With the aim to help large scale cultivation, Senna macranthera (Collad.) Irwin et
Barn. seeds were placed to germinate at constant temperature, at 6, 9, 12, 15, 18, 21, 24, 27, 30,
33, 36, 39 and 42ºC, after scarification to overcome dormancy. For each treatment, four samples
with 50 seeds were incubated in Petri dishes of 15cm diameter, covered with a double filter-paper
and soaked with 8ml of captan 0.2%. Daily observations were made and the germinated seeds
(radicle protrusion 2mm and with positive geotropic curve) were eliminated, as well as the dead
ones. The lower entropy value was 2.84 bits and the smaller mean time, 2.17 days, observed at
27ºC; the higher germination rate, 90.5%, was obtained at 21ºC. No seed germinated between 6ºC
to 9ºC nor 39 to 42ºC. The enthalpy value of the system was calculated, reaching its minimum
point at 285K and its maximum, at 315K; the point at which the curve crossed the absciss axis was
297.5K. Statistical analysis showed no significant difference among 18, 21, 27, 30 and 33ºC. The
optimum range for germination, between 27 and 30ºC, was determined through the combination
of the analysis of entropy, mean time and total germination rate.