Rozprawy doktorskie na temat „Agricultural Growth System”

The local food movement in the Portland Metro Region of Oregon is as prevalent as anywhere in the Country. To a large degree this is driven by the Portland Metro area food culture and the diverse agricultural landscape present in the Willamette Valley and throughout the State. Portlanders demand local food and thus far the rural periphery has been able to provide it; driving a new food economy that has economic implications throughout the region. As this regional food economy emerges much attention has been focused on harnessing its power for economic development perpetuated by the belief that there exists an opportunity to foster a cluster of economic activity pertaining to the production, processing, distribution and sale of regional foods that might generate economic opportunities throughout the value chain. The research presented here constitutes an attempt to characterize the local and regional food system that currently exists in the Portland Metro Region and to bring to light the opportunities present at the regional scale that link the agricultural periphery to the urban core. I present two different definitions of local and regional food systems and show how these different conceptions have very different implications for economic development. Once defined, I test for differences between local and regional food systems and the export-oriented, agro-food sector by analyzing aspects of geographic space and processes of knowledge accumulation and innovation in the context of aspects of regional economic development such as agglomeration economies, knowledge spillovers, business life cycle and industrial location. My analysis showed that there are significant differences between local and regional food systems and the export-oriented agro-food industry specific to supply chains, actors and products of the different systems. Furthermore, through spatial analysis, I found that there are differences in terms of the spatial structure and distribution between producers who participate in the different systems. Local and regional producers tend to cluster closer together at smaller scales, are smaller in size and are found to be closer to the urban core. Through a qualitative inquiry I found that this clustering facilitates forces of agglomeration economies specific to food producers who participate in local and regional supply chains, particularly non-pecuniary effects of knowledge accumulation. This underlying structure has significant effects on economic outcomes and as such has implications in terms of regional economic development when local and regional food systems are considered in terms of the city-region.

It is a known fact that the whole agriculture system is suffering from the diseases caused by plant pathogens, affecting negatively the crop yield production, food security, biodiversity, agricultural ecosystem and hence agricultural economy. In many countries, the containment strategies of plant pathogens are still depending on chemical pesticides that cause adverse effects in the long term. According to the implementations reinforced by European council 2009/128/EC, biocontrol strategies are considered as the most profound and integrated approach for sustainable disease management. Defining biocontrol in terms of plant pathology, it is the purposeful utilization of beneficial microbes, or its molecules, to suppress phytopathogens’ ability to colonize or induce symptoms in the host. In spite of their lesser shelf-life and unreliability as compared to conventional pesticides, their targeted biological interaction with the phytopathogens reduces the possibility of affecting non-target organisms, environment and the development of resistance in the pathogen. In this context, exploitation of bacterial endophytes has gained much attention during the past decades. Endophytic plant growth promoting bacteria (ePGPBs) mediate their biocontrol efficacy by targeting species through a multitude of direct or indirect biological interactions, often employing both modes of action, such as plant growth promotion, host’s resistance induction, allelochemicals secretion, and nutrients and niche competition. Another strategy that has gained popularity is the exogenous application of double stranded RNA (dsRNA), which is considered as the key trigger molecule of RNA interreference (RNAi), a post-transcriptional gene silencing mechanism, and has been shown to provide protection without the need for integration of dsRNA-expressing constructs as transgenes. In the present doctoral thesis, the above-mentioned biocontrol strategies were adapted, utilizing “ePGPBs as microbial inoculants” and “exogenously applied dsRNA as RNAi based natural product”, against several phytopathogens belonging to different families of viruses and fungi. Regarding ePGBPs as microbial inoculants, the objective of this study was to extend our understanding of five endophytic bacterial strains; Pantoea agglomerans (255-7), Pseudomonas syringae (260-02), Lysinibacillus fusiformis (S4C11), Paraburkholderia fungorum (R8), Paenibacillus pasadenensis (R16); that have shown a promising result in previous studies. In the present doctoral study, these strains were tested in planta to evaluate their role in providing plant growth promotion and broad-spectrum protection against two target pathosystems (viruses and fungi) that might have direct, indirect or simultaneous effects, proceeded with two following aims: (Aim 1) action against viruses: Cymbidium ringspot virus (CymRSV), Cucumber mosaic virus (CMV), Potato virus X (PVX), and Potato virus Y (PVY) on Nicotiana benthamiana plants, comparing their effects with those of three chitosan-based products, which are known to induce resistance in plants; and (Aim 2) action against fungal pathogens: Rhizoctonia solani, Pythium ultimum and Botrytis cinerea on Lactuca sativa plants, comparing their effects with Bacillus amyloliquefaciens strain (CC2) and Trichoderma spp. based product, under controlled conditions. To test the priming efficacy of ePGPBs against target viruses, several phenotypic parameters were observed along with the evaluation of three plant defense related genes (EDS1, PR2B and NPR1) on Nicotiana benthamiana plants. Interestingly, the symptoms reduction was successfully registered against CymRSV and CMV with increased heights of the plants. Some of the treatments were shown correlation between severity of symptoms and the virus concentration in the plants. Furthermore, the molecular interaction indicated the involvement of a salicylic acid (SA) mediated defense pathway as evidenced by the increased expression levels of EDS1 gene in strains R16 and 260-02. Whereas, strain S4C11 showed downregulation of PR2B gene, suggesting that SA-independent pathways could be involved. These findings opened queries regarding the duration of the protective effect, host-plant- pathogen interaction, and epidemiological implications of the use of similar biocontrol strains, that reduce the symptoms but not the concentration of virus in the host. To test the ePGPBs role against target fungi (pre- and post-harvest stage), several experiments were conducted including phenotypic paraments, gene expression analysis (PR1, PAL, ThlP3, ERF1 and ACCS1), microbiota analysis in bulk soil, rhizosphere, and root associated with Lactuca sativa in the presence or absence of the inoculants, and nutritional quality parameters at time of harvest and during shelf-life of Romaine lettuce. The results were accompanied in terms of symptoms reduction by strain R16 (P. ultimum, R. solani, B. cinerea) and strain 260-02 (R. solani, B. cinerea); % seed germination by strains R16, 260-02, 255-7, S4C11 in some healthy and R. solani infected lettuce varieties; inhibition of R. solani population in soil and rhizosphere soil by strains R16, 260-02 and 255-7. Furthermore, composition of the bacterial microbiota was radically different in the rhizosphere and the root endosphere among treatments, while the bulk soil formed a single cluster regardless of treatment, indicating that the use of these treatments did not have an ecological impact outside of the plant. Also, these strains were able to contribute to the maintenance of nutritional quality indexes of lettuce at harvest and during storage. All the obtained results indicated that these strains were involved directly (via antibiosis) and indirectly (via SA or ET/JA) in the observed reduction of symptoms. Particularly, strain R16 upregulated both PAL and ACCS1 gene in R. solani infected L. sativa (suggesting co-activation of SA- and JA/ ET mediated ISR resistance); strain 260-02 upregulated PAL gene in R. solani infected romaine lettuce and showed higher levels of ascorbic acid (AsA) production in B. cinerea infected romaine lettuce (suggesting the activation of SA- and AsA-mediated antioxidant resistance); and strain 255-7 triggered PAL and ThlP3 gene up-stream expression levels indicating SA mediated pathways in R. solani infected romaine lettuce. These findings affirmed the previous conclusions and added valuable pieces of information regarding the traits these ePGPB carried, most importantly, in individuating different mode of action of the different strains in different host plants with or without the presence of pathogen. Regarding the second approach, non-transgenic strategy was employed to induce resistance against Tomato Aspermy Virus (TAV) in N. benthamiana plants. DsRNA molecules for coat protein (CP) gene was produced by a two-step PCR assay followed by in vitro transcription and purification and was exogenously applied. The implementation of CP-derived dsRNA TAV was not successful in reducing observed symptoms (mosaics, blisters, crinkling, leaf distortion, and systemic vein clearing), regardless of treatments or days of post inoculation. Only a slight difference was found in plant heights indicating that the treatment managed to reduce stunted growth of the plant at dilution 01:10 (6 and 12 dpi). The reasons could involve inappropriate concentration of dsRNA inoculum. Therefore, future studies will be conducted to optimize in vitro dsRNA molecules production to obtain higher concentrations or more specific sequences, and more suitable viral genes. Both strategies have shown interesting outcomes and gave us the future direction which will help us in designing the adequate trials (in planta or semi-field) for the disease management and diseases control through the application of ePGPBs as a microbial inoculants and dsRNA-based product individually or in combination.

RESUME :

Comme la plupart des villes africaines, Yaoundé, capitale du Cameroun, est confrontée aux phénomènes d’urbanisation croissante. Cette urbanisation rapide n’est pas accompagnée d’une croissance économique. En fait, le pouvoir d’achat extrêmement bas, le chômage, le sous-emploi, la pauvreté, voire la misère, ont amené une frange importante de la population à inventer de nouvelles solutions pour s’assurer un revenu. C’est alors qu’apparaît le phénomène d’agriculture urbaine et périurbaine. La caractérisation de cette agriculture a mis en évidence une interaction entre les catégories d’acteurs, les types d’espaces, les types de cultures, les produits obtenus et les revenus moyens générés. Il ressort de l’analyse des résultats que cette forme d’agriculture emploie près de 2000 personnes, pour la plupart des jeunes et, surtout, des femmes, dont la moyenne d’âge est de 35 ans. C’est une activité basée principalement dans les bas-fonds marécageux, le bas des pentes, les abords des routes avec une forte pression sur l’espace. Les cultures sont diversifiées et sont à dominance maraîchère, vivrière et floricole. Elles varient en fonction des trois espaces étudiés, à savoir l’auréole urbaine, la zone périurbaine et l’hinterland rural.

L’analyse du système de commercialisation a mis en évidence trois types de circuits à travers lesquels les produits transitent des producteurs aux consommateurs. Ce sont notamment les circuits longs, les circuits courts et les circuits directs. Dans ces circuits de commercialisation, la régulation du marché se réalise au niveau de tous les intervenants. Cela signifie que les prix des produits ne sont pas fixés d’avance, mais varient en fonction de la demande. En ce qui concerne la rentabilité, l’analyse sur les comptes d’exploitation des cultures de céleri, de ndolé et de morelle noire indique que cette agriculture est rentable avec un gain moyen journalier de près de trois euros pour les producteurs. C’est la raison pour laquelle certains maraîchers estiment qu’à la place d’un travail salarial de près de 75euros / mois, ils préfèrent rester dans leur jardin.

Cependant, aucun cadre juridique et réglementaire lié à l’exercice de cette activité n’est disponible. Aucun article de loi ne l’autorise. Nous avons noté également de nombreuses autres contraintes liées à l’organisation des producteurs, aux pratiques, à la structuration et la mise en marché des produits. Ces résultats ont alors d’importantes implications quant à la compréhension des interactions entre les agriculteurs en ville et le monde politique de Yaoundé. Les fonctions multiples de cette activité tel que l’emploi pour les jeunes, les revenus substantiels pour les couches des populations les plus vulnérables, la gestion des déchets urbains et la beauté du paysage étant autant d’attraits qui concourent à son encouragement.

Les stratégies qui visent à susciter l’implication des producteurs urbains dans le développement de la ville de Yaoundé ont été mises en œuvre à travers la CAUPA (Coalition pour la promotion de l’agriculture urbaine et périurbaine en Afrique). L’intégration de ces stratégies dans les schémas directeurs d’aménagements urbains, pourrait contribuer à concilier les défis d'une amélioration du bien-être des populations en quête de survie. Cette thèse met en évidence la nécessité d’une médiation entre les différentes catégories d’acteurs pour une agriculture urbaine et périurbaine de qualité. Les résultats pourront permettre aux décideurs et administrateurs des villes de disposer d‘informations utiles sur l’importance de cette forme d’agriculture qui est, non seulement montante, mais aussi controversée.

SUMMARY:

As in most African cities, Yaounde, the capital city of Cameroon, is faced with the phenomenon of urbanization. This leads to socio-economic problems especially in food supply and acquisition of basic necessities. The extremely low purchasing power, unemployment, underemployment, poverty - say misery, brought a significant proportion of the population to invent new solutions to ensure basic income through urban and peri-urban agriculture. The characterization of this agricultural system highlights the interaction between various stakeholders, types of spaces and crops, productivity and average revenue generated. Results show that this agricultural system has generated employment for about 2000 people, mainly youths and especially women, with 35 years average age. The activity is based mainly in lowland floody zones, low slope, landscaping roads with increase land pressure. Vegetables, gardening and flowers are dominant diversified crops noticed in the area. These crops vary from urban, peri-urban and rural areas, three landscape which were studied.

The analysis of the marketing chain show three main types of distribution chains through which products pass from producers to consumers. These include long distribution, short distribution and direct channel. In these channels, the regulation of the market is achieved at the level of all stakeholders. This means that the prices of the products are therefore fixed in advance, and also are functions of demand. Regarding profitability, the analysis on the farmer’s accounts of Celery, Bitter leaf and Black nightshade indicates that this agriculture is profitable with an average daily gain of almost 3 euro per producers. That's why some gardeners believes that instead of a salary of almost 75 euro per month, they prefer to stay in their farm.

However, no legal and regulatory framework related to this activity is available in the case of Yaounde. Also, there are many other constraints related to the organization of producers, practices, structuring and implementation of products in the markets. These results have important implications to the understanding of the interaction between farmers and policy makers. The multiple functions of this activity such as youth employment, income for substantial segments of the most vulnerable populations, urban waste management and the beautification of the landscape is as much attraction that contribute to its promotion.

A strategy to encourage the implication of urban producers in the development of the city of Yaounde has been implemented through CAUPA. The integration of these strategies in urban planners, could help for the challenges of improving people’s welfare. Subsequently, this thesis brings forth the need for a mediation between different stakeholders and contributes to good quality of peri-urban agriculture. The results can therefore enable decision-makers and policy to provide useful information on the importance of this form of agriculture which is not only rising, but also controversial.

Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished

The history of now-developed countries implies a common transformation path of economic development. That is, within an economy, as wage grows in non-farm sectors, labour migrates out of agriculture. With fewer workers, agricultural land resources may concentrate into the hands of fewer but larger farm operations (agricultural land consolidation), with more investment and higher production specification. However, the development process of China is less likely to trace the same path as it does in these countries, given its distinctive institutions. To examine the development process in the unique context of China, this dissertation focuses on two questions: (1) how do China’s rural workers self-select into off-farm employment (OFE)? (2) How does agricultural land consolidation occur in China? In addressing the first question, I use Roy’s self-section model to analyze the following three occupational choices of China’s rural residents: farming only, local OFE, and migratory OFE. Based on household survey data from 101 communities in rural China in 2004 and 2007, the empirical results show that individual and household characteristics are important self-selecting factors for OFE participation. More importantly, I find that the increase of OFE in China is largely consistent with market-driven expectations. In addressing the question of whether and why the consolidation of farm operations develops in China’s agriculture, I assess the divergence between the size of farm operations from equal entitlements. The theoretical model predicts that a higher opportunity cost of farm labour, in the form of the urban wage, exerts a positive influence on consolidation of farm operations through rental arrangements. A Gini index is used to measure the inequality of farmland operations relative to equal farmland entitlements, with greater inequality being consist with higher consolidation of farm operations. Empirical results support the theoretical prediction, specifically, a 1000-yuan increase in the annual urban wage, holding all other influences constant, increases the Gini index by 0.012 (mean=0.26) over the 2004-2007 period.

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.

碩士
國立屏東科技大學
熱帶農業暨國際合作研究所
93
Cultivation of Agricus blazei Murill in Taiwan traditionally utilize the plastic bags containing fermented tree barks or sawdust fortified with necessary nutrients. The materials used are primarily imported which result in high production cost yet low yield, consequently deter the application desire of growers. The initial idea of this study came from the utilization of rice straw which is a common agricultural waste in Taiwan. The concern of heavy metal residues originated from industrial pollution strongly daunted the usage of rice straw. On the contrary, no major industrial establishment in Taitung would eliminate the worry of heavy metal pollutants. Preliminary test confirmed the feasibility of using rice straw from Taitung area in cultivating Agricus blazei Murill. One metric ton of dried rice straw was cut into strips of 15 cm long, first soaked in water for 2 days, compiled with animal manure (cow, swine, and poultry in 3 equal parts) and circled by wooden blocks. After 7 days, the temperature of central composts reached 65 ~ 70 C, and subjected to first agitation. Stack was replied up after additional water added, two air venting ducts were inserted, and then the second stage of fermentation initiated until temperature reached 65 C. Agitating then re-supply water before 5 days of fermentation completed (temperature 55 C). The fourth and the last agitation was carried out after 3 days when the temperature dropped to 50 C. 30 kg of sample was selected for analysis; the remainder was adjusted until moisture content was greater than 70%. Compost was put on mushroom bed, sealed and further fermentation took place, temperature rose to above 60 C. After 2 days, the seal was broken and let the bed cooled down to below 29 C. The plantation was carried out followed by covering with newspaper. The mycelium flourished to almost full after 20 days of growth, and then covered with soil (irrigated with 0.5 % CaCO3). The irrigation period lasted for 15 days, when the baby mushroom came out, irrigated more until sporocarp could be collected for analyses. Rice straw from both first and second seasons of paddy rice were conducted and analyzed. The results confirmed that the heavy metal contents all fell within national standards. These findings not only eliminate the necessity of incinerating rice straw thus preventing the air pollution occurred, but also improve the utilization of animal waste, especially alleviate the pollution to air and water. By combining the new application of agricultural resources and the cultivation of healthy foods, this study could enhance the income of farmers, encourage the upgrade of agricultural products, and consequently benefit the agro-business of Taiwan.

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2016.
The economy of Bokoni was centred on farming, with terrace agriculture playing a fundamental role in the construction and location of village sites. This dissertation examined the recursive relationship between soil chemistry and site location at three Bokoni sites: Doornkop, Khutwaneng and Kranskloof. These sites represent the three different phases of occupation in Bokoni. Analysis focused on the correlation of Ca, Mg, K, P, NH4, NO3, CEC and %C to the site contexts. At a macro scale there are substantial similarities with regards to the geology and the soil chemistry; suggesting a strong preference for locating village sites on relatively nutrient rich clay soils. On a more localised scale chemical analysis of the different contexts of these sites (i.e. domestic areas, central enclosures, terraces and non-archaeological areas) explored the agricultural potential of the soil in the various areas. These analyses showed a distinct difference in agricultural potential of soils in stone walled areas. This profile was the result of the nutrient contribution from the underlying soils in combination with either enrichment at the time of occupation, or the ongoing influence of the stone walled structures on the soils. The enrichment of soil in residential sites, whether intentional or accidental, could explain why Bokoni villagers continually reused sites during the earlier part of the sequence, before violence repeatedly disrupted settlement, and thus choice of settlement location, in the area.
LG2017

A agricultura de precisão tem atualmente uma grande importância, uma vez que junta o conhecimento adquirido através das tradicionais técnicas de cultivo com a precisão e a automação tecnológica. Uma das técnicas inerentes da agricultura de precisão é a hidroponia, sendo as plantas cultivadas com recurso a soluções aquosas e sem a disponibilidade do solo. Para apoio ao projeto foi montada uma pequena estufa com todo o equipamento necessário à hidroponia, na Ponta do Sol. Dentro desta, realizou-se todo o desenvolvimento e, consequentemente, a obtenção dos resultados deste projeto. Uma das grandes desvantagens dos sistemas de automatização em hidroponia é encontrarem-se ainda num patamar de elevado investimento, tornando-se numa realidade pouco possível para uma pequena/média escala ou para regiões de minifúndio, como é o caso da Ilha da Madeira. Foi, por isso, desenvolvido um sistema com recurso a elementos de baixo custo que automatizassem todo o controlo. Foram utilizados microcontroladores com Wi-Fi, que realizam a medição dos diversos valores dos sensores (por exemplo: da temperatura interior e da exterior, da humidade do ar, da altura da água do poço, etc.) e que comunicam até ao centro de processamento, sendo este um Raspberry Pi. Neste dispositivo, os dados são tratados para depois serem enviados e guardados numa base de dados remota. Além disto, foi desenvolvido uma aplicação web para apoio ao utilizador, sendo possível verificar as condições ambientais ao longo do tempo, os gastos e a gestão das suas produções, utilizando para isso, relatórios de produção e gráficos que permitem a correlação de valores. Foi também dada grande importância à monitorização e à recuperação de erros, já que este é um sistema suscetível a falhas. Neste trabalho, além de toda a parte do desenvolvimento arquitetural entre camadas de cliente, camada intermédia e camadas de dados, foi ainda estudada a utilização de sensores de humidade na raiz da planta. Desta forma, foi possível automatizar a recirculação de água, utilizando algoritmos que tornam possível uma elevada poupança no tempo total em que a bomba de água se encontra ligada. A poupança evidenciada rondou os 89%. Um dos equipamentos de elevado custo nestes sistemas é o equipamento de monitorização e de calibração automática da quantidade de nutrientes, sendo também criado um equipamento que realizasse estas funções, recorrendo a bombas de dosagem de baixo custo. Por fim, é de notar que os algoritmos de rega e todos os mecanismos de poupança presentes neste projeto tornam este sistema facilmente transformável num projeto que utilize, maioritariamente, energia fotovoltaica (em vez de ser só nos pontos de aquisição de dados, como é mais recorrente). Isto deve-se ao facto de o sistema ativar-se quando é apenas necessário e é ativado com maior frequência nos picos de produção de energia fotovoltaica.
Nowadays, precision agriculture has a great importance, once it uses both the acquired knowledge of the traditional techniques of precision farming and the technological automation. Hydroponics is one of the inherent techniques of the precision agriculture. The plants are grown using aqueous solutions and without the availability of the soil. To support the project, a small greenhouse with all the equipment necessary for hydroponics was set up in Ponta do Sol. Within this project, all the development was carried out and, consequently, the results of this project were obtained. One of the major disadvantages of hydroponics automation systems is that they require high investment levels, which it makes too difficult to implement in a small/medium scale or for small-scale regions such as Madeira. Therefore, a system was developed using low-cost elements that automated all control. Wi-Fi microcontrollers were utilised, which measure the various values of the sensors (for example: indoor and outdoor temperature, air humidity, well water height, etc.) and which communicate to the processing centre, being this a Raspberry Pi. In this device, the data is processed to be sent afterwards and stored in a remote database. In addition, a web application was developed to support the user, being possible to verify the environmental conditions over time, the expenses and the management of their productions, using for this, production reports and graphs that allow the correlation of values. A great importance has also been given to monitoring and recovering errors, as this is a system susceptible to failures. In this work, besides all the architectural development between client layers, intermediate layer and data layer, the utilisation of moisture sensors in the root of the plant was also studied. In this way, it was possible to automate the recirculation of water, using algorithms that make possible a high saving in the total time in which the water pump is on. Savings were around 89%. One of the expensive equipment in these systems is the equipment for monitoring and the automatic calibration of the quantity of nutrients, being also created an equipment which performs these functions using low-cost dosing pumps. Finally, it should be noted that the irrigation algorithms and all the saving mechanisms present in this project make this system easily transformable in a project that uses, mainly, photovoltaic energy (rather than just at data acquisition points, as it is most recurrent). This happens because the system is activated when it is only necessary, and it is more frequently activated at the peaks of photovoltaic energy production.

Genetically modified (GM) crops were introduced in South Africa in 1989 and commercially available by 1998. Legislation to control the use of GM crops was only implemented in 1999, with the genetically modified organisms (GMO) act (15 of 1999). In 2012 2.9 million ha of GM crops were planted in South Africa alone. GM Crops, such as Bt maize, are promoted as safer for the environment since no chemical pesticides are needed. However, recently GM crops have been making headlines as more and more studies find adverse effects of these crops on non-target organisms. The effects on aquatic environments have not yet been fully determined, even though traces of Bt residue have been found in water systems surrounding agricultural lands. The aim of this study was to establish the effects of the Bt toxin on fecundity, development and growth of Bulinus tropicus, a freshwater snail. The experiment made use of a static renewal tests to expose B. tropicus to 50 cm2 Bt maize and cotton leaves in 900 ml of synthetic freshwater. The snails were exposed for the duration of one full life cycle (embryo to adult). Endpoints measured included the development, growth, fecundity, and deformities of the reproductive organs. The results obtained showed retarded development and low embryo survival when the snails were exposed to cotton leaves, irrespective of the presence or absence of Bt, indicating to the possibility of trace residues of chemical pesticides may have been present on the leaves. Initial stimulated growth of hatchlings was observed for both Bt cotton and maize exposures, but after sexual maturity has been reached, ‘surplus’ energy was probably shared between growth and fecundity, resulting in a reduction of growth rate. Energy is gained from their diet, thus a sub-optimal diet would result in less energy available to functions such as growth and fecundity. Signs of developmental instability were found in the formation of the shell opening of the snails exposed to Bt. Fecundity decreased significantly after snails had been exposed to Bt maize / cotton leaves. No differences were found in the penis sheath-preputium length ratio, indicating that Bt had no deleterious effects on the reproductive organs.
MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Urban agriculture and the local food movement have taken main stage both in academic discourse and public and political media. Socio-environmental downfalls of our current industrial food systems have been highlighted, compelling the public and political spheres to engage in activities that support the integration of local, urban food-growing systems. This thesis aims to contribute to that integration by examining possibilities for urban agriculture within the city limits of Atlanta. Through geospatial analysis methods and consultation of city and county property records, possible future sites were ascertained using socioeconomic and ecological factors, with 21 key neighborhoods found to have the greatest potential and need to transform existing land use for agricultural purposes. This research contributes to the larger goal of systemic integration of urban and local food systems into our current economic, political and social landscape, and the study is framed using social theoretical insights from urban geography. While further examination of these urban agricultural food systems is vital, this thesis contributes to broader discussions about urban environmental sustainability and supports the roots of the local food movement by identifying possible sites for food cultivation and food markets.

Sixteen native shrub species with various breeding systems and pollination syndromes were investigated in geographically separated populations to determine breeding systems, reproductive success, population structure, and habitat characteristics. Of the sixteen species, seven are hermaphroditic, seven dioecious, and two gynodioecious. Two of the dioecious species are cryptically dioecious, producing what appear to be perfect, hermaphroditic flowers, but that function as either male or female. One of the study species, Raukaua anomalus, was thought to be dioecious, but proved to be hermaphroditic. Teucridium parvifolium, was thought to be hermaphroditic, but some populations are gynodioecious. There was variation in self-compatibility among the four Alseuosmia species; two are self-compatible and two are self-incompatible. Self-incompatibility was consistent amongst individuals only in A. quercifolia at both study sites, whereas individuals in A. macrophylla ranged from highly self-incompatible to self-compatible amongst four study sites. The remainder of the hermaphroditic study species are self-compatible. Five of the species appear to have dual pollination syndromes, e.g., bird-moth, wind-insect, wind-animal. High levels of pollen limitation were identified in three species at four of the 34 study sites. Moderate to high levels of pollen limitation were evident in 50% of the gender dimorphic populations compared with 31% of hermaphroditic populations. Melicope simplex populations were female-biased in 14 study plots and successful fruit set was influenced by combinations of male plant density, male flower numbers and distance to the nearest pollen. Natural fruit set in wind-pollinated species was generally higher than in animal-pollinated taxa. Populations of Coprosma spathulata were mostly malebiased, and male plant density and proximity influenced natural fruit set, with a correlation between low fruit set and low male density. Population recruitment was evident in 32 of the 34 sites. In Pimelea arenaria, recruitment failure was widespread in populations throughout the North Island despite high seed set. Gender ratios showed variation from north to south, with a lower proportion of females with increasing latitude. Many of the sixteen shrubs in this study show remarkable resilience to the effects of fragmentation of natural ecosystems, and many of the species have benefited from the creation of new edge habitat after perturbation - it may be that edges are important refugia for some native taxa, especially shrubs.

Intelligent Systems are one of today’s greatest strengths, while environmental sustainability is one of today’s biggest challenges. This study aims to integrate the most recent innovations in intelligent technologies with the development of smart energy grids and Peer-to-Peer (P2P) systems for energetic distribution. Specifically, it investigates the complex relations between these concepts, while analysing how developments in each field both influence and are influenced by each other. To do so, this study answers three research questions. The first one regards the implementation of Intelligent Systems, the second concerns the development of Smart Grids, while the third is concerned with the possibility of building P2P Systems. To provide relevant conclusions, an extensive literature review regarding all subjects was carried, along with a statistical analysis of three online surveys. The obtained results show that there are significant influences and connections between the development of intelligent technologies and the implementation of smart grids and P2P Systems, thus supporting several hypotheses formulated for this study. On this basis, conclusions are drawn concerning the high value of each topic in separate, and the even higher value of the topics when integrated.
Sistemas Inteligentes são um dos maiores benefícios dos dias de hoje, enquanto a sustentabilidade ambiental é um dos maiores desafios. Este estudo pretende integrar as mais recentes inovações em tecnologias inteligentes com o desenvolvimento de redes de energia inteligentes (Smart Grids) e sistemas Peer-to-Peer (P2P) para distribuição energética. Especificamente, investiga as relações complexas entre estes conceitos, enquanto analisa como desenvolvimentos em cada área influenciam e são influenciados pelas outras. Para isso, este estudo responde a três questões de pesquisa. A primeira relaciona-se com a implementação de Sistemas Inteligentes, a segunda com o desenvolvimento de Redes Inteligentes, e a terceira está relacionada com a possibilidade de construir Sistemas P2P. Para obter conclusões relevantes, foi feita uma extensa revisão de literatura relativa a todos os temas, assim como uma análise estatística de três questionários online. Os resultados obtidos mostram que existem influências e conexões significativas entre o desenvolvimento de tecnologias inteligentes e a implementação de Smart Grids e Sistemas P2P, suportando assim múltiplas hipóteses formuladas para este estudo. Com esta base, são retiradas conclusões que confirmam o elevado valor de cada tópico em separado, e o ainda maior valor dos tópicos quando integrados.

Value-added (VA) technologies can help farmers in the specialty crop industry generate new products, increase off-season income sources, expand market access, and improve overall profitability. These technologies can support the development of rural economies through the generation of new businesses and job creation. The USDA defines VA products as those 1) changed physical, 2) produced in a manner that enhances their value, and 3) physically segregated in a manner that results in enhancement of their value. Drawing from this definition, this study investigated VA technologies such as drying, cutting into customer-ready portions, washing and labeling specialty crops. The objectives of this study are threefold. First, we analyze how market access and diversification drive specialty crop farmers to adopt VA technologies. Second, we address the potential endogeneity between the adoption of VA technologies (vertical diversification) and the number of crops (horizontal diversification). Lastly, we investigate how market access drives farmers to utilize food labels for VA products. Data for this study came from a 2019 web-based survey of specialty crop farmers. A total of 766 farmers completed the survey, with a response rate of 21.5%. The questionnaire included questions related to farmer’s demographics (i.e., educational attainment, gender, farming experience), farm characteristics (i.e., crops, markets, and growing technologies), and farmers’ beliefs regarding their farm system. Results suggest that market access is a significant driver of VA technology adoption. Also, the size of the farm, networks, farmer’s perceptions, and employment growth influence adopting VA technologies. The results also show us that farmers adopting VA technologies tend to experience economic growth.