Effect of light, temperature and scarification on the germination of Mimosa foliolosa (Leguminosae) seeds

Mimosa foliolosa Benth. subsp. pachycarpa (Benth.) Barneby var. pachycarpa (Leguminosae), an endemic shrub from the rupestrian fields of Serra do Cipo, southeastern Brazil, is a potential species for land rehabilitation. In this work we studied the effects of (i) light and temperature on seed germination and (ii) mechanical and chemical scarification (with sulfuric acid) on overcoming seed dormancy. Seeds were collected during April and May of 2001, placed in Petri dishes and incubated at 15, 20, 25, 30 or 35 degrees C under either a 12h-photoperiod or total darkness for 30 consecutive days. Light had no significant effect on seed germination. M. foliolosa seeds have an impermeable seed coat (physical dormancy) and mechanical scarification was the most reliable method for breaking seed dormancy increasing germination to over 80% at all temperatures tested. Chemical scarification also increased seed germination at all temperatures, but only at 20 degrees C germination did not differ from that of mechanically scarified seeds. Also, keeping non-scarified seeds at 35 degrees C increased their germination. The results are discussed in regard to the natural factors accounting for dormancy break in nature.