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Print version ISSN 0100-6762
ALVES, Edna Ursulino et al. Methods for dormancy breaking of Zizyphus joazeiro Mart. dispersal units. Rev. Árvore [online]. 2008, vol.32, n.3, pp. 407-415. ISSN 0100-6762. http://dx.doi.org/10.1590/S0100-67622008000300003.
Z. joazeiro is a forest species of great socioeconomic importance for the Brazilian Northeast region, but of difficult germination caused by the water impermeability of dispersal units. The present study evaluated pre-germinative treatments for overcoming dormancy in Zizyphus joazeiro seeds. The experiment was carried out in greenhouse conditions at Centro de Ciencias Agrárias, Universidade Federal da Paraíba, Areia-PB, Brazil. The treatments were as follow: control (intact dispersal units), mechanical scarification with sandpaper, immersion in water at room temperature for 24, 48, 72, 96 and 120 hours, immersion in water at 70 C for three minutes and, immersion in concentrated sulfuric acid for 30, 60, 90, 120 and 150 minutes. The evaluated variables included emergence percentage, first count and emergence speed index, length and weight of plant dry matter. The treatments showing higher Z. joazeiro seedling emergence were immersion of dispersal units in cold water for 48 hours, immersion in water at 70 C for three minutes and manual scarification with sandpaper, overcoming tegument hardness in dispersal units of this species.
Keywords : Juazeiro; emergence; vigor; forest species; medicinal plant.