Quebra da dormência de sementes de quatro leguminosas arbóreas

Abstract

In legume seeds dormancy imposed by the hard seed coat is common. Seeds of four legumes, Samanea saman (Jacq.) Merr., Piptadenia moniliformis Benth., Caesalpinia ferrea Mart. ex. Tul., and Mimosa caesalpiniifolia Benth. were scarified with sand paper; hot water (80°C) for 1, 2.5 and 5.0 min; water at room temperature for 12, 24 and 48h; concentrated sulphuric acid for 1, 5 and 10 min; and in ethilic alcohol for 5, 10 and 25 min, to break seed coat dormancy. In M. caesalpiniifolia the treatments were applied to both articule and naked seeds. A completely randomized experimental design with four replications (50 seeds/replication) was used. The treatments with sulfuric acid were the most effective on S. saman (98.5-99.0% germination) and C. ferrea (76.5-89%). For P. moniliformis, germination was best achieved after the application of hot water (1 or 2.5 min) and sulphuric acid during 10 min (82.5, 74 and 87% germination, respectively). For M. caesalpiniifolia, the results with naked seeds were better than with articules, the hot water, sulphuric acid (5 and 10min), and ethilic alcohol (5min) treatments being especially effective, with germination ranging from 73% to 93.5%. Due to the costs and risks when using sulphuric acid, it would be recommended the use of hot water treatments, even if some increase in sowing density becomes necessary.