Document: SAC-3-35-15

Seed dormancy/germination traits of Polygonum species and their implication in soil seed bank strategy.

ARAKI, S.* and I.WASHITANI

The University of Tokyo, Tokyo, Japan ¹

Abstract:
In order to predict species-specific potential to form persistent soil seed banks and to characterize the dynamics of their seed bank, the seed dormancy/germination traits of seven Polygonum (Persicaria sensu stricto) species sharing lakeshore habitats in central Japan were examined. Strict light requirements for seed germination were not observed in any of the species examined. Although all species required moist chilling (0 - 6 wks) to break seed dormancy and were sensitive to temperature fluctuation (18 C < 12/24 C), the degree of both responses varied between species. Seed germination of P. hydropiper, P. lapathifolium, and P. longisetum was more accelerated by temperature fluctuation and required shorter chilling periods compared with P. japonicum, P. maackianum, P. thunbergii, and P. sieboldi. Secondary dormancy was induced in all species at higher temperatures (24 C, 30 C). A persistent seed bank strategy suggested by the dormancy/germination traits of the studied species was also demonstrated by seedling emergence from surface soils collected from the natural habitat immediately before seed dispersal, as well as by viable seed persistence for 13 months in the field in a seed burial experiment. In the natural habitat, the species with longer chilling requirements occurred in various microhabitats, including the interior of moist tall grasslands, whereas the species having higher sensitivity to temperature fluctuation were most frequently found in sparsely vegetated microhabitats.

Keywords: distribution pattern, gap, moist chilling

This abstract is being presented at: 4:15 PM in session:
Oral Session #68: Dispersal of Seeds and Fruits.