Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T13:30:35Z No. of bitstreams: 5 41.pdf: 467693 bytes, checksum: 46ea478cf12119fee773189de4a6bf91 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T18:50:14Z (GMT) No. of bitstreams: 5 41.pdf: 467693 bytes, checksum: 46ea478cf12119fee773189de4a6bf91 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5) / Made available in DSpace on 2015-02-27T18:50:14Z (GMT). No. of bitstreams: 5 41.pdf: 467693 bytes, checksum: 46ea478cf12119fee773189de4a6bf91 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2109 bytes, checksum: aa477231e840f304454a16eb85a9235f (MD5) Previous issue date: 2013 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes) / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / Dentre as esp?cies mais utilizadas na implanta??o de pastagens est?o as do g?nero Brachiaria. Os benef?cios do uso de sementes de alta qualidade para forma??o de pastagem podem ser facilmente constatados pelo r?pido estabelecimento da forrageira, pastagem formada uniformemente e cobertura mais r?pida do solo, resultando em uma utiliza??o da pastagem em menor espa?o de tempo. Por?m, as metodologias utilizadas para avaliar a qualidade de suas sementes ainda n?o est?o bem definidas. O uso de testes de vigor ? uma ferramenta imprescind?vel para a avalia??o do potencial fisiol?gico dos lotes de sementes. Assim, objetivou-se com este estudo adequar os testes de envelhecimento acelerado e de condutividade el?trica, para avaliar o potencial fisiol?gico de lotes de sementes de Brachiaria brizantha das cultivares Marandu e Xara?s, cada uma delas representada por quatro lotes. Para o teste de envelhecimento acelerado as sementes foram submetidas ao envelhecimento acelerado tradicional e com solu??o saturada de NaCl, em cinco per?odos de envelhecimento, 0; 24; 48; 72 e 96 horas. Para o teste de condutividade el?trica, as sementes foram submetidas a 12 per?odos de imers?o em ?gua, por 2; 4; 6; 8; 10; 12; 14; 16; 18; 20; 22 e 24 horas, utilizando-se 25 sementes em 25 mL e em 50 mL, 50 sementes em 50 mL e em 75 mL de ?gua. Para caracterizar o perfil dos lotes, foi determinado o grau de umidade, os testes de germina??o, primeira contagem da germina??o, ?ndice de velocidade de germina??o, estande inicial, emerg?ncia e ?ndice de velocidade de emerg?ncia. Conclui-se que o teste de envelhecimento acelerado possibilita a separa??o dos lotes de B. brinzatha cv. Marandu e cv. Xara?s, pelo m?todo com solu??o saturada de NaCl por 72 horas e 24 horas, respectivamente. No teste de condutividade el?trica, o per?odo de imers?o de 14 horas, utilizando-se 50 sementes em 50 mL, para a cv Marandu, e utilizando-se 25 sementes em 25 mL ou 50 sementes em 50 mL de ?gua, para a cv Xara?s ? adequado para avalia??o do potencial fisiol?gico das sementes. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT Among the species most commonly used in the implementation of the pastures are of the genus Brachiaria. The benefits of using high quality seeds for pasture formation can be easily found by the rapid establishment of forage, pasture formed uniformly and cover the ground more quickly, resulting in a pasture utilization in shorter time. However, the methodologies used to evaluate the quality of their seeds are still poorly defined. The use of vigor testing is an essential implement for the evaluation of the physiological potential of seed lots. The objective of this research was adjust the accelerated aging tests and electrical conductivity, to evaluate the physiological potential of seed lots from Brachiaria brizantha Marandu and Xara?s cultivars, each represented by four lots. For the accelerated aging test, seeds were submitted to traditional accelerated aging and with saturated NaCl solution, five periods of aging, 0, 24, 48, 72 and 96 hours. For the electrical conductivity test, seeds were submitted to 12 periods of imbibitions in water for 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24 hours, using samples of 25 seeds in 25 mL and 50 mL, 50 seeds in 50 mL and 75 mL of water. To characterize the profile of lots, were determined moisture content, germination tests, first count of germination, speed of germination, initial stand, emergence, and? speed of emergence index. The accelerated aging test makes possible the separation of lots of B. brinzatha cv Marandu and cv Xara?s by the method with saturated NaCl solution for 72 hours and 24 hours, respectively. For the electrical conductivity test, the imbebition period during 14 hours using 50 seeds in 50 mL to Marandu and using 25 seeds in 25 mL or 50 seeds in 50 mL of water for cultivar Xara?s is appropriate for evaluating the seed physiological potential.