RESUMO -A utilização de sementes de boa qualidade é fundamental para o estabelecimento adequado de uma lavoura. Para uma análise mais precisa da qualidade de sementes, faz-se necessário complementar as informações fornecidas pelo teste de germinação com testes de vigor, possibilitando, assim, selecionar os melhores lotes para comercialização e semeadura. Dentre esses testes, destaca-se o de condutividade elétrica. Objetivou-se neste trabalho estabelecer uma metodologia adequada para o teste de condutividade elétrica em sementes de feijão-mungoverde, considerando períodos de embebição e número de sementes. Foram utilizados seis lotes de sementes e o teste de condutividade elétrica foi realizado com as seguintes variações: 100, 75 e 50 sementes embebidas em 75 mL de água destilada a 25 °C, com leituras realizadas após 3, 6, 9, 12, e 15 horas de embebição. O teste de condutividade elétrica conduzido com quatro subamostras de 50 sementes embebidas em 75 mL de água destilada permite a separação dos lotes a partir de 3 horas de embebição, mostrando-se promissor na avaliação da qualidade das sementes de feijão-mungo-verde. Termos para indexação: vigor, Vigna radiata (L.) R. Wilczek, teste de vigor. ELECTRICAL CONDUCTIVITY TEST FOR MUNG BEANS SEEDSABSTRACT -Good quality seeds are indispensable for successful crop establishment. A more precise analysis of seed quality requires a complementation of the information supplied by the germination with vigor tests to allow selection of the best lots for commercialization and sowing. Among these tests, the electric conductivity test is important. The objective of this study was to develop a suitable methodology for the electric conductivity test in mung bean seeds, with treatments of different imbibition periods and seed numbers. Six seed lots were used with the following treatments: 100, 75 and 50 seeds imbibed in 75 mL of 25 °C distilled water, and evaluations after 3, 6, 9, 12, and 15 hours of imbibition. The electrical conductivity test done with four subsamples of 50 pure seeds soaked in 75 mL of distilled water at 25 °C, permits a separation of the lots after three hours of soaking, and this procedure would make a quality evaluation of mung bean seeds viable.

Termos para indexação: Ricinus communis L., beneficiamento, peneira, germinação. PhYSIOLOgICAL quALITY Of CASTOR BEAN SEEdS CLASSIfIEd BY SIzEABStRACt -Seed size in many species may be an indication of their physiological quality. the objective of this study was to evaluate the physiological performance of castor bean seeds sorted by size. The experiment was conducted at the Seed Research Laboratory of the department of Plant Science at the Federal University of Viçosa. Seeds of four castor bean cultivars, IAC 226, IAC 80, Al Guarany 2002 and BRS 188 Paraguaçu were used. the seeds were harvested from all the plant racemes and classified into three different seed sizes for each cultivar. Tests were conducted to evaluate germination and vigor: germination at the 4 th day, germination at the 7 th day, accelerated ageing, seedling length of roots and shoots and fresh and dry weights of the seedlings. Based on the results for IAC 226 and BRS 188 Paraguaçu there is a tendency for smaller seeds to show higher speeds and final percentage of germination but this was not the case for the IAC and 80 AL Guarany 2002.

cassava (Manihot esculenta crantz) is a highly mycotrophic crop, and prior soil cover may affect the density of arbuscular mycorrhizal fungi (aMfs), as well as the composition of the aMfs community in the soil. the aim of this study was to evaluate the occurrence and the structure of aMfs communities in cassava grown after different cover crops, and the effect of the cover crop on mineral nutrition and cassava yield under an organic farming system. the occurrence and structure of the aMfs community was evaluated through polymerase chain reaction (pcr) and denaturing gradient gel electrophoresis (dgge). a randomized block

RESUMO -O período de embebição é de grande importância para a padronização do teste de condutividade elétrica, pois influencia de forma direta os resultados do teste. O objetivo neste trabalho foi determinar a curva de embebição e a condutividade elétrica de sementes de mamona de diferentes tamanhos. Foram utilizadas sementes de quatro cultivares de mamona, IAC 80, IAC 226, BRS 188 Paraguaçu e Al Guarany 2002. As sementes foram colhidas de todos os racemos da planta e beneficiadas quanto ao peso e forma. Posteriormente, as sementes foram classificadas por tamanho em peneiras, conforme a cultivar. A curva de embebição e os valores de condutividade elétrica, para as sementes de mamona, foram obtidos pela pesagem e leitura sistemática de quatro repetições de 50 sementes em processo de embebição continuo. Sementes das cultivares de mamona IAC 80, BRS 188 Paraguaçu e Al Guarany 2002 de maior espessura e largura apresentam maior absorção de água, e isto pode aumentar a lixiviação de solutos durante a embebição. Nas sementes da cultivar de mamona IAC 226, o teor de água e a lixiviação de solutos de sementes com diferentes espessuras estão relacionados com a qualidade destas.Termos para indexação: Ricinus communis, absorção, lixiviação.Imbibition and electrical conductivity of castor bean seeds classified by size ABSTRACT -The soaking period is very important for standardizing the electrical conductivity test since it directly influences the test results. The objective of this study was to evaluate the curves of absorption and electrical conductivity for different-sized castor bean seeds. Seeds of four castor bean varieties, IAC 80, IAC 226, BRS 188 Paraguaçu and Al Guarany 2002, were studied. Seeds were collected from all racemes of the castor bean plants and classified by weight and shape. Subsequently, the seeds were classified by size using screens according to the cultivar. The curves of the absorption and electrical conductivity values were obtained by the weighing and systematic reading of four replications of 50 castor bean seeds until the end of the soaking process. Seeds of the IAC 80, BRS 188 Paraguaçu and Al Guarany 2002 cultivars with a greater thickness and width had a higher moisture content, and this may increase solute leaching during soaking. In the IAC 226 cultivar, the seed moisture content and solute leaching from seeds with different thicknesses is related to their quality.

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