Dormancy in Winter Buds of American Pondweed, Potamogeton nodosus Poir

Winter buds of American pondweed (Potamogeton nodosus Poir.)were found to be strongly dormant at maturity. Under normalconditions the dormancy lasted for several months. Cold treatmentdecreased the period required for after-ripening, and exposureof dormant buds to 32° C for three days caused most of thebuds to grow in two weeks. Removal of bud scales in light wasvery effective in promoting growth. Soaking of dormant budsin solutions of gibberellic acid, sucrose, combinations of gibberellicacid and sucrose, -naphthylacetic acid and fenac (2,3,6-trichlorophenylaceticacid) partially relieved the growth suppression. Treatmentswith indole-3-acetic acid at 1,000 ppm for 18 hours broke dormancycompletely in all buds, indicating that low levels of this substancemay be the primary cause of dormancy in this species.