The influence of uniformity of heat transfer with respect to the effect of heat treatment was investigated by correlating engineering parameters with the quantified heat treatment effects. Differences in treatment effect in terms of quality, anti-pathogen and chilling injury (CI) control properties among commodities was studied by exposing them to different target temperatures. Similar effects were also evaluated and quantified within an individual commodity by a custom-designed device. This device, whose design parameters were based on a heat transfer simulation, insured that one hemisphere of a tomato was exposed to air at 39°C and 0.24 m s-1; while the other hemisphere was exposed to air at a lower temperature with a velocity of0.24 m s-1 or 0.12 m s-1. / Single-temperature heat treatment was most effective in limiting pathogen development and varied according to the parameter measured: 38°C for hypersensitive response (HR), 36°C for tissue breakdown, 36°C, 38°C or 39°C for mycelium abundance, and 38°C or 39°C for lesion size. Bilateral differences in temperature across the fruit significantly affected disease control: decreasing temperature differences significantly improved the uniformity of disease control. / Some of the effects of heat treatment on tomato quality, such as color development and resistance to CI, appear to be localized. A significant difference in redness was identified between heated parts and unheated parts of tomato fruits immediately after treatment; and the differences persisted during storage. Differences in lightness and chroma were noted on day 4. Delay in ripening caused by heat treatment was confirmed through the higher TA and TSS values of heated tomatoes or heated portion of partially heated tomatoes. / The heated parts of tomatoes showed a stronger resistance to chilling injury. The effective temperature control range for CI was wide, but temperatures higher than 39.5°C for 23 h hot air treatment could lead to adverse effects. / Differences in physiological effects between hemispheres in two chambers was reduced by directly decreasing the temperature difference between upper and lower chambers or relatively increasing the heating air flow rate, highlighting the importance of improving the uniformity of air flow around each individual treated fruit.

Lycopersicon esculentum Mill. cv. Rodade was developed in South Africa for the fresh produce market. This cultivar is also of major importance for South African tomato breeding programmes because of its resistance to bacterial wilt. In this study, aspects of the effects of 6-benzyladenine on adventitious shoot formation by both L. esculentum cv. Rodade and Lycopersicon peruvianum Mill. were studied in vitro. These included the regeneration of adventitious shoots, the effects of different incubation times, the uptake and metabolism of BA and the effect of auxin on the metabolism of BA in both leaf and callus tissue of the two species. Adventitious buds could be regenerated on all tissue types except for callus tissue of L. esculentum. A stepwise increase in the percentage shoots produced was observed indicating a period of induction wherein incubation on a medium containing BA is beneficial to the production of shoots. Leaf tissue was more responsive to BA treatments than callus tissue of both species. The main route of BA metabolism in both species is from BA to [9R]BA and [9R-MP]BA. Callus tissue of L. esculentum cv. Rodade however converted BA to the 3- and 9- glucosides of BA rather than to metabolically active forms of the cytokinin. The auxin, indole-3-acetic acid, played a definite role in the conversion of BA to [3G]BA and [9G]BA in leaf tissue of the tomato cultivar tested, but had no effect in callus tissue of this species. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.

Orientador: Maristela Simões do Carmo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-15T19:53:22Z (GMT). No. of bitstreams: 1 Salomon_MarcusVinicius_D.pdf: 591848 bytes, checksum: dbc49c2d11790976003f4d40d7a59e65 (MD5) Previous issue date: 2010 / Resumo: O plantio do tomateiro tem uma extraordinária relevância no Brasil, pela sua representação em área plantada, sendo o segundo mais importante cultivo da área olerícola, com mais de três milhões de toneladas produzidas. Assim, é relevante estudar de que modo está estruturado o sistema de produção e como se relaciona com os demais elos da cadeia. O objetivo deste trabalho foi caracterizar e analisar a cadeia produtiva do tomate de mesa na região de Campinas (SP), com base na relação do setor produtivo com os demais setores, e apontar possibilidades de melhoria de sua capacidade competitiva no setor agrícola. O princípio metodológico utilizou dados primários obtidos por meio de entrevistas com os agentes da cadeia produtiva, e dados secundários e informações de pesquisa disponíveis na literatura. A pesquisa teve um caráter quantitativo na formulação dos custos de produção, e um qualitativo no levantamento das informações referentes ao sistema produtivo e a relação deste com os demais agentes da cadeia. Foi realizada uma análise do processo de produção e suas relações com os fornecedores de insumo e com os compradores de tomate. Os produtos de uso mais geral são adquiridos em agropecuárias, geralmente localizadas na região de produção, já os produtos fitossanitários são comprados de revendas especializadas, as quais possuem técnicos de além da venda de produtos oferecem assistência técnica. Uma característica importante é o caráter nômade da cultura, devido ao grande número de problemas fitossanitários, principalmente, relacionados aos patógenos de solo. Como consequência desta particularidade existem dificuldades para a realização de levantamentos sistemáticos junto aos agricultores pela mudança constante da área de plantio, e sua preferência em trabalhar no sistema de arrendamento da terra. Nos municípios visitados foi possível identificar três vias de comercialização partindo-se dos agricultores (intermediários, packing house e CEASA). Os agricultores estão situados próximos ao centro dos municípios, onde existem vias de acesso em bom estado de conservação, não representando maiores problemas para a aquisição de insumos ou comercialização da produção. Os agricultores entrevistados apresentam como característica mais de cinco anos na atividade, propriedades que variam de 2 a 50 hectares, utilizam em média dois funcionários registrados por hectare de cultura, e em sua maioria trabalham com terras arrendadas. O nível tecnológico utilizado pelos agricultores no EDRCampinas pode ser considerado bom, sendo bastante alta a utilização de insumos como calcário, adubos e defensivos agrícolas. Eles não participam de associações e a forma de acesso à assistência técnica bastante utilizada pelos agricultores é por meio dos técnicos de revendas de produtos fitossanitários, que visitam as propriedades para oferecer produtos e fazer a recomendação de seu uso / Abstract: The planting of tomato has a special relevance in Brazil, for its representation in area planted and the second most important vegetable crop growing area, with over three million tons. Thus, it is important to review how it is structured the production system and how it relates to the other links in the chain. The objective of this study was to characterize and analyze the production chain of fresh tomato in Campinas (SP), based on the ratio of the productive sector with other sectors, and indicate possibilities of improving their competitiveness in the agricultural sector. The methodological principle used primary data obtained through interviews with the actors of the production chain and secondary data and research information available in the literature. The study had a quantitative character in the formulation of the production costs and a qualitative survey of the information relating to the production system and its relationship with other actors in the chain. Analyzing the production process and its relations with input suppliers or buyers of tomatoes this can be characterized by the formation of seedlings to be performed by specialist nurseries, but the seeds are purchased by farmers. The products of more general use are purchased in farming, mainly located in the region of production, plant protection products are purchased from specialized dealers, which are well organized and in small numbers, with a good portion of the market. These work directly with farmers, and beyond the provision of products they too provide technical assistance, which in the case of tomato farmer in the region studied, it is the only one they receive. An important feature is the character of the nomadic culture, due to the large number of health problems, mainly related to soil pathogens. As a result of this arrangement there are difficulties to conduct systematic surveys with local farmers due for the constant change of acreage, and their preference to work in the system of land tenure. In the cities visited it was possible to identify three marketing channels starting from the farmers (intermediate, packing house and CEASA). Farmers are located near the center of towns and have access roads that are in good condition, which does not pose major problems for the purchase of inputs and marketing outputs. The interviewed farmers showed to have as feature more than five years in the activity, properties that range from 2 to 50 hectares, using on average two employees per hectare recorded culture, mostly working with holdings. The level of technology used by rural farmers in the EDR-Campinas can be considered medium, being high enough the use of inputs such as lime, fertilizers and pesticides. The farmers Do not participate in associations and the access to technical assistance is much used by farmers is through the reseller technical protection products, visiting the properties to offer products and make a recommendation for its use / Doutorado / Planejamento e Desenvolvimento Rural Sustentável / Doutor em Engenharia Agrícola

No description available.

No description available.

No description available.

Call number: LD2668 .T4 1962 A48

Call number: LD2668 .T4 1962 F64

No description available.

published_or_final_version / abstract / Botany / Master / Master of Philosophy