Orientador: Marcelo Andreotti / Resumo: Os Sistemas Integrados de Produção Agropecuária tornam-se cada vez mais importantes, devido principalmente às dificuldades encontradas pelos pecuaristas em investir o capital na reforma das pastagens, e, dos agricultores, na recuperação do potencial produtivo das lavouras, no tocante a problemas relacionados à redução do teor de matéria orgânica do solo, ocorrência de pragas, doenças, nematoides e plantas daninhas. Nestes sistemas, a utilização de pastagens na entressafra pode servir como auxílio a estes entraves. Portanto, este trabalho de pesquisa objetivou determinar a produtividade e a qualidade de silagens de sorgo forrageiro em consórcio com a Urochloa brizantha cv. Marandu, Megathyrsus maximum cv. Mombaça e/ou guandu-anão (Cajanus cajan); e a produtividade e qualidade da pastagem de capim-marandu e capim-mombaça, após o consórcio com o sorgo no Sistema Integrado de Produção Agropecuária em um LATOSSOLO VERMELHO distrófico típico argiloso na região de Cerrado de baixa altitude, no período de dois anos agrícolas (2013/2014 e 2014/2015). E ao final do experimento avaliar as alterações nos atributos químicos e físicos do solo, nas camadas de 0 a 0,10 m e de 0,10 a 0,20 m de profundidade, bem como analisar o desempenho econômico da produção das silagens de sorgo em consórcios com gramíneas tropicais e/ou guandu-anão em Sistema Integrado de Produção Agropecuária durante o período de estudo. Os resultados demonstram que o consórcio do sorgo forrageiro com as gramíneas U. briz... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Currently, integrated agricultural production systems become increasingly important, mainly due to difficulties encountered by farmers to invest capital in the reform of the pastures, and farmers in the recovery of the potential productive of crops, in respect of related problems in reducing the organic matter of soil, occurrence of pests, diseases, nematodes and weeds. In these systems, the use of pastures in the off season can serve as an aid to these barriers. Therefore, this research aimed to determine the productivity and quality of sorghum forage in consortium with Urochloabrizantha cv. Marandu, Megathyrsusmaximum cv. Mombaça and/or dwarf pigeon pea (Cajanuscajan); and productivity and quality Marandu and Mombaça grass pasture after the consortium with sorghum in the Integrated Agricultural Production System in a LATOSSOLO VERMELHO distrófico típico argiloso soil in lowlying Cerrado region during the two agricultural years in 2013/2014 and 2014/2015. At the end of the experiment was to evaluate changes in chemical and physical properties of soil, layer 0 to 0.10 m and 0.10 to 0.20 m deep and analyze the economic performance of the production of sorghum silage in consortia with tropical grasses and/or pigeon pea dwarf in Integrated Agricultural Production during the study period. The results demonstrate that the consortium of sorghum with the Marandu, Mombaça and/or pigeon pea dwarf at the first cut were viable for the production of silage both in quantity and in bromato... (Complete abstract click electronic access below) / Doutor

The population in the high mountains of the northwest provinces of Vietnam belongs to the poorest population in the country. Among the reasons behind this are the high frequency of minority groups in the region and the infertile soils of the steep slopes. As a result of the diversified elevation in northwest Vietnam, farmers are forced to cultivate fields with a gradient of more than 25 %. Additionally, the heavy rainfall events in the region increase the runoff, which is the main mechanism in erosion. Erosion leads to loss of bulk soil, and large losses of plant nutrients. In addition to erosion, nutrient leakage also occurs especially where a surplus of nutrients is applied. This is often the case when fertilizers are not applied with care. Nutrients are a limiting factor within agriculture, and with better nutrient management, the yield, and thus the farmers' economy, increases.The overall aim of this study was to locate and quantify sources and sinks of nutrients within the ten chosen farms. To achieve this aim, two specific objectives were researched. The first objective was to quantify the farm gate balance to get an overall idea of nutrient surplus and deficit and environmental risks. The second objective was to quantify and map out the internal flows i.e the field balances and the nutrients lost during manure storage. This will help locate sources and sinks of nutrients within each farm. Additionally, it will show if the grass strips help absorb nutrients lost through erosion.The study was carried out in Mai Son District in Son La Province in northwest Vietnam. The data was mainly collected through interviews with farmers on ten farms in the study area, as well as observations made during the field visit. Five farms with cows were chosen, while five farms had no cows. The farms mainly grew maize, longan, mango, and forage grass. Additionally, analyses were made on the nitrogen, phosphorous and potassium concentration in the compost, and the nitrogen concentration of the Guinea grass (Panicum maximum Jacq) which made up the grass-strips in the sloping land. The analysis of Guinea leaves was made to calibrate the SPAD-meter used in the field to gather nitrogen-values of the grass strips in the fields.The calculated balances indicated that the elements N, P and K on each farm varied between 32 to 580 kg/ha/year for N, -680 (16) to 53 kg/ha/year for P and -130 to 220 kg/ha/year for K. It also showed that Guinea grass, when grown along the contour lines, did as anticipated; absorb excess nutrients from the soil. However, the result shows that the forage grass mines the soil from potassium. Finally, the result showed that the farmers seem to over fertilize the plants. When estimating the nutrient lost from manure storage, the calculation showed significant losses of both nitrogen, phosphorus, and potassium during storage.The result of the study shows that the handling of manure, choice of compost or mineral fertilizer and fodder and use of grass strips on the farms affects the nutrient loss within the farm. It also shows that a system with forage grass on the contour is, above all, effective when used on farms with grass eating animals as the farmers otherwise don’t harvest the grass.

Lam, Shu Kee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 206-219). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgements --- p.vi / Table of contents --- p.vii / List of tables --- p.xii / List of figures --- p.xvi / List of plates --- p.xvii / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1.1 --- Research background --- p.1 / Chapter 1.2 --- Conceptual framework --- p.4 / Chapter 1.3 --- Objectives of the study --- p.8 / Chapter 1.4 --- Significance of the study --- p.9 / Chapter 1.5 --- Organization of the thesis --- p.10 / Chapter CHAPTER 2 --- LITERATURE REVIEW / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Use of hydroseeding in slope bioengineering works --- p.12 / Chapter 2.3 --- Problems associated with hydroseeded slopes --- p.12 / Chapter 2.4 --- Common Bermudagrass used in hydroseeding --- p.13 / Chapter 2.5 --- "Sludge disposal, potentials and problems" --- p.14 / Chapter 2.5.1 --- Properties and disposal of sludge --- p.14 / Chapter 2.5.2 --- Use of sludge and potential problems --- p.16 / Chapter 2.5.3 --- Heavy metals in sludge --- p.19 / Chapter 2.5.3.1 --- Cadmium --- p.22 / Chapter 2.5.3.2 --- Chromium --- p.22 / Chapter 2.5.3.3 --- Copper --- p.23 / Chapter 2.5.3.4 --- Nickel --- p.24 / Chapter 2.5.3.5 --- Lead --- p.24 / Chapter 2.5.3.6 --- Zinc --- p.25 / Chapter 2.5.4 --- Speciation of heavy metals --- p.25 / Chapter 2.5.5 --- Factors affecting the bioavailability of heavy metals --- p.26 / Chapter 2.5.5.1 --- Reaction pH --- p.26 / Chapter 2.5.5.2 --- Organic matter --- p.28 / Chapter 2.5.5.3 --- Fertilizers --- p.29 / Chapter 2.5.6 --- Effect of heavy metals on plant growth --- p.29 / Chapter 2.5.7 --- Effect of heavy metals on animals and water bodies --- p.31 / Chapter 2.6 --- "Lime, heavy metals and plant growth" --- p.32 / Chapter 2.6.1 --- Effect of lime on heavy metal dynamics --- p.32 / Chapter 2.6.1.1 --- Competition with heavy metals for adsorption sites --- p.32 / Chapter 2.6.1.2 --- Immobilization of heavy metals --- p.32 / Chapter 2.6.2 --- Effect of lime on plant growth --- p.34 / Chapter 2.7 --- Effect of precipitation on slopes --- p.35 / Chapter 2.7.1 --- Infiltration --- p.35 / Chapter 2.7.2 --- Surface runoff --- p.38 / Chapter 2.7.3 --- Soil erosion --- p.39 / Chapter 2.8 --- Summary --- p.42 / Chapter CHAPTER 3 --- EFFECT OF SLUDGE AND LIME ON ABOVEGROUND BIOMASS OF COMMON BERMUDAGRASS / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.2 --- Materials and methods --- p.44 / Chapter 3.2.1 --- Materials --- p.45 / Chapter 3.2.2 --- Experimental design --- p.46 / Chapter 3.2.3 --- Grass clipping and pre-treatment --- p.49 / Chapter 3.3 --- Chemical analysis --- p.50 / Chapter 3.3.1 --- Properties of decomposed granite --- p.50 / Chapter 3.3.2 --- "Properties of sludge," --- p.52 / Chapter 3.3.3 --- Nitrogen of grass clippings --- p.52 / Chapter 3.4 --- Statistical analysis --- p.53 / Chapter 3.5 --- Results and discussion --- p.54 / Chapter 3.5.1 --- Properties of DG and sludge --- p.54 / Chapter 3.5.2 --- Aboveground biomass of grass --- p.56 / Chapter 3.5.3 --- Effect of sludge on aboveground biomass --- p.63 / Chapter 3.5.4 --- Effect of lime on aboveground biomass --- p.66 / Chapter 3.5.5 --- Synergic effect of sludge and lime on aboveground biomass --- p.68 / Chapter 3.5.6 --- "Effect of sludge on nitrogen uptake by grass shoots," --- p.69 / Chapter 3.6 --- Summary --- p.72 / Chapter CHAPTER 4 --- EFFECT OF SLUDGE AND LIME ON HEAVY METAL UPTAKE BY COMMON BERMUDAGRASS / Chapter 4.1 --- Introduction --- p.74 / Chapter 4.2 --- Materials and methods --- p.77 / Chapter 4.2.1 --- Materials and experimental design --- p.77 / Chapter 4.2.2 --- Analysis of heavy metals in grass shoots --- p.77 / Chapter 4.2.3 --- Reaction pH at the end of Part 1 --- p.77 / Chapter 4.2.4 --- Statistical analysis --- p.78 / Chapter 4.3 --- Results and discussion --- p.78 / Chapter 4.3.1 --- Cumulative uptake of heavy metals by common Bermudagrass --- p.79 / Chapter 4.3.2 --- Effect of sludge on heavy metal uptake --- p.84 / Chapter 4.3.3 --- Effect of lime on heavy metal uptake --- p.86 / Chapter 4.3.4 --- Synergic effect of sludge and lime on cumulative heavy metal uptake --- p.88 / Chapter 4.3.5 --- Effect of fertilizer addition --- p.91 / Chapter 4.3.6 --- Concentration of heavy metals in grass --- p.93 / Chapter 4.3.7 --- Effect of pH on heavy metal uptake --- p.98 / Chapter 4.3.8 --- Effect of heavy metal uptake on aboveground biomass --- p.100 / Chapter 4.4 --- Summary --- p.103 / Chapter CHAPTER 5 --- EFFECT OF SLUDGE AND LIME ON HEAVY METALS IN LEACHATE / Chapter 5.1 --- Introduction --- p.106 / Chapter 5.2 --- Materials and methods --- p.107 / Chapter 5.2.1 --- Leachate collection --- p.108 / Chapter 5.2.2 --- Analysis of leachate --- p.109 / Chapter 5.2.3 --- Statistical analysis --- p.109 / Chapter 5.3 --- Results and discussion --- p.110 / Chapter 5.3.1 --- Effect of sludge and lime on leachate volume --- p.110 / Chapter 5.3.2 --- Leachate pH and the effect of sludge and lime --- p.115 / Chapter 5.3.3 --- Heavy metal contents in leachate --- p.119 / Chapter 5.3.4 --- Effect of sludge and lime on the leaching of heavy metals --- p.121 / Chapter 5.3.5 --- Effect of pH on the leaching of heavy metals --- p.125 / Chapter 5.4 --- Summary --- p.126 / Chapter CHAPTER 6 --- "LEACHATE, SURFACE RUNOFF, SEDIMENT YIELD AND THEIR HEAVY METALS" / Chapter 6.1 --- Introduction --- p.128 / Chapter 6.2 --- Materials and methods --- p.130 / Chapter 6.2.1 --- Materials --- p.130 / Chapter 6.2.2 --- Experimental design --- p.132 / Chapter 6.2.3 --- Rainfall intensities in simulation experiment --- p.134 / Chapter 6.2.4 --- Selection of slope gradient --- p.136 / Chapter 6.2.5 --- Rainfall simulation --- p.136 / Chapter 6.2.6 --- "Leachate, surface runoff and runoff sediment" --- p.137 / Chapter 6.2.7 --- Properties of decomposed granite and sludge --- p.138 / Chapter 6.2.8 --- "Heavy metals in leachate, surface runoff and runoff sediment" --- p.139 / Chapter 6.2.9 --- Statistical analysis --- p.140 / Chapter 6.3 --- Results and discussion --- p.140 / Chapter 6.3.1 --- Properties of DG and sludge --- p.140 / Chapter 6.3.2 --- "Leachate, surface runoff and runoff sediment production" --- p.142 / Chapter 6.3.3 --- "Heavy metal concentrations in leachate, surface runoff and runoff sediment" --- p.153 / Chapter 6.3.3.1 --- Heavy metal concentrations in leachate --- p.153 / Chapter 6.3.3.2 --- Heavy metal concentrations in runoff --- p.163 / Chapter 6.3.4 --- Cumulative loss of heavy metals --- p.170 / Chapter 6.3.4.1 --- Cumulative loss of heavy metals from leachate --- p.170 / Chapter 6.3.4.2 --- Cumulative loss of heavy metals from runoff --- p.178 / Chapter 6.3.4.3 --- "Heavy metal loss from leachate, surface runoff and runoff sediment" --- p.185 / Chapter 6.4 --- Summary --- p.189 / Chapter CHAPTER 7 --- CONCLUSIONS / Chapter 7.1 --- Summary of major findings --- p.192 / Chapter 7.2 --- Implications of the study --- p.196 / Chapter 7.2.1 --- Potential use of sludge in slope bioengineering works --- p.196 / Chapter 7.2.2 --- Measures to optimize the benefits of sludge in land application --- p.198 / Chapter 7.3 --- Limitations of the study --- p.200 / Chapter 7.4 --- Suggestions for further study --- p.202 / REFERENCES --- p.206 / APPENDICES --- p.220

South African dairy farmers have generally used kikuyu pasture to tide them over from one ryegrass season to the next, and as a result of its resilient nature, have assumed careful management of it to be unnecessary. This has resulted in its mismanagement which is unaffordable in current times where the profitability of dairy farming is increasingly dependent on low input, pasture-based systems. Kikuyu pasture may play a larger role in supplying nutrients to dairy cattle over the summer months in future as the alternative home produced feed sources such as silage and perennial ryegrass become increasingly unaffordable. Improving animal production from kikuyu is difficult as there is little information relating kikuyu pasture management to dairy cow performance. Efficient utilization and quality of temperate pasture have been more comprehensibly researched. The relations discovered between the chemical compounds in temperate grass species have been applied to tropical pastures such as kikuyu with limited success and often confusing results. For example, crude fibre in kikuyu was found to be positively related to digestibility. In South Africa, much research has been done on the use of kikuyu in beef production systems. This information has been applied to dairy farming systems with limited success, owing to the higher metabolic demands of dairy animals. Pasture farming needs to become more precise to improve pasture quality and hence milk yields as research trials focussing on stocking rate and grazing system comparisons have yielded results that are too general with little application at the farming level. A need for integrated and flexible management of animals and pastures has been recognised. The grazing interval is a key aspect in improving pasture and animal performance and fixed rotation lengths and stocking rates have been identified as being detrimental to performance. The relation between growth stage and pasture quality has lead researchers to identify plant growth characteristics, such as pasture height and leaf stage, as signs of grazing readiness. At the four and a half leaves per tiller stage of regrowth, the chemical composition ofthe kikuyu plant is more in line with the requirements ofthe dairy cow, with the leaf to stem ratio at its highest. The primary limitation of kikuyu pasture is a lack of energy, particularly readily fermentable carbohydrate, which makes the fermentation of structural carbohydrates difficult and dry matter intakes are reduced. Other limitations to animal performance include high cell wall constituents, low calcium, magnesium and sodium content and antinutritional factors such as nitrate and insoluble oxalate. These deficiencies and antinutritional factors are in some cases unique to 5 kikuyu pasture, meaning that kikuyu specific supplementation may be the key to improving performance from dairy cattle grazing kikuyu pasture. The objectives are to evaluate current kikuyu management systems in South Africa and their impact on dairy cow performance and to evaluate the use of pasture height and burning as quality control tools. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Univ., Diss.--Budapest, 2001.

The objective if this degree work is creating a survey of possible uses of surplus grass material which is caused by animal farming reduction and by bringing the ground in less fertile areas of our country to a standstill. In the work possible uses of the grass are described, especially its use in the energy industry as a fuel source for the production of heat and biogas. Classical usage of the grass material as a food source for livestock or for the production of compost is described here as well. Examples are shown there of energy kinds of grass, which seems to be a promising renewable resource of biomass for favourable economic results. The harvest of the grass material and its consequent prossesing is done by production lines, that is why a survey of such lines and their economic figures connected with the operation of these machines is also included in this work. The economic part of this work contains many formulae that can be used for counting out all the costs connected with the operation of the grass harvest machine and for evaluating the effectiveness of the return on investment into this machine

Este trabalho foi baseado na realização de simulações computacionais 3D de parâmetros de RQD obtidos de classificação geomecânica de sondagens rotativas realizadas nas fases de investigação geológico-geotécnica e construção da barragem de Itaipu (PR), Brasil. Tais simulações foram desenvolvidas em duas áreas dispostas no entorno da barragem principal da usina, utilizando como ferramenta o programa GRASS, que executa interpolações tridimensionais pelo método numérico Spline Regularizado com Tensão (RST). Os resultados obtidos foram comparados com dados previamente interpretados e obtidos por outros métodos como os geoestatísticos e apresentaram resultados razoáveis devido as dimensões dos voxels adotados, diferenças dos métodos e distribuição espacial dos dados. / This work was based on three-dimensional computer simulations of the parameters RQD of the boreholes on geological and geotechnical research phases and construction of the Itaipu dam (PR), Brazil. These simulations were carried out in two areas arranged around the plant the main dam, using as tool the GRASS program, which performs three-dimensional interpolation by mathematical method Regularized Spline with Tension (RST) . The results were compared with data previously obtained and interpreted by other methods such as geostatistical and had reasonable results because the dimensions of the voxels adopted, differences in methods and spatial distribution of the data.

O capim-Tanzânia pode ter maior ou menor dependência do cálcio, quando há variação na disponibilidade de nitrogênio no substrato. O objetivo foi avaliar as informações relativas às alterações fisiológicas, nutricionais e produtivas desse capim, quando suprido com combinações de doses de nitrogênio e de cálcio, e verificar a ocorrência de carência de cálcio nesse capim em relação ao fornecimento desse nutriente na solução nutritiva, em presença de elevado suprimento de nitrogênio. O capim-Tanzânia foi cultivado em solução nutritiva, utilizando sílica como substrato, em experimentos em casa-de-vegetação, no período de setembro de 2004 a janeiro de 2005, em Piracicaba-SP. Dois experimentos foram realizados com delineamento estatístico de blocos ao acaso e quatro repetições. Na ocasião de cada corte a parte aérea foi separada em folhas emergentes (FE), lâminas de folhas recém-expandidas (LR), lâminas de folhas maduras (LM) e colmos mais bainhas (CB) e após o corte final da parte aérea, realizou-se a avaliação do sistema radicular. No primeiro experimento, utilizou-se o esquema fatorial 52 fracionado, com combinações de cinco doses de nitrogênio (2; 9; 16; 23 e 30 mmol L-1) e de cinco doses de cálcio (0,50; 1,75; 3,00; 4,25 e 5,50 mmol L-1) na solução nutritiva. Foram realizados três cortes nas plantas, sendo o primeiro aos 39 dias após o transplantio, o segundo aos 30 dias após o primeiro e o terceiro aos 28 dias após o segundo corte. No segundo experimento foi realizado apenas um corte nas plantas, aos 33 dias após o transplantio e as doses de cálcio na solução nutritiva foram: 0,00; 0,25; 0,50; 2,50 e 5,00 mmol L-1. A combinação entre doses de nitrogênio e de cálcio foi determinante para área foliar e valor SPAD no terceiro crescimento, para a produção de massa seca da parte aérea e de raízes e concentração de cálcio nas LR no segundo e terceiro cortes, e para a concentração de enxofre nas LR em todos os crescimentos e a de nitrogênio nas raízes do capim. O número de perfilhos e de folhas, o comprimento e a superfície radicular, as concentrações de nitrogênio, fósforo e potássio nas LR dependeram apenas do suprimento de nitrogênio. As doses de cálcio exclusivas foram determinantes para a concentração de cálcio em cada componente da parte aérea, na parte aérea total e nas raízes. A concentração de magnésio nas LR do capim decresceu tanto com o incremento no suprimento de nitrogênio como no de cálcio isoladamente. O cálcio participou em 9 a 36%, o magnésio com 17 a 28% e o potássio com 47 a 63% da carga positiva na parte aérea. A utilização de dose de cálcio correspondente a 40% daquela empregada na solução de Sarruge não restringiu parâmetros produtivos, fisiológicos e nutricionais desse capim, mesmo em presença de elevado fornecimento de nitrogênio. Sintomas de deficiência de cálcio nesse capim somente foram observados com baixíssimo suprimento ou ausência de cálcio, em condição de alta disponibilidade de nitrogênio no substrato. / Tanzânia grass may depend on calcium availability as nitrogen is changed in the substrate. The objective was to evaluate the changes in physiological, nutritional and productive parameters of this grass, when combined rates of nitrogen and calcium were supplied, and search for calcium deficiency related to the supply of this nutrient in the nutrient solution having high nitrogen rate. Tanzânia grass was grown in nutrient solution with ground quartz as substrate, in greenhouse experiments from September 2004 to January 2005 at Piracicaba, State of São Paulo, Brazil. Two experiments were carried out in Randomized Blocks design, with four replications. At each plant harvest, plant tops were separated in emergent leaves (EL), recently-expanded leaf lamina (RL), mature leaf lamina (ML) e culms plus sheaths (CS), and following the final harvest the root system was evaluated. In the first experiment, a fractionated 52 factorial was used, with combinations of five nitrogen rates (2; 9; 16; 23 e 30 mmol L-1) and five calcium rates (0.50; 1.75; 3.00; 4.25 e 5.50 mmol L-1). Three harvests were performed, the first one 39 days after seedlings transplanting, the second 30 days after the first and the third one 28 days after the second harvest. In the second experiment only one harvest was done at 33 days after seedlings transplanting and the calcium rates were: 0; 0.25; 0.50; 2.50 and 5.00 mmol L-1. Combination of nitrogen and calcium rates was necessary for Tanzânia grass leaf area and SPAD value at the third growth, for the plant tops and roots yield, and calcium concentration in the RL at the second and third growths, for the sulfur concentration in RL in all three grass growth periods, and nitrogen concentration in the roots. The number of tillers and leaves, roots length and surface, concentrations of nitrogen, phosphorus and potassium in the RL depended only on nitrogen rates. Calcium rates affected calcium concentration in each component of plant tops, in total plant tops and in the roots. Magnesium concentration in the RL decreased with both nitrogen and calcium rates. Calcium ranged from 9 to 36%, magnesium from 17 to 28% and potassium from 47 to 63% of the positive charge in plant tops. The use of calcium rate in the nutrient solution equal to 40% of that recommended by Sarruge did not reduce physiological, nutritional and productive parameters of this grass, even with the supply of high nitrogen rate. Calcium deficiency symptoms in this grass were only observed with very low or no supply of this nutrient in the growth medium having high nitrogen availability.

Diverse native seed mixtures have many benefits for prairie restoration or seeded pastures. In natural grasslands, species naturally coexist with hundreds of other species in complex communities. Commercial seed mixtures rarely contain more than a small number of species, often with haphazard ratios of the component species. Thus there is no natural template for combining selected species into an optimally productive community and there is limited knowledge on how to compose a suitable species mixture. Identifying which features of a community drive increased productivity may aid in screening species and community compositions, leading to mixtures that are more specifically designed to be stable, and highly productive for the region. There is renewed interest native species as they have the potential to provide non-invasive, productive, and drought resistant rangelands that may prove more sustainable. Seven species with high agronomic potential and a broad native geographic distribution were selected for testing including: nodding brome [Bromus anomalus (Coult.)], blue bunch wheatgrass [Pseudoregneria spicata (Pursh)], western wheatgrass [Pascopyrum smithii (Rydb.)], side oats grama [Bouteloua curtipendula (Michx.)], little blue stem [Schizachyrium scoparium (Michx.)], purple prairie clover [Dalea purpurea (Vent.)], and white prairie clover [Dalea candida (Willd.)]. The early productivity and nutritional quality of these species was determined in simple mixtures in two field sites: Saskatoon and Swift Current. In the field sites the mixtures included all seven monocultures, 21 two-species mixtures and a mixture with all species. Productivity may be driven by the species richness, functional group richness, and species evenness of the community, the abundance and occurrence of particular species or functional groups, and average plant trait values within the community. Therefore, identifying the features of a community that drive increased productivity and applying them as predictive tools may aid in screening species and community compositions. Many complex mixtures of the species were planted in greenhouse experiments to determine the strongest drivers of productivity for communities of these species. The experimental approach was validated in a confirmatory experiment where optimum communities were tested. These results did not differ under a moderate drought treatment. Results were generally consistent between field and greenhouse studies. Western wheatgrass (WWG) had the highest overall plant density and the strongest effect on the forage yield of the mixtures and communities. In the field study, productivity and crude protein content were not reduced when other species were also included with WWG in the mixture. Dalea spp. did not establish as well as the other species, but had the highest crude protein concentrations. The strongest predictors of productivity were the presence and abundance of perennial C3 grasses. Increases in species richness, functional group richness, and the presence of C3s (more specifically western wheatgrass) also increased productivity, likely because of the high early relative growth rate and strong competitive ability of western wheatgrass. Overall, communities screened in the greenhouse reflected early establishment field results. The systematic approach for evaluating communities can be modified to consider enhancing other ecological functions in addition to high productivity, in other regions.

Absorption of drug substances across the intestinal epithelium is a complex and dynamic process. Counter transport proteins are responsible for the efflux of specific drug molecules after they have been absorbed. One of the key counter transport efflux proteins, which is of importance in this study, is P–glycoprotein. The efflux pump P–glycoprotein plays a major role in altering the pharmacokinetics of a wide variety of drugs limiting their absorption and therefore also bioavailability. Many flavonoids have been shown to interact with P–glycoprotein mediated efflux in vitro studies. Numerous in vitro methods have been used to study drug absorption across the intestinal membranes, but it is often not possible to use only one in vitro model to accurately predict permeability characteristics. The purpose of this study was to determine the effect of four selected hydroxy– and methoxy– flavonoids on the in vitro transport of Rhodamine 123, a known P–gp substrate, across excised rat and pig intestinal tissue using the Sweetana–Grass diffusion apparatus. The results were further used to determine if the two different animal tissue models corresponded with regard to the flavonoids' effects on P–glycoprotein related efflux. Two control groups were included in the experimental design. In the negative control group, the transport of Rhodamine 123 was tested alone and no modulator was added. In the positive control group, the transport of Rhodamine 123 was determined in the presence of Verapamil, which is a known P–glycoprotein inhibitor. The experiments with the flavonoids Morin, Galangin, 6–Methoxyflavone and 7–Methoxyflavone were done in triplicate to determine repeatability of the results. The transport of Rhodamine 123 was evaluated in both the apical to basolateral (absorptive) and basolateral to apical (secretory) directions. The relative transport of Rhodamine 123, the apparent permeability coefficient (P app) values and flux (J) values in both directions as well as the efflux ratio (ER) and net flux (J net) were calculated. The concentration Rhodamine 123 present in the acceptor chamber was determined by means of a validated HPLC method. Statistical analysis was used to compare the results of the test groups with the control groups in order to indicate significant differences. It has been found that Morin, Galangin and 6–Methoxyflavone have a significant inhibitory effect on the Rhodamine 123 efflux (probably P–glycoprotein related) in both the rat and pig intestinal tissue models with p–values smaller than 0.05. On the other hand, 7–Methoxyflavone showed a significant effect on the efflux of Rhodamine 123 in the pig intestinal tissue model (p < 0.05) but not in the rat intestinal tissue model (p > 0.05). These flavonoids may increase the bioavailability of drugs that are substrates for P–glycoprotein and thereby cause clinically significant pharmacokinetic interactions, however, this should be confirmed with in vivo studies. On the other hand, these flavonoids may be used for drug absorption enhancement when applied under controlled circumstances. With regard to the different animal tissue models used it can be concluded that data obtained from the rat intestinal tissue model cannot be compared and extrapolated to data obtained from the pig intestinal tissue model. It is recommended that the in vitro results be correlated to in vivo findings to identify the most suitable model. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2011.