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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.2009.tde-10092009-080056
Document
Author
Full name
Marcia Provinzano Braga
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2009
Supervisor
Committee
Marcos Filho, Julio (President)
Cicero, Silvio Moure
Vieira, Roberval Daiton
Title in Portuguese
Relações entre termoterapia, germinação, vigor e sanidade de sementes de tomate
Keywords in Portuguese
Armazenamento agrícola
Germinação de sementes - Vigor
Sementes - Patologia - Tratamento térmico
Tomate - Fisiologia.
Abstract in Portuguese
O presente trabalho objetivou estudar a relação da termoterapia com o potencial fisiológico e sanidade de sementes de tomate, imediatamente após o tratamento e durante o armazenamento, identificando combinações eficientes de temperatura e período de exposição através do teste de sanidade e testes de vigor. O trabalho, dividido em dois experimentos diferenciados pelos tratamentos e métodos de secagem, foi realizado nos laboratórios de Análise de Sementes do Departamento de Produção Vegetal e Patologia de Sementes do Departamento de Fitopatologia da USP-ESALQ e no Centro de Pesquisa Mokiti Okada M.O.A. No experimento I, sementes de dois lotes dos cultivares de tomate UC-82 e Rio Grande foram submetidas à termoterapia úmida com diferentes combinações de tempo e temperatura (52, 53, 54, 55 e 60°C/30 e 60 min), além das testemunhas (sementes tratadas com fungicida e não tratadas) e secadas ao ar livre por 72 horas. Após o tratamento as sementes tiveram seus desempenhos e sanidades avaliados em duas épocas, após a secagem e após 90 dias de armazenamento, através dos testes de porcentagem e primeira contagem de germinação, velocidade e porcentagem de emergência de plântulas, lixiviação de potássio, envelhecimento acelerado e sanidade. No experimento II, as sementes dos mesmos lotes foram submetidas à termoterapia nas combinações de tempo e temperatura de 55°C/30 min e 60°C/60 min, além das testemunhas, sementes tratadas com fungicida e não tratadas. Após o tratamento, as sementes foram cobertas com papel toalha e secadas por 12 horas e, em seguida, avaliadas através dos testes de sanidade, porcentagem e primeira contagem de germinação e envelhecimento acelerado. Os resultados permitiram concluir que a termoterapia (água quente a 55°C/30 min) é uma opção consistente para o controle de fungos associados às sementes de tomate, sem prejudicar o potencial fisiológico das sementes, dependendo da qualidade inicial do lote; os tratamentos 52 a 54°C por 30 ou 60 min não causam prejuízo ao potencial fisiológico de sementes de tomate, enquanto o efeito do tratamento a 55°C/60 min está associado à qualidade inicial do lote; o tratamento com água quente a 60°C por 30 ou 60 min não constitui opção para o tratamento de sementes de tomate, pois é eficiente para o controle de fungos, mas é letal às sementes; os tratamentos com água quente variando de 52 a 55°C por 30 ou 60 min não são eficientes em eliminar a bactéria Clavibacter michiganensis subsp. michiganensis e acarretam queda da resistência de sementes de tomate, tornando-as vulneráveis à manifestação dos sintomas de cancro bacteriano na plântula; o período de 90 dias de armazenamento em condições controladas (20°C e umidade relativa do ar de 50%) pode reduzir o potencial fisiológico de sementes de tomate tratadas com água quente, mas há necessidade de estudos adicionais com períodos maiores de armazenamento para obtenção de resultados mais consistentes; a termoterapia com água quente deixa as sementes de tomate vulneráveis à contaminação por fungos saprófitos, havendo necessidade de estudos adicionais para determinação de opções de tratamentos complementares que ofereçam efeito residual para evitar futuras contaminações, no armazenamento ou no substrato.
Title in English
Relationship between thermotherapy, germination, vigor and health of tomato seeds
Keywords in English
Health test
Physiological potential
Seeds
Storage.
Thermotherapy
Tomato
Abstract in English
The research had as objective to investigate the relationship between thermotherapy and physiological potential and health of tomato seeds immediately after the treatment and during the storage period, then to identify efficient combinations between temperature and exposure time, through seed health test and seed vigor tests. The research was carried out at the Seed Analysis Laboratory of the Department of Vegetal Production and Seed Pathology Laboratory of Phytopathology Department of USP-ESALQ and at Mokichi Okada Research Center M.O.A.. and was divided in two experiments with different treatment and drying methods. In experiment I, seeds from two lots of UC-82 and Rio Grande tomato cultivars were submitted to humid thermotherapy with different combinations of time and temperature (52,53,54,55 and 60ºC/30 and 60 min.), besides the control treatment (seeds with fungicide treatment and without treatment) and dried at air during 72 hours. After the treatment, seeds were evaluated on their performances and seed health in two different periods (after drying and after 90 days storage), through percentage and first count of germination tests, speed and percentage of seedling emergence, potassium leachate, accelerated aging and seed health test. In experiment II, seeds from the same lots were submitted to thermotherapy under two combination of time and temperature (55ºC/30min and 60ºC/60min), besides the control treatment (seeds with fungicide treatment and without treatment). After treatment, seeds were covered with paper towel and dried during 12 hours, and then evaluated through seed health test, percentage and first count of germination tests and accelerated aging. The results lead to the conclusion that thermotherapy (hot water at 55ºC/30min) is a consistent option to control tomato seedborne fungi, without damaging the physiological potential of the seeds, depending on the initial quality of the seeds lots. Treatments with hot water at 52 to 54ºC during 30 to 60 min do not cause damage to tomato seeds physiological potential, while 55ºC/60 min treatment results are associated with the initial quality of the lots. The treatment with hot water at 60ºC during 30 or 60 min cannot be considered as an option because is very effective to control fungi, otherwise is lethal to the seeds. The treatments with hot water temperature between 52 and 55ºC during 30 or 60 minutes were not effective to eradicate Clavibacter michiganensis subsp. michiganensis and caused the fall of the tomato seed resistance to diseases, turning the seeds vulnerable to bacterial canker symptoms show up in the seedling. Ninety days storage period under controlled conditions (20ºC and relative humidity of 50%) may reduce physiological potential of the hot water treated seeds, but further investigation is needed with longer periods of storage to obtain more consistent results. Thermotherapy with hot water make the tomato seeds more vulnerable to saprophytic fungi contamination, needing additional studies to define the options of complementary treatments that offer residual effect to avoid future contaminations, during storage and in the substrate.
 
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Publishing Date
2009-09-19
 
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