Tuesday, August 9, 2016
Georgia Ballroom (Sheraton Hotel Atlanta)
The North American Pawpaw (Asimina triloba (L.) Dunal) is a temperate member of the mostly tropical Annonaceae family native to the Eastern United States. Pawpaws are forest understory trees that often grow in wet, fertile bottomlands and are a common inhabitant of riparian zones. Due to the abundance of pawpaw trees in riparian zones and its wide dispersal throughout the United States, a question has grown for understanding the tree’s natural ability to proliferate and the methods by which this occurs. Animals, humans, and river systems have been speculated to play roles in the dispersal of pawpaw seeds. It has been demonstrated that riparian vegetation can greatly extend its range through hydrochory or the dispersal of seeds by water, especially if the seeds are buoyant. Pawpaw seeds can be subjected to many different lengths of time in the water and the seeds have varying floating capacities. Seed buoyancy is also of interest to nurseries who wish to clean seed through float protocols and propagate trees for sale. The objective of this study was to determine the viability of pawpaw seeds that float or sink when placed in water for 24 hours. Pawpaw fruit of mixed backgrounds were collected from Kentucky State University’s Harold R. Benson Research and Demonstration Farm in September 2015 and their seeds removed. Seeds were divided into 100 seed batches and were either: subjected to a floating treatment and placed in a growth chamber, subjected to a floating treatment and stratified, or stratified and then subjected to a floating treatment. For the floating treatment, 100 seeds were placed in a tray with 6 cm of water and an air stone to provide water circulation. Sinking seed were removed at 0, 1, 3, 5, 12, and 24 hours and placed into labeled bags. After 5 hours, the majority of the seeds had sunk. Seeds were placed into a 20° C incubator to evaluate germination rates of the different groups of seeds, which will be discussed.