Seeds of Zizania aquatica which had been afterripened for a period of 90 days at 1–3 °C remained dormant. Treatment of afterripened seeds with ultrasonic vibrations at 70 kc/s for 10 minutes showed a germination count of 74%. Increasing either the intensity or duration of treatment resulted in lower germination. Warm water treatment of dormant seeds resulted in improved germination for some treatments. Exposure in water at a temperature of 45 °C for 240 minutes resulted in a germination of 71%. Treatment with varying ratios of ethanol to water gave only small improvements in seed germination.