Dormancy-break of arboreal species seeds

Abstract

With the aim of aiding the reforestation process, the production of new seedlings of native arboreal species and the even growth of seedlings in large scale chemical and physical techniques were applied to ‘Pau-ferro’ (Caesalpinia ferrea M.) and ‘Sobrasil’ seeds (Colubrina glandulosa perkins). ‘Pau-ferro’ seeds were submitted to submersion (flooding) treatments using sulfuric acid (90% for five seconds), immersion in hot water (± 80ºC, for five minutes) and scarification with sandpaper. ‘Sobrasil’ seeds received the following treatments: submersion in sulfuric acid 90% for a period of 1, 2 and 3 hours and greenhouse treatment, at 85°C, for 12, 14 and 16 hours. The percentage of germination (%G) and the index of germination speed (IGS) were measured in both species. Mechanical scarification, followed by immersion in sulfuric acid, resulted in the most effective treatment for ‘Pau-ferro’ species. The treatment with hot water showed to be non-effective for this species. Regarding Colubrina glandulosa perkins species, the most efficient treatment was the one with sulfuric acid. Immersion treatments in sulfuric acid for 2 and 3 hours and greenhouse treatment at 85°C for 12 hours led to a significant reduction in the time usually necessary for germination and emergency (sprouting) of seedlings from this species.