Misunderstanding on germination sensu stricto leads us to a false positive germination-dormancy balance in diaspores of Paepalanthus chiquitensis Herzog (Eriocaulaceae), a threatened everlasting flowering species

Although germination sensu stricto and germination-dormancy balance are essential to each other, few reports demonstrate the effects of their relationship on patterns of seed-seedling transition. We studied this relationship by using diaspores of Paepalanthus chiquitensis, a threatened everlasting flowering species. We assessed three aspects: (a) water dynamics in germinating diaspores, (b) thermal stimulation (35, 40, 50, 60 and 70 degrees C for 30 min) and (c) imbibition (4 hr) in growth stimulators (100, 200 or 300 mg center dot L-1 GA(3); 0.1% KNO3). Our findings demonstrate that there are no barriers in the diaspore for diffusion. Additionally, there is high variability in diaspore permeability, and the germination of the species has two steps divided into five stages. These stages were defined by inflections on velocity in water dynamics, which ranged from -0.05 to 0.05 g center dot hr(-1), where only the last stage (Phase V) is associated with the second step of germination sensu stricto. The imbibition phase was the shortest germination phase (1.3 hr), whereas the predominantly biochemical phase was the longest (5 days after sowing [DAS]). Germinability was high (77.5-86.5%), with high daily embryo protrusion (2.46-3.03 diaspores center dot day(-1)). Protocorm emergence marked the end of the first step of germination sensu stricto (9 DAS), and first protocorm rupture (11 DAS) marked the end of the second step. The growth stimulus only concentrated the germination process, showing that the diaspores do not have primary dormancy. Knowing these diaspores' peculiarities during germination sensu stricto avoids a false positive statement on the existence of diaspore dormancy.