Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-10-13T20:11:22Z No. of bitstreams: 1 2016 - Leonardo dos Santos Fran?a Shockness.pdf: 1003791 bytes, checksum: efd5f4204bec8c095ea24c37002fd302 (MD5) / Made available in DSpace on 2017-10-13T20:11:22Z (GMT). No. of bitstreams: 1 2016 - Leonardo dos Santos Fran?a Shockness.pdf: 1003791 bytes, checksum: efd5f4204bec8c095ea24c37002fd302 (MD5) Previous issue date: 2016-02-29 / CAPES / One of the main factors that affect growth and persistence of grasses in the tropics, thus increasing the degradation of pastures, is a nitrogen deficiency in the soil. However, nitrogen fertilizers much burden the production costs, and the demand for food increasing year by year, has emphasized the need for sustainable alternatives, such as biological nitrogen fixation. It is necessary to do more research on Biological Nitrogen Fixation (BNF) in forage grasses, especially about diversity among nitrogen-fixing bacteria associated with these plants, so that new bacteria can be discovered, as well as its potential to FBN. This study aimed to isolate diazotrophic bacteria of the genus Azospirillum spp. or Herbaspirillum spp., from two cultivars of B. brizhanta (Marandu and Xara?s) and one of B. decumbens (IPEAN), to test them, and to assess their contribution to the growth of Brachiaria brizhanta cv. Marandu identifying the three most promising. This study was conducted at Embrapa Agrobiology in Serop?dica - RJ, in two stages. The first was to isolate possible diazotrophic bacteria from Brachiaria brizantha and B. decumbens plants, using the cultivars Marandu and Xara?s B. brizantha, and the cultivar IPEAN of B. decumbens. The isolation was performed using three semi-solid media, NFB, LGI and JNFb, where the first two selected bacteria of the genus Azospirillum, and the third one Herbaspirillum bacteria. There were selected 46 isolates and, after purification, it was obtained 15 isolates pure, and made the phenotypic characterization thereof. Further biochemical tests were the phosphate solubilization, acetylene reduction analysis (ARA), and production of acid-3-indole acetic (IAA). All tested isolates produced ARA ethylene, even in small quantities, with prominence for isolates L2, L4, J3, J6, J7 and J8. In the phosphate solubilization the isolates N1, L1, J2, J3, J4, J5, J6, J7, J8, and T14 were able to solubilize phosphate. In the EIA production the isolates N1, J1, J2, J3, J4, J5, J6, J7, J8 and J9 excelled. In the second phase it was conducted an experiment to study plant - bacteria interaction. It consisted of the inoculation of 15 isolates from the first phase plus three isolates known as references (SP245, Z94, CBAMC) in B. brizhanta cultivar Marandu, plus the control without inoculation and without N. In this experiment the isolates L2, L4 and J6 outstand when compared to the other seven parameters evaluated. On the basis of this study we can conclude that there are nitrogen fixing bacteria, phosphate solubilizing, and that produce 3-indoleacetic acid, associated to Brachiaria brizhanta and Brachiaria decumbens. The isolated bacteria of the two B. brizhanta cultivars (Marandu and Xara?s), and the Brachiaria decumbens (IPEAN) cultivar were more efficient in the growth of B. brizhanta cultivar Marandu than the bacteria standards obtained from other plant species. Also, among the 15 isolates from Brachiaria plants, the J6, L2 and L4 were statistically different from the others, and are considered the three most promising. / Um dos principais fatores que afeta o crescimento e a persist?ncia de gram?neas nos tr?picos, aumentando assim a degrada??o das pastagens, ? a defici?ncia de nitrog?nio no solo. Entretanto, fertilizantes nitrogenados oneram muito os custos de produ??o, e com a demanda por alimentos crescendo ano a ano, tem-se enfatizado a necessidade de alternativas sustent?veis, tal como a fixa??o biol?gica de nitrog?nio. Faz-se necess?rio pesquisas com Fixa??o Biol?gica de Nitrog?nio (FBN) em gram?neas forrageiras, principalmente sobre diversidade de bact?rias diazotr?ficas associadas a essas plantas, para que novas bact?rias possam ser descobertas, assim como seu potencial de FBN. Este trabalho teve como objetivo isolar bact?rias diazotr?ficas do g?nero Azospirillum Spp. ou Herbaspirillum Spp., provenientes de duas cultivares de B. brizhanta (Marandu e Xar?es) e de uma cultivar de B. decumbens (Ipean), testar as mesmas, e avaliar sua contribui??o no crescimento de Brachiaria brizhanta cv. Marandu identificando as tr?s mais promissoras. O trabalho foi realizado na Embrapa Agrobiologia em Serop?dica ? RJ, em duas etapas. Na primeira foi feito o isolamento de poss?veis bact?rias dizotr?ficas provenientes de plantas de Brachiaria brizantha e Brachiaria decumbens, sendo utilizadas as cultivares Marandu e Xara?s de B. brizantha e a cultivar IPEAN de B. decumbens. O isolamento foi realizado utilizando tr?s meios semiss?lidos, NFB, LGI e JNFB, onde os dois primeiros selecionaram bact?rias do g?nero Azospirillum, e o terceiro bact?rias do g?nero Herbaspirillum. Foram selecionados 46 isolados, e ap?s a purifica??o obteve-se 15 isolados puros, sendo feita a caracteriza??o fenot?pica dos mesmos, e posteriormente os testes bioqu?micos de solubiliza??o de fosfato, an?lise da redu??o de acetileno (ARA) e produ??o de ?cido-3-indolac?tico (AIA). Na ARA todos isolados avaliados produziram etileno, mesmo em pequenas quantidades, tendo destaque os isolados L2, L4, J3, J6, J7, e J8. Na solubiliza??o de fosfato os isolados N1, L1, J2, J3, J4, J5, J6, J7, J8 e T14 foram capazes de solubilizar fosfato. Na produ??o de AIA se sobressa?ram os isolados N1, J1, J2, J3, J4, J5, J6, J7, J8 e J9. Na segunda etapa foi realizado o experimento de intera??o planta - bact?ria; que consistiu da inocula??o dos 15 isolados da primeira etapa, acrescidos de tr?s isolados conhecidos como padr?es (SP245, Z94, CBAMC) em B. brizhanta cv. Marandu, mais a testemunha n?o inoculada e sem N. Neste experimento os isolados L2, L4 e J6 se destacaram em rela??o aos outros nos sete par?metros avaliados. Com base neste trabalho podemos concluir que existem bact?rias fixadoras de nitrog?nio, solubilizadoras de fosfato e que produzem ?cido-3-indolac?tico associadas a Brachiaria brizhanta e Brachiaria decumbens. As bact?rias isoladas de duas cultivares de B. brizhanta (Marandu e Xar?es) e de uma cultivar de B. decumbens (Ipean) se mostraram mais eficientes no crescimento de B. brizhanta cv. Marandu do que as bact?rias padr?es provenientes de outras esp?cies de plantas. Ainda, dentre os 15 isolados de plantas do g?nero Brachiaria, os isolados J6, L2 e L4 diferiram estatisticamente dos demais, sendo considerados os tr?s mais promissores.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-08-22T18:12:38Z No. of bitstreams: 1 2017 - Helio Jos? de Ara?jo Filho.pdf: 1260983 bytes, checksum: 99a5ebc69e0f2db8e73b43a3fbf3d09d (MD5) / Made available in DSpace on 2018-08-22T18:12:38Z (GMT). No. of bitstreams: 1 2017 - Helio Jos? de Ara?jo Filho.pdf: 1260983 bytes, checksum: 99a5ebc69e0f2db8e73b43a3fbf3d09d (MD5) Previous issue date: 2017-02-22 / FAPERJ / CNPq / The growth of the world population has increased the demand for food, this implies in reduction of the available areas for animal production, which makes imperative the development, evaluation and application of techniques that propitiate the increase of the productivity of Brazilian livestock. Thus, the objective of this study was to evaluate and compare the productive and economic performance of beef cattle finishing under three management and feeding systems, namely: at pasture with mineral supplementation (PSM); at pasture with protein-energy supplementation (SPE); And raised at feedlot with high concentrate diet (AG). For this purpose, 60 castrated male bovines, crossbreed Nelore x Angus, which were distributed in a design Completely randomized, with three systems and twenty animals in each. The study was conducted at Fazenda Tr?s Morros, in the city of Casimiro de Abreu. The means of the studied variables were estimated by LSMEANS and compared by PDIFF, at 5% of probability (p<0.05%), of SAS?. The feedlot (AG) presented shorter finishing time (76 days) and higher weight gain (102.2 kg), total daily average gain (1.35 kg.animal-1.day-1) and average daily gain of carcass (1.02 kg.animal-1.day-1), followed by SPE and PSM, respectively, in relation to the finishing time and the average daily gain of carcass. Regarding weight gain and average daily gain, there was no significant difference (p <0.05) between SPE and PSM. In turn, the average carcass weights (ACW), carcass yields (CY), and carcass gains (CG) of AG (ACW 298.3 kg or 19.9@, CY 55.1% and CG 78.3 kg) and SPE (ACW 288.2 kg or 19.2@, CY 56.1% and CG 68.1 kg) were similar to each other and higher (p<0.05) to PSM. The system PSM had the lowest production costs (effective operational cost R$ 2,277, total operational cost R$ 2,323 and total cost R$ 2,466), while the highest effective operational cost was AG (R$ 2,598) and the highest total operational cost (TOC) and total cost (TC) of SPE (TOC of R$ 2,632 and R$ 2,668). The highest gross margin (R$ 341.1) and net margin (R$ 295.9), net result (R$ 153.0), profitability (5.84%) and simple rentability (4.54%) were obtained by PSM, followed by SPE and AG, in that order. However, when the cash flows were corrected by the general price index - domestic availability (GPI-DA), the gross margins (R$ 199.6) and net margin (R$ 152.2) of PSM remained the highest and followed by SPE and AG (respectively), but the other economic indicators were the lowest among the systems. In this way, the highest net result (R$ 70.7), profitability (2.43%) and simple rentability (1.81%) were observed in SPE. Therefore, the feedlot provided the smallest production cycle and increased animal productivity, the pasture system with mineral supplementation allowed the reduction of production costs, while the concentrate supplementation presented better economic result during the dry season of the year 2015. According to the information obtained, both confinement and supplementation with whole maize diet have the potential to be strategic alternatives to the finishing cattle at exclusively pasture, provided satisfactory market conditions. / O crescimento da popula??o mundial tem elevado a demanda por alimento, isso implica em redu??o das ?reas dispon?veis para produ??o animal, o que torna imperativo o desenvolvimento, avalia??o e aplica??o de t?cnicas que propiciem o aumento da produtividade da pecu?ria brasileira. Desta forma, o objetivo deste estudo foi avaliar e comparar o desempenho produtivo e econ?mico da termina??o de bovinos sob tr?s sistemas de manejo e alimenta??o, a saber: a pasto com suplementa??o mineral (PSM); a pasto com suplementa??o prot?ico-energ?tica (SPE); e confinamento com fornecimento de dieta alto gr?o (AG). Para tanto, foram utilizados 60 bovinos machos castrados, ? sangue Nelore x Angus, distribu?dos em um delineamento inteiramente casualizado, em tr?s sistemas e vinte animais em cada. O estudo foi conduzido na Fazenda Tr?s Morros, no munic?pio de Casimiro de Abreu/RJ. As m?dias das vari?veis estudadas foram estimadas pelo LSMEANS e comparadas pela PDIFF, a 5% de probabilidade (p<0,05), do SAS?. O confinamento (AG) apresentou menor tempo de termina??o (76 dias) e maiores ganho de peso (102,2 kg), ganho m?dio di?rio total (1,35 kg.animal-1.dia-1) e ganho m?dio di?rio de carca?a (1,02 kg.animal-1dia-1), seguido por SPE e PSM, respectivamente, em rela??o ao tempo de termina??o e ao ganho m?dio di?rio de carca?a. No que se refere ao ganho de peso e ao ganho m?dio di?rio total, n?o houve diferen?a significativa (p<0,05) entre SPE e PSM. Por sua vez, os pesos m?dios de carca?a (PMC), os rendimentos de carca?a (RC) e os ganhos de carca?a (GC) de AG (PMC de 298,3 kg ou 19,9 @, RC de 55,1% e GC de 78,3 kg) e SPE (PMC de 288,2 kg ou 19,2 @, RC de 56,1% e GC de 68,1 kg) foram semelhantes entre si e superiores (p<0,05) a PSM. J? o sistema PSM obteve os menores custos de produ??o (custo operacional efetivo de R$ 2.277, custo operacional total de R$ 2.323 e custo total de R$ 2.466), enquanto o maior custo operacional efetivo foi de AG (R$ 2.598) e os maiores custo operacional total (COT) e custo total (CT), de SPE (COT de R$ 2.632 e CT R$ 2.668). As maiores margem bruta (R$ 341,1) e l?quida (R$ 295,9), resultado l?quido (R$ 153,0), lucratividade (5,84%) e rentabilidade simples (4,54%) foram obtidas por PSM, seguidas por SPE e AG, nesta ordem. Por?m, quando os fluxos de caixa foram corrigidos pelo ?ndice geral de pre?os ? disponibilidade interna (IGP-DI), as margens bruta (R$ 199,6) e l?quida (R$ 152,2) de PSM permaneceram as mais elevadas e acompanhadas por SPE e AG (respectivamente), contudo, os demais indicadores econ?micos foram os menores entre os sistemas. Desta forma, os maiores resultado (R$ 70,7), lucratividade (2,43%) e rentabilidade simples (1,81%) foram observados em SPE. Portanto, o confinamento proporcionou o menor ciclo de produ??o e maior produtividade animal, o sistema a pasto com suplementa??o mineral possibilitou a redu??o dos custos de produ??o, enquanto a suplementa??o com concentrado apresentou melhor resultado econ?mico, durante a esta??o seca do ano de 2015. De acordo com as informa??es obtidas, tanto o confinamento quanto a suplementa??o com dieta ? base de milho inteiro possuem potencial para serem alternativas estrat?gicas ? termina??o de bovinos exclusivamente a pasto, desde que presentes condi??es satisfat?rias do mercado.

Estudos foram conduzidos com o objetivo de caracterizar a composição morfológica e química, as frações de carboidratos e proteínas e as taxas de degradação em amostras de estrato pastejável de capim Colonião, Marandu e Mulato manejados com altas taxas de lotação e com intervalos de desfolhas variáveis (95% de IL) durante a primavera, verão e outono. Foi realizada avaliação comparativa dos capins quanto a sua composição morfológica, produção de massa de forragem (kg MS.ha-1), composição química, frações protéicas e de carboidratos, assim como o fracionamento in situ e as taxas de degradação da PB, FDN e MS e ainda as taxas de degradação in vitro das frações protéicas entre as estações da primavera, verão e outono. No primeiro experimento, a massa de forragem e componentes morfológicos variaram com a estação do ano (P<0,05). A composição química do capim variou (P<0,05) entre as estações do ano, para teores de MS, FDN, EE, PB, NIDN, NIDA e MM. As frações de carboidratos (CHOT, frações A, B1 e B2) e as frações protéicas (A, B1, B2 e B3) foram afetadas pelas estações do ano (P<0,1). Os valores das taxas de degradação da proteína (B1, B2, B3 e B1+B2) e os valores estimados pelo método in situ para MS, FDN e PB não variaram (P<0,1) entre as estações do ano. No entanto, os valores de degradabilidade efetiva (DE) da MS e FDN foram significativos. No segundo experimento a estação do ano causou variação (P<0,05) para a massa de forragem, para os teores de MS, FDN, FDA, EE, MM e para as frações A+B1 e CHOT. Apenas a fração B1 das frações protéicas foi afetada (P<0,1) entre as estações do ano. Os valores das taxas de degradação da proteína (B1, B2 e B3) não variaram (P<0,1) entre as estações do ano. As variáveis estimadas pelo método in situ para MS, PB e FDN não variaram (P<0,1) entre as estações do ano. No terceiro experimento houve efeito (P<0,05) para massa de forragem, entre as estações do ano. Quanto a composição morfológica houve variação (P<0,05) na proporção de colmos, sendo maior no outono. A composição química apresentou efeito significativo (P<0,05) para os teores de MS, FDN, FDA, PB e MM. As frações A+B1 e B2 de carboidratos variaram (P<0,05), da mesma forma que as frações de proteína (P<0,1) também variaram conforme as estações do ano. Os valores das taxas de degradação da proteína (B1, B2 e B3) não variaram (P<0,1) entre as estações do ano. As variáveis estimadas pelo método in situ para MS, PB e FDN variaram (P<0,1) para Lambda, taxa de degradação (kdNRC) e degradabilidade efetiva (DE), entre as estações do ano. As forrageiras estudadas apresentaram-se pobre em frações de carboidratos de alta fermentabilidade ruminal (A+B1), enquanto que o teor de proteína prontamente degradada no rúmen foi elevado (A, B1 e B2). Isto pode limitar a eficiência de uso da proteína degradável no rúmen das forragens, especialmente quando adubadas intensamente com N para a obtenção de altas taxas de lotação animal. / Studies were conducted in order to characterize the morphological and chemical composition, carbohydrate and protein fractions and the degradation rate of potentially degradable CP in samples of grazed stratum of Colonião, Marandu and Mulato grasses intensively grazed at high stocking rates and variable defoliation intervals ( 95% LI) during spring, summer and autumn. Comparative analyses for grasses chemical and morphological composition forage mass production (kg MS.ha-1), protein and carbohydrates fractions, in situ fractionation and CP, NDF and MS degradation rates, and protein fractions in vitro degradation rates during seasons. On first trial, statistical effects among seasons were found for forage mass and morphological components (P<0.05), DM, NDF, fat, CP, NDIN, NIDA and ash chemical contents (P<0.05), and for carbohydrates (TC, A, B1 and B2) and protein (A, B1, B2 and B3) (P<0.1) fractions. Protein degradation rates (B1, B2, B3 and B1+B2) and the values estimated by in situ degradation method for DM, NDF and CP did not differ (P<0.1) among seasons. However, statistical effects were found for effective degradability (ED) of DM and NDF (P<0.1). On second trial statistical effects were found among season for forage mass yield, DM, NDF, ADF, fat and ash, A+B1 and TC fractions (P<0.05). Only B1 protein fraction was affected (P<0.1) by seasons. Values of protein fractions degradation rates (B1, B2 and B3) did not differ (P<0.1) among seasons. Estimation of in situ degradability of DM, CP and NDF did not differ (P<0.1) among seasons. On third trial, statistical effects were not observed for forage mass yield among seasons. In relation to morphological composition, stems proportion presented the higher values in autumn (P<0.05). Statistical effects were found among seasons for DM, NDF, ADF, fat and ash, A+B1 and B2 carbohydrate fractions (P<0.05) and for A, B1 and B2 protein fractions (P<0.1). The values of protein fraction degradation rates (B1, B2, B3 and B1 + B2) did not differ (P <0.1) among seasons. The estimation of in situ degradability of DM, CP and NDF showed statistical effects (P <0.1) for Lambda, degradation rate (kdNRC) and effective degradability (ED) among seasons. The grasses evaluated have low proportion of high ruminal degradability carbohidrates (A+B1), while the values for rapidly degraded protein fractions (A, B1 e B2) was high. As consequence, a limitation on efficiency of use of degradable protein on rumen may occur, especially when pastures were intensively fertilized with N to elevate stocking rate.

Com o crescimento da população mundial aumenta a preocupação com a produção de alimentos. Hoje em dia aproximadamente 40 % da área de superfície do planeta livre de gelo é usada para a agricultura. O Brasil se destaca no cenário mundial como um dos grandes produtores e um dos países com maior potencial de crescimento em área para produção de alimentos. As culturas brasileiras que ocupam maior espaço territorial são a soja, cana-de-açúcar, milho e pastagem. Este trabalho tenta representar esses agrossitemas no modelo da biosfera SiB2 (Simple Biosphere Model) com a implementação de algumas rotinas para melhor representar as culturas agrícolas como: épocas de plantio e colheita, alocação de carbono nas diferentes partes da planta (raiz, folha, caule e grãos), acúmulo de biomassa, dinâmica da vegetação(crescimento da vegetação, emergência, crescimento e senescência das folhas), enchimento de grãos, cálculo do perfil de velocidade do vento dentro do dossel, decomposição da matéria orgânica e transformação em Nitrogênio. A validação do modelo se deu por meio da comparação com dados mensurados de biomassa e índice de área foliar (IAF). Comparando as observações da matéria seca dos ciclos da cana-de-açúcar, o ciclo 2005/2006 foi mais produtivo que o ciclo 2006/2007 (48,1±10,9 e 32,0±5,4 Mg ha-1). As simulações da cana-de-açúcar foram superestimadas (52,3 e 35,8 Mg ha-1) quando comparadas com as observações, devido ao fato da biomassa seca das folhas estar superestimada. A simulação da produtividade (17,1 Mg ha-1) do milho ficou um pouco abaixo do valor observado porém dentro do intervalo do intervalo de confiança das medidas de campo (17,6±2,5 Mg ha-1). A simulação da soja (3,9 Mg ha-1) foi aquela que mais se aproximou da observação (3,7±0,5 Mg ha-1). A comparação entre os valores simulados e observados de IAF da pastagem mostrou a sazonalidade dessa variável, sendo que os meses de maiores e menores valores estão compatíveis com a observação. Outra analise feita neste trabalho, foi a análise de sensibilidade do modelo às variações do clima.Para tanto, foram simulados cenários de mudanças climáticas, alterando-se as variáveis precipitação e temperatura, considerando-se a cultura da soja. Os resultados que o modelo demonstrou uma maior sensibilidade ao déficit hídrico, pois diminuindo-se a precipitação houve menor acúmulo de biomassa durante o ciclo. Porém com mais precipitação não ocorre mudanças significativas no acúmulo de biomassa. Há maior produção de biomassa quando o ambiente é mais frio e menor produção quando a temperatura é mais elevada, devido ao fato de tardar o florescimento o que faz com que aumente a biomassa acumulada nas folhas e com o IAF maior a planta acumula mais biomassa. / The constant increasing of world population raises the concern about food production. Nowadays approximately 40% of the planet surface that is free of ice is used for agriculture. Brazil stands out on the world stage as a major producer, and presents a potential to grow even more in food production. The Brazilian crops that occupy the largest territorial area are sugar cane, soybeans, corn and pasture. This work tries to represent these agrosystems in a biosphere model (Simple Biosphere Model, SiB2) with implementation of some routines for better representation of agricultural crops such as planting and harvesting times, allocation of carbon in different parts of the plant (root , leaf, stem and grains), accumulation of biomass, vegetation dynamics (vegetation growth, emergence, growth and senescence of leaves), grain filling, wind speed profile within the canopy, organic matter decomposition and transformation into Nitrogen. Model validation was carried out through comparison with measured data of biomass and leaf area index (LAI). Comparing the simulations of sugar cane cycles, the 2005/2006 was more productive than the 2006/2007 cycle (48.1 ± 10.9 and 32.0 ± 5.4 Mg ha-1). Simulations of sugar cane yield overestimated (52.3 and 35.8 Mg. ha-1) observed values when compared with the observations due to the fact that the biomass in leaves is overestimated. The simulation of corn productivity (17.1 Mg ha-1) was a little lower than observed but within the range of error (17.6 ± 2.5 Mg ha-1). Simulation of soybean (3.9 Mg ha-1) is the one closest to observation (3.7 ± 0.5 Mg ha-1). The comparison of pasture LAI showed the seasonality of the IAF and the months of highest and lowest values are compatible with observations. Another analysis in this study was the sensitivity of this model to climate change scenarios. Scenarios were simulated by changing the climatic variables precipitation and air temperature. Soybean crop was used as an example. The model showed sensitivity to water deficit, since decreasing rainfall the plants accumulated less biomass in the total cycle, and with more precipitation significant changes do not occur in biomass accumulation. There is a greater biomass production when the environment is cooler and less production when the temperature is higher, due to the fact that the latest flowering causes increase biomass accumulated in the leaves and the IAF greater plant biomass accumulates more.

A matéria orgânica particulada (MOP) é a principal fonte de energia em ecossistemas lóticos, podendo ser gerada dentro ou fora do ecossistema. Os processos de produção e decomposição são particularmente importantes para a ciclagem dos nutrientes no ecossistema, afetando as relações entre biodiversidade e suas funções e propriedades. No Brasil existem poucas informações sobre a dinâmica deste material orgânico nos sistemas aquáticos, apesar das grandes dimensões das bacias hidrográficas brasileiras, e da associação destas com a vegetação ripária. Sendo assim, o presente trabalho tem como objetivo a avaliação dos efeitos dos fatores reguladores da decomposição de matéria orgânica alóctone em sistemas aquáticos, bem como os padrões de retenção, acúmulo de detritos e ciclagem de nutrientes em três rios localizados em áreas distintas, sendo dois em área florestada conservada e outro localizado em área de pastagem. Os resultados obtidos contradizem as duas hipóteses iniciais na qual a espécie de gramínea C4 (B. brizantha), devido a alta relação C:N, alto teor de lignina e baixa concentração de nitrogênio, apresentaria menores taxas de decomposição quando comparada a espécie C3 (M. schottiania) e que a decomposição de ambas as espécies seria maior no rio situado na áreas de pastagem, devido a maior temperatura causada pela maior incidência de sol neste área, que estimularia a atividade microbiana e, portanto a decomposição do resíduo. A temperatura, frequentemente relatada na literatura como principal parâmetro ambiental regulador da decomposição, não se mostrou determinante no processo de decomposição, uma vez que as maiores de perda dos detritos ocorrem no rio situado na floresta, onde os menores valores de temperatura da água foram encontrados. Sendo assim, outros fatores se mostraram mais atuantes neste processo, como as características dos substratos e a concentração de nitrato dissolvido na água. Com relação à decomposição das espécies, a B. brizantha, apesar de nutricionalmente pobre, com baixa concentração inicial de nitrogênio e alta razão C:N, foi a espécie que teve maior perda de massa nos três rios analisados, devido sua baixa concentração de lignina, composto mais recalcitrante encontrado no tecido vegetal. A lignina também se mostrou determinante na dinâmica de perdas dos demais nutrientes das duas espécies, visto que este composto pode interagir com demais constituintes celulares, formando complexos que \"mascaram\" a decomposição dos compostos mais lábeis. Sendo assim, a interação entre quantidade de nutrientes e a forma na qual este estão disponíveis será de extrema importância para a definição da velocidade de decomposição dos detritos foliares no meio ambiente / The particulate organic matter (POM) is the main energy source in stream ecosystems, which may be generated inside or outside the ecosystem. The production and decomposition processes are particularly important for nutrient cycling at the ecosystem, affecting the relationships between biodiversity and its functions and properties. In Brazil, there is little information on the dynamics of organic matter in aquatic systems, besides the great dimensions of Brazilian watersheds, and its association of those with riparian vegetation. Thus, the present study aims to evaluate the effects of factors that regulate decomposition of allochthonous organic matter in aquatic systems, as well as the patterns of retention, accumulation of debris and nutrient cycling in three rivers located in different areas, two in a preserved forest area and one in a pasture area. Our results contradict the two initial hypothesis that decomposition would be slower for C4 plants (grass), due its higher C:N, higher lignin content and low nitrogen ratios, in any environment, and that decomposition rates would be faster in the pasture streams due to the higher water temperature caused by the high incidence of sun in this area, which would stimulate microbial activity, and thus the decomposition of the residue. Temperature, commonly reported in the literature as the main environmental regulator of decomposition, was not decisive in the decomposition process, since the larger losses of mass leaf occurred at the river located at the forest, where the lowest water temperature values were found. Therefore, other factors were more effective to determine the decomposition process, such as the characteristics of the substrate and the concentration of dissolved nitrate in the water. Regarding the differences at the decomposition rates of the species, B. brizantha, although nutritionally poor, with low initial nitrogen concentration and high C: N ratio, was the species with greater weight loss at the three rivers studied, due to its low lignin concentration, which is the most recalcitrant compound found in the plant tissue. Lignin also influenced the dynamic of nutrient losses of the two species, since this compound can interact with other cellular constituents, preventing the decomposition of the most labile compounds. Thus, the balance between the amount of nutrients and the form in which they are available will be extremely important to define the decomposition rate of leaf litter at the environment

The influence of agronomic practices on forage production and chemical composition of an orchardgrass-bromegrass pasture mixture was studied at the Greenville Farm, Logan, Utah, during 1960-1964. The soil is a well drained Millville Silt loam that has about a one percent slope and occurs on an alluvial fan. It is high in potash, phosphorus and calcium and is alkaline having a pH of 7.9 to 8.2. Analysis of the clipping frequency showed that the yield of forage from four harvests was greater than from five harvests. This difference was greater on plots receiving high rates of nitrogen fertilization, and frequent irrigation. Nitrogen, phosphorus, calcium, copper, iron and zinc contents were lower with five harvests. Forage production increased significantly as the available moisture in the soil increased, producing the highest yields for the 5-day irrigation interval. Nitrogen, copper, iron and zinc in the foliage decreased and phosphorus and calcium increased with increasing soil moisture. On the contrary, potassium content did not show a specific trend with increasing soil moisture. Nitrogen fertilization increased the forage dry matter production significantly giving the highest yield for 200 pounds of applied nitrogen per acre per season. The percentage of nitrogen in harvested forage decreased up to 100 pounds per acre of applied nitrogen and slightly increased with 200 pounds. Calcium, iron and manganese contents decreased and zinc content slightly increased with an increase in the amount of nitrogen fertilization. On the other hand, phosphorus, potassium and copper contents did not show a consistent trend with increasing nitrogen fertilization. A difference was noted between the amount of forage produced for different years. However, there was a tendency of decreasing forage yield with increasing age of stand. Nitrogen and phosphorus contents increased and copper, iron and manganese decreased significantly with the increasing age of stand. Potassium, calcium, and zinc contents showed a gradual decrease with the age of forage but there was a fluctuating tendency in their content for different years.

This thesis describes the research undertaken for the degree of Doctor of Philosophy, testing the hypothesis that spectrometer data can be used to establish usable relationships for prediction of pasture quality attributes. The research data consisted of reflectance measurements of various temperate pasture types recorded at four different times (years 2000 to 2002), recorded by three hyperspectral sensors, the in situ ASD, the airborne HyMap and the satellite-borne Hyperion. Corresponding ground-based pasture samples were analysed for content of chlorophyll, water, crude protein, digestibility, lignin and cellulose at three study sites in rural Victoria, Australia. This context was used to evaluate effects of sensor differences, data processing and enhancement, analytical methods and sample variability on the predictive capacity of derived prediction models. Although hyperspectral data analysis is being applied in many areas very few studies on temperate pastures have been conducted and hardly any encompass the variability and heterogeneity of these southern Australian examples. The research into the relationship between the spectrometer data and pasture quality attribute assays was designed using knowledge gained from assessment of other hyperspectral remote sensing and near-infrared spectroscopy research, including bio-chemical and physical properties of pastures, as well as practical issues of the grazing industries and carbon cycling/modelling. Processing and enhancement of the spectral data followed methods used by other hyperspectral researchers with modifications deemed essential to produce better relationships with pasture assay data. As many different methods are in use for the analysis of hyperspectral data several alternative approaches were investigated and evaluated to determine reliability, robustness and suitability for retrieval of temperate pasture quality attributes. The analyses employed included stepwise multiple linear regression (SMLR) and partial least squares regression (PLSR). The research showed that the spectral research data had a higher potential to be used for prediction of crude protein and digestibility than for the plant fibres lignin and cellulose. Spectral transformation such as continuum removal and derivatives enhanced the results. By using a modified approach based on sample subsets identified by a matrix of subjective bio-physical and ancillary data parameters, the performance of the models were enhanced. Prediction models from PLSR developed on ASD in situ spectral data, HyMap airborne imagery and Hyperion and corresponding pasture assays showed potential for predicting the two important pasture quality attributes crude protein and digestibility in hyperspectral imagery at a few quantised levels corresponding to levels currently used in commercial feed testing. It was concluded that imaging spectrometry has potential to offer synoptic, simultaneous and spatially continuous information valuable to feed based enterprises in temperate Victoria. The thesis provide a significant contribution to the field of hyperspectral remote sensing and good guidance for future hyperspectral researchers embarking on similar tasks. As the research is based on temperate pastures in Victoria, Australia, which are dominated by northern hemisphere species, the findings should be applicable to analysis of temperate pastures elsewhere, for example in Western Australia, New Zealand, South Africa, North America, Europe and northern Asia (China).

Pasture plants already adapted to acidic soil conditions are required as part of an integrated approach (with lime amelioration) to managing acid soils on the Tablelands of New South Wales, Australia. The objective of this thesis is to evaluate the usefulness of Austrodanthonia species for this purpose. The material evaluated in this study was collected during a previous survey of the distribution of Austrodanthonia on the Central, Southern and Monaro Tablelands of New South Wales. It was hypothesised that the genus Austrodanthonia has a wide range of tolerance to acid soils. A series of experiments that provided information on the growth and physiology of Austrodanthonia in relation to soil acidity, with a view to the identification and eventual domestication of the most promising plant material have been conducted through pot, hydroponics and field investigations. Firstly, soils were acidified or limed to obtain a range of soil pH and Al concentrations. This experiment showed that adding aluminium sulfate and calcium carbonate followed by washing excess salts with water is a simple, rapid and convenient method for adjusting soil pH for pot experiments. The pH of the amended soils remained relatively unchanged eight months after treatment. The experimental set-up also resulted in a wide range of soluble Al (2-52 mg/kg) across the soils. The relative Al-tolerance of 183 accessions from 15 Austrodanthonia species was tested in a pot experiment using a range of soil pH. Emergence, survival and growth of all accessions were drastically reduced by high soil acidity (pH 3.9, P < 0.001). About 11% of plants emerged at pH 3.9, whereas at pH 4.4 and 5.3, ~72% of plants emerged. Accessions exhibited large variation within and between species in their tolerance to soil acidity. From the species/accessions tested, 49 accessions from eight species were selected for further study (on the basis of being more acid tolerant). Hydroponic experiments conducted in the glasshouse evaluated: (i) formulation of nutrient solution with a stable pH, (ii) effectiveness of the formulation using tap water and deionised water and (iii) estimation of free ion activities of Al and Mn in the nutrient solution and their effects on Austrodanthonia growth. These experiments showed that a NO3-N/NH4-N ratio of 9:4 is the most appropriate ratio to obtain a stable pH 4.0 without affecting plant growth; that there was little difference between tap water and deionised water on the ionic effects of Al and Mn, and plant-size did not play a role on accession survival and that accessions of Austrodanthonia could grow well within a wide range of pH (3.5-5.5), Al (50-250 �M) and Mn (100-2000 �M). Growth of Austrodanthonia accessions declined under high acidity (pH < 3.5) and Al (300 �M), but tolerated high concentrations of Mn (2000 �M). Root-tips stained with hematoxylin grouped accessions in a similar way to the pot and hydroponic experiments for most of the accessions tested. The intensity of root staining with hematoxylin and the differential distribution of Al in the shoots and roots provided an indication that different tolerance mechanisms may be involved with Austrodanthonia accessions. It appears that both exclusion and internal mechanisms may operate for Al- and Mn-tolerance. A field experiment was conducted at Carcoar (33037�S, 149013�E, elevation 800 m) using gradients in soil pH and Al available on-site to grow selected accessions of Austrodanthonia. The accessions exhibited a range of responses to soil acidity. The accession responses to acidity from the pot and hydroponic experiments were similar to those obtained in the field, especially where Al was present as a low Al-challenge. Overall, this study shows that Austrodanthonia exhibits a wide range of acid tolerance between species and accessions within species. Among the species tested, A. duttoniana and A. fulva appeared to have the greatest commercial potential, because of their productivity and acid tolerance. The variability that exists in the accessions may be exploitable in breeding and selection programs for improved cultivars.

The transformation of the rangelands of the South Island of New Zealand during the pastoral era fits into the wider international context of European expansion into the 'new' world. European settlers displaced native peoples, introduced 'old' world animals and plants, and imposed a capitalist system that converted local resources into international commodities. In New Zealand the orthodox explanation of the pastoral impact on the rangelands claims that pastoralists introduced an unsustainable system of land use to the region. The pastoralists� indiscriminate burning practices and overstocking with sheep opened up the country to invasion by rabbits. Burning and overgrazing by sheep and rabbits stripped the natural fertility of the soils and left the country depleted, eroded, and overwhelmed by pests and weeds. This thesis sets out to test those claims. It explores burning, the stocking of the rangelands with sheep and the impact of rabbits in detail. It also examines other land management practices, as well as sheep breeding, to see what impact they had on the landscape. The timeframe is set between 1841, when formal British settlement was established in the South Island, and 1912, by which time most of the great estates and stations had been broken up into smaller runs and farms. The thesis uses station diaries, memoirs, contemporary newspapers and farming journals to assess what happened on the ground during the pastoral era. In particular, the thesis uses Mt Peel Station as a case study to examine the intensification in land use that took place between 1841 and 1912, in order to explain the transformation of the landscape and to answer the questions: what happened, how did it happened and why did it happened as it did? These sources illustrate that the pastoral era was characterised by innovation. Pastoralists had access to technical and scientific information from around the world. Some conducted their own experiments to improve the productivity of the land and their stock. There was also a learning process involved in adapting their methods to fit the local rangeland environments. They were not simply rapacious capitalists out to strip the wealth from the land for their own personal gain; indeed, many pastoralists set out to establish viable and sustainable enterprises. The thesis argues that the rangelands consisted of a variety of landscapes and climates. Differences in resource endowments had a considerable influence in shaping the environmental outcomes on different stations. Aridity and rabbits were two key factors in the depletion of the vegetation and the degradation of the landscape in the rangelands. Runs in semi-arid districts that were overwhelmed by rabbits suffered long-term damage. In districts where rainfall was more reliable stations that had been overrun by rabbits recovered remarkably quickly. Stations like Mt Peel, that were largely unaffected by the first rabbit plague, were able to maintain and even increase their productivity up to the time they were subdivided. The orthodox analysis of the transformation of the rangelands in the pastoral era does not account for these differences in outcomes.

The experiments described in this thesis were designed to assess changes in pasture dynamics (biomass and species composition of pasture) of grazing land on the Southern Tablelands of ACT and NSW, after 16 combinations of rabbit control treatments had been applied. The rabbit control performed by CSIRO Division of Wildlife and Ecology consisted of all combinations of presence-absence of Poisoning (using sodium monofluoroacetate, 1080: POIS), Ripping (ripping warrens using a tractor fitted with ripping tynes: RIP), Fumigation (pressure fumigation using chloropicrin: FUM) and repeated follow-up fumigation (using phostoxin pellets one, six and eighteen months after completion of the initial treatment: ANN). The pasture was assessed before treatments were applied, and every six months after rabbit control treatments. Treatment combinations were assigned randomly in a 24 factorial design on a total of 32 sites. There was a significant increase of pasture biomass at the RIP+ANN treatment at post-treatment sample 5. The analysis of covariance did not detect any other significant increase or decrease of pasture biomass for any rabbit control treatment, at any posttreatment sample. A significant increase of grass species occurred for the treatments of POIS+RIP+FUM, POIS and RIP+ANN for the post-treatment samples of 1, 3 and 5 respectively. There was a significant increase of thistles at the rabbit control treatments of POIS+RIP+FUM+ANN (post-treatment sample 1), RIP, ANN, RIP+FUM, RIP+FUM+ANN and POIS+RIP+FUM+ANN (post-treatment sample 3) and RIP and FUM+ANN (post-treatment sample 5). A significant increase of weeds occurred at FUM (post-treatment sample 3) and at FUM+ANN (post-treatment sample 5). No significant changes in the amount of herbs or legumes was apparent for any rabbit control treatment or post-treatment sample. There were no significant decreases for any species group. Except for the significant results for post-treatment sample 1, all significant increases of biomass for any species group occurred during spring (post-treatment sample 3 and 5) which suggests a growth phase during spring then subsequent dieback (particularly for thistles and weeds), as any change was not detected in the following autumn sample. No strong trend is evident for any particular rabbit control treatments, or any combination of treatments. Analysis of covariance revealed that the rabbit control treatment of RIP+ANN showed significant increases in both total biomass of pasture and grass biomass during post-treatment sample 5. This treatment reduced the number of active entrances the most. Significant positive correlations were found between pasture biomass (total) with grass, herb, legume, thistle and weed species groups. Significant negative correlations between grass biomass and the number of active entrances were found when the rabbit control had been highly effective in reducing the number of active entrances. When rabbit control had not been very successful, there was a significant positive but low correlation with the number of active entrances. There was no significant relationship between the number of active entrances with the weight of rabbit dung pellets. It is reasoned that they are different measures of rabbit abundance. More rabbit dung pellets were found closer to the warren than further away from the warren, but there was no correlation between rabbit dung and pasture biomass. Rainfall was above average for most of the experiment, biomass increased accordingly, and rabbit control was highly successful. The resulting changes in the pasture were difficult to detect, although some increases in species composition groups occurred. It is reasoned that the changes observed are partly attributable to seasonal conditions, and to high rainfall. Grazing by domestic animals, sheep and cattle, had been found to be consistent throughout the experiment.