• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 1
  • Tagged with
  • 4
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Himenópteros parasitoides associados a cultivos orgânico e convencional de tabaco (nicotiana tabacum l.) em Santa Cruz do Sul, RS, Brasil / Parasitic hymenoptera associated with organic and conventional tobacco (nicotiana tabacum l.) in Santa Cruz do Sul, RS, Brazil

Dorfey, Cecília 28 February 2011 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The fauna of parasitic Hymenoptera is not well known in Brazil, despite its great diversity and biological, ecological and economical importance. In the cultivation of tobacco (Nicotiana tabacum L.) there is the need to inventory the species of natural enemies that occur associated and perform the natural biological control of pests. The objectives of this study were to inventory the biodiversity of parasitic Hymenoptera associated with tobacco under conventional and organic management; to examine the seasonal and spatial distribution; and to check the effect of the presence of adjacent vegetation on populations of parasitoids. The study was conducted in two crops of conventional tobacco and one certified as organic in Santa Cruz do Sul, RS, Brazil. Sampling points were determined and located Outside , at the Border , Inside and in the Middle of the tobacco fields, in which were installed a Malaise trap and four pit-fall traps. Samples were weekly collected from November 2008 to February 2009 and from November 2009 to February 2010. Statistical analysis was performed using the software PAST. Were collected 7.913 hymenopterans parasitoids in conventional tobacco crops during the 2008/2009 and 2009/2010 crop, and 31.574 hymenopterans parasitoids associated with organic tobacco in both seasons of study. The families Ichneumonidae, Braconidae, Scelionidae and Eucoilidae were the most abundant in both types of crop management, as well as Encyrtidae, Eulophidae and Mymaridae. The sampling point "Outside" was the most representative in both crops, reflecting, in general, the need to maintain areas of adjacent vegetation that differ from the main crop in order to contribute to hymenopterans parasitoids associated with tobacco cultivation. However, application of agrochemicals reflected in the decrease of parasitoids sampled, underscoring the need for studies on selectivity of products currently used to control pests in tobacco on beneficial insects. / A fauna de himenópteros parasitoides é pouco conhecida no Brasil, apesar de sua grande diversidade e importância biológica, ecológica e econômica, principalmente no manejo integrado de pragas agrícolas. Com relação ao cultivo do tabaco (Nicotiana tabacum L.), o conhecimento dos inimigos naturais associados nativamente servirá de base a programas de controle biológico na cultura. Assim, os objetivos deste trabalho foram estudar a diversidade, sazonalidade e distribuição espacial de himenópteros parasitoides associados ao tabaco de acordo com o método de cultivo (convencional e orgânico) e verificar o efeito de bordadura sobre populações de parasitoides. O estudo foi realizado em duas lavouras de tabaco convencionais e uma certificada como orgânica, no município de Santa Cruz do Sul, RS. Foram determinados, nas diferentes lavouras, pontos de coleta Fora , Borda , Dentro e Meio nos quais foram instaladas uma armadilha de Malaise e quatro armadilhas tipo pit-fall. As coletas foram realizadas, semanalmente, de novembro de 2008 a fevereiro de 2009 e de novembro de 2009 a fevereiro de 2010. As análises estatísticas foram realizadas utilizando o software PAST. Foram coletados 7.913 himenópteros parasitoides em lavouras convencionais de tabaco nas safras 2008/2009 e 2009/2010; e 31.574 himenópteros parasitoides associados a lavoura orgânica de tabaco em ambas as safras de estudo. As famílias Ichneumonidae, Braconidae, Eucoilidae e Scelionidae foram as mais abundantes em ambos os tipos de manejo da cultura, além de destaque para Encyrtidae, Mymaridae e Eulophidae. O ponto de amostragem Fora foi o mais representativo em ambos os tipos de lavouras, refletindo, de modo geral, a necessidade de manutenção de áreas de vegetação adjacente que difiram da cultura principal para maior aporte de himenópteros parasitoides associados à cultura do tabaco. Também a aplicação de agroquímico refletiu na diminuição de parasitoides amostrados, destacando a necessidade de estudos sobre seletividade dos produtos atualmente utilizados no controle de pragas em tabaco.
2

Arbuscular mycorrhizal fungi: crop management systems alter community structure and affect soybean growth and tolerance to water stress

Lisseth Zubieta (5930507) 03 January 2019 (has links)
<p>Arbuscular mycorrhizal fungi (AMF) are best known for their potential to help plants acquire nutrients, especially phosphorous. These microbes improve soil health by promoting soil aggregation and carbon sequestration, and further benefit plants by helping them withstand biotic and abiotic stress. Currently, there are 200 recognized species of AMF within the phylum Glomeromycota. Recent studies indicate that individual AMF species differ in the benefits they provide, with some even acting as parasites. Moreover, AMF community composition can be altered by soil and crop management practices, but the effect of these changes on the benefits conferred by AMF are still not well understood. Consequently, the goal of this study was to determine how two widely used crop management systems can alter the composition of AMF species, and affect the potential for these communities to promote the productivity and drought tolerance. To accomplish this goal, we collected AMF inoculum from a long-term crop systems trial comparing organic and conventional management for use in greenhouse trials where we subjected plants to drought. We collected AMF inoculum during mid-summer when differences between the two management systems were likely cause larger effects on AMF communities, and again in autumn after harvest to see if differences in AMF communities would persist. We determined AMF species composition using next generation sequencing. Results of this study confirm that soil-building practices commonly used in organic farming systems can improve soil health and increase the productivity of food-grade soybeans. They also demonstrate that AMF communities in Indiana croplands are highly diverse, and some of these taxa can improve soybean growth and help plants tolerate water stress. Although the overall diversity of AMF communities did not differ between the organic and conventional management systems in mid-summer, individual AMF taxa did differ between the systems, which were likely responsible for the greater tolerance to water stress observed when plants were amended with inoculum from the organic system. AMF communities present during autumn were significantly different between the two crop management systems, but did not result in differences in drought tolerance of soybeans, indicating that the loss of key AMF taxa in the organic system from the first relative to the second experiment was likely responsible. Finally, plants grown using inoculum from both crop management systems in autumn had greater tolerance to water stress than plants that received a AMF commercial inoculum. This provides further evidence that individual AMF species vary in the benefits they provide, and that the presence of a diverse consortium of AMF species is needed to optimize plant health and productivity in agricultural systems. Agricultural producers should consider incorporating soil-building practices that are commonly used in organic farming systems such as planting winter cover crops, to improve the health of their soil and enhance the productivity of their crops. <b></b></p> <br>
3

An adjusted material flow cost accounting framework for process waste-reduction decisions in the South African Brewery industry

Fakoya, Michael Bamidele 03 1900 (has links)
While contemporary environmental problems arise partly from increased industrial activities resulting in waste creation, the continued extraction and depletion of earth’s natural resources by organisations to meet consumers’ demand have led to unsustainable business practices (Jennings & Zandbergen 1995). Moreover, reversing the negative environmental impact caused by unsustainable business practices is the responsibility of the organisations whose activities cause harm to the environment (Ahuja & Khamba 2008). More importantly, managers require adequate and accurate financial and non-financial information on their unsustainable business practices to successfully manage both internal and external environmental effects of their actions (Schaltegger & Burritt 2000). But the lack of contemporary management accounting tools to capture waste information in the brewery process reduces the chance to improve waste-reduction decisions while opportunities for cost savings are also lost. Admittedly, Gale (2006:1231) argues that conventional management accounting Systems (MASs) do not have the ability to adequately monitor the increasing material costs and overheads in production processes with sufficient transparency. Nevertheless, this inability to provide adequate process waste information may likely limit organisations’ effort to implement and achieve desired waste-reduction strategies. As a result, it is imperative to integrate both physical and monetary waste information for sound decision-making. The main objective of this study is to adopt and adjust the existing MFCA framework to support and improve on managers’ process waste-reduction decisions in the South African brewery industry. In order to achieve this main objective, the study: • examines the extent to which conventional MASs provides process waste information to support waste-reduction decisions in a micro-brewery (Hope Brewery) and a large brewery (SAB Ltd); • assesses the impact of insufficient process waste information as provided by the conventional MASs on brewery waste-reduction decisions in a micro-brewery (Hope Brewery) and a large brewery (SAB Ltd); and • adjusts the existing MFCA framework to include waste categories subsumed or neglected in the provision of waste information to improve brewery waste-reduction decisions. vi The study adopted an exploratory multiple case study approach by means of in-depth interviews and a pilot study in two breweries- a micro-brewery and a large brewery to achieve the study objectives. Findings revealed that, while the use of technology is essential to reduce brewery process waste, there is lack of appropriate waste-capturing management accounting tool in both organisations. Besides it is essential for organisations to adopt appropriate management accounting tool to capture waste-related information for improved waste-reduction decisions and selection of appropriate waste management strategy. The study therefore suggests the adoption of an adjusted MFCA framework for a more robust approach to improve waste-reduction decisions since ‘what cannot be measured cannot be managed’. / Management Accounting / D. Comm. (Management Accounting)
4

An adjusted material flow cost accounting framework for process waste-reduction decisions in the South African Brewery industry

Fakoya, Michael Bamidele 03 1900 (has links)
While contemporary environmental problems arise partly from increased industrial activities resulting in waste creation, the continued extraction and depletion of earth’s natural resources by organisations to meet consumers’ demand have led to unsustainable business practices (Jennings & Zandbergen 1995). Moreover, reversing the negative environmental impact caused by unsustainable business practices is the responsibility of the organisations whose activities cause harm to the environment (Ahuja & Khamba 2008). More importantly, managers require adequate and accurate financial and non-financial information on their unsustainable business practices to successfully manage both internal and external environmental effects of their actions (Schaltegger & Burritt 2000). But the lack of contemporary management accounting tools to capture waste information in the brewery process reduces the chance to improve waste-reduction decisions while opportunities for cost savings are also lost. Admittedly, Gale (2006:1231) argues that conventional management accounting Systems (MASs) do not have the ability to adequately monitor the increasing material costs and overheads in production processes with sufficient transparency. Nevertheless, this inability to provide adequate process waste information may likely limit organisations’ effort to implement and achieve desired waste-reduction strategies. As a result, it is imperative to integrate both physical and monetary waste information for sound decision-making. The main objective of this study is to adopt and adjust the existing MFCA framework to support and improve on managers’ process waste-reduction decisions in the South African brewery industry. In order to achieve this main objective, the study: • examines the extent to which conventional MASs provides process waste information to support waste-reduction decisions in a micro-brewery (Hope Brewery) and a large brewery (SAB Ltd); • assesses the impact of insufficient process waste information as provided by the conventional MASs on brewery waste-reduction decisions in a micro-brewery (Hope Brewery) and a large brewery (SAB Ltd); and • adjusts the existing MFCA framework to include waste categories subsumed or neglected in the provision of waste information to improve brewery waste-reduction decisions. vi The study adopted an exploratory multiple case study approach by means of in-depth interviews and a pilot study in two breweries- a micro-brewery and a large brewery to achieve the study objectives. Findings revealed that, while the use of technology is essential to reduce brewery process waste, there is lack of appropriate waste-capturing management accounting tool in both organisations. Besides it is essential for organisations to adopt appropriate management accounting tool to capture waste-related information for improved waste-reduction decisions and selection of appropriate waste management strategy. The study therefore suggests the adoption of an adjusted MFCA framework for a more robust approach to improve waste-reduction decisions since ‘what cannot be measured cannot be managed’. / Management Accounting / D. Comm. (Management Accounting)

Page generated in 0.0993 seconds