Dormancy breaking methods for baru seeds

The baru has a sexual propagation with a low germination index. Thus, the aim of the present study was to evaluate dormancy breaking methods on baru seeds in order to get information to improve the baru seeds germination, even after the pericarp extraction. The experiment was carried out at the Biology Laboratory of the Mato Grosso State University using a completely randomized experimental design with eight seed dormancy breaking treatments: control; immersion on water at room temperature for 12, 24 and 48 hours; temperatures of 40oC during 3 and 6 hours; mechanical scarification with a nº 80 sand paper; 2-minute boil. The seeds were extracted with a hammer. For each treatment the seeds were placed on a moistened paper towel, rolled up and placed in a perforated plastic trayon a countertop in a protected environment under normal conditions of temperature, photoperiod and air relative humidity. At 4 and 10 days after seeding, the germination percentage and the germination speed index were evaluated. The maximum germination percentage was achieved just with the extraction of the pericarp that involves the seed. For the earlier and uniform germination the immersion on water at room temperature for 48 hours or the scarification in a nº 80 mechanical sander is recommended. The baru dormancy is only due to the tegument hardness and after the seed extraction, no dormancy was observed.