Germina??o e qualidade de sementes de Adenostemma brasilianum (pers.) cass., Asteraceae nativa de sub-bosque de Floresta Atlantica

摘要

The objectives of this study were to analyze germinative behavior of Adenostemma brasilianum from natural population, to evaluate their physical quality and imbibition time. Seeds were collected from individuals in a semideciduous seasonal forest fragment in Vi?osa, Zona da Mata of Minas Gerais State, in southeastern Brazil. For physical quality evaluation, newly collected seeds (month 0) were classified as perfect (dark seeds with embryo) or imperfect (dark or pale seeds without embryo). Samples of 50 newly collected seeds were germinated at three temperatures (20, 25 and 30°C) and at three luminosity conditions: light supplementation (SUP), environment light (AMB) and continuous darkness (ESC). The germination of seed stored for two, four and six months was tested by utilizing the same methodology. Seeds stored for 12 and 18 months were germinated at 25oC SUP. Seed dormancy and imbibition were tested with tetrazolium solution and methylene blue stain, respectively. About 74.7% of the seeds were physically perfect and partenocarpy was observed (10%).Seeds started to germinate on the eighth day after sowing. The factors light, temperature and storage acted synergistically on seed germination. The highest mean germination percentages were observed in newly collected seeds and submitted to temperatures of 25 and 30oC SUP (respectively 85.5 and 88.5%). Seed dormancy was found in low temperature (20oC), in presence or absence of light. Storage increased mortality and seed dormancy breakage; germination was null at 12 months. Water absorption by seeds occurred 24 hours after immersion in methylene blue solution.