Germinação de sementes de espécies arbustivo arbóreas com diferentes mecanismos de dispersão do Parque Estadual da Mata Seca, MG

Abstract

This study aims to verify whether species with different dispersion strategies are also different in their germinative capacity, in a Deciduous Dry Forests, at the "Parque Estadual da Mata Seca” (PEMS), municipality of Manga, North of Minas Gerais. With this purpose, eight species were compared by their presence or absence of dormancy and five species by the germinative comportment of the seeds after storage for a period of four months. Being so, were selected the following four species with biotic dispersion (zoochorics) Spondias tuberosa, Pereskia bahiensis, Pilosocereus pachycladus and Commiphora leptophleos, and also four species with abiotic dispersion, being two autochorics, Mimosa hostilis and Senna spectabilis, and two anemochorics, Myracrodruon urundeuva and Pseudopiptadenia contorta. The presence of dormancy in the seeds was verified by treatments of chemical scarification (chloride acid), mechanical scarification (sandpaper), and thermic scarification (hot water), while the storage tested was accomplished in the soil of the PEMS and in laboratory (control) during a period of four months. In this last test, at each 30 days, a nylon bag was unearthed, and it's germination was compared with the control, until the completion of 120 days, maximum storage time. The witness seeds of abiotic species, specifically those of anemochoric syndrome highlighted over the others, getting higher percentage and velocity of germination. Also, the species Myracrodruon, Pseudopiptadenia and Pilosocereuss had demonstrated that they don't have dormancy. In the other hand, the autochoric species, Senna and Mimosa, demonstrated dormancy in their seeds, like the most of the studied zoochoric species (Spondias, Commiphora and Pereskia), getting better results with the treatment of mechanical scarification. Between the five species which were evaluated the germination after storage in the soil, just the anemochoric specie (Myracrodruon) showed seeds with short viability. Some species had increases in the percentage of germination over the time, showing that their seeds didn't had fisiological maturity during the collecting period, or had overcame the dormancy during their storage. The species of syndromes autochoric and zoochoric, had a similar germinative comportment, likely due to the presence of dormancy in their seed and to the fact that the dispersion process occurs in the rainy season, they also showed a capacity to compose the soil seeds bank, once they have higher longevity, compared to the anemochoric.