Buoyancy and germination of pond apple (Annona glabm L.) propagules in fresh and salt water

摘要

Pond apple (Annona glabra L) is an aggressive woody weed which has invaded many wetlands, drainage lines and riparian systems across the Wet Tropics bioregion of Far North Queensland. Its threat is so great to these ecosystems that it has been listedas one of 20 Weeds of National Significance (WoNS). The majority of fruit and seed produced by the plant during the summer wet season fall directly into creeks, river banks, flood plains and swamps. Creeks and rivers can channel the seeds into the oceanwhere they can spread along the coastline. Dispersal by water, or hydrochory of the whole fruit, portions of the fruit or the individual seed is an important vector that requires study. This paper reports that pond apple seeds can remain afloat for up to12 months in either fresh or salt water, with approximately 38% of these seeds germinating in a soil medium once removed from the water tanks.