The objective of this study was to investigate the effect of temperature on the germination of Melanoxylonbrauna seeds and identify cardinal temperatures for germination, as well as to evaluate the efficiency of the electrical conductivity test to determine the cardinal temperatures. Therefore, three testswere performed. In the first test, the determination of imbibition curves was performed at each temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45ºC), the seeds were weighed every two hours for a period of 12 hours and after every 12 hours until the root protrusion of 50% of the seeds, or 120 hours when there was no germination. In the second test, to identify the cardinal temperatures, seeds were kept under each temperature for a period of 10 days in DBO under constant light. In the third test, an electrical conductivity test was performed with the seeds incubated for 24, 48 and 72 hours of imbibition in each of the temperatures, and then were placed inerlenmeyer flasks with 75 mL of deionized water at 25ºC for 24 hours for subsequent reading of the electrical conductivity. It is more judicious to recommend temperature ranges for germination than punctual temperatures. The cardinal temperatures (theoretical) for the characteristic germination rates are: 12.3ºC - minimum - 30.0ºC optimal (theoretical) and 42.7ºC maximun. The temperature ranges considering all the variables investigated were: 12.1 to 12.6ºC (minimum); 30.0-35.8ºC (optimum) and 42.4-43.0ºC (maximum). The specie has a wide range of germination with respect to temperature, and germination was observed in the temperature range from 12.0 to 42.0ºC. The electrical conductivity test was efficient to evaluate the effect of temperature onseeds and according to this test the optimal temperature is 27.0ºC.
Imbibition; Electrical conductivity; Forest seeds
