Ciência e Agrotecnologia
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/9885
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Resultados da Pesquisa
Item Magnetic field in coffee seed germination(Editora UFLA, 2020-07-13) Braga Júnior, Roberto Alves; Azevedo, Roberto Luiz de; Guimarães, Renato Mendes; Reis, Leandro VilelaThe effective production of coffee seedlings faces many challenges, including seed germination. Therefore, a reduced seed germination period can be one of the most relevant contributions to enhance the testing and production of robust seedlings. The objective of this research was to evaluate the effects of a constant magnetic field on the germination of coffee seeds (Coffea arabica L.). The analyses were performed using a biospeckle laser (BSL) in conjunction with traditional seed viability tests. The coffee seeds were subjected to magnetic fields of constant intensity at values of 10 mT and 28 mT for a time interval of 6 days during their germination process. The embryo region was illuminated, and the images obtained by the BSL were processed. The activity levels of this region were compared with the data obtained using traditional physiological seed analysis. In addition to the results of BSL activity, the results of the seed analysis, such as isoenzymatic catalase (CAT), esterase (EST), superoxide dismutase (SOD), malate dehydrogenase (MDH) and endo-β-mananase, membrane integrity, germination, germination speed index (GSI), emergence speed index (ESI), and radicular protrusion levels, were obtained during the germination process. In conclusion, magnetic pretreatment with both intensities during the first six days of germination improved the permeability of the cellular membranes and advanced the activation of the antioxidant system, thus promoting faster and more uniform seed germination.Item Magnetic field in coffee seed germination(Editora UFLA, 2020) Braga Júnior, Roberto Alves; Azevedo, Roberto Luiz de; Guimarães, Renato Mendes; Reis, Leandro VilelaThe effective production of coffee seedlings faces many challenges, including seed germination. Therefore, a reduced seed germination period can be one of the most relevant contributions to enhance the testing and production of robust seedlings. The objective of this research was to evaluate the effects of a constant magnetic field on the germination of coffee seeds (Coffea arabica L.). The analyses were performed using a biospeckle laser (BSL) in conjunction with traditional seed viability tests. The coffee seeds were subjected to magnetic fields of constant intensity at values of 10 mT and 28 mT for a time interval of 6 days during their germination process. The embryo region was illuminated, and the images obtained by the BSL were processed. The activity levels of this region were compared with the data obtained using traditional physiological seed analysis. In addition to the results of BSL activity, the results of the seed analysis, such as isoenzymatic catalase (CAT), esterase (EST), superoxide dismutase (SOD), malate dehydrogenase (MDH) and endo-β-mananase, membrane integrity, germination, germination speed index (GSI), emergence speed index (ESI), and radicular protrusion levels, were obtained during the germination process. In conclusion, magnetic pretreatment with both intensities during the first six days of germination improved the permeability of the cellular membranes and advanced the activation of the antioxidant system, thus promoting faster and more uniform seed germination.Item Efeitos de tempos e temperaturas de condicionamento sobre a qualidade fisiológica de sementes de cafeeiro (Coffea arabica, L.) sob condições ideais e de estresse térmico(Editora UFLA, 2004-05) Lima, Sílvia Mara Pacheco; Guimarães, Renato Mendes; Oliveira, João Almir; Vieira, Maria das Graças Guimarães CarvalhoObjetivou-se com a presente pesquisa estudar tempos e temperaturas mais adequadas para o condicionamento fisiológico e avaliar os efeitos desses tratamentos na germinação sob condições de estresse térmico, de sementes de cafeeiro armazenadas. O estudo foi conduzido nos Laboratórios de Análise de Sementes e Técnicas Moleculares do Departamento de Agricultura da Universidade Federal de Lavras, utilizando-se sementes de café da cultivar Acaiá do cerrado. As sementes foram colhidas nos campos de produção da UFLA e armazenadas em condições de ambiente de agosto/2000 a janeiro/2001, quando foram submeti- das ao condicionamento em água nas temperaturas de 15, 25 e 35 o C por 4, 8 12 dias de embebição. O condicionamento foi realizado em câmara tipo BOD, na presença de luz, e a aeração foi feita com compressores e bombas de aquário. Após cada tratamento, as sementes foram imediatamente submetidas à determinação do teor de água e avaliadas pelos testes de germinação e índice de velocidade de germinação sob estresse térmico (20 e 35 o C) e eletroforese de enzimas. Para comparação, foram utilizadas sementes sem tratamento de embebição. Pelos resultados, conclui-se que as sementes condicionadas em água a 15 e 25 o C apre- sentaram melhor desempenho da germinação em condições de estresse térmico; o condicionamento a 35 o C não foi apropriado; o condicionamento por 4 dias foi o menos eficiente em melhorar a qualidade fisiológica das sementes, e o condicionamento fisio- lógico em água mostrou-se eficaz ao revigoramento, principalmente a 25 o C por 12 dias.Item Suitability of the tetrazolium methodology for recently harvested and stored coffee seeds(Editora UFLA, 2012-07) Clemente, Aline da Consolação Sampaio; Carvalho, Maria Laene Moreira de; Guimarães, Renato MendesGermination of coffee seeds occurs in a slow and non-uniform manner and the tetrazolium test (TZ) may be a quick alternative for assessment of viability, as long as the preparation and imbibition of the seeds is established. This study was performed in two stages: in the first, recently harvested seeds from three coffee cultivars were submitted to four methodologies for removal of the parchment: manual extraction or use of sodium hypochlorite (NaClO at 5%) and two periods of imbibition of the seeds in water (36 and 48 hours) for removal of the embryos. In the second phase, manual removal and the use of NaClO were compared for elimination of the parchment of stored seeds for monthly performance of the tetrazolium test for six months. Sodium hypochlorite is not efficient in total extraction of the parchment and has a negative effect on the results of the TZ test on low moisture coffee seeds. An imbibition time of 48 hours facilitates extraction of embryos and does not affect test results. The tetrazolium test on coffee seeds with different moisture and deterioration levels must be undertaken with manual removal of the parchments