Potencial germinativo de sementes de fava-d'anta (Dimorphandra mollis Benth. - Fabaceae: Mimosoideae) sob diferentes procedências, datas de coleta e tratamentos de escarifica??o

摘要

Forest species with hard and impermeable seeds often have problems to germinate. The present work aimed to select pre-germinative treatments in laboratory to homogenize the germination of Dimorphandra mollis seeds and to compare the germination rates of seeds collected from different periods and locations. D. mollis seeds were collected at four different regions in northern Minas Gerais: Montes Claros, Lontra, Mirabela and Jequitaí, in two distinct periods: August and September/2004. The seeds were submitted to five scarification treatments: sanding (mechanical scarification), immersion in sulfuric acid to 10 and 20 minutes, immersion in hot water (70 oC) and control (intact seeds). For the germination tests, a randomized experimental design was used, with ten replicates of ten seeds for each treatment, site and period of collection. The effects of the different treatments on seed germination were tested through an analysis of variance and t test. The germinative potential was significantly higher for seeds collected in August (X= 47.8 ± 6.8%), at the Montes Claros site (X= 41.7 ± 9.7%), and submitted to mechanical scarification (X= 83.0 ± 8.2%). Our results indicate that fava-d'anta seeds present dormancy imposed by the tegument, with the highest germinative potential under the sanding treatment. In addition, the degree of seed maturation and local ecological factors seem to interfere with seed germination in D. mollis.