Water will become increasingly scarce in the 21st century. Agriculture dominates anthropogenic water use and accounts for about 70% of water withdrawals globally. Unique challenges face tropical small-plot agricultural water management that differs from region to region. This dissertation examines two challenges facing tropical small-plot agriculture. Chapter 2 uses an experimental trial in Western Tanzania to create a unique longitudinal dataset of crop water stress measured over the growing season. The trial tests the effect of seed variety and fertilizer treatment on crop water stress over the growing season and during dry spells. Results demonstrate that hybrid varieties yield significantly more than the locally adapted traditional variety because they are better able to access nutrients and have better stomatal regulation over dry spells. Chapters 3 and 4 shift the focus to India. Chapter 3 characterizes the inter-annual dynamics of anthropogenic water stress across the Central Indian Highlands (CIH), while Chapter 4 examines the hydrological impacts of increasing forest cover on regional water supply and its implications for sustainable irrigation as well as food production. Within Chapter 3, I use extensive data sourced from the Indian government to spatially characterize water demand over the past decade by spatially mapping multiple waves of the Minor Irrigation Scheme Census and Livestock Census collected at the household level, along with monthly power generation datasets. The patio-temporal water demand data is coupled with remotely sensed precipitation and evapotranspiration data to force a customized Sacramento Soil Moisture Accounting Model that computes water supply. Finally, I developed a Groundwater Supply Stress Index to account for the impact of irrigation groundwater withdrawals over the course of the year. Chapter 3 finds that 70% of CIH is water-stressed during some portion of the year and that irrigation makes up approximately 95% of anthropogenic water withdrawals. Chapter 4 extends the findings of chapter 3 in utilizing the infiltration-evapotranspiration trade-off hypothesis to understand the impact of converting croplands to forest on groundwater recharge within the CIH. In this Chapter, I collected and analyzed field data on field-saturated hydraulic conductivity to find that forested land has significantly higher infiltration rates than croplands. These finding are then included in a Spatial Processes in Hydrology model to simulate intra-annual hydrological dynamics of current forest cover versus a forest cover increased to 30% within the river basins of the CIH. Increased forest cover is one of India’s Nationally Determined Commitments at COP21 within the Mission to Green India with a stated aim of improving landscape hydrological functioning. I demonstrate that forest cover increase has the potential to increase groundwater recharge, which could be used to irrigate a second growing season and help offset the loss of cropland through conversion to forest. Collectively, these three chapters harness multiple sources of data and leverage a wide array of innovative methods at multiple scales to shed light on important water management issues faced by small-plot agriculture in the tropics and on opportunities for better agricultural water resource management across two continents.

This dissertation presents the results of an archaeological investigation into the environmental strategies of emergent aggregated societies in coastal Lebanon over the course of the Early Bronze Age (c. 3200-2400 BCE). The Early Bronze Age marked not only the rise of large-scale urbanized polities in neighboring regions of Mesopotamia and, to a lesser extent, the Southern Levant, but it took place during the dramatic climate variability of the Middle Holocene. This dissertation uses the analysis of microbotanical and ground stone tool data to assess agricultural strategies, land use, and plant processing technologies at two settlements along the Lebanese littoral during this time of political and climatic upheaval. By comparing phytolith data, stone tool use-wear and microbotanical residues from grinding tools from the sites of Sidon and Tell Fadous-Kfarabida, this project reconstructs local plant and stone environments and the choices that populations were making about those resources over time. It concludes that selectivity between conservative and innovative plant management technologies allowed these settlements to maintain small-scale local networks built into the landscape and to participate with, while resisting incorporation into, growing urban and state economies nearby.

Current crop and climate modeling studies predict temperature extremes that may add future challenges to global food and agriculture production systems due to yield decreases in our staple cereal crops. Although there have been some temperature stress adaptation traits and a few associated genes discovered in plants for enhanced thermotolerance, very little is known about these traits in our major cereal crops, particularly in maize. Furthermore, the limited availability of appropriate selection environments and accurate phenotyping, including functional traits for selection, have been major hurdles to overcome in making meaningful gains towards improved thermotolerance in breeding programs. Previous reports have established that dynamic changes in leaf membrane lipids occur when exposed to temperature stress and many have tried to identify specific lipid classes, individual species, or levels of unsaturation as indicators of tolerance or susceptibility. In this study, several types of cereals, with special emphasis on maize, are studied with the goal to expand the understanding of the leaf lipid membrane characteristics and responses when exposed to temperature stress and to find evidence of heritable lipid biomarker(s) that could be used in breeding for enhanced thermotolerance. Leaf lipids for maize inbred lines and twelve hybrids exhibiting differential tolerance to high temperature stress were analyzed after growing in a controlled environment at optimal and high temperature stress conditions. It was hypothesized that the newly introduced ratios of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) containing acyl chains with total 36 carbons and 6 double bonds (36:6) compared to those with 36 carbons and 5 double bonds (36:5), here termed the MGDG and DGDG “Unsaturation Ratios” can be used to differentiate the changes in the plastidic lipid membrane unsaturation levels and to aid in identifying heat tolerant genotypes. An analysis of the MGDG and DGDG Unsaturation Ratios was performed on twenty-five diverse parents of the nested-association mapping (NAM) population, Mo17, and one hundred and ninety-one B73 x B97 recombinant inbred lines (RILs) grown in field conditions. The selected lipid phenotypes were found to be as diverse as the inbred lines in which they were measured and showed a large differential between the temperate inbred lines B73 and B97. Allelic variation controlling the differences in MGDG and DGDG Unsaturation Ratios was identified in the B73 x B97 RIL subpopulation through linkage mapping analysis. Finally, an analysis of the MGDG and DGDG Unsaturation Ratios was performed across eight of the world’s most important cereal crops. The results of these studies provide preliminary evidence that the MGDG and DGDG Unsaturation Ratios may be beneficial lipid biomarkers that can be used to screen germplasm in breeding programs for improved thermotolerance for our most important cereal crops with the potential to differentiate tolerance in germplasm even without the presence of the ideal selection environment.

Made available in DSpace on 2014-06-11T19:22:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-03-02Bitstream added on 2014-06-13T19:27:20Z : No. of bitstreams: 1 janegitz_mc_me_botfca.pdf: 874943 bytes, checksum: f462f6ac62e6ff84ca80afe66071e353 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os solos tropicais são carentes em fósforo (P), em consequência do material de origem e dos altos conteúdos de Fe e Al. Como o P é uma fonte mineral não renovável, as reservas mundiais são finitas e o custo da adubação é significativo, a utilização do nutriente deve obedecer a uma filosofia de maximização da eficiência. O uso do sistema de semeadura direta promove o aumento de matéria orgânica nos horizontes superficiais do solo, em decorrência da deposição de palhada, alterando a dinâmica do P e, recentemente, tem-se atribuído à braquiária a característica de disponibilizar P às culturas subsequentes. O objetivo principal deste trabalho foi avaliar o efeito do cultivo de braquiária como espécie de cobertura na ciclagem e disponibilidade de P no sistema, assim como na resposta da soja à adubação fosfatada, em sistema de semeadura direta. O experimento foi conduzido na Fazenda Experimental Lageado, na Faculdade de Ciências Agronômicas, UNESP-Botucatu, Estado de São Paulo. Constou de 3 tratamentos iniciais (adubação com Fosfato Natural e Solúvel, mais uma testemunha), presença ou não de braquiária e 3 doses de P na semeadura da soja. É uma área conduzida em semeadura direta com rotação de culturas há dez anos, sendo a braquiária introduzida nos últimos cinco anos, de modo que as aplicações de P na área até hoje já chegaram a 800 kg de P2O5 ha-1. Foram realizadas amostragens de solo na época da semeadura da soja (após a dessecação da braquiária), para fins de análise de fertilidade e determinação das formas de P presentes no solo, como: P microbiano, capacidade máxima de adsorção de fósforo (CMAP), índice de saturação de fósforo e também no estádio R6 (em plena maturação fisiológica) para avaliação do P microbiano e P disponível. A palhada de braquiária... / The Brazilian soils are deficient in phosphorus, as a result of the source material and the interaction strong with the ground. Considering that phosphorus is a finite mineral source, the introduction of a brachiaria as cover crop might increase the use of less labile soil P forms, increasing P availability to subsequent crops, which is a fundamental component of a sustainable crop rotation system. This work compares the ability of brachiaria to recycle phosphorus and increase soil P availability and its effects on soybean yields in no till systems. The experiment was carried out on Lageado Experimental Farm. This experimental area is conducted with no-tillage and crop rotation since 2000, and brachiaria introduced in the last five years. In another hands, the phosphorus application in area reaches 350 kg ha-1 of P. The treatments consisted of a control (0.0 P), soluble and reactive rock phosphate spread over the soil (80 kg ha-1 P2O5), and brachiaria was cropped in half of the plots. Soybean was fertilized with 0, 30 and 60 kg ha-1 of P2O5 as triple superphosphate. Brachiaria was chemically desiccated and soybean was planted over the straw in November. Soil samples were taken before soybean planting (November, 2010) and at the R6 stage (February, 2011). P was analyzed in the soil profile down to 40 centimeters in the first sample, and the second sample was soil profile until to 10 centimeters. The brachiaria straw was sampled and drying at before and 15, 30, 60 and 90 days after desiccation, to analyze the P accumulation. Phosphorus accumulation in soybeans, soybean production, dry matter and agronomy efficient of use of P in the system were determined. It´s conclude the phosphorus sources spread over the soil on total area without incorporation increases the P content in the soil profile and Brachiaria plant... (Complete abstract click electronic access below)

我們在大豆的耐鹽候選基因中進行了篩選和調查，確定了一個穀胱甘肽-S -轉移酶（Glutathion-S-transferase ）基因（ GmGSTL1 ）具抗鹽特性，其表達量也跟隨鹽處理上調。系統發育分析表明，GmGSTL1 屬於LAMBDA 類，文獻對這類蛋白功能的記載甚少。我們在異源系統，包括煙草BY- 2 細胞和擬南芥，測試其保護細胞/植物對鹽脅迫的功能。結果表示GmGSTL1 轉基因細胞的活性氧積累比對照顯著降低，存活率也有所改善。同樣，轉基因擬南芥在鹽處理壓力下的症狀也得以緩解。為了進一步剖析GmGSTL1 的保護機制，我們在大豆葉片中提取多元酚，並發現兩個候選黃酮（槲皮素，山奈酚）與GmGSTL1 起相互作用。槲皮素的外源性應用同樣可以緩解細胞/植物在鹽脅迫下的症狀，表示槲皮素在功能上與GmGSTL1 相約。 / In a survey of candidate genes located in the salinity tolerance locus of soybean, we identified a putative glutathione-S-transferase (GST) gene (GmGSTL1) which was up-regulated in response to salt treatment. Phylogenetic analyses revealed that this putative GST belongs to the Lambda class, a plant-specific group with unknown functions. We expressed GmGSTL1 in heterologous systems, including tobacco BY-2 cells and Arabidopsis thaliana, to test its ability to protect cell/plant against salinity stress. Compare to the wild type control, we observed a marked reduction of ROS accumulation in transgenic cells under salt treatment, and their survival rate was also improved. Similarly, expression of GmGST1 in transgenic A. thaliana also alleviated stress symptoms under salt treatment. To further address the possible protective mechanisms of GmGSTL1, we identified two candidate flavonoid interactants (quercetin and kaemferol) of the GmGSTL1 protein from soybean leaf extract. Exogenous application of quercetin could reduce salinity-induced ROS accumulation in BY-2 cells and leaf chlorosis in A. thaliana. / Detailed summary in vernacular field only. / Chan, Ching. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 80-104). / Abstracts also in Chinese.

Wong Wai Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 175-192). / Abstracts in English and Chinese. / Declaration --- p.ii / Acknowledgements --- p.iii / Abstract --- p.iv / Abbreviation --- p.vi / Table of Contents --- p.vii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Section I --- The Making of Genetically Modified Organisms --- p.2 / Chapter 1.1 --- Conventional breeding in agriculture --- p.2 / Chapter 1.2 --- What is genetic engineering? --- p.4 / Chapter 1.3 --- Plant transformation --- p.5 / Chapter 1.3.1 --- Agrobacterium-mediated --- p.6 / Chapter 1.3.2 --- Direct gene transfer --- p.8 / Chapter 1.3.2.1 --- Microparticle bombardment --- p.8 / Chapter 1.3.2.2 --- Protoplasts --- p.9 / Chapter 1.3.3 --- Gene silencing --- p.10 / Chapter 1.4 --- Examples of genetically modified crops --- p.13 / Chapter 1.5 --- Foreign genes commonly found in transgenic plants --- p.14 / Chapter Section II --- Benefits and Environmental Concern of GMOs --- p.17 / Chapter 2.1 --- Mechanism of GMO --- p.17 / Chapter 2.1.1 --- Herbicide tolerant crops --- p.18 / Chapter 2.1.2 --- Insect resistant crops --- p.19 / Chapter 2.1.3 --- Delayed ripening crops --- p.20 / Chapter 2.1.4 --- Virus resistant crops --- p.20 / Chapter 2.2 --- Benefits of GMOs --- p.21 / Chapter 2.3 --- Impact of GM foods to human health and the environment --- p.22 / Chapter 2.3.1 --- Human health --- p.22 / Chapter 2.3.1.1 --- GM potatoes --- p.23 / Chapter 2.3.1.2 --- CaMV risks? --- p.24 / Chapter 2.3.1.3 --- Food allergy --- p.25 / Chapter 2.3.2 --- Environmental concerns --- p.26 / Chapter 2.3.2.1 --- Horizontal gene transfer --- p.27 / Chapter 2.3.2.1.1 --- Selectable marker genes --- p.27 / Chapter 2.3.2.1.2 --- Herbicide resistant genes --- p.29 / Chapter 2.3.2.1.3 --- Insect resistant genes --- p.29 / Chapter 2.3.2.2 --- Ecology --- p.30 / Chapter 2.3.2.2.1 --- Monarch butterfly --- p.30 / Chapter Section III --- Future developments of GMO --- p.32 / Chapter 3.1 --- Designer Food and engineered plants --- p.32 / Chapter 3.1.1 --- Insect resistance --- p.33 / Chapter 3.1.2 --- Viral resistance --- p.33 / Chapter 3.1.3 --- Fungal resistance --- p.34 / Chapter 3.1.4 --- Nutritional quality --- p.34 / Chapter 3.1.5 --- Modifications of oil composition --- p.35 / Chapter 3.1.6 --- Medical applications --- p.37 / Chapter 3.1.7 --- Environmental applications --- p.40 / Chapter 3.1.7.1 --- Tolerance to high salinity and drought --- p.40 / Chapter 3.1.7.2 --- Tolerance to frost --- p.41 / Chapter 3.1.7.3 --- Bioremediation --- p.42 / Chapter 3.1.7.4 --- Biodegradable products --- p.43 / Chapter Section IV --- Regulation of GMO --- p.44 / Chapter 4.1 --- The question of labeling --- p.44 / Chapter 4.1.1 --- Moral and ethical issues --- p.44 / Chapter 4.1.2 --- Animal welfare --- p.45 / Chapter 4.2 --- International practice in GMO labeling --- p.46 / Chapter 4.2.1 --- United States of America --- p.46 / Chapter 4.2.2 --- Canada --- p.48 / Chapter 4.2.3 --- European Union --- p.49 / Chapter 4.2.4 --- Australia and New Zealand --- p.50 / Chapter 4.2.5 --- Japan --- p.51 / Chapter 4.2.6 --- Republic of Korea --- p.52 / Chapter 4.2.7 --- China --- p.53 / Chapter 4.2.8 --- Taiwan --- p.53 / Chapter 4.2.9 --- Hong Kong --- p.54 / Chapter Section V --- Uses of crops --- p.56 / Chapter 5.1 --- Uses of crops --- p.56 / Chapter 5.1.1 --- Soybean --- p.56 / Chapter 5.1.2 --- Corn --- p.57 / Chapter 5.1.3 --- Tomato --- p.58 / Chapter 5.1.4 --- Potato --- p.59 / Chapter 5.1.5 --- Rice --- p.60 / Chapter 5.1.6 --- Rapeseed --- p.61 / Chapter 5.1.7 --- Oil --- p.62 / Chapter 5.2 --- "Food additives, hormones and flavourings" --- p.63 / Chapter Chapter 2 --- Materials & Methods --- p.65 / Chapter 2.1 --- Materials --- p.66 / Chapter 2.1.1 --- Growth media & agar --- p.66 / Chapter 2.1.2 --- Reagents for agarose gel electrophoresis --- p.67 / Chapter 2.1.3 --- Reagents for preparation of competent cells --- p.67 / Chapter 2.1.4 --- Reagents for measurement of DNA concentration --- p.68 / Chapter 2.1.4.1 --- Measurement of DNA concentration by PicoGreen --- p.68 / Chapter 2.1.5 --- Reagents for Southern hybridization --- p.68 / Chapter 2.2 --- Methods --- p.70 / Chapter 2.2.1 --- Restriction endonuclease digestion --- p.70 / Chapter 2.2.2 --- Agarose gel electrophoresis of DNA --- p.70 / Chapter 2.2.3 --- DNA recovery from agarose gel --- p.71 / Chapter 2.2.3.1 --- QIAquick® gel extraction --- p.71 / Chapter 2.2.4 --- Ligation of purified DNA fragment into vector --- p.72 / Chapter 2.2.5 --- Transformation --- p.72 / Chapter 2.2.6 --- Rubidium chloride method for making competent cells --- p.12 / Chapter 2.2.7 --- Plasmid DNA preparation --- p.73 / Chapter 2.2.7.1 --- Concert Rapid Mini Prep --- p.73 / Chapter 2.2.7.2 --- QIAprep® Miniprep --- p.74 / Chapter 2.2.8 --- Extraction of plant genomic DNA --- p.75 / Chapter 2.2.8.1 --- Qiagen DNeasy´ёØ Plant Mini Kit --- p.75 / Chapter 2.2.9 --- Southern Hybridization --- p.75 / Chapter 2.2.9.1 --- Denaturation --- p.76 / Chapter 2.2.9.2 --- Blot transfer --- p.76 / Chapter 2.2.9.3 --- Pre-hybridization --- p.77 / Chapter 2.2.9.4 --- Synthesis of radiolabelled probe --- p.77 / Chapter 2.2.9.5 --- Hybridization of radiolabelled probe on filter --- p.77 / Chapter 2.2.9.6. --- Detection of hybridized probes --- p.78 / Chapter 2.2.10 --- Measurement of DNA concentration --- p.78 / Chapter 2.2.10.1 --- Determination of DNA on EtBr stained gel --- p.78 / Chapter 2.2.10.2 --- Determination of DNA by UV spectrophotometer --- p.78 / Chapter 2.2.10.3 --- Determination of DNA by PicoGreen --- p.79 / Chapter 2.2.11 --- DNA sequencing --- p.80 / Chapter 2.2.11.1 --- Automated sequencing by ABI Prism 377 --- p.80 / Chapter Chapter 3 --- PCR Diagnostics --- p.81 / Chapter 3.1 --- Applications of PCR to processed foods --- p.82 / Chapter 3.1.1 --- DNA quality --- p.82 / Chapter 3.1.2 --- PCR & Multiplex PCR --- p.83 / Chapter 3.1.3 --- Choice of primers --- p.84 / Chapter 3.1.4 --- Inhibitors --- p.84 / Chapter 3.2 --- Materials & Methods --- p.85 / Chapter 3.2.1 --- Selection of primers --- p.85 / Chapter 3.2.2 --- Amplification of target sequences --- p.86 / Chapter 3.2.3 --- Multiple amplification of target sequences --- p.87 / Chapter 3.3 --- Results --- p.88 / Chapter 3.4 --- Discussion --- p.93 / Chapter Chapter 4 --- Quality Control in GMO detection --- p.95 / Chapter 4.1 --- Standardization of pre- and post- PCR analysis --- p.96 / Chapter 4.1.1 --- General guidelines --- p.96 / Chapter 4.1.2 --- UV irradiation --- p.97 / Chapter 4.1.3 --- Inactivation protocols --- p.93 / Chapter 4.1.4 --- Positive and negative controls --- p.99 / Chapter 4.1.5 --- PCR verification --- p.99 / Chapter 4.1.6 --- Equipment decontamination --- p.100 / Chapter 4.2 --- Materials & Methods --- p.101 / Chapter 4.2.1 --- Selection of primers for external control --- p.101 / Chapter 4.2.2 --- Development of the external control --- p.101 / Chapter 4.2.3 --- Selection of primers for internal control --- p.103 / Chapter 4.3 --- Results --- p.104 / Chapter 4.4 --- Discussion --- p.107 / Chapter Chapter 5 --- DNA extraction from food samples --- p.110 / Chapter 5.1 --- Introduction --- p.111 / Chapter 5.2 --- Reagents and Buffers for DNA extraction from food samples --- p.112 / Chapter 5.2.1 --- Cetyltrimethylammonium bromide (CTAB) extraction method --- p.112 / Chapter 5.2.2 --- Organic-based extraction method --- p.113 / Chapter 5.2.3 --- Potassium acetate/sodium dodecyl sulphate precipitation method --- p.113 / Chapter 5.2.4 --- Hexane-based extraction method --- p.114 / Chapter 5.3 --- Weight and names of samples --- p.115 / Chapter 5.4 --- DNA extraction methods --- p.115 / Chapter 5.4.1 --- CTAB extraction method --- p.115 / Chapter 5.4.2 --- Qiagen DNeasy´ёØ plant mini kit --- p.116 / Chapter 5.4.3 --- Promega Wizard® genomic DNA purification --- p.116 / Chapter 5.4.4 --- Promega Wizard® Magnetic DNA purification system --- p.117 / Chapter 5.4.5 --- Promega Wizard® DNA Clean-Up system --- p.118 / Chapter 5.4.6 --- Qiagen QIAshreddrer´ёØ and QIAamp spin column --- p.119 / Chapter 5.4.7 --- Chelex-based extraction method --- p.119 / Chapter 5.4.8 --- Organic-based extraction method --- p.120 / Chapter 5.4.9 --- Nucleon PhytoPure extraction and purification method --- p.120 / Chapter 5.4.10 --- Potassium acetate/SDS precipitation method --- p.121 / Chapter 5.4.11 --- Hexane-based extraction method --- p.122 / Chapter 5.5 --- Results --- p.123 / Chapter 5.5.1 --- Comparison of eleven extraction methods --- p.123 / Chapter 5.5.2 --- Comparison of DNA extraction on selected methods --- p.125 / Chapter 5.6 --- Discussion --- p.132 / Chapter Chapter 6 --- Quantitative Analysis --- p.136 / Chapter 6.1 --- Introduction --- p.137 / Chapter 6.1.1 --- Chemistry of quantitative PCR --- p.138 / Chapter 6.1.2 --- PCR system --- p.140 / Chapter 6.2 --- Materials & Methods --- p.142 / Chapter 6.2.1 --- Design of primers and probes --- p.142 / Chapter 6.2.2 --- Methods --- p.145 / Chapter 6.3 --- Results --- p.146 / Chapter 6.3.1 --- Selection of primer/probe --- p.146 / Chapter 6.3.2 --- Primer optimization --- p.149 / Chapter 6.3.3 --- Quantitative analysis of real samples --- p.158 / Chapter 6.4 --- Discussion --- p.152 / Chapter Chapter 7 --- Conclusion --- p.168 / References --- p.175 / Appendix --- p.193

One out of every three workers on the planet is employed in agriculture. Consequently, major changes to the way that agriculture is practiced will have outsized effects on society. This dissertation focuses on technology and climate change, two key variables that will exert increasing influence on the rural sector and broader patterns of economic development. While the implementation of new technologies to increase crop productivity will be essential in satisfying rising global food demand, shifts in global climate may undermine those productivity gains in terms of both agronomic and labor market output. Chapter 2 exploits a quasi-experimental research design to assess how crop productivity gains resulting from a new technology affect gender wage disparities in agricultural labor markets. Using high-frequency temperature data merged with nationally representative time use data from Indian workers, Chapter 3 estimates a labor supply response function to temperature shocks that informs projected labor market effects under climate change. Chapter 4 demonstrates that a very parsimonious statistical model offers accurate out-of-sample predictions and provides a discussion on modeling weather's role in agriculture and the current state of adaptation research.

Submitted by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-04-20T15:44:20Z No. of bitstreams: 2 Dissertação - Frederico Rodovalho de Oliveira - 2018.pdf: 2263442 bytes, checksum: cbb8bc9baf7eeb48e475bd0b59f97f64 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-04-23T11:53:43Z (GMT) No. of bitstreams: 2 Dissertação - Frederico Rodovalho de Oliveira - 2018.pdf: 2263442 bytes, checksum: cbb8bc9baf7eeb48e475bd0b59f97f64 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-04-23T11:53:43Z (GMT). No. of bitstreams: 2 Dissertação - Frederico Rodovalho de Oliveira - 2018.pdf: 2263442 bytes, checksum: cbb8bc9baf7eeb48e475bd0b59f97f64 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-03-26 / The onion is a vegetable consumed by a large part of the world population. Brazil occupies an important position on the world stage, ranking ninth among the largest producers. Most of the national production is concentrated in the Southern Region, which accounts for 45% of the onion production in the country. The state of Goiás currently ranks sixth among the largest domestic producers, accounting for 14% of Brazilian production. The literature on the marketing of horticultural products indicates the existence of a concentration process, which is exercised by the wholesale market, but it is also worth mentioning the fact that the retail market influences the productive chain due to the market power of the large supermarket chains. Thus, the objective of this work is to analyze the existence of Asymmetry in Price Transmission (ATP) among the agents of the onion production chain in Goiás. For the conduction of the study it was necessary to use econometric models such as the one developed by Houck 1977). In general terms, the results indicate that 30% of the income from the sale of the onion, are directed to the rural producer, and the rest is divided between the wholesale market and the retailer. In addition, the results show that asymmetry occurs in the speed of transmission of prices among the agents of the onion production chain, with relative advantage to retail over the other productive links. / A cebola é uma hortaliça consumida por grande parcela da população mundial. O Brasil ocupa importante posição no cenário mundial, ficando com a nona posição entre os maiores produtores. A maior parte da produção nacional está concentrada na Região Sul, que é responsável por 45% da produção de cebola no país. O estado de Goiás atualmente ocupa a sexta posição entre os maiores produtores nacionais, respondendo por 14% da produção brasileira. A literatura sobre comercialização de produtos hortifrutigranjeiros indica a existência de um processo de concentração, que é exercido pelo mercado atacadista, mas merece destaque também, o fato de o mercado varejista influenciar a cadeia produtiva, devido ao poder de mercado das grandes redes de supermercados. Dessa forma, o objetivo deste trabalho é analisar a existência de Assimetria na Transmissão de Preços (ATP) entre os agentes da cadeia produtiva da cebola em Goiás. Para a condução do estudo foi necessário o uso de modelos econométricos, como o desenvolvido por Houck (1977). Em termos gerais, os resultados apontam que 30% da renda pela venda da cebola, são direcionados para o produtor rural, e o restante é divido entre o mercado atacadista e o varejista. Além disso, os resultados mostram que ocorre assimetria na velocidade de transmissão de preços entre os agentes da cadeia produtiva da cebola, com vantagem relativa para o varejo sobre os demais elos produtivos.

Thesis (M. Sc. (Agricultural Management)) -- University of LImpopo, 2002 / Refer to document / NRF (National Research Foundation) and WRC (Water Research Commission)

Onion production in the United States is seriously affected by the tospovirus Iris Yellow Spot (IYSV), whose symptoms include lenticular-shaped lesions that reduce photosynthesis and bulb yield. Thrips tabacai Lindeman, onion thrips (OT), is the only known vector of the disease and a primary arthropod pest of onion. Frequent insecticide applications, increasing resistance in OT populations to insecticides, high nitrogen (N) fertilization rates and loss of yield to disease and insect pressure threaten sustainable onion production. The objectives of this study were to identify crop management strategies to enhance onion productivity while suppressing OT and IYSV. Three fertilizer rates and two crop rotations were assigned to replicated plots to assess effects on onion growth, yield, bulb storage quality, soil quality, thrips populations and IYSV incidence. Trap crops of carrot, buckwheat and lacey phacelia were established in commercial fields to evaluate impact on thrips populations and IYSV occurence. Reduced nitrogen (N) rates, one-third the standard grower rate (133.8 kg N ha-1), resulted in no yield loss as compared with the standard N rate, despite slower crop maturation. Onions treated with a standard N rate(401.8 kg N ha-1) had greater numbers of adult and immature OT than other treatments. Soil nitrate levels were lower and microbial activity measured as dehydrogenase and biomass were greater in reduced N treatments. Plots with buckwheat and phacelia had greater numbers of both adult and immature OT when trap crop apparancy was high (i.e. when onion plants were relatively smaller). There was no observed effect of trap crops on IYSV levels. Results suggest that reduced rate N applications lower numbers of OT while enhancing the microbial population, reducing potential for nitrate leaching while still maintaining yields. Potential for trap crops of buckwheat and lacey phacelia to attract onion thrips from onions exists with successive stands of highly apparent trap crops.