Alterações fisiológicas e bioquímicas durante a hidratação de sementes de Dalbergia nigra ((Vell.) Fr. All. Ex Benth

• Ano de defesa: 2011
• Autor(a) principal: Ataíde, Glauciana da Mata
• Orientador(a): Borges, Eduardo Euclydes de Lima e
• Banca de defesa: Rezende, Sebastião Tavares de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Ciência Florestal
• Departamento: Manejo Florestal; Meio Ambiente e Conservação da Natureza; Silvicultura; Tecnologia e Utilização de
• País: BR
• Palavras-chave em Português: Sementes; Germinação; Hidratação; Bioquímica
• Palavras-chave em Inglês: Seeds; Germination; Hydration; Biochemical
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::SILVICULTURA
• Link de acesso: http://locus.ufv.br/handle/123456789/3083

The production and use of seeds with high quality are basic factors for successful of seedling production and establishment of forests with native species. The hydration of the seeds in water is a methodology used to improve germination and vigor, by soaking the seeds in water under controlled conditions, to initiate the first events of germination, however, without reach the stage III of germination and occur radicle emergence. Among the changes resulting from this hydration, have been linked to various physiological and biochemical processes associated with the preparation of metabolism, such as the system of membranes, onset of respiratory activity, increased production of ATP and enzyme activity and protein synthesis. Considering that water is an essential factor for the reactivation of metabolism of seeds, the objective of this study was to investigate the physiological and biochemical alterations resulting from the hydration of jacaranda-da-bahia (Dalbergia nigra) seeds. To this end, experiments were conducted at the Seed Analysis Laboratory of Department of Forest Engineering, Federal University of Viçosa - UFV. In this work were used seeds collected in arrays of two different origins of Dalbergia nigra, which were the lots I and II. Then, seeds belonging to the two lots were placed in water to hydrate in desiccators with relative humidities of 95-99% at temperatures of 15 and 25 °C, to achieve approximately four hydration levels: 10, 15, 20 and 25%. In the first chapter, lots I and II were initially characterized as biometric data (length, width, thickness), weight of thousand seeds, germination percentage, germination speed index (IVG) and electrical conductivity. Next, were assessed the physiological changes in seeds of both lots after reaching the desired moisture levels, and analyzed the curve of seed imbibition, germination, IVG and electrical conductivity. In the second chapter were studied the mobilization of reserve substances in the cotyledons of jacaranda-da-bahia seeds during hydration, by quantifying the levels of lipids, soluble sugars, starch and soluble proteins in the seeds of lots I and II after treatment hydration at temperatures of 15 and 25°C. The third chapter dealt with the changes in reserves of monosaccharides in the cotyledons and the activities of the enzymes α-galactosidase, β-mannanase and polygalacturonase in cotyledons and embryos during hydration of the two lots seeds. Seeds belonging to the lot I had superior physiological quality than the lot II, they have higher average of germination and germination rate and lower leachates in the electrical conductivity test. There were no significant differences between the temperatures of hydration 15 and 25°C for the tests in this paper. The slow hydration in water favored the germination and seed vigor of two lots of jacaranda-da-bahia, but more significant effects were observed in lot II. The maintenance of seed hydration up to 15% moisture was the most suitable for increasing the quality of seeds in lots of different physiological qualities. The mobilization of reserves during the slow hydration in water was similar between the two lots evaluated, with little variation in levels of lipids, while the content of soluble carbohydrates and starch showed a decrease from the level of hydration of 15%, and soluble proteins showed a gradual tendency of fall from the control (dry seeds) to the level of 25% humidity. In two lots, the levels of rhamnose and xylose showed high values in the control and reduction during hydration up to 15% humidity, at which time increased again. Differences were observed between the glucose content between the lots, lot I, with superior quality, showed higher synthesis and degradation of sugar during the hydration of seeds. The enzyme α-galactosidase is preformed initially and has greater activity in the embryo, generating substrate for respiration and formation of carbon structures for growth. The activities of enzymes β-mannanase and polygalacturonase increased with seed imbibition and are different between cotyledons and embryos, reaching higher values in the cotyledons than in embryonic axis.