Seed structures in water uptake, dormancy release, and germination of two tropical forest Fabaceae species with physically dormant seeds

Abstract

The morphoanatomy and germination of dormant seeds of Peltophorum dubium (Spreng.) Taub. and Mimosa bimucronata (DC) O. Kuntze, Atlantic forest Fabaceae species, were examined. Temperature treatments for breaking physical dormancy were applied, and the effects of three forest environment on seed germination were examined. The location of water inlet was carried out soaking in water nondormant seeds with parts of the integument waterproofed with glue. Scanning electron microscopy and optical microscopy were employed to observe the morphoanatomy of seed coat’s surface. Wet shocks of 40 and 50 °C were effective in breaking the physical dormancy of seeds. Higher temperatures in forest clearing had greater effect on germination and emergence of seedlings. Both species presented external and internal seed morphology similar to that of most Fabaceae species. In P. dubium seeds, the water inlet appears to occur not only by the lens, but also by the micropyle and hilum. In M. bimucronata, the sites of water intake were the micropyle and lens.