Dormancy-breaking and the influence of sowing depth on seed germination in Desmodium tortuosum.
The Desmodium tortuosum is an invasive plant in the crops, but it has a high crude protein content and good palatability, and it can be used to feed ruminants. However, its seeds present dormancy due to the impermeability of the integument. Thus, the objective of this work was to evaluate the dormancy overrun and influence of different sowing depths on the germination of desmodium seeds. Two experiments were carried out under controlled conditions using the completely randomized design, both with five treatments and six replicates. In the first experiment five seed dormancy cracking modes were tested, and in the second five seeding depths (0, 1, 2, 4 and 6 cm). The sowing in the second experiment took place in plastic trays, using washed and autoclaved sterilized substrates. It was verified that the most suitable method for overcoming dormancy of seed of D. tortuosum is the manual scarification with sandpaper no 180. The germination of seeds of demodium, when manually scarified with sandpaper no 180, has a direct influence of the seeding depth, with drastic reduction with the increase of the depth in the substrate. The percentage of seed germination is abruptly reduced to depths greater than 1.0 cm. Seedling survival increases with increasing seeding depth.