Influência da temperatura e da quantidade de água no substrato sobre a germinação de sementes de Ochroma pyramidale (Cav. ex Lam.) Urban (pau-de-balsa)

Abstract

This work was carried out to evaluate the effects of different temperature levels and water contents in the substrate on the germination of Ochroma pyramidale (Cav. ex Lam.) Urban. Prior to the germination tests, all seeds were immersed in hot water (80º C) to overcome the dormancy. Then, they were left on germitest paper, which were wetted using volume (mL) of water equivalent to 1.5, 2.0, 2.5 and 3 times the weight of the substrate, at temperature levels of 25, 30 and 35º C. The experimental design used was a completely randomized in a 4x3 factorial with four replicates of 25 seeds per treatment. Twenty-one days after germination tests started, the following variables were analyzed: germination percentage, germination speed and the length of primary roots and hypocotyle. The percentage of germination was not influenced by the studied factors. Higher temperatures, 30 and 35º C, increased the speed rate of germination. At 30º C, combined with water content equivalent to 1,5 times the paper weight, and at 35º C with 3,0 times, resulted in higher development to root and hypocotyle length.