Requirements for seed germination in North AMerican pawpaw (Asimina triloba (L.) Dunal)

North American pawpaw is a temperate species in the mostly tropical Annonaceae. A small proportion (12%) of the seed population used in this study germinated after removal from the fruit. The remaining seed required 8 weeks of chilling stratification to satisfy dormancy. In addition, pawpaw seeds displayed a moderate form of recalcitrance. Seeds lost 50% viability when seeds were dried from their initial 37 to 25% moisture. Critical value for total loss in viability was between 15 and 5% moisture. Also, following stratification, pawpaw seeds germinated at 45% without additional water in the germination medium. There was no significant effect of light or temperature (25, 30 or 20/30°C) on standard germination. Seeds showed the best germination with 1ml of water added to the germination medium in petri dishes. For standard germination testing, pawpaw seeds should be stratified for 100 days at 5°C followed by germination in rolled towels at constant 25 or alternating 20/30°C. Light was not required and final germination counts should be after 5 weeks.