Made available in DSpace on 2016-12-08T16:24:12Z (GMT). No. of bitstreams: 1 PGCA13MA094.pdf: 3484558 bytes, checksum: 4cd098df0840598b9d19fbbc52ff65cb (MD5) Previous issue date: 2013-03-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In regions with subtropical climates the use of grasses intercropping, mainly oats and ryegrass is a common practice, but the advantages and disadvantages of the intercrop in relation the pure culture are little studied. The aim of this work was to evaluate the production and persistence of black oat and ryegrass swards grown pure or intercropping throughout the period of use. The three treatments were randomly distributed into a complete blocks design with four replicates. The pre-grazing sward heights were 23, 20 and 17 cm for the oat, intercrop and ryegrass treatments, respectively. The post-grazing sward heights were 40% lower than their initial heights. Morphogenesis was performed using the technique of marked tillers and dynamic and tiller population density (TPD) was determined with three 10-cmdiameter PVC rings per paddock. The treatments did not differ in the final length of intact leaf, being the October month with the lowest values (approximately 48% lower). The phyllochron was not affected by the form of cultivation, but the values were increasing with the advance of the growing season. The leaf elongation rate decreased over the months, with a mean value of 0.14 cm / perfilhos.graus-day for all treatments. The advance of the growing season resulted in increases stem elongation rates, with the species in the intercrop having smaller increments in the final months. In general, rates of senescence reduced with the advance of months, and the intercrop increased tissue death of ryegrass. The intercrop TPD remained constant until October, inverting the participation of species in August. Of the tillers existing on the last grazing cycle, approximately 0, 40 and 20% were first generation of the oats, ryegrass and intercrop, respectively. Thus, despite of ryegrass pure have the lowest rate of tillering, it have the same rate of population stability of the intercrop. The pure ryegrass had the highest average net accumulation rates by offering smaller forage losses by senescence. Tiller size/density compensation was observed in the three plant communities (treatments) according to the self-thinning rule. In addition, no relationships were found when each species was analysed individually in the intercrop treatment. For the species tested the developmental stage of sward has greater influence on the morphogenesis and structural characteristics than cultivation form. The morphological similarity of oats and ryegrass enables evaluated traits similar in both forms of cultivation. When intercropping the temperate climate grasses under rotational grazing, size/density compensation mechanisms occurred throughout the grazing cycles and in the plant communities the same form of the pure cultivation to maintain the leaf area index and production capacities of the pastures / Em regiões de clima subtropical a utilização de gramíneas em consórcio, principalmente aveia e azevém, é uma prática comum, porém as vantagens e desvantagens do consórcio em relação ao cultivo puro são pouco estudadas. Objetivou-se avaliar a produção e a longevidade de pastos de aveia-preta e azevém anual cultivados puros ou em consórcio ao longo de todo o período de utilização. Os três tratamentos foram distribuídos em blocos completos casualizados com quatro repetições, tendo cada unidade experimental 98 m2. As alturas em pré-pastejo foram 23, 20 e 17 cm para a aveia, o consórcio e o azevém, respectivamente, sendo rebaixados em 40% destas alturas. A morfogênese foi realizada por meio da técnica de perfilhos marcados e a dinâmica e densidade populacional de perfilhos (DPP) em três anéis de PVC com 10 cm de diâmetro por piquete. Os tratamentos não diferiram quanto ao comprimento final de folha intacta, ficando o mês de outubro com os menores valores (aproximadamente 48% menor). Não houve efeito da forma de cultivo para os valores de filocrono, porém os valores foram crescentes com o avanço da estação de crescimento. A taxa de alongamento foliar reduziu com o passar dos meses, com valor médio de 0,14 cm/perfilho.grau-dia para todos os tratamentos. O avanço da estação de crescimento resultou em incrementos nas taxas de alongamento de colmos, com as espécies no consórcio apresentando menores incrementos nos meses finais. De maneira geral, as taxas de senescência foliar reduziram com o avanço dos meses, sendo que o consórcio aumentou a morte de tecidos do azevém. O consórcio manteve a DPP constante até outubro, apresentando uma inversão na participação das duas espécies em agosto. Dos perfilhos existentes no último ciclo de pastejo, aproximadamente 0, 40 e 20% eram da primeira geração no azevém, na aveia e no consórcio, respectivamente. Com isso, apesar de apresentar a menor taxa de aparecimento de perfilhos o azevém cultivado puro apresentou o mesmo índice de estabilidade populacional do consórcio. O azevém cultivado puro apresentou as maiores taxas de acúmulo líquido médio por apresentar as menores perdas de forragem por senescência. A compensação tamanho/densidade de perfilhos foi observada segundo a lei do auto-desbaste (self thinning rule) nos três tratamentos quando levados em conta todos os perfilhos da área, não sendo encontrada relação quando as espécies foram analisadas individualmente no consórcio. Para as espécies testadas o estádio de desenvolvimento dos pastos apresenta maior influência sobre as características morfogênicas e estruturais do que a forma de cultivo. A semelhança morfológica da aveia e do azevém possibilita características morfogênicas e estruturais parecidas em ambas as formas de cultivo. É sugestivo que em consórcios entre gramíneas de clima temperado sob lotação intermitente os mecanismos de compensação tamanho/densidade operem na comunidade de plantas e ao longo dos ciclos de pastejo da mesma forma que nos cultivos puros, mantendo elevado índice de área foliar e capacidade produtiva

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this research was to evaluate tree pasture-based systems (PS) with elephant grass (EG) + spontaneous growing species (SGS), ryegrass (RG), for PS1; EG + SGS + forage peanut, for PS2; and EG + SGS + RG + red clover, for PS3. EG was planted 4 m spaced rows. In the cool-season, ryegrass was sowed between rows of EG; red clover was sowed and the forage peanut was preserved in respectively PS. Experimental design was completely randomized with tree treatments (SF), two replicates (paddocks) in completely split-plot time (grazing cycles). Holstein cows receiving 5.5 kg-daily and a complementary concentrate feed were used in the evaluation. The herbage mass parameters, botanical composition, forage production and stocking rate were evaluated. Samples were collected by the hand-plucking method to analyze the organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and organic matter in situ digestibility (OMISD) of pasture; phenols and tannins on legumes. Nine grazing cycle were performed during the experimental period (341 days). The mean values of forage production, stocking rate, crude protein and digestibility were 17.14; 16.80; and 19.47 t/ha; 3.28; 3.34; and 3.60 UA/ha; 13.86; 15.39; and 14.78%; 78.33; 79.23; and 79.94% on the respective PS. SGS increased significantly (P≤0,05) relation to the PS without forage legume. Similar results were observed for forage production OM an NDF in comparison to PS. Nutritive value was similar between forage legumes. Differences (P≤0,05) on condensed tannin tenors were observed between forage legumes. Considering the forage production, stocking rate and nutritive value, the PS mixed to forage legumes showed better performance. / O objetivo desta pesquisa foi avaliar três sistemas forrageiros (SF) com capim elefante (CE), espécies de crescimento espontâneo (ECE), azevém anual (AZ), como SF1; CE + ECE + AZ + amendoim forrageiro (AF), como SF2; e CE + ECE + AZ + trevo vermelho (TV), como SF3. O capim elefante foi estabelecido em linhas afastadas a cada 4 m. No período hibernal fez-se o estabelecimento do AZ entre as linhas do capim elefante; o trevo vermelho foi semeado e o amendoim forrageiro foi preservado, considerando os respectivos tratamentos. O delineamento experimental foi o inteiramente casualizado, com três tratamentos (SF), duas repetições (piquetes) em parcelas subdivididas no tempo (pastejos). Para avaliação foram usadas vacas da raça Holandesa que receberam complementação alimentar com concentrado à razão de 5,5 kg/dia. Foram avaliados parâmetros da massa de forragem pré-pastejo, a composição botânica, a produção de forragem e a lotação. Para analisar a matéria orgânica (MO), a fibra em detergente neutro (FDN), proteína bruta (PB) e digestibilidade in situ da MO (DISMO) da pastagem e os teores de fenóis e taninos das leguminosas, foram coletadas amostras de pastejo simulado. Durante o período experimental (341 dias) foram efetuados nove ciclos de pastejo. Os valores médios de produção de forragem, lotação, PB e de DISMO foram 17,14; 16,80; e 19,47 t/ha; 3,28; 3,34; e 3,60 UA/ha; 13,86; 15,39; e 14,78%; 78,33; 79,23; e 79,94% nos respectivos SF. Houve aumento significativo (P≤0,05) para espécies de crescimento espontâneo na pastagem sem leguminosa. Resultados similares foram observados entre SF para MO e FDN. O valor nutritivo foi similar entre as leguminosas forrageiras. Foram observadas diferenças (P≤0,05) entre as leguminosas para os teores de taninos condensados. Considerando a massa de forragem, a lotação e o valor nutritivo, as pastagens consorciadas com leguminosas forrageiras apresentaram melhor desempenho.

In Australia, significant effort goes into reducing the amount of nitrogen and phosphorus entering inland waters from point sources. However, little is known of the extent to which riparian organic matter may act as a source of these nutrients. Also, whilst the relationships between the nitrogen, phosphorus and carbon cycles are broadly known, there is little quantitative data regarding the release of these elements from Australian riparian organic matter and their subsequent microbial mineralisation within aquatic environments. In particular, comparatively little is known of their comparative role in nutrient and organic matter cycling within anoxic zones, and the influence that different riparian organic matter may have on stream water quality. This lack of such data presently hampers the ability of water managers to make educated decisions regarding the management of riparian zones in Australia. In order to improve understanding in this area, a combination of laboratory and in situ experiments were carried out in order to compare the abiotic release and aerobic/ anaerobic mineralisation of leaf derived dissolved organic carbon (DOC), dissolved nitrate/nitrite (NOx) and soluble reactive phosphorus (SRP) under different environmental conditions. Four plants common to Australian riparian zones were investigated: two native species, Eucalyptus camaldulensis (gum) and Phragmites australis (common reed), and two exotic species, Salix babylonica (willow) and Lolium multiflorum (rye grass). After 30 days, formaldehyde inhibited 1g willow and rye grass extracts contained the most SRP (0.7 mg/L), whilst gum extracts contained 0.3 mg/L and common reed 0.1 mg/L of SRP.Willow and rye grass abiotically released twice as much NOx than gum and common reed, although concentrations were only between 0.05-0.1 mg/L. Gum and common reed released the most DOC per gram of leaf matter (14 and 12 mmol/g of leaf matter respectively), but based on the initial carbon content of each leaf type, the largest percentage contributor of DOC under abiotic conditions was common reed and rye grass (both 38% mass/mass), with gum (33% mass/mass) and willow (30% mass/mass) being smaller contributors. The most bioavailable DOC was released by rye grass and common reed, with between 83 and 94% of this DOC microbially mineralised after 30 days in oxic conditions. When conditions were not inhibited, microbial growth was evident almost immediately in willow, rye grass and common reed leaf extracts. However, microbial growth was suppressed for the first 48 hours in gum leaf extracts. After this suppression period, the rate of DOC mineralisation was equal in willow and gum leaf extracts (0.1 day-1). Under anoxic conditions, the rate and extent of DOC mineralisation of willow and gum leaves depended on the type of electron acceptor provided. Added nitrate and iron III enhanced the mineralisation of both willow and gum leaves relative to no terminal electron acceptors (from zero to 0.01-0.04 and 0.002- 0.004 moles/day respectively), but added sulphate only enhanced the mineralisation of gum leaves (0.04 moles/day). When no additional electron acceptors were provided, particulate leaf mineralisation was more extensive under oxic than anoxic conditions. However, the mineralisation of leaf derived DOC were the same regardless of oxygen availability, and after 35 days in either condition the percentage of leaf DOC mineralised for each leaf type was of the order common reed > rye grass > willow > gum. All the leaf types tested were able to sustain the caddis fly larvae Triplectides australis under controlled laboratory conditions, and survival rates were high using all four leaf types as a food source. Triplectides australis did not significantly increase the amount of DOC released from each type of leaf matter, but they did consistently increase the proportion of simple carbohydrates present within the DOC fraction. The results of these experiments suggest that changes to riparian vegetation, particularly from the native to exotic species used in this study, will inherently alter in-stream concentrations of dissolved carbon and nutrients (particularly SRP). This potentially will affect in-stream, hyporheic and subsurface processes, particularly in areas where surface water flow is low and riparian leaf inputs are high.

Made available in DSpace on 2014-08-20T13:44:36Z (GMT). No. of bitstreams: 1 dissertacao_alberto_bohn.pdf: 586241 bytes, checksum: 0568eec20a5d22d087fb11ebc9a8fb75 (MD5) Previous issue date: 2014-03-17 / The experiment was conducted at the Experimental Station of Embrapa Clima Temperado/Lowlands and Seed Analysis Laboratory of the Department of Plant Science, UFPel. Different densities in the soil seeds (T1 - 777.70 kg.ha-1; T2 - 736.63 kg.ha-1; T3 - 624.59 kg.ha-1 and T4 - 234.42 kg.ha-1) were tested in annual ryegrass (Lolium multiflorum Lam.) in succession to soybean crop. Forage harvesting has occurred twice and after the second defoliation, were tested different levels of urea (null; 45; 90 and 135 kg.ha-1). The highest densities produced more rapid crop establishment and greater mass of harvested forage, both at first and in the second cut. In this sense, from the application of different doses of urea was found, only significant effect of nitrogen on seed yield, so the addition of a unit of urea increased by 1.7 units seeds. Occurred relationship between levels of SPAD when the assessment was conducted before flowering. Prior to harvest seed regression models between SPAD and urea levels were not significant. The seed physiologic quality was not affected by the levels of in the soil seeds and urea. / O experimento foi conduzido na Estação Experimental da Embrapa Clima Temperado/Terras Baixas e no Laboratório de Análises de Sementes do departamento de Fitotecnia da Universidade Federal de Pelotas - UFPel. Foram avaliadas diferentes densidades de sementes no solo (T1 - 777,70 Kg.ha-1; T2 - 736,63 Kg.ha-1; T3 - 624,59 Kg.ha-1 e T4 - 234,42 Kg.ha-1) de azevém anual (Lolium multiflorum Lam.) em sucessão a cultura da soja. Ocorreu a colheita de forragem em duas ocasiões e, após a segunda desfolha, utilizada diferentes doses de ureia (zero; 45; 90 e 135 kg.ha-1). As maiores densidades proporcionaram mais rápido estabelecimento da cultura e maior massa de forragem colhida, tanto no primeiro, quanto no segundo corte. Neste sentido, a partir da aplicação das diferentes doses de ureia verificou-se, apenas, efeito significativo do nitrogênio sobre o rendimento de sementes, de modo que o acréscimo de uma unidade de ureia aumentou 1,7 unidades de sementes. Através do clorofilômetro foi possível predizer o rendimento de sementes pelos níveis de SPAD, quando comparadas antes do florescimento. Previamente a colheita da semente os modelos de regressão entre SPAD e níveis de nitrogênio não foram significativos. A qualidade fisiológica da semente não influenciada pelos fatores avaliados.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.