Seed Coat Impermeability and Physical Dormancy in Amazonian Mimosa L. Species: Anatomical, Ecophysiological, and Germination Insights

Plants have developed several dormancy mechanisms essential for resilience in adverse environments. Understanding these mechanisms allows for the development of weed control strategies and enhances seedling production. This study aimed to investigate the anatomical and ecophysiological mechanisms associated with seed coat impermeability and physical dormancy in Mimosa camporum Benth. and other Amazonian Mimosa L. species, emphasizing their effects on water uptake, germination behavior, and ecological adaptation. For M. camporum, the imbibition curve, seed coat anatomy through scanning electron microscopy, and germination tests of seeds subjected to chemical scarification (H2SO4) were determined. Data from 25 Amazonian Mimosa species were compiled for ecological and physiological characterization, with subsequent Multiple Correspondence Analysis. Immersion in H2SO4 for 5 min is adequate to break dormancy in Mimosa camporum Benth. seeds. In Mimosa camporum Benth., sulfuric acid scarification effectively promoted water uptake and germination, demonstrating the close relationship between seed anatomy, imbibition behavior, and dormancy regulation. Physical dormancy in Amazonian Mimosa L. species is directly associated with seed coat impermeability, especially the presence of macrosclereids in the palisade layer. In the Amazon, the reproductive success and resilience of Mimosa L. species are related to the physical dormancy and desiccation tolerance of their seeds.