Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 99-113).

Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on June 14, 2010). Includes bibliographical references (p. 93-104).

Thesis (M. Sc. (Zoology and Entomology))--Rhodes University, 2006.

Made available in DSpace on 2014-06-11T19:32:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-08Bitstream added on 2014-06-13T19:22:09Z : No. of bitstreams: 1 mogor_af_dr_botfca.pdf: 1208903 bytes, checksum: a7acfef29f42609f36bd07ab1e09dcdb (MD5) / Este trabalho teve como objetivo avaliar o efeito da cobertura do solo com aveia preta (Avena strigosa) cultivada no inverno, após a fertilização da área experimental, e manutenção da palhada sobre o terreno para transplante direto de alface cultivada no verão. Utilizaram-se cinco manejos da cobertura do solo (sem cobertura, coberto com plástico preto, coberto com aveia deitada, coberto com aveia ceifada e coberto com aveia na sua forma natural, ou seja, em pé) para o cultivo de três cultivares de alface: Elisa, Verônica e Lucy Brown. O experimento foi conduzido na Associação Brasileira de Agricultura Biodinâmica (ABD), Botucatu, S.P., em delineamento experimental de blocos ao acaso, com quatro repetições. As médias foram comparadas pelo teste de Tukey, em análise estatística com parcelas subdivididas. O plantio da alface ocorreu em dois anos consecutivos, buscando avaliar o efeito residual dos tratamentos, com semeadura em dezembro de 2000 e 2001. Avaliou-se o efeito dos tratamentos nos dois anos consecutivos, sobre a temperatura e a fertilidade do solo, nível nutricional das plantas de alface, parâmetros biométricos das plantas (número de folhas, altura das plantas, produção de massa fresca), ocorrência de plantas invasoras, distúrbios fisiológicos e problemas fitossanitários. Concluiu-se que o trasplantio direto de alface sobre a palhada da aveia preta é uma tecnologia eficiente. / The goal of this research was to evaluate the effect of the soil covering with black oats cultivated during the winter, after the fertilization of an experimental area, and maintenance of the straw on the ground for a direct transplantation of the lettuce, during the summer. There have been defined five handling systems for soil covering (soil without cover, soil covered with black plastic, soil covered with laying oats, soil covered with harvested oats and soil covered with oats in natural form) for growing three cultivars of lettuce: Elisa, Veronica and Lucy Brown. The trials were conducted on the Brazilian Association of Biodynamic Agriculture (ABD) during two consecutive years, searching to evaluate the residual effect of the treatments, with seeding in December 2000 and 2001. The effect of the treatment has been evaluated in the two consecutive years by the soil temperature and fertility, nutritional level of the lettuce plants, biometrical parameters of the plants (quantity of leaves, plants highness, fresh mass production), occurrence of weeds, physiological disturbs and diseases. It has been concluded, that direct transplantation of lettuce on the straw of the black oats, is an efficient technology.

Made available in DSpace on 2014-06-11T19:34:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-11-26Bitstream added on 2014-06-13T18:45:53Z : No. of bitstreams: 1 jadao_as_dr_botfca.pdf: 4870280 bytes, checksum: 702ceb8823684649d4b7e4b9babd11b0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A família Sequiviridae é constituída por dois gêneros: Waikavirus e Sequivirus. Os vírus apresentam partículas isométricas com aproximadamente 30nm de diâmetro e uma única fita de RNA sentido positivo, sendo que o genoma dos waikavírus é poliadenilado e dos sequivírus não. Dandelion yellow mosaic virus (DaYMV) foi relatado infectando alface em diferentes países da Europa e classificado no gênero Sequivirus, porém dados moleculares não estão disponíveis para este vírus. No Brasil, um vírus isométrico infectando alface foi isolado por Marinho et al., (1982) no Distrito Federal e denominado de Lettuce mottle virus (LeMoV). Um provável isolado deste vírus isométrico foi descrito mais tarde no estado de São Paulo por Stangarlin (1995), sendo encontrado frequentemente em infecções mistas com o Lettuce mosaic virus (LMV). Em ensaios de microscopia eletrônica utilizando antissoro policlonal específico para Dandelion yellow mosaic sequivirus (DaYMV) e extrato foliar de plantas infectadas pelo LeMoV, foi verificada uma reação sorológica parcial (Chaves, 1999), indicando que o LeMoV possivelmente seria um membro do gênero Sequivirus, família Sequiviridae. Um protocolo funcional de purificação tanto para o LeMoV como para o DaYMV foi desenvolvido e sequências parciais do genoma de ambos os vírus foram obtidas usando preparações virais purificadas e... / The Sequiviridae family is constituted by two genus: Waikavirus and Sequivirus. The virus have approximately 30nm of diameter and a single-stranded of positive sense RNA. The genome of waikavirus is polyadenylated and of sequivirus not. Dandelion yellow mosaic virus (DaYMV) was reported in different countries of the Europe infecting lettuce and classified in the Sequivirus genus however, molecular data are not available for this virus. In the region of Federal District, Brazilan isometric virus infecting lettuce was isolated by Marinho et. al., (1982) and called of Lettuce mottle virus (LeMoV). Probable a strain of this isometric virus was described later in the Sao Paulo state by Stangarlin (1995), frequently found in mixed infections with the Lettuce mosaic virus (LMV). Using specific polyclonal antiserum for Dandelion yellow mosaic sequivirus (DaYMV) and foliar extract of plants infected for the LeMoV, a partial serological reaction was verified for this virus (Chaves, 1999), indicating that the LeMoV could be possibly a member of Sequivirus genus, Sequiviridae family. A functional protocol of purification was developed for LeMoV and DaYMV and partial genome sequences for both virus was obtained using virus purified preparation and degenerated primers for the Sequiviridae family. Sequences of the LeMoV-AF197 and the DaYMV-DSM2 were analyzed and showed a high identity with other members of the family. Universal primers that detect both viruses and specifics primers for LeMoV and DaYMV were used in diagnosistic tests based on RT-PCR. The specific primers amplified one fragment of 300bp for the LeMoV and 331bp for the DaYMV, being highly specific for diagnosis because no antiserum with good properties are available for these viruses. Different sequivirus proceeding from Brazil (BR11), Chile (Ch36), Holland (DSM2) and France (2227) were also evaluated in this work... (Complete abstract click electronic access below)

Orientador: Francisco Luiz Araújo Câmara. / Resumo: Este trabalho teve como objetivo avaliar o efeito da cobertura do solo com aveia preta (Avena strigosa) cultivada no inverno, após a fertilização da área experimental, e manutenção da palhada sobre o terreno para transplante direto de alface cultivada no verão. Utilizaram-se cinco manejos da cobertura do solo (sem cobertura, coberto com plástico preto, coberto com aveia deitada, coberto com aveia ceifada e coberto com aveia na sua forma natural, ou seja, em pé) para o cultivo de três cultivares de alface: Elisa, Verônica e Lucy Brown. O experimento foi conduzido na Associação Brasileira de Agricultura Biodinâmica (ABD), Botucatu, S.P., em delineamento experimental de blocos ao acaso, com quatro repetições. As médias foram comparadas pelo teste de Tukey, em análise estatística com parcelas subdivididas. O plantio da alface ocorreu em dois anos consecutivos, buscando avaliar o efeito residual dos tratamentos, com semeadura em dezembro de 2000 e 2001. Avaliou-se o efeito dos tratamentos nos dois anos consecutivos, sobre a temperatura e a fertilidade do solo, nível nutricional das plantas de alface, parâmetros biométricos das plantas (número de folhas, altura das plantas, produção de massa fresca), ocorrência de plantas invasoras, distúrbios fisiológicos e problemas fitossanitários. Concluiu-se que o trasplantio direto de alface sobre a palhada da aveia preta é uma tecnologia eficiente. / Abstract: The goal of this research was to evaluate the effect of the soil covering with black oats cultivated during the winter, after the fertilization of an experimental area, and maintenance of the straw on the ground for a direct transplantation of the lettuce, during the summer. There have been defined five handling systems for soil covering (soil without cover, soil covered with black plastic, soil covered with laying oats, soil covered with harvested oats and soil covered with oats in natural form) for growing three cultivars of lettuce: Elisa, Veronica and Lucy Brown. The trials were conducted on the Brazilian Association of Biodynamic Agriculture (ABD) during two consecutive years, searching to evaluate the residual effect of the treatments, with seeding in December 2000 and 2001. The effect of the treatment has been evaluated in the two consecutive years by the soil temperature and fertility, nutritional level of the lettuce plants, biometrical parameters of the plants (quantity of leaves, plants highness, fresh mass production), occurrence of weeds, physiological disturbs and diseases. It has been concluded, that direct transplantation of lettuce on the straw of the black oats, is an efficient technology. / Doutor

Orientador: Vivaldo Silveira Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T02:26:51Z (GMT). No. of bitstreams: 1 Afonso_MarcosRodriguesAmorim_D.pdf: 11650736 bytes, checksum: 7e5d5f2552930a2f6fab23787c54259b (MD5) Previous issue date: 2005 / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

Lettuce is a cool-seasoned vegetable, which is very fragile and should therefore be handled with great care. Processed lettuce (loose leaves and shredded lettuce), is more prone to handling damage than intact lettuce crisp heads. Lettuce produces very little ethylene (less than 0,1 ul/kg-1/h-1), but is extremely sensitive to damage from ethylene. In lettuce, ethylene induces a postharvest physiological disorder known as russet spotting. Due to its climacteric nature, lettuce is very sensitive to ethylene. Ethylene sets in motion a programmed series of events that accelerates senescence in lettuce. Besides causing russet spotting, ethylene also stimulates cell membrane and cell wall damage. In wounded (lightly processed) tissue ethylene production increases, resulting in increased russet spotting and accelerated senescence. Reactive oxygen species are likely role-players involved in membrane damage. Hydrogen peroxide is the primary mediator in membrane degradation; hydrogen peroxide levels remained constantly high during storage. Plant free radical scavengers, such as ascorbate peroxidase, catalase and superoxide dismutase protect membranes from damage by free oxygen radicals. The activities of ascorbate peroxidase and catalase was determined during storage and was found not to increase during senescence. Applying different postharvest treatments such as controlled atmospheric storage, 1-MCP, and short heat-shocks to iceberg lettuce significantly suppressed the negative effects of ethylene. These treatments were effective in suppressing russet spotting and senescence as indicated by reduction in moisture loss and ion leakage. Treatment with electro-activated water, did not affect ethylene sensitivity, but did limit moisture loss by lowering the rate of transpiration by increasing stomatal resistance, thus contributing to the retention of crispness and improved longevity. / Prof. C.S. Whitehead

A number of techniques were used to obtain a variety of bacterial and fungal species antagonistic to Pythium - F group in hydroponic systems. Isolations were made from roots of ‘escape’ lettuce plants in a commercial hydroponic gravel system as well as Pythium mycelium exposed to the hydroponic solution. Seventy four bacterial and eighteen fungal isolates were obtained and were screened for in vitro activity against Pythium by means of the dual culture method. Twenty-two bacterial isolates rendered between 10.8 and 48 % inhibition and ten fungal isolates rendered between 24.3 and 54 % inhibition of Pythium mycelial growth. Potential biocontrol agents were screened in a static aquaculture system on butterhead lettuce seedlings in the greenhouse prior to evaluation in a re-circulating gravel bed hydroponic system in the greenhouse and field, for both growth promoting and biocontrol ability. Significant increases of between 689 % and 922 % in total fresh yield were obtained from plants preventatively treated with isolates JH49, JH41, JH83, JM6R and JM16W. The eight best performing isolates were further evaluated for biocontrol activity against Pythium as well as growth promotion on butter head lettuce in a re-circulating gravel bed hydroponic system in the greenhouse. Significant increases of 1.5 % - 63.5 % and 0.9 % - 38.8 % in total fresh yield were obtained from plants evaluated for growth promotion and Pythium control, respectively. Based on their performance five of the eight isolates were selected for evaluation in a re-circulating gravel bed hydroponic field system. Treatment with Pseudomonas fluorescens and Bacillus subtilis significantly increased fresh leaf weight of lettuce plants in comparison with the untreated control indicating effective suppression of Pythium. Of the isolates that were previously evaluated against Pythium wilt and root rot of lettuce in a hydroponic system (Chapters 2 and 3), 6 bacteria and 2 fungi were most effective. The following possible modes of action of these isolates, were investigated, namely competition, production of inhibitory substances and induced resistance. The root colonizating ability of the isolates was also assessed. Competition between the isolates and the pathogen were confirmed by testing for siderophore and hydrolytic enzyme production. Five of the isolates produced siderophores much faster than the rest, demonstrating that these isolates were able to take-up iron from the media at a faster rate, thus indicating a significant competitive ability. Antibiotic production by the isolates was confirmed in vitro by means of the dual culture technique. Of the eight isolates screened, only one isolate showed in vitro inhibition of the pathogen. This result was confirmed by a TLC assay, where fluorescent bands were formed by the same isolate, indicating the presence of phenolic compounds. These compounds were separated by HPLC. Analysis of total soluble and cell wall phenolic levels in Pythium infected and non-infected plants treated and untreated with the biocontrol isolates did not render conclusive results. Three of the eight isolates were able to colonize 100% of the lettuce roots. / Dissertation (MSc (Plant Pathology))--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

abstract: Phosphorus (P) is a limiting nutrient in ecosystems and is mainly used as fertilizer to grow food. The demand for P is increasing due to the need for increased food supply to support a growing population. However, P is obtained from phosphate rock, a finite resource that takes millions of years to form. These phosphate rock deposits are found in only a few countries. This uneven distribution of phosphate rock leads to a potential imbalance in socio-economic systems, generating food security pressure due to unaffordability of P fertilizer. Thus, the first P-sustainability concern is a stable supply of affordable P fertilizer for agriculture. In addition, improper management of P from field to fork leaves an open end in the global P cycle that results in widespread water pollution. This eutrophication leads to toxic algal blooms and hypoxic “dead zones”. Thus, the second P-sustainability concern involves P pollution from agriculture and cities. This thesis focuses on P flows in a city (Macau as a case study) and on potential strategies for improvements of sustainable P management in city and agriculture. Chapter 2 showed a P-substance-flow analysis for Macau from 1998-2016. Macau is a city with a unique economy build on tourism. The major P flows into Macau were from food, detergent, and sand (for land reclamation). P recovery from wastewater treatment could enhance Macau’s overall P sustainability if the recovered P could be directed towards replacing mined P used to produce food. Chapters 3 and 4 tested a combination of P sustainability management tactics including recycling P from cities and enhancing P-use efficiency (PUE) in agriculture. Algae and biosolids were used as recycled-P fertilizers, and genetically transformed lettuce was used as the a PUE-enhanced crop. This P sustainable system was compared to the conventional agricultural system using commercial fertilizer and the wild type lettuce. Chapters 3 and 4 showed that trying to combine a PUE-enhancement strategy with P recycling did not work well, although organic fertilizers like algae and biosolids may be more beneficial as part of longer-term agricultural practices. This would be a good area for future research. / Dissertation/Thesis / Doctoral Dissertation Biology 2020