LIFE HISTORY, BIOMASS AND CUT-BRANCH PROPAGATION OF POT AMOGETON CRISPUS L.

Life history, monthly changes of biomass, vertical distribution of biomass and nutritive value of Potamogcton crispus were studied during 1963—1964 and 1981—1983. The rooting, growth rate and turion formation of the cut branches of this species were also studied during the period.Potamogeton crispus is a submerged macrophyte which germinates in the autumn and grows throughout the winter. Turion forming period is from April to July; dormant stage of turion is from July to September, while turion germinating period is from September to next January. The maximun biomass occurs during April to May.The experimental cut-branches used for the study of rooting, growth rate and turion formation were 7—13 cm long and 0.5—4 g in fresh weight. They were suspended in water during the experiment. The period for the branches to reach 100% rooting was 29± 13 days during September to March, with the water temperature ranged 3—25℃. The relative growth rate of the cut branches was found to be 5.49—30.25 mg/g/day during turion forming stage.