The objective of this work was to evaluate the germination and vigor of seeds and seedlings of Guazuma ulmifolia in response to salinity and to different temperatures. The experiment was carried in laboratory where the seeds were placed in Petri plates with saline solutions of KCl, NaCl and CaCl2 in the osmotic potentials of 0.0 (control); -0.4; -0.8; -1.2; -1.6; -2.0 MPa added(CE) or not (SE) with spermidine (100ppm). The seeds were incubated in BOD at the temperatures of 15, 20, 30 and 35ºC. For each salt, the experimental design was completely randomized with 3 replicates of 20 seeds. There was no germination at 15ºC. For the three salts, values for germination percentage were the greatest at 30ºC. The values of the germination speed index (GSI) were reduced with the reduction of osmotic potentials (PO). The IVG and fresh mass (FM) presented the greatest means at 30ºC. The relationship root/aerial part was significantly higher at 20ºC, which did not significantly differed between CE and SE. The values of FM of CE seeds reduced with the reduction of the PO. The greatest values of dry mass (DM) occurred at 30 and 35ºC in the treatments with KCl and NaCl and at 30ºC for CaCl2. There was no significant difference in the interaction between salt and osmotic potentials for dry mass. In the controlled conditions of the present study, Guazuma ulmifolia presented germination and seedling growth in -2.0MPa salinized environment and temperature around 30ºC, not showing limit of tolerance up to this concentration in none of the evaluated salts.
Native trees; Spermidine; Stress
