Gcnuinaíiou of submerged seeds froni jloodplains 
MATERIAL AND METHODS 
Twelve tree species from Central Amazonian floodplains were 
chosen for this study. They display a wide variety of ecological features 
including distribution (occuirence in nutrient-rich whitewater floodplains 
or nutrient-poor blackwater floodplains), successional status (pioneer/ 
non-pioneer), leaf phenology (evergreen/deciduous), levei in the flooding 
gradient, andgermination type (epigeal/hypogeal) (Table 1). 
Mature seeds of each species were collected during the period of 
high water leveis (July/August) in the floodplains of the Rio Amazonas 
(Solimões) and Rio Negro in the vicinity of Manaus, Brazil. They were 
transported to the Amazon Research Institute (INPA) in Manaus and 
kept in plastic basins filled with river water, which was changed at 3-d 
intervals until the experiment started. All species were subjected to 
submergence for 6-33 d before the experiment. This was necessary 
because not all seeds matured at the same time, and because some 
species (e.g. Crateva henthawi, Tabehiiia barbata, Nectandra 
ciwazonum) require submergence to break dormancy (Ziburski 1991). 
Seeds of all species, intended for other experiments, were kept in the 
water-filled basins for up to 76 days. 
The germination experiment was performed at an open 
experimental site at the INPA below a tree, so that it was sunny in the 
moming and in the aftemoon, but shady between 1 1.00 and 14.00 h. 
Air tempcrature varied between 23°C and 35°C, with an average of 
30.8°C during the experimental period. Soil and water temperature did 
not exceed 30. 1°C, with an average of 28.9°C. The timing of the 
experiment corresponded to the non-flooded period, in which seedling 
cstablishmcnt occurs naturally in the field. 
Ten pairs of seeds of each species, consisting of 1 plastic cup 
(300 ml) with 1 seed and wcll watered floodplain soil or 1 cup with 
1 seed, floodplain soil and floodplain water, were tested for 
"crmination. Seeds were sown on lhe soil surface and submerued 
323 
cm 
SciELO 
10 11 12 13 14 15 
