This work deals with the germination of seeds and seedling emergence of Digitaria ciliaris (Retz.) Koel., D. horizontalis Willd. and D. insularis (L.) Fedde and shows significant scientific and economical interest since the three weed grasses are very agressive and present ample geographical distribution in the tropical and subtropical American continent. The germination tests were performed monthly with seeds and caryopsis stored in a dry room or submitted to natural aging over the period of 360 days. This work was also realized to verify the effect of depth of seed planting on seedling emergence. Results of percentage and rate of seed germination showed strong inhibition of germination caused by the bracts on the caryopsis. However, in the treatments with naked caryopsis the inhibition yet persist on germination process, indicating that these seeds may require a period of after ripening. Results of seedling emergence showed that the seeds which were planted on the surface and at 2cm depht gave best seedling emergence percentages. The interpretation of the results of germination and seedling emergence shows important aspects of the germination behaviour of these species and permits their rational control in cultivated areas.
Digitaria; seeds; germination; weed grass