Efeito do local de coleta nas características de sementes de capim-gordura (Melinis minutiflora P. Beauv.) no Distrito Federal, Brasil

the objective of the present study was to evaluate the effect of the collecting location on the sterility, viability and dormancy of melinis minutiflora seeds, an important weed of conservation units in the cerrado regions in brazil. seeds of two cultivars, roxo and cabelo-de-negro, were collected in the following conservation units, located in the federal district (distrito federal), brazil: parque nacional de brasília, reserva ecológica do ibge and esta？？o ecológica de águas emendadas. the percentage of full seeds (containing caryopsis), seed viability and seed dormancy were evaluated. the results showed that seed viability was adequately evaluated using a germination test at the alternating temperatures of 20-30oc, in potassium nitrate at 0.5% with light, and seed dormancy at 25oc, in water and darkness. the collecting location affected the percentage of full seeds, specially in the cultivar roxo (17.5% to 36.1%). it also affected seed dormancy in both cultivars (20% to 80%) and seed viability in the cultivar roxo (80% to 96%). these results help to explain the ecological behavior of melinis minutiflora.