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Title: Factors affecting enterprise choice : an analysis of traditional food production in southeastern Minas Gerais, Brazil
Creator: Da Silva, Carlos Arthur B.
Date: 1981
Collection: Electronic Theses & Dissertations

Title: Certain social factors associated with the adoption of recommended agricultural practices by rural local leaders and ordinary farmers in India
Creator: Thorat, Sudhakar
Date: 1966
Collection: Electronic Theses & Dissertations

Title: Decision theory : a review and critique of applications in agriculture
Creator: Fleisher, Beverly
Date: 1983
Collection: Electronic Theses & Dissertations

Title: Marketing board taxation of Nigerian agriculture : some implications
Creator: Idachaba, Francis Sulemanu
Date: 1972
Collection: Electronic Theses & Dissertations

Title: Appropriate development strategies for developing countries : lessons and policy implications for promoting small-scale agriculture in Nigeria
Creator: Eziakor, George Ikechukwu
Date: 1983
Collection: Electronic Theses & Dissertations

Title: Diffusion of innovations in a development system : a study of collective adoption of innovations by village cooperatives in Pakistan
Creator: Rahim, Syed A. (Syed Ataur), 1930-
Date: 1968
Collection: Electronic Theses & Dissertations

Title: Elucidating the genetic mechanisms of flowering and the repression of floral initiation by fruit in apple (Malus x domestica Borkh.)
Creator: Gottschalk, Christopher Charles
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Many tree fruit crops exhibit yearly cyclical fluctuations in flowering and fruiting, including apple (Malus × domestica Borkh.). This phenomenon, known as biennial bearing, is an intriguing biological problem, as well as a production limitation of many high-value apple cultivars. The current hypotheses to explain biennial bearing focus on the repressive effects of fruit on the initiation of floral primordia, which would develop into flowers the following year. This floral repressive response...
Show moreMany tree fruit crops exhibit yearly cyclical fluctuations in flowering and fruiting, including apple (Malus × domestica Borkh.). This phenomenon, known as biennial bearing, is an intriguing biological problem, as well as a production limitation of many high-value apple cultivars. The current hypotheses to explain biennial bearing focus on the repressive effects of fruit on the initiation of floral primordia, which would develop into flowers the following year. This floral repressive response could be the result of nutrient competition between the spur apex and the strong sink of the developing fruit, or flowering-inhibitory gibberellins (GAs) that are produced in the seeds of the developing fruit and exported to the spur apex. However, the molecular mechanism by which fruit load and/or GAs represses floral initiation is unknown.The first aim of my dissertation was to identify the genes involved in the floral initiation pathway. Utilizing transcripts assembled from a transcriptome of the biennial cultivar 'Honeycrisp' and the known flowering genes from Arabidopsis, I identified a comprehensive list of flowering-related homologs based on sequence homology, phylogenetic relationship, and syntenic organization. The second aim was to characterize the expression of the flowering-related homologs during the period of floral initiation under crop load conditions that either promote or repress flowering. Homologs of AGL24/SVP, AP1, FT, LFY, and SPLs were strongly expressed in apices of floral-induced trees, supporting their presumed role as floral promoters. In contrast, a homolog of the floral repressor TERMINAL FLOWER 1 (MdTFL1-2), was strongly up-regulated in apices of fruit-bearing, floral-repressed trees. Additionally, genes involved in the deactivation of bioactive GAs were strongly up-regulated in the floral-repressed trees. The timing of floral initiation is also known to vary between cultivars in apple. However, the diversity in flowering gene regulation that underlies this variation is unknown. The third aim of my dissertation was to investigate diversity of gene expression in six different apple species and cultivars. Generally, the expression profiles of the flowering-related genes were similar, suggesting a widely conserved mechanism. However, a few key genes involved in the regulation of floral initiation and development exhibited differential expression. For example, during the floral initiation period, five of the six genotypes were found to have differentially expressed MdTFL1s. This result implicates a potential role for the MdTFL1s in determining the timing of floral initiation in addition to a role in biennial bearing. Plant growth regulators (PGRs) offer the potential to control flowering and biennial bearing in established apple plantings. This final aim was to evaluate and improve the efficacy of foliar-applied GA regiments to repress flowering in apple. This study included the evaluation of application timings, GA formulations and concentrations, and cultivar-specificity. The most successful PGR trial used GA3 to inhibit flowering in 'Honeycrisp' when a strong return bloom was expected. As a result of the decreased flowering and fruit load, the harvested fruit in the year following GA application exhibited higher fruit-quality. The results from this collection of studies provide insight into the molecular control of flowering and biennial bearing while demonstrating a practical approach to managing flowering in a high-value apple cultivar.
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Title: Scaling Up Production of Local Salad Mix for Retail Grocery Markets : A Feasibility Study in Southeast Michigan
Creator: Gerhart, Jennifer A.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Changes to the supermarket supply chain over the last few decades have “squeezed out” local and small farmers in place of more consolidated and global suppliers. As a result, local farmers have turned to more direct to consumer markets for farm sales, which capture a higher price point but also bear higher marketing costs. Previous research has revealed saturation and lack of profitability in this market type. As a result, researchers have explored strategies for “scaling up” local farmers...
Show moreChanges to the supermarket supply chain over the last few decades have “squeezed out” local and small farmers in place of more consolidated and global suppliers. As a result, local farmers have turned to more direct to consumer markets for farm sales, which capture a higher price point but also bear higher marketing costs. Previous research has revealed saturation and lack of profitability in this market type. As a result, researchers have explored strategies for “scaling up” local farmers into intermediary supply chains, such as grocery retail, and have tested the profitability of hybrid marketing strategies with positive results. However, none of this research has used production costs to test market feasibility and this component is critical for a small farmer’s willingness to “scale up” into intermediary markets. Using salad mix as a test crop and Southeast Michigan as a sample region, this research uses farmer-generated production costs for four production methods to examine the feasibility of previously identified strategies for scaling up into intermediary supply chains. The data reveal that central processing has the greatest impact on lowering both the farmgate cost of production and the output price for the buyer. In addition, the minimal costs of organic certification for small farmers justifies the price premium received in grocery retail markets. Lastly, hydroponic production was found to be infeasible at a small scale but could potentially meet retailers price preferences at larger scales. Based on these findings, further research on the realistic costs for centralized processing, distribution, and marketing for this crop type to be sold to grocers is recommended.
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Title: PRECISION DIAGNOSTICS AND INNOVATIONS FOR PLANT BREEDING RESEARCH
Creator: Hugghis, Eli
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Major technological advances are necessary to reach the goal of feeding our world’s growing population. To do this, there is an increasing demand within the agricultural field for rapid diagnostic tools to improve the efficiency of current methods in plant disease and DNA identification. The use of gold nanoparticles has emerged as a promising technology for a range of applications from smart agrochemical delivery systems to pathogen detection. In addition to this, advances in image...
Show moreMajor technological advances are necessary to reach the goal of feeding our world’s growing population. To do this, there is an increasing demand within the agricultural field for rapid diagnostic tools to improve the efficiency of current methods in plant disease and DNA identification. The use of gold nanoparticles has emerged as a promising technology for a range of applications from smart agrochemical delivery systems to pathogen detection. In addition to this, advances in image classification analyses have allowed machine learning approaches to become more accessible to the agricultural field. Here we present the use of gold nanoparticles (AuNPs) for the detection of transgenic gene sequences in maize and the use of machine learning algorithms for the identification and classification of Fusarium spp. infected wheat seed. AuNPs show promise in their ability to diagnose the presence of transgenic insertions in DNA samples within 10 minutes through colorimetric response. Image-based analysis with the utilization of logistic regression, support vector machines, and k-nearest neighbors were able to accurately identify and differentiate healthy and diseased wheat kernels within the testing set at an accuracy of 95-98.8%. These technologies act as rapid tools to be used by plant breeders and pathologists to improve their ability to make selection decisions efficiently and objectively.
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Title: MARKET OPPORTUNITIES FOR THE USE OF BIOTECHNOLOGY TO IMPROVE FARM ANIMAL WELFARE
Creator: Ufer, Danielle Jayne
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Novel biotechnologies offer an avenue to improve farm animal welfare but face several potential challenges in the market. Consumers are demanding stricter animal welfare standards in livestock production but are wary of biotechnology applications in food and agriculture. This dissertation explores the market opportunities for biotechnology and animal welfare improvements in the pork and dairy industries. I take a comprehensive approach, employing experimental methods to investigate consumer...
Show moreNovel biotechnologies offer an avenue to improve farm animal welfare but face several potential challenges in the market. Consumers are demanding stricter animal welfare standards in livestock production but are wary of biotechnology applications in food and agriculture. This dissertation explores the market opportunities for biotechnology and animal welfare improvements in the pork and dairy industries. I take a comprehensive approach, employing experimental methods to investigate consumer receptivity to products with biotechnology and animal welfare traits; and producer intent to adopt such technologies into their operations.The first chapter explores the economic foundations, challenges, and opportunities for consumer acceptance of biotechnology applications in animal welfare, especially gene editing techniques. I review the food economics literature on consumer acceptance of biotechnology to improve animal welfare and discuss the emerging opportunities for future improvements through gene editing. I also discuss industry and policy implications of consumer demand for animal welfare and biotechnology in livestock applications. One of the first challenges at the nexus of biotechnology and animal welfare is effective communication between producer and consumer. Product labels communicate valuable traits to consumers but, when a single label represents multiple traits, communication can be hindered by consumer misinformation. The second chapter addresses the emerging phenomenon of redundant labels, which can address misinformation by explicitly indicating included qualities within a comprehensive label. I utilize data from a field experiment on willingness to pay for redundant labels in the U.S. organic fluid milk market when consumers are either uninformed or informed of the redundancy. Market share simulations demonstrate the market impacts and effectiveness of introducing a redundant label as a response strategy to recapture market share lost to increasingly prevalent individual labels. The third chapter also employs a field experiment and investigates the market viability of novel biotechnology applications that improve animal welfare. I evaluate U.S. consumer demand for pork produced using two animal welfare-improving biotechnologies – immunocastration and gene editing. Results indicate negative attitudes toward biotechnology outweigh animal welfare benefits, though products still garner a slight average premium due to heterogeneity in preferences. Findings support policies that balance regulatory approval costs with observed market acceptance and policies that provide for animal welfare demands. Market opportunities are dictated by all decision-makers in the market, including both consumers and producers. The complexities of the decision to adopt gene-editing technology at the farm gate are likely to be greater than a simple matter of profitability. In the final chapter, I investigate ex-ante technology adoption intent to address how non-pecuniary motivations influence a dairy producer’s decision to adopt gene-editing technology with animal welfare-improving benefits. This chapter extends random utility theory to account for situational influences on producer decision outcomes. I employ the experimental vignette methodology, and a random parameters ordered logit modeling approach. Findings point to a general resistance among dairy farmers towards gene-edited genetics, even with an animal welfare-improving application. Farmers can, however, become more amenable to the prospect of adopting gene-edited genetics through situational influences.
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Title: GENETIC ANALYSIS OF IMPORTANT METABOLITES IN FENNEL AND STEVIA
Creator: Bahmani, Keivan
Date: 2021
Collection: Electronic Theses & Dissertations
Description: History of medicinal plants usage goes back to 60 thousand years ago in Shanidar cave in Kurdistan. Among the oldest medicinal plants, stevia (Stevia rebaudiana) and fennel (Foeniculum vulgare var. vulgare) are used as flavoring and curative agents in food and pharmaceutical goods, due to possessing certain metabolites. These metabolites in fennel are essential oils and fatty acids stored in the seeds, and in stevia are steviol glycosides (SGs) stored in the leaves. To keep up with the...
Show moreHistory of medicinal plants usage goes back to 60 thousand years ago in Shanidar cave in Kurdistan. Among the oldest medicinal plants, stevia (Stevia rebaudiana) and fennel (Foeniculum vulgare var. vulgare) are used as flavoring and curative agents in food and pharmaceutical goods, due to possessing certain metabolites. These metabolites in fennel are essential oils and fatty acids stored in the seeds, and in stevia are steviol glycosides (SGs) stored in the leaves. To keep up with the increasing demand for fennel and stevia products, developing high yielding cultivars is a necessity. For this, understanding the existing diversity and genetic basis of desired metabolites is important. To do so, in the first part of this study, 50 Iranian fennel landraces in a field study were evaluated for their agro-morphological traits and five high yielding synthetic cultivars were developed. In the second part of this study, RNA seq and QTL analysis were used to find genes / genomic regions underlying biosynthesis of Rebaudioside D (Reb D) which is one of the most desired SGs. The results from the fennel experiment showed the fennel landraces were early, medium, or late maturities, with life spans of three to five years. During life spans of the landraces, a wide diversity for seed and essential oil production was observed, and in each maturity group high yielding landraces were identified. A single year analysis of total fatty acid content followed by GCMS analysis, indicated that some of these fennel landraces have the potential to be complementary sources of certain fatty acids, such as oleic and linoleic acids. The main compositions of fatty acids, measured in twelve of the landraces, were oleic acid and linoleic acid. Landraces with high oleic acid content originated from regions with a dry and warm climate, while landraces with high linoleic acid content originated from regions with a humid and cool climate. Understanding relationships between fatty acid profile and landrace origin climate may improve the efficiency of identifying landraces with specific fennel chemotypes. After observing the diversity among these 50 fennel landraces, five fennel synthetic cultivars with different maturity habits, three with the goal of high essential oil yield, and the other two with the goal of high seed yield under drought conditions, were developed. Evaluation of the five synthetic cultivars showed, in drought stress conditions, the five synthetic cultivars had a higher essential oil yield and seed yield than their parents. Given that fennel is also an orphan crop, and pollination control in fennel is really challenging, synthetic cultivar development is a viable breeding method for fennel, especially in early and medium maturity fennels. In the QTL analysis on stevia, a genetic linkage map was constructed using 2298 SNPs across 11 linkage groups and a total map distance of 2190 cM, for an average distance of 0.95 cM between markers. Using this linkage map and phenotypic data from three field locations, seven QTL on linkage group five for Reb D concentration and proportion, explaining 13.5 to 39.6% of variance were identified. Six of these QTL overlapped, and QTL peaks for three and two of them were the same positions. These regions can go under further investigation to narrow down the region to specific genes. Additionally, QTL for Reb A, stevioside, Reb B, and total steviol glycosides were identified. The RNA seq experiment on stevia identified 63 upregulated, and 44 downregulated transcripts as being differentially expressed between high and low Reb D genotypes. Five modules containing from 99 to 421 transcripts, with significant and positive correlations with Reb D concentration, were identified. The differentially expressed transcripts, modules and their hubgenes are interesting targets for future investigations on Reb D production in stevia.
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Title: FEEDSTOCK AND AMENDMENT EFFECTS ON COMPOST CHARACTERISTICS AND USE IN VEGETABLE PRODUCTION
Creator: Comer, Brooke Michele
Date: 2020
Collection: Electronic Theses & Dissertations
Description: The research objectives were the production of compost for transplant root media and managing fertility and disease in vegetable cropping systems. The priorities were on using local organic materials to capture carbon and nutrients, proliferation of beneficial microorganisms and reducing the need for off farm inputs, particularly in an organic certification system. Composts were made and the soluble and total nutrients, electrical conductivity, pH, percent organic matter, the final C:N ratio...
Show moreThe research objectives were the production of compost for transplant root media and managing fertility and disease in vegetable cropping systems. The priorities were on using local organic materials to capture carbon and nutrients, proliferation of beneficial microorganisms and reducing the need for off farm inputs, particularly in an organic certification system. Composts were made and the soluble and total nutrients, electrical conductivity, pH, percent organic matter, the final C:N ratio and bulk density are reported and correlated to the growth of transplants in greenhouse bioassays. In the first experiments (Chapter I), small-scale (1yd3) thermophilic compost piles were constructed with variations in feedstocks to produce ten treatments focused primarily on starting carbon to nitrogen ratios, and the feedstock contributions observed in the physiochemical characteristics of the finished composts. Fall-collected leaves and on-farm fresh cut grass (1:1 v:v) as a base recipe and variations thereof by adjusting volume ratios of those feedstocks, or adding (1:1:1) dairy/horse manure, coffee grounds, shredded office paper, softwood shavings, or sphagnum peat, wrapping the base mix in plastic, and a standard mixture developed and used in previous research. Three species of plants: cucumber (Cucumis sativus), kale (Brassica oleracea), and tomato (Solanum lycopersicum) were grown and evaluated for dry and wet weights, plant heights, root ratings and number of leaves. Growth response in compost substrates were not consistent between species. Composts containing peat as an ingredient had lower pH and generally resulted in better growth of transplants while growth was minimal in wood shavings compost. Cucumber transplants were grown in the composts after storage for 2, 3 or 4 years which identified differences in growth as the compost characteristics had changed over time. A second group of experiments (Chapter II) had the same base feedstocks with the addition of biochar (BC) and anaerobic digester effluent (ADE), on their own and combined. For cucumbers grown in these compost mixes, addition of biochar improved all metrics of transplant growth; in contrast, addition of ADE reduced several metrics of transplant health including shoot dry weight and root ratings. Most of the compost media produced acceptable transplants of varying quality without additional fertility added over the 3 to 5-week greenhouse production period. A laboratory vermicomposting bioassay (Chapter III) was designed to evaluate the effects of pineapple, melon, onion, carrot, spent coffee grounds (SCG) and a mixture of all five kitchen preparation residues from campus food service as vermicomposting feedstocks. Data were collected for the impact on worms, finished compost chemical characteristics and biota by community level physiological profiling using Biolog EcoPlates. SCG as a feedstock had elevated total N but nearly undetectable soluble NO3-N, and greater microbial community functional diversity. Compost teas from three composts (dairy-manure based and leaf/grass/coffee based thermophilic composts, and food waste based vermicompost) were assessed for impacts on tomato leaf mold (Fulvia fulva) and winter squash powdery mildew (Podosphaera xanthii) management in a farm setting (Chapter 4). Aerated compost teas (CT) were produced for weekly foliar application on two tomato (Solanum lycopersicum) varieties and three winter squash varieties (Cucurbita moschata, C. pepo, and C. maxima) (five separate experiments). While there was some efficacy for management of disease in some of these plant/pathogen systems, this varied by species/variety; and as disease pressure increased over the season CT efficacy ceased. Use of a spreader-sticker appeared to increase disease management in some trials.
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Title: Phenology, density and distribution of the invasive asian chestnut gall wasp (dryocosmus kuriphilus yasumatsu) and evaluation of two systemic insecticides in michigan chestnut orchards
Creator: Labbate, Louise
Date: 2020
Collection: Electronic Theses & Dissertations
Description: This thesis, presented in three chapters, focused on evaluating the phenology, density, distribution and parasitism of Asian chestnut gall wasp (ACGW) (Dryocosmus kuriphilus Yasumatsu), as well as the level and persistence of two systemic insecticides in chestnut orchards in southwest Michigan. In chapter one, phenology, density and parasitism of ACGW were monitored in up to nine Michigan chestnut orchards from 2017 to 2019. Phenology was related to cumulative degrees days which provided...
Show moreThis thesis, presented in three chapters, focused on evaluating the phenology, density, distribution and parasitism of Asian chestnut gall wasp (ACGW) (Dryocosmus kuriphilus Yasumatsu), as well as the level and persistence of two systemic insecticides in chestnut orchards in southwest Michigan. In chapter one, phenology, density and parasitism of ACGW were monitored in up to nine Michigan chestnut orchards from 2017 to 2019. Phenology was related to cumulative degrees days which provided precise timing recommendations for scouting activities or applying cover spray insecticide applications that target the adult wasp. After cold winter temperatures in 2019, the ACGW population was significantly reduced at all monitored locations. The parasitoid of ACGW is established in Michigan and naturally spreading with ACGW.In chapter two, spread and distribution of ACGW was monitored at both the local and regional scale. Diffusion of ACGW through individual orchards progressed quickly and annual spread across Michigan showed large jump distances. Cold winter temperatures in 2019 halted ACGW spread across the state, suggesting ACGW may face a climatic barrier.In chapter three, imidacloprid and emamectin benzoate residues were assessed in chestnut foliage, catkins and nuts. Both insecticides were occasionally found in catkin samples and rarely found in nut samples. Imidacloprid foliage residues were generally high, but variable. Emamectin benzoate foliage residues varied considerably between two treatment years.
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Title: The role of International Soybean Trade in Telecoupled Human and Natural Systems
Creator: Herzberger, Anna Jean
Date: 2020
Collection: Electronic Theses & Dissertations
Description: International food trade and globalized agriculture production connects humans and the environment around the world. As consumption demands are increasingly met abroad by importing food products, environmental and socioeconomic effects of production are left in the producing region, while the effects on the importing countries’ domestic production remain understudied due to the complexity and low visibility of the impacts. As population growth increases the caloric demand and rising affluence...
Show moreInternational food trade and globalized agriculture production connects humans and the environment around the world. As consumption demands are increasingly met abroad by importing food products, environmental and socioeconomic effects of production are left in the producing region, while the effects on the importing countries’ domestic production remain understudied due to the complexity and low visibility of the impacts. As population growth increases the caloric demand and rising affluence drives changes in consumption patterns, connections via food trade will continue to increase. Therefore, to identify local impacts of global phenomena, this dissertation analyses the environmental and socioeconomic impacts of international soybean trade within Brazil (e.g., largest producer), China (e.g., largest consumer) and the U.S. (e.g., the former largest producer). Drawing from both natural and social science disciplines, global trade data, satellite-imagery, farmer interviews and soil samples were combined for an interdisciplinary assessment of how international soybean trade couples distant human and the environment systems, the true extent of land-use change driven by soybean trade and the resulting impacts within each respective country. Chapter 1 provides a review of the published literature and background on international soybean trade and production. In chapter 2, the influence of China’s soybean demand was measured on Brazil’s production and trade. The results suggest that export-oriented soybean expansion in Brazil displaced the production of other crops and increased imports from nearby countries. For chapter 3, the impact of imported soybeans on production in China’s main agricultural region was explored. Competition from imported soybeans has resulted in many farmers switching cultivation to corn or to abandon farming in search of more lucrative options. This cultivation shift requires changes in management that involve increased nitrogen inputs and residual crop biomass – both of which have resulted in environmental spillovers. Chapter 4 furthered the analysis by considering the impacts of farmer cultivation and management decisions on soil properties. Soil texture, pH, total organic carbon and 16S rRNA gene sequence were used in combination with detailed farmer management surveys to understand how changes in residue management effect efficiency, productivity, profitability and sustainability of the system. The results indicated that the accumulation of residual corn biomass has increased the use of residue fires and decreased the amount of crop residue being returned to the soil. The culminating chapter used an agent-based modeling (ABM) to integrate the above chapters into a TeleABM. The teleABM models land use change in Brazil and China based on global soybean demand. Land-use change decisions are made by farmer agents which have parametrized using the farmer interviews. Next, the farmer agent cultivation and management decisions have environmental impacts that were determined by analyzing the soil samples under the context of management decisions. Finally, production and the impact of farmer agent decisions on the soil properties feedback to the farmer’s future cultivation and management decisions. Because of the economic, environmental and political importance of international soybean trade, the results of this dissertation are of great interest for future soybean production and trade between the specified countries as well as food security and environmental sustainability across the world.
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Title: Strategies for Increasing Farmer Input and Control of Food Labeling Initiatives in Michigan and the United States
Creator: Bardenhagen, Christopher James
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Quality labels are one type of marketing strategy employed in efforts to renew small and mid-size farming. The declining number of farms in the United States has raised concerns about the negative impacts of these trends on rural communities, such as population loss and a weakening social fabric. Quality labels are voluntary seals or logos that distinguish food credence attributes, such as geographic origin and/or a particular production method, or environmental, social, and/or animal welfare...
Show moreQuality labels are one type of marketing strategy employed in efforts to renew small and mid-size farming. The declining number of farms in the United States has raised concerns about the negative impacts of these trends on rural communities, such as population loss and a weakening social fabric. Quality labels are voluntary seals or logos that distinguish food credence attributes, such as geographic origin and/or a particular production method, or environmental, social, and/or animal welfare criteria. The benefits of participating in these labeling initiatives for farmers may include market niches and price premiums. Some of the most successful labels are becoming less effective for contributing to small- and medium-scale farm economic viability, however, despite growing consumer support and market share. Organic and fair trade labels have attracted new and larger entrants, which contributed to declining price premiums. These changes have also resulted in less farmer input with respect to certification and changes to standards, facilitating the participation of larger-scale operations. Could greater farmer input and control over labeling initiatives in the US increase their contributions to small- and medium-scale farm economic viability, and if so, how? To begin to answer this question, I examined farmer interest in one particular practice that has strong potential for inclusion in a quality label: the installation nest boxes for American Kestrels, a predator of smaller birds, including those that eat fruit crops. The first study analyzed Michigan blueberry and cherry farmer’s mental models to understand how they relate to the adoption of nest boxes. Farmers who used more biological factors in their mental models for pest management were more likely to adopt this conservation practice. The use of mental models in outreach may improve understanding the relationships between biological factors in farming systems, which could potentially increase the adoption of conservation practices. The second study was an online survey of cherry and blueberry farmers in the United States, to assess perspectives of nest boxes as a pest management strategy for their farm, and as an industry marketing strategy. The majority of respondents indicated a high degree interest in both. Most farmers also shared the perception that natural predators lower pest pressure and bird damage, and help to raise fruit quality and income. The third study involved interviews and a comparative legal analysis of France’s Organismes de Défense et de Gestion (ODGs). ODGs are self-governing nonprofit associations that focus on the development of production standards, and management and promotion of the related quality label or brand. The ODG model is structured in a manner that can be compliant with US anti-trust laws, and the core purposes can easily be replicated in Michigan and other states. Its high degree of farmer input may have greater potential to resist weakening of standards and lowering of price premiums, in comparison to other labeling approaches. The ODG model could potentially be employed to label the use of nest boxes and other conservation practices for sweet cherries in the Michigan, for example, via the creation of a non-profit organization, which trademarks a logo to represent its farmer-member developed standards. More research is needed to determine the feasibility of labeling initiatives and their potential contributions to farm viability, however, in particular the food items and attributes that are most desirable to consumers.
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Title: FACTORS INFLUENCING STERILE CODLING MOTH (Cydia pomonella L.) RECAPTURE, DISPERSION, AND EFFECTIVENESS AS A CONTROL TACTIC IN APPLE ORCHARD SYSTEMS
Creator: Curtiss III, Robert T.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: The sterile insect technique is a proven technology used in the control and eradication of a number of pest insects over large areas. However, using this technology on a farm scale is a new and unproven application that until now has not been explored. This dissertation examines the impact of integrating the sterile insect technique for codling moth (Cydia pomonella) into existing farm-scale commercial apple pest management programs, methods of release, the sterile insect’s interactions with...
Show moreThe sterile insect technique is a proven technology used in the control and eradication of a number of pest insects over large areas. However, using this technology on a farm scale is a new and unproven application that until now has not been explored. This dissertation examines the impact of integrating the sterile insect technique for codling moth (Cydia pomonella) into existing farm-scale commercial apple pest management programs, methods of release, the sterile insect’s interactions with the orchard, how existing management schemes are compatible with releases of sterile C. pomonella, the role of sterile female moths and dispersive distances. The main objectives were to 1) determine the impact of release methods on moth dispersal; 2) measure moth dispersal in contemporary trellised or netted orchards, and in orchards planted on steep terrain; 3) determine male and female dispersal in orchards treated with pheromone mating disruption; 4) establish release densities and timings to manage C. pomonella; 5) integrate sterile codling moths into existing commercial apple pest management programs; 6) elucidate the role of sterile females in controlling C. pomonella males; 7) determine the probability of male and female codling moth catches from specified distances using traps baited with a pheromone/kairomone combination lure in a single-trap, multiple-release experimental design; and 8) apply this information for estimating trap plume reach, maximum moth dispersive distance and absolute pest density based on moth catch in traps. Comparison of releases by hand at a single central location versus evenly released throughout the orchard showed higher overall recapture of sterile moths in all traps placed within the orchard when they were released at the center, suggesting that higher numbers of moths were retained in targeted areas with this method. For releases by hand or by unmanned aerial systems (UAS), recapture of sterile moths was higher when released by UAS. Orchard characteristics were found to impact sterile moth dispersal from single central locations; moths moved away from release points more in trellised orchards than in those with large old single trees. Male and female dispersal in orchards with mating disruption was similar, but shorter than in orchards without mating disruption. Sterile codling moths released on commercial farms controlled wild populations when released at densities ranging from 500 to 2000/ha and increasing numbers of sterile females were shown to increase the disruption of wild populations. Deploying sterile males and females at lower densities than the standard 2000/ha or targeting the peak flight of one or both generations showed promise as a means of making SIT a more cost-effective tactic for managing C. pomonella at a farm scale. In orchards with mating disruption, the plume reach of a single codling moth trap baited with a PHEROCON® CM-DA COMBOTM Lure + AA Lure (Trece, Inc.) was found to be very small, maximum dispersal distance was ca. 100-130m, corresponding to a trapping radius of ca 3-5ha. Pest density estimates, based on capture of a single moth in traps, were shown to correspond to 113-180 moths/ha.
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Title: DISSECTING THE MULTIMODAL SIGNALING NETWORK MEDIATED BY CYCLIC-DI-GMP IN ERWINIA AMYLOVORA
Creator: Kharadi, Roshni Russi
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Erwinia amylovora is the bacterial phytopathogenic causal agent of fire blight, an economically impactful disease that affects apple and pear production worldwide. The successful orchestration of infection by E. amylovora within the host entails a coordinated implementation of several different virulence strategies. A key step in the disease cycle of E. amylovora is the transition from a primarily Type III secretion system (T3SS) effectors-dependent phase in the leaf apoplast to a biofilm...
Show moreErwinia amylovora is the bacterial phytopathogenic causal agent of fire blight, an economically impactful disease that affects apple and pear production worldwide. The successful orchestration of infection by E. amylovora within the host entails a coordinated implementation of several different virulence strategies. A key step in the disease cycle of E. amylovora is the transition from a primarily Type III secretion system (T3SS) effectors-dependent phase in the leaf apoplast to a biofilm-dependent phase within xylem vessels. Cyclic-di-GMP (c-di-GMP), a ubiquitous bacterial second messenger mediates this phase transition into a sessile, attached lifestyle within biofilms in E. amylovora. This body of work encompasses several aspects of the complex and multifactorial signaling network dependent on c-di-GMP in E. amylovora. Diguanylate cycles enzymes (encoded by edc genes) dimerize GTP subunits to synthesize c-di-GMP and phosphodiesterase enzymes (encoded by pde genes) hydrolyze c-di-GMP. We found that the deletion of the three active pde genes in E. amylovora, singly and in combinations of two and all three genes, led to a measurable increase in intracellular c-di-GMP levels. In addition, the elevated c-di-GMP levels correlated with increased production of amylovoran, which is the most abundant exopolysaccharide (EPS), and, a pathogenicity factor in E. amylovora. The expression of T3SS, quantified by the transcriptional level of hrpL as well as by virulence measurements in the apple and pear models, was found to be negatively regulated by c- di-GMP. While biofilm formation generally increased with elevated levels of c-di-GMP, the total pde deletion mutant, ΔpdeABC, showed a relative depreciation in the ability to form biofilms, owing to the physical autoaggregative characteristic of this strain when grown in liquid media. Autoaggregation also impaired cell separation post division, leading to the presence of filamentous cells within cellular aggregates. In addition to the EPSs amylovoran and cellulose, EagA, a peptidoglycan hydrolase was found to be a major contributor to the facilitation of autoaggregation in E. amylovora. The eagA/znuABC zinc uptake gene cluster, was found to be transcriptionally regulated by c-di-GMP and the zinc-dependent repressor Zur. Further, we evaluated the impact of a systemic deletion of all genetic components involved in c-di-GMP metabolism, including active and degenerate dgc and pde encoding genes. The resulting mutant, Ea1189Δ12 was found to be impaired in surface sensing and attachment, which are key steps in the initiation of biofilm formation both in-vitro and in-planta. The transcriptomic profile of WT Ea1189 and Ea1189Δ12 at various stages of biofilm development revealed marked differences in critical metabolic and signal transduction pathways. The correlational clustering of phenotypic data gathered from single gene complemented strains generated from Ea1189Δ12, enabled the functional categorization of each of the systemic components.
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Title: Localized Habitat Use by Humboldt’s Flying Squirrels and Dusky-Footed Woodrats in Northern California
Creator: Quiles Delgado, Tessaliz
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Primary prey for the protected subspecies California spotted owls (Strix occidentalis occidentalis) include dusky-footed woodrats (Neotoma fuscipes) (DFW) and Humboldt’s flying squirrels (Glaucomys oregonensis) (HFSQ). The goal of my thesis is to describe fine-scale habitat use of DFW and HFSQ in industrially-managed timberlands in the Sierra Nevada Mountains of California. From 2018 to 2019, I live trapped and tagged 12 HFSQ and 31 DFW. From this sample, I fit five DFW and two HFSQ with...
Show morePrimary prey for the protected subspecies California spotted owls (Strix occidentalis occidentalis) include dusky-footed woodrats (Neotoma fuscipes) (DFW) and Humboldt’s flying squirrels (Glaucomys oregonensis) (HFSQ). The goal of my thesis is to describe fine-scale habitat use of DFW and HFSQ in industrially-managed timberlands in the Sierra Nevada Mountains of California. From 2018 to 2019, I live trapped and tagged 12 HFSQ and 31 DFW. From this sample, I fit five DFW and two HFSQ with radio transmitters (VHF) to assess fine-scale habitat use. I focused trapping on forest patches with mature and decadent trees, which are common habitat features associated with HFSQ and DFW occurrence. In Chapter One, I describe factors affecting trapping success of DFW and HFSQ. I used trapping success as an index of habitat use by prey, where higher trapping success equated to greater localized use by target species. I found a positive correlation between trap nights and capture probability for HFSQ. For DFW, I found capture probability positively correlated with trap nights and precipitation. In Chapter Two, I describe localized habitat features associated with HFSQ and DFW radio telemetry locations. I compared forest vegetation structure and composition in the immediate vicinity (within 5 m) of daytime locations used by HFSQ and DFW to more distal (>35m) vegetation conditions to determine if micro-forest structures corresponded to HFSQ and DFW use. I found species – level differences in percent ground and basal area where dusky-footed woodrats used areas with significantly more forest litter and shrub cover while Humboldt’s flying squirrels used sites with larger diameter trees.
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Title: INFLUENCE OF LIGHT QUANTITY AND DURATION, AND TEMPERATURE ON GROWTH AND DEVELOPMENT OF SUCCULENTS
Creator: SOSTER, ANTHONY J.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Succulents have continued to grow in popularity in recent years due to their diverse colors, forms, and suitability as houseplants. However, few if any scientific publications exist on how to optimize growth and promote flowering of the most popular genera. Therefore, the objectives of Expt. 1 were to 1) establish the critical photoperiod for flowering and 2) quantify the interaction of photoperiod and radiation intensity on growth and development of Echeveria. In Expt. 2, I wanted to 1)...
Show moreSucculents have continued to grow in popularity in recent years due to their diverse colors, forms, and suitability as houseplants. However, few if any scientific publications exist on how to optimize growth and promote flowering of the most popular genera. Therefore, the objectives of Expt. 1 were to 1) establish the critical photoperiod for flowering and 2) quantify the interaction of photoperiod and radiation intensity on growth and development of Echeveria. In Expt. 2, I wanted to 1) establish if a single paclobutrazol drench could prevent excessive stem elongation in a low light environment and 2) determine the duration of paclobutrazol drenches efficacy. Lastly, in Expt. 3 I quantified the interaction of radiation intensity and day and night temperature on growth and development of seven succulent genera and cultivars. In Expt. 1, DLI and photoperiod interacted to affect the growth index of Echeveria ‘Apus’, ‘Canadian’, ‘Elegans Blue’, and ‘Jade Point’, suggesting that day lengths ≥13-h and DLIs of 5 mol·m‒2·d‒1 resulted in larger plants, but not higher quality plants compared to those grown under short photoperiods and DLIs of 12 mol·m‒2·d‒1 . In Expt. 2 plants under low DLIs exhibited an increase in extension growth. However, plants treated with increasing rates of paclobutrazol resulted in reduced stem elongation, even under low DLIs. Lastly, in Expt. 3 growth index increased under moderate DLIs and cooler temperatures for some genera and moderate DLIs and high temperatures for others. These results greenhouse growers with information regarding how succulents respond to the environmental stimuli of photoperiod, temperature, and radiation intensity.
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Title: EFFECTS OF NUTRIENT MANAGEMENT STRATEGIES ON DRY MATTER AND GRAIN YIELD OF SOYBEAN AND DRY BEAN CROPPING SYSTEMS
Creator: Terwillegar, Christian Raymond
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Increases in soybean (Glycine max L. Merr.) grain yield can be partially attributed to greater total dry matter (TDM) accumulation, but the relationship between dry matter (DM) accumulation and nutrient uptake across irrigated and non-irrigated conditions remains uncertain. Two multi-year trials investigated soybean dry matter and nutrient accumulation and partitioning, grain yield, and net economic return across multiple seeding rates and fertilizer strategies. The 148,000 seeds ha-1 rate...
Show moreIncreases in soybean (Glycine max L. Merr.) grain yield can be partially attributed to greater total dry matter (TDM) accumulation, but the relationship between dry matter (DM) accumulation and nutrient uptake across irrigated and non-irrigated conditions remains uncertain. Two multi-year trials investigated soybean dry matter and nutrient accumulation and partitioning, grain yield, and net economic return across multiple seeding rates and fertilizer strategies. The 148,000 seeds ha-1 rate significantly decreased yield in two of four site-years but no differences occurred at the remaining two site-years. Fertilizer strategies did not interact with seeding rate to influence grain yield across all site-years. When contemplating fertilizer application strategies, soil test values should still be the first factor considered. Greater grain yield potential from improved dry bean (Phaseolus vulgaris L.) varieties coupled with potential decreases in soil sulfur (S) supply may have affected the likelihood of a grain yield response to nitrogen (N) and sulfur application. Three multi-year trials were established in Michigan to evaluate nitrogen rate, sulfur rate, and sulfur source on dry bean growth and grain yield. Nitrogen and S application including S source did not improve grain yield or interact with variety to affect grain yield across site-years. Other factors including plant nodulation, biomass, and residual nitrate after harvest were affected by N or S treatments. Nutrient application, especially N, may still be required but in nominal quantities to account for the variable June planting conditions of this shorter-season cropping system. Sulfur applications may be better suited for more N-responsive crops within the dry bean cropping rotation.
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