INFLUENCE OF ANOXIA ON SPROUTING OF VEGETATIVE PROPAGULES OF 3 SPECIES OF AQUATIC PLANT PROPAGULES

Vegetative propagules of Potamogeton pectinatus, P. gramineus, and Hyd rilla verticillata were exposed to aerobic or anaerobic atmospheres fo r 7, 14, or 21 days in the dark at 18 degrees C or 7 degrees C. There were no differences in the proportion of propagules sprouting due the presence or absence of oxygen. However, propagules exposed to an anaer obic atmosphere at 18 degrees C sprouted sooner than those exposed to an aerobic atmosphere. This effect was less apparent when exposure to anaerobic conditions was at 7 degrees C. in field experiments, Potamog eton gramineus winter buds were buried at 4 depths in Byrnes Canal sed iment. Those buried for 25 days at 25 cm (where sediment redox potenti al is < 50 mV and conditions are likely hypoxic) showed discoloration consistent with sulfide deposition, and they sprouted more rapidly tha n winter buds buried at 5 or 15 cm. As the duration of burial in Byrne s Canal sediment increased, propagule sprouting time decreased. Predic ting the timing of propagule sprouting in habitats with fluctuating wa ter levels may benefit from information on seasonal changes in the oxy gen status of the sediments.