Seed germination characteristics of Polygonum longisetum (Polygonaceae) with reference to wildfire

Abstract

The seed germination of Polygonum longisetum (Polygonaceae) was examined in relation to wildfire, i.e. smoke, soil surface substrates (charcoal and wood ash), litter (fresh and crushed) and water potential because this species is widely distributed as an invasive species and has the ability of smoke-induced seed germination. Previous studies confirm that this species requires light and cold stratification for high seed germination. The effects of seed density and fertilizer on seed germination and seedling growth were also examined. Seed germination was highest at a certain concentration of smoke liquid, while it was lower on woody ash and higher without litter. Since seed germination decreased more with lower water potential, low seed germination on litter and substrates should be induced by water limitation. Seed density and fertilizer did not affect germination rates but changed biomass and shoot height. In conclusion, the effects of smoke liquid on seed germination changed synchronously with the quality and quantity of litter and substrates. These seed characteristics should be advantageous for germination in dry habitats after wildfires and other disturbances.