazil, was studied during four years to evaluate the influence of cutting and burning shrub plants on dynamic of herbaceous vegetation. The cover of each species in 44 permanent quadrats (0,25 m2) and in each area (cut and burned) was evaluated. The results suggested that grasses and legumes were favored by cutting shrub plants. Burning favored forbs in the first years after disturbance and retarded the development of native forage species desirable for grazing

    Direct Drilling of Soybean in a Pensacola Bahiagrass Pasture in the Northwest Region of Rio Grande Do Sul, Brazil

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    The response of methods of soil preparation (M1=conventional tillage, and with notillage using the following herbicides M2=50% Paraquat plus 50% Orizalin; M3=50% Paraquat plus 50% Diquat and M4=Paracol (20% Paraquat plus 20 Diuron)) and row spacing (E1=17 cm, E2=24 cm, E3=51 cm and E4=68 cm) on soybean grain yield direct drilled in an eight-year-old grazed sward of Bahiagrass cv. Pensacola (Paspalum notatum var. saurae Parodi) were studied in southern of Brazil. The results showed that direct drilling of soybean on Pensacola accompanied by desiccant herbicides is a viable agronomic practice. The narrow row spacing is beneficial to this agronomic practice resulting in higher grain yields. The relationship between soybean grain yield and Pensacola dry matter yield was expressed by a negative linear regression. In spite of the damage to the Pensacola caused by herbicides and by soybean competition the sward recovered immediately after the soybean maturation and harvest

    Herbage Allowance and Nitrogen Fertilization Effects on Morphological Characteristics of \u3ci\u3ePaspalum notatum\u3c/i\u3e Flügge

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    The grazing study was conducted at the Estação Experimental Agronomica – UFRGS, 30o S, on a native pasture, to evaluate the leaf area index and structural morphological traits of bahiagrass (Paspalum notatum Fl.), within the requirements of a Central Composite Rotatable experimental design, providing for equal precision, with two blocks, encompassing two factors at five levels each, namely: Herbage Allowance (HA) = 4.0; 5.5; 9.0; 12.5 and 14.0 kg green dry matter per 100 kg liveweight per day (% LW), in association with Nitrogen (N) fertilization levels of 0; 30; 100; 170 and 200 kg ha-1 as urea, The leaf length and leaf area index (LAI) were increased as HA and N levels increased. The tiller density was increased at higher HA where the N contribution showed to be more effective. More lenient grazing also increased leaf life span and leaf lamina length, while N promoted canopy density and reduced leaf life span and number of leaves per tiller. The higher LAI values developed were accomplished by reduced tiller densities that supported small number of leaves per tiller, with increased leaf sizes

    Overexpression, purification and crystallization of a choline-binding protein CbpI from Streptococcus pneumoniae

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    The choline-binding protein CbpI from S. pneumoniae has been purified and crystallized and diffraction data have been collected to 3.5 Å resolution

    Planos e métodos amostrais em pomares.

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    Estas notas são resultado da experiência em pesquisa com fruteiras onde se vivenciam situações em que a teoria da amostragem nem sempre pode ser diretamente aplicada na prática. Este texto compõe, com outros dois que o suscedem, o registro de alguns aspectos sobre metodologia estatística na pesquisa experimental em fruticultura, em consonância com o painel intitulado Estatística Experimental Aplicada à Pesquisa em Fruticultura. O que motivou a concepção e proposta deste painel no XXII Congresso Brasileiro de Fruticultura foi, no entender dos autores, a necessidade de reforçar ou alertar pesquisadores e futuros pesquisadores em fruticultura quanto à importância do bom uso da Estatística e do planejamento da pesquisa experimental, bem como apresentar exemplos de análise de dados experimentais, pelo uso de ferramentas com originalidade e criatividade, mas sem abrir mão do rigor inerente aos métodos de inferência estatística. Obviamente, as três apresentações não são completas e não visam aprofundar aspectos teóricos da Estatística, mas espera-se instigar o público da Fruticultura a buscar constante aprimoramento em Estatística Experimental. Como pano de fundo da concepção do painel, considerem-se as grandes etapas de um programa experimental representadas na figura 1. As três abordagens apresentadas permeiam o planejamento de experimentos e o levantamento por amostragem e a análise de dados experimentais. Com este trabalho, pretendeu-se levantar aspectos práticos da amostragem no contexto da pesquisa científica em fruticultura, especificamente para o caso de levantamento amostral em pomares.Painel

    Identification and rejection of scattered neutrons in AGATA

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    Gamma rays and neutrons, emitted following spontaneous fission of 252Cf, were measured in an AGATA experiment performed at INFN Laboratori Nazionali di Legnaro in Italy. The setup consisted of four AGATA triple cluster detectors (12 36-fold segmented high-purity germanium crystals), placed at a distance of 50 cm from the source, and 16 HELENA BaF2 detectors. The aim of the experiment was to study the interaction of neutrons in the segmented high-purity germanium detectors of AGATA and to investigate the possibility to discriminate neutrons and gamma rays with the gamma-ray tracking technique. The BaF2 detectors were used for a time-of-flight measurement, which gave an independent discrimination of neutrons and gamma rays and which was used to optimise the gamma-ray tracking-based neutron rejection methods. It was found that standard gamma-ray tracking, without any additional neutron rejection features, eliminates effectively most of the interaction points due to recoiling Ge nuclei after elastic scattering of neutrons. Standard tracking rejects also a significant amount of the events due to inelastic scattering of neutrons in the germanium crystals. Further enhancements of the neutron rejection was obtained by setting conditions on the following quantities, which were evaluated for each event by the tracking algorithm: energy of the first and second interaction point, difference in the calculated incoming direction of the gamma ray, figure-of-merit value. The experimental results of tracking with neutron rejection agree rather well with Geant4 simulations
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