Abstract: Six nutritional levels were designed to study the effects of different nitrogen (N) and phosphorus (P) contents in sediment on the growth and reproduction of Potamogeton crispus. The results revealed that the germination rate of P. crispus was not affected by the N and P contents in sediment, and all reached 100%. With the increasing N and P contents in sediment, the N content in plant tissues increased first and approached to a stationary level then, while the P content presented a slow increasing trend. In the meantime, the initial fluorescence (F_o) declined rapidly, while the potential maximum quantum yield (F_v/F_m) increased first followed by a slight decrease, indicating that the photosynthetic efficiency was enhanced by the increasing N and P contents in sediment but decreased at excessively high N and P contents. The rapid light curves showed that P. crispus could effectively use weak light and was more susceptible to photoinhibition under intense light, but its resistance capability against intense light could be improved by the high N and P contentsin sediment. The high N and P contents in sediment could also promote the total biomass of P. crispus, but reduce the root:shoot ratio of the plant. Under the increasing N and P contents in sediment, the asexual reproduction of P. crispus was improved, reproductive strategy was optimized, and also, the sexual reproduction occurred but the seed setting rate was low, only 19.6% on average.

Key words: Potamogeton crispus, sediment, germination rate, fluorescence parameter, biomass, reproductive strategy, phosphorus and nitrogen contents