Senna macranthera (Fabaceae: Caesalpinoideae) seeds were submitted to several pre-treatments
in order to break mechanical dormancy, such as imersion in sulphuric acid, in flowing and boiling water, organic
solvents, dry heating or cooling and mechanical abrasion. For each treatment, it was used four sets with 50 seeds,
incubated at 27ºC in Petri dishes of 15cm diameter, covered with a double filter-paper, soaked with captan 0,2%.
Daily observations were made, and the germinated seeds were eliminated. Imersion in sulphuric acid during 10 min
and thermal shock at 65ºC 72 hours produced germination times longer than the control, 5,27 days; mechanical
scarification, imersion in organic solvents during 30 and 60 min., at flowing water and both thermal shocks during
24, 48 and 72 hours resulted in imbibition and germination percents smallers than 50%. Imersion in sulphuric acid
by less than 30 min. resulted in less than 100% of imbibition and than 80% of germination. Imbibition of all seeds
was obtained with the other periods of imersion in sulphuric acid and boiling water, but with 21 e 0% of germination
with the last, respectively at 30 and 60 min. The bigger synchronization of the germination process was obtained
with 50 min. in sulphuric acid, giving 90% of the seeds germinated in 2,17 days. Different times of scarification with
sulphuric acid were tested at temperatures of 39, 36, 33, 30, 24, 21, 18, 15, 12 and 9ºC. At temperatures higher
than 27ºC, it was observed diminution of the germination and larger contamination. At 21ºC it was observed
90,5% of germination, but in 3,34 days, with informational entropy to 4,16 bits.