Abstract: The timing, duration and frequency of inundation greatly affect ecological conditions, wetland plant regeneration and biodiversity in the water-level-fluctuating zone. Based on the spatiotemporal variation of hydrology in the water-level-fluctuating zone of the Three Gorges Reservoir, we analyzed the effects of multiple abiotic factors such as inundation, temperature, light, and germination substrate on the population sexual recruitment of Typha orientalisto reveal the effects of abiotic factors on sexual recruitment. The results showed that freshly-collected ripe seeds of T. orientalisis were light-required, with obvious preference for temperature and substrate. In the lake water, seed germination rate decreased with increasing water depth. When water depth was 2 m, germination rate decreased to 4.5%. In the simulated flooding trail, seedling survival rates were 21% and zero after 56 and 60 days in full flooding, respectively. However, the seedlings grew well under non-flooded and semi-flooded conditions. It is concluded that severe flooding stress is the direct cause of germination inhibition and seedling death of Typha orientalis. The seeds would germinate well under appropriate combination of light, temperature and germination substrate. The failure of sexual regeneration of T. orientalisis population is driven by a variety of abiotic factors in the water-level fluctuating zone of the Three Gorges Reservoir.

Key words: light-required seed, seedling establishment, waterlogging stress, sexual recruitment, wetland plant, Three Gorges Reservoir area, water-level-fluctuating zone.