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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Reservas orgânicas, índice de área foliar e produção de forragem em Brachiaria brizantha cv. Marandu submetida a intensidades de pastejo por bovinos de corte. / Organic reserves, leaf area index and herbage yield in brachiaria brizantha cv. marandu submitted to grazing intensities by beef cattle.

Adriano Vecchiatti Lupinacci 03 July 2002 (has links)
As áreas de pastagens no Brasil ocupam cerca de 180 milhões de hectares, que são responsáveis por cerca de 90% da carne bovina produzida no país. No entanto, em torno de 80% das pastagens cultivadas apresentam algum grau de degradação, sendo este apontado como o maior problema relacionado com a sustentabilidade da produção animal em pastagens. Uma das principais razões para esse fato está relacionada a erros grosseiros no manejo das pastagens, conseqüência do desconhecimento dos limites ecofisiológicos e de resistência ao pastejo das plantas forrageiras. Dentro desse contexto, o objetivo deste experimento foi determinar quantitativamente o índice de área foliar, os teores e estoques de carboidratos não estruturais e frações nitrogenadas (N total, N solúvel, N aminoácidos, N amônio, N nitrato) de reserva, a taxa de acúmulo e a produção de forragem em pastos de Brachiaria brizantha cv. Marandu pastejados por bovinos em regime de lotação contínua e taxa de lotação variável. O experimento foi realizado em área do Departamento de Produção Animal da USP/ESALQ, em Piracicaba, SP, entre 27 de agosto de 2001 e 28 de fevereiro de 2002. Os tratamentos corresponderam a quatro alturas de pasto (10, 20, 30 e 40 cm), mantidas em steady state, e foram alocados às unidades experimentais conforme um delineamento de blocos completos casualizados, com quatro repetições. Os valores de IAF (1,7; 3,5; 4,0 e 3,8) foram crescentes para as alturas de pasto estudadas (10, 20, 30 e 40 cm, respectivamente) e semelhantes para as alturas de 20, 30 e 40 cm. Comportamento semelhante foi identificado para as taxas de acúmulo (102,0; 118,5; 121,6 e 113,9 kg ha -1 dia -1 MS) e acúmulo total de forragem (10.300; 13.340; 12.620 e 13.880 kg ha -1 ). Os teores (88,5; 111,7; 109,8 e 118,4 g kg -1 ) e estoques (0,152; 0,167; 0,180 e 0,157 kg m -2 ) de carboidratos não estruturais foram crescentes com as alturas de pasto (10, 20, 30 e 40 cm, respectivamente), ao passo que o inverso foi detectado para os teores e estoques de todas as frações nitrogenadas (10,65; 8,93; 8,64; 8,04 g kg -1 N total e 0,018; 0,017; 0,014; 0,012 kg m -2 N total, respectivamente). Com relação ao meses, houve uma redução acentuada ao longo do período experimental nos teores (118,8 para 87,2 g kg -1 de setembro a fevereiro) e estoques (0,225 para 0,111 kg m -2 de setembro a fevereiro) de carboidratos não estruturais e, também nos teores e estoques correspondentes às frações nitrogenadas (12,76 para 3,98 g kg -1 N total e 0,031 para 0,005 kg m -2 N total de setembro a fevereiro), motivadas inicialmente pelo início do verão (estação de crescimento) e posteriormente pelo início do desenvolvimento reprodutivo das plantas. Os estoques de carboidratos e de frações nitrogenadas foram consistentemente maiores para a base do colmo relativamente às raízes, tendo sido utilizados como fonte preferencial de matéria prima para o crescimento das plantas, razão pela qual sofreram as maiores reduções ao longo do tempo. As inflorescências se mostraram drenos metabólicos muito fortes durante a fase reprodutiva, assim como os meristemas apicais durante a fase vegetativa. O teor de N total nas folhas dos perfilhos diminuiu com o tempo (17,4 para 13,1 g kg -1 de dezembro a fevereiro), sendo os valores crescentes para folhas senescentes, maduras e em expansão (11,4, 14,0 e 16,7 g kg -1 , respectivamente). A altura de pasto de 10 cm correspondeu a uma condição de desfolha drástica, de modo que o manejo do pastejo deveria ser efetuado entre as condições de pasto de 20 e 40 cm. A escolha da condição de pasto mais indicada deve ser feita mediante o objetivo da atividade e a natureza da exploração animal proposta. / Grassland areas in Brazil occupy around 180 million hectares and support about 90% of the country’s beef production. However, approximately 80% of the cultivated pasture areas present some degree of degradation, that being the main problem related to the sustainability of pasture-based animal production systems. One of the main reasons for this is the mismanagement of pastures, consequence of the lack of knowledge and understanding about the ecophysiological limits and tolerance to grazing of forage plants. Against this background, the objective of this experiment was to determine the leaf area index (LAI), concentrations and pools of non structural carbohydrates (NSC) and nitrogenous reserve compounds (total N, soluble N, amino acid N, ammonium N, nitrate N), herbage dry matter accumulation rates and forage yield from Brachiaria brizantha cv. Marandu pastures continuously stocked by cattle, with variable stocking rate. The experiment was carried out at Departamento de Produção Animal, USP/ESALQ, Piracicaba, SP, from 27 August 2001 until 28 February 2002. Treatments corresponded to four steady state conditions characterized by sward surface heights (SSH) of 10, 20, 30 and 40 cm, assigned to experimental units according to a complete randomized block design, with four replications. LAI values (1.7, 3.5, 4.0 and 3.8) increased with increasing SSH (10, 20, 30 and 40 cm, respectively) and were not different among the 20, 30 and 40 cm treatments. Similar trend was recorded for herbage accumulation rates (102.0, 118.5, 121.6 and 113.9 kg ha -1 ) and forage yield (10,300, 13,340, 12,620 and 13,880 kg ha -1 ). The concentration (88.5, 111.7, 109.8 and 118.4 g kg -1 ) and pool (0.152, 0.167, 0.180 and 0.157 kg m -2 ) of NSC increased with increasing SSH (10, 20, 30 and 40 cm, respectively), whereas the inverse occurred with the concentration and pool of all nitrogenous compounds (10.65, 8.93, 8.64 and 8.04 g kg -1 total N and 0.018, 0.017, 0.014 and 0.012 kg m -2 total N, respectively). In relation to time of the year, there was a sharp decrease in the concentration and pool of NSC throughout the experimental period (118.8 to 87.2 g kg -1 and 0.225 to 0.111 kg m -2 , respectively, from September to February) as well as in the concentration and pool of all nitrogenous compounds (12.76 to 3.98 g kg -1 total N and 0.031 to 0.005 kg m -2 total N, respectively, from September to February), initially motivated by the commencement of summer (growing season) and followed by the beginning of reproductive development of plants. Pools of NSC and all nitrogenous compounds stored in stem base were consistently higher than those stored in roots and comprised the prime source of substances for plant growth, that being the reason for presenting the greatest reductions throughout the experimental period. Reproductive stems proved to be very strong metabolic drains during the reproductive phase of plant development as well as tiller growing points during the vegetative phase. The total N concentration in tiller leaves decreased with time (17.4 to 13.1 g kg -1 from December to February), with values increasing for senescent, mature and elongating leaves (11.4, 14.0 and 16.7 g kg -1 , respectively). The 10 cm SSH corresponded to a drastic defoliation condition, indicating that grazing management should be conducted within the 20 to 40 cm SSH range. The choice of the most appropriate SSH condition must take into account the main objective and nature of the animal production system proposed.
12

Svenska baljväxter från förr : en sensorisk beskrivning / Swedish legumes from the past : a sensory description

Dahl Petersson, Charlotta, Rojas Carvajal, Carlos, Uhlmann, Jenny January 2013 (has links)
Inledning: Baljväxter har flera miljö- och näringsmässiga fördelar och spås att bli framtidens föda. I Sverige finns det en värdefull kulturskatt som består av svenska baljväxter från förr som har samlats in av Programmet för odlad mångfald, POM. För att nå ut till konsumenter kan en sensorisk beskrivning vara en framkomlig väg som samtidigt ger ett mervärde för produkten och befrämjar en ökad konsumtion av baljväxter. Syfte: Syftet med detta examensarbete, inom ämnet mat och måltidskunskap, är att ta fram sensoriskt beskrivande ord för sex svenska baljväxter från förr. Examensarbetet ska sedan beskriva de utvalda svenska baljväxterna med hjälp av de framtagna sensoriskt beskrivande orden för att kunna presentera eventuella sensoriska skillnader. Material och metod: Sex olika sorters baljväxter ingick i undersökningen som bestod av en kvalitativ gruppdiskussion där sensoriskt beskrivande ord togs fram och ett andra steg en kvantitativ intensitetsbedömning av de olika sorterna. Båda undersökningarna gjordes av en expertpanel utvalda för sin kunskap om baljväxter. Resultat: De sensoriska ord som beskriver baljväxter är sötma, syrliga, beska, kastanj, nötig, smörig, frisk och fyllig smak samt med en varierande eftersmak. Munkänslan beskrivs med orden mjölig, krispig, fast och len. Intensitetsbedömningarna visade på små smakskillnader mellan baljväxterna men trots detta fanns särskiljande attribut för de sex olika baljväxtsorterna. Slutsats: De beskrivande sensoriska ord som detta examensarbete har utmynnat i kommer att hjälpa konsumenten att hitta rätt och öka mervärdet på produkterna. Samtidigt bevaras den svenska kulturskatten och konsumenten kan utveckla sin kulturella identitet tillsammans med alla de fördelaktiga egenskaper baljväxter besitter. / Introduction: Legumes have many favourable health and environmental benefits and are predicted to be the diet of the future. Sweden sits on a cultural treasure when it comes to legumes from the past that have been collected by The programme of cultivated diversity, POM. A sensory description would be a valuable tool to reach the consumer and a way to increase the consumption and value of the product. Purpose: The purpose of this thesis is to identify and bring forward sensory descriptive words for six Swedish legumes from the past. This thesis will also describe the Swedish legumes using the sensory descriptive words to evaluate whether there are sensory differences. Method: Six different types of legumes were used in the two surveys. The first survey consisted of a qualitative group discussion and the goal was to bring forward sensory descriptive words for the legumes. The second survey consisted of a quantitative intensity evaluation of the legumes. Both surveys were made by a panel of experts, chosen for their knowledge of legumes. Result: The sensory words which best describes the legumes are sweet, sour/acidic, bitter, chestnut, nutty, buttery, fresh, rich taste and with variations in aftertaste. The mouthfeel can be described as mealy, crisp, solid and tender. The evaluation of intensity proved the legumes to have few taste varieties, but despite the sensory descriptions each of the six legumes were possible to distinguish. Conclusion: The sensory descriptive words that this thesis have lead to can help the consumer to chose the right product, increase the value of the product an at the same time preserve a cultural treasure of Sweden. It is also possible for the consumer to create a cultural identity with all the good benefits that the legumes possess.

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