Abstract: In order to explore the effects of water level change in the hydro-fluctuation belt of the Three Gorges Reservoir area on the growth of Rhizoma cyperi seedlings, a simulation experiment was conducted to study the response mechanisms of the seedling’s photosynthetic physiology to different submerged environments induced by the water level change. Four treatments were installed, i.e., no submergence (CK), root submergence (T1), semi-plant-submergence (T2), and whole plant submergence (T3). After treated for 45 days, the plant basal diameter, stem height, and non-photochemical quenching in all treatments tended to be increased, illustrating that R. cyperi could adapt to different submerged environments. The leaf length, leaf width, and aboveground biomass in different submerged environments differed. As compared to CK, the leaf length, leaf width, and aboveground biomass in T2 had some increase, while those in T1 and T3 had some decrease. With the increasing time of submergence, the specific leaf area, net photosynthetic rate, stomatal conductance, transpiration rate, maximal photochemical efficiency, electron transfer rate, and photochemical quenching were significantly lower than those in CK. However, all the parameters in T1 and T2 were still maintained at a higher level, while those in T3 were declined to an extremely lower level. This study indicated that R. cyperi could well adapt to submerged environment (especially partially submerged environment), and thus, could be applied to the re-vegetation of the hydro-fluctuation belt in the Three Gorges Reservoir area, especially in the low altitude region (145-160 m) which had suffered from long-term water level fluctuation. The submergence-tolerance characteristics of R. cyperi also provided a basis for screening riparian plants in the hydro-fluctuation belt of the Three Gorges Reservoir area.

Key words: slope aspect, altitude., plant diversity, soil moisture and temperature