Seeds of Caesalpinia echinata Lam. Under Water Stress at Different Temperatures

The Caesalpinia echinata Lam. species, belongs to the Fabaceae family, popularly known as Pau Brazil, is a large tree, native to Brazil, that can be found from Ceará to Rio de Janeiro, with a relevant national historic and economic value. The objective of this study was to evaluate the effects of water stress at different temperatures on germination and seed vigor. The experiment was carried out at the Laboratório de Análise de Sementes of the Centro de Ciências Agrárias of the Universidade Federal da Paraíba, Areia-Paraíba. The water stress was formulated with solutions of polyethylene glycol 6000 (PEG 6000) in different osmotic potentials of 0.0 (control), -0.2; -0.4; -0.6 MPa at constant temperatures of 25, 30 and 35 °C, in a completely randomized design. The percentage of germination, first counting of germination, germination speed index, length and dry matter of seedlings were evaluated to determine the effects of the treatments. Decreases of the osmotic potential negatively influenced the germination and vigor of C. echinata seeds at the three evaluated temperatures (25 ºC, 30 ºC, 35 °C).