Pyrenes (pits) of muruci (Byrsonima crassifolia (L.) Rich.), clone Açu, an accession of the Tropical Fruit Tree Germplasm Collection of Embrapa Eastern Amazonian were characterized and different methods to overcome the seed dormancy were evaluated. Pyrene color, shape, weight, length, diameter, number of seeds per pyrenes, and thickness of the external and internal walls of the endocarp were characterized; seed color, weight, length, diameter and thickness were characterized. The treatments to overcome seed dormancy were: : a) control; b) soaking in water for 24 hours; c) soaking in gibberellicc acid (500 mg.L-1) for 24 hours; d) soaking in water for 24 hours followed by compression fracturing of the endocarp; e) soaking in gibberellic acid (500 mg.L-1) for 24 hours and fracturing of the endocarp. The pyrenes of muruci "Açu" are ovate, with a reticulate surface design, creamy brown in color, weight 0.62±0.09 g and are 1.10±0.07 cm long by 1.02±0.09 cm in diameter. The pyrenes generally contain two seeds (minimum zero and maximum three), located in the loculus whose external walls are thicker than the internal walls. The endocarp is water permeable and the seeds absorb water rapidly. The seeds represent 10.12±2.87% of the pyrene weight. The best treatments to overcome dormancy were soaking in giberellic acid or water followed by fracturing the endocarp. This combination of results suggests that germination of muruci "Açu" seeds is regulated by exogenous and endogenous dormancy mechanisms. The first is caused by the endocarp, which offers considerable resistance to the growth of the embryo, and the second is the seed physiological dormancy.
Byrsonima crassifolia; dormancy; gibberellin
