Vigor tests assessing the quality of crambe seeds.

A cultura do crambe (Crambe abyssinica Hochst) tem se destacado no cen?rio nacional pelo seu potencial para produ??o de biodiesel devido ? facilidade de cultivo, qualidade do ?leo e possibilidades de uso dos subprodutos da extra??o do ?leo. Para o estabelecimento da cultura no pa?s ? necess?rio que sejam usadas sementes de qualidade. No entanto, as informa??es sobre metodologias para avalia??o da qualidade de sementes dessa cultura s?o escassas. Dessa forma, objetivou-se adequar as metodologias dos testes de envelhecimento acelerado e condutividade el?trica para avalia??o do vigor de sementes de crambe e investigar a atividade enzim?tica em rela??o ?s diferen?as de vigor. Foram utilizados cinco lotes de sementes da cultivar FMS Brilhante das safras 2008, 2009, 2010 e 2011. Foram realizadas a caracteriza??o morfol?gica de sementes e pl?ntulas e a composi??o centesimal da semente de crambe. Para caracteriza??o do perfil dos lotes realizou-se a determina??o do grau de umidade e os testes de primeira contagem de germina??o, germina??o, ?ndice de velocidade de germina??o, emerg?ncia, estande inicial, ?ndice de velocidade de emerg?ncia e sanidade. Foi tamb?m realizada a an?lise eletrofor?tica das isoenzimas super?xido dismutase, esterase, catalase, ?lcool desidrogenase e malato desidrogenase. Para o teste de envelhecimento acelerado, as sementes foram submetidas ao m?todo tradicional e com solu??o saturada de NaCl, pelos per?odos de envelhecimento de 0; 24; 48; 72 e 96 horas. No teste de condutividade el?trica, as sementes foram submetidas aos per?odos de 2; 4; 6; 8; 10; 12; 14; 16 e 18 horas de embebi??o utilizando-se 25 sementes em 25 mL e 50 mL e 50 sementes em 50 mL e 75 mL. Concluiu-se que ? poss?vel avaliar o vigor de sementes de crambe pelo m?todo tradicional do teste de envelhecimento acelerado a 42 ?C por 96 horas. O teste de condutividade el?trica n?o foi adequado para avalia??o da qualidade fisiol?gica de crambe. Quando associado ? atividade das isoenzimas observou-se que o lote de maior vigor teve maior atividade dos grupos enzim?ticos super?xido dismutase, catalase e esterase. O lote de menor vigor n?o teve atividade das enzimas isocitrato liase e ?lcool desidrogenase. N?o houve altera??o na atividade da isoenzima malato desidrogenase.Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes)Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG)Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013.ABSTRACT Crambe (Crambe abyssinica Hochst) has been highlighted in the national scenery for its potential in producing biodiesel due to its ease of cultivation, quality of the oil and possibilities of use of the oil extraction byproducts. In order to establish the culture in the Country, the use of quality seeds is necessary. However, the information on methodologies for seed quality evaluation for this culture is scarce. Thus, we aimed at adapting the methodologies to the accelerated aging and electric conductivity tests to evaluate the vigor of crambe seeds and investigate the enzymatic activity in relation to the vigor differences. Five seed lots of cultivar FMS Brilhante of the 2008, 2009, 2010 and 2011 harvests were used. We performed the morphologic characterization of seeds and seedlings and the centesimal composition of crambe seeds. For the profile characterization of the lots, we performed the determination of the humidity degree and the tests for first germination count, germination, germination speed index, emergence, initial stand, emergence speed index and sanity. We also performed the electrophoretic analysis of the superoxide dismutase, esterase, catalase, alcohol dehydrogenase and malate dehydrogenase isoenzymes. For the accelerated aging test, the seeds were submitted to the traditional method and with NaCl saturated solution, for the aging periods of 0; 24; 48; 72 and 96 hours. In the electrical conductivity test, the seeds were submitted to the periods of 2; 4; 6; 8; 10; 12; 14; 16 and 18 hours of soaking using 25 seeds in 25 mL and 50 mL, and 50 seeds in 50 mL and 75 mL. We concluded that it is possible to evaluate crambe seed vigor by the traditional method of the accelerated aging test at 42 oC for 96 hours. The electric conductivity test was not adequate for evaluating crambe physiological quality. When associated with isoenzymes activity, we observed that the lot with highest vigor presented the highest activity of the superoxide dismutase, catalase and esterase isoenzymes groups. The lot of lowest vigor did not present activity of the isocitrate liase and alcohol dehydrogenase enzymes. There was no interaction of the activity of the malate dehydrogenase isoenzymes