水位抬升对4种沉水植物生长及光合特性的影响

Growth and Photosynthetic Fluorescence Characteristics Responses of Four Submersed Macrophytes to Rising Water Level

通过滆湖现场实验的方法模拟水位抬升,研究其对4种沉水植物的生长和光合荧光特性的影响。实验前30 d相应水位为2.6 m(控制水深为1 m),之后2 d内迅速抬升水位,32 d时各实验组相应水位为2.6、3.0、3.4和3.8 m,分别模拟水位不变、低水位抬升、中水位抬升和高水位抬升,各组水位一直保持到第70天实验结束。结果表明:随着水位抬升幅度增加,4种植物的株高显著增加(P<0.05)。冠层型植物狐尾藻(Myriophyllum spicatum)、马来眼子菜(Potamogeton malaianus)生物量相应增加,高水位抬升下直立型黑藻(Hydrilla verticillata)生物量显著减小(P<0.05),莲座型植物密刺苦草(Vallisneria denseserrulata)生物量随水位抬升幅度的增加而减小。在一定范围内,水位抬升减弱了狐尾藻、马来眼子菜和黑藻的定植能力,增强了密刺苦草的定植能力。冠层型植物在光合作用方面的表现同样优于直立型和莲座型植物,这说明不同的沉水植物对水位抬升的响应具有不同的生理生化特征。水位抬升促进了以狐尾藻、马来眼子菜为代表的冠层型植物的生长,高水位抬升不利于直立型植物黑藻的生长,抑制了莲座型植物密刺苦草的生长。以狐尾藻、马来眼子菜为代表的冠层型植物从形态学响应和光合作用能力上更适合水位抬升。该研究可为湖泊河流中沉水植物的恢复提供参考。

A field experiment was conducted to investigate the plant growth and photosynthetic fluorescence characteristics of four submersed macrophytes by simulating the rising of water level. The water depth was controlled to be 1 m at the first with the corresponding water level of 2. 6 m. The water levels increased sharply in two days. On the 32 nd day,the water level arrived at 2. 6,3. 0,3. 4 and 3. 8 m to simulate constant water level,low water level,medium water level and high water level. The water level remained to the end of experiment for 70 days. The results show that the plant growth of the four species was significantly increased by raising water level（ P〈0. 05）. Canopy species,such as Myriophyllum spicatum and Potamogeton malaianus,tended to increase biomass. Biomass of erect species,such as Hydrilla verticillata,decreased significantly in high water level（ P〈0. 05）. With the rising water level increased,the biomass of rosette species,such as Vallisneria denseserrulata,followed the trend of decline. According to the water level of Gehu Lake,rising water levels weakened the root performances of canopy species and erect species and strengthened the root performances of rosette species. Rapid light curves of canopy species also reflected the result of the experiment. The results show that different submerged macrophytes on rising water level has different physiological and biochemical characteristics. Rising water level promoted the growth of canopy species. High water level is not conducive to the growth of Hydrilla verticillata. Rising water level inhibited the growth of Vallisneria denseserrulata. Canopy species（ Myriophyllum spicatum and Potamogeton malaianus） is more suitable for the historical water level rising of Gehu Lake on the morphological response and the ability of photosynthesis. The results can provide reference for recovery of submersed macrophytes in lakes and rivers.