Qualidade física e fisiológica de sementes de Acacia mangium Willd provenientes de plantios com diferentes idades

Abstract

The objective of this work was determinate the physic and physiologic quality of ten lots of Acacia mangium Willd. from different commercial established plant ages in Roraima’s savanna. Fruits were collected from plantations in Serra da Lua, in Cantá and Bonfim, from plants with 4, 5, 7, 9 and 10 years-old. Seeds from five plant ages, after the determinations of 1000 seeds weight, were classified in small and large, composing 10 lots. Germination test has been done, after dormancy overcoming, in four repetitions with 50 seeds, per lot, above germination paper and inside gerbox in 25°C. The imbibition was observed in the times 0, 1, 3, 5, 8, 12, 16, 24, 48, 60, 72, 96 and 120 hours to seeds put between papers. The Seed aging test was made in gerbox in four repetitions with 50 seeds, maintained in BOD in 41°C for 0, 24, 48 and 72 hours. The electrical conductivity test was made to seeds without and with dormancy overcoming, in four repetitions with 50 seeds immersed in 75 mL of water for 24 hours. Seeds of A. mangium do not exhibit the three-stage water absorption process in 120 hours, after dormancy overcoming. Small seeds of acacia, after dormancy overcoming, absorb more water and show higher mean of percentage and speed of initial germination and lower time mean of germination than large seeds. Exposition the A. mangium seeds for 24 hours in seed age test reduces the percentage and speed of germination and increases the percentages of dead seeds and abnormal seedlings. The immersion of the seeds in 75 mL of water for 24 hours in 25°C results in value of electrical conductivity with no relation to germination. The plant age do not show relation to 1000 seeds weight and to water absorption process for 120 hours, from seeds submitted to dormancy overcoming. Seeds from plants with 10 years-old show higher percentage and speed of germination than seeds from plants with 4 years-old.