ABSTRACT. The objectives of the present study were to determine heterotic groups of germplasm lines of tropical maize by test crosses and by simple sequence repeat (SSR) markers and to compare five grouping methods of heterogeneous maize. Sixteen lines of nine populations in the S 5 generation were evaluated in test crosses with three testers. The results of four experimental trials over two years were used to group the lines by five methods: evaluation based on the hybrid mean in top-cross tests, hybrid index, genetic diversity by the Mahalanobis distance, genetic diversity by the Euclidean distance, and genetic diversity by SSR markers. The concordance of grouping by the Mahalanobis and Euclidean distance amounted to 87.50%, and the concordance of these methods and grouping by SSR markers was 56.25%. Grouping by SSR markers was consistent with

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5Marizangela Rizzatti ÁVILA 6 Marcibela STÜLP 7 RESUMOA semeadura antecipada da soja, particularmente com cultivares precoces, é prática que vem sendo adotada por muitos produtores paranaenses com o intuito de antecipar a colheita da cultura e viabilizar o cultivo de milho safrinha. Com o objetivo de avaliar a influência da antecipação da semeadura na qualidade fisiológica e sanitária das sementes de soja, foram instalados ensaios de competição de cultivares na unidade da COODETEC, em Palotina, PR. O delineamento foi em blocos casualizados, conduzido em duas safras (2003/2004 e 2004/2005), com três cultivares precoces (CD 202, CD 215 e CD 216), semeadas em cinco épocas (15/09, 30/09, 15/10, 30/10 e 15/11). A qualidade fisiológica das sementes de soja foi avaliada por meio dos testes de germinação (primeira contagem e contagem final) e de tetrazólio (vigor e viabilidade). O "blotter test" foi aplicado para caracterizar a sanidade das sementes. Os dados coletados foram submetidos à análise de variância conjunta e realizados os desdobramentos das interações quando necessários. Os resultados obtidos indicaram que a semeadura em 30/ 10 foi favorável à obtenção de sementes com melhor qualidade.Palavras-chave: Glycine max; época de semeadura; germinação e vigor. ABSTRACTAn early soybean sowing, especially early maturing varieties is a practice that has been adopted by many growers in the state of Paraná in order to anticipate the harvest of the crop and enhance the fall corn. For this reason, experiments of corn cultivar competition trials were carried out at COODETEC in the county of Palotina, Paraná State, to evaluate the influence of the early sowing on the quality of soybean seeds produced. A randomized block design, during two harvests (2003/2004 and 2004/2005); three early maturing varieties (CD 202, CD 215 and CD 216); and five sowing dates (09/15, 09/30, 10/15, 10/ 30 and 11/15) were utilized. The physiological trait of soybean seeds was evaluated by the germination test (first and final count); and tetrazolium (vigor and viability) tests. The blotter test was used to evaluate sanitary quality of the seeds. The data were submitted to variance analysis between groups along with all necessary adjustments. The results showed that the sowing dates 30/10, was favorable for the production of seeds with better quality.

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