Abstract: The species composition, productivity and its influence factors of aquatic macrophytes were estimated in saline-alkaline ponds in Zhaodian Fish Farm, Gaoqing County, Shandong Province, during from April to September in 1998.The results indicated that 12 species of the large aquatic plants were collected in this localities, common species were Potamogeton crispus, Zannichellia palustris, Nelumbo nucifera, Ceratophyllum demersum [Emergent vascular plants];Phragmites communis, Scirpus yagara and Typha orientalis [Submerged vascular plants];Lemna minor [Floating vascula plants] and Chara braunii [Macrophytic algae]. Simple of species composition and prominent of dominant species are marked characteristics of aquatic macrophytes in saline-alkaline ponds. The transparency and pH values of ponds with grass were higher than that of ponds without grass, and biomass and Chla of phytoplankton and nutrients lever in the former ponds lower than that of the latter. The grass primary production of P. crispus, Z. palustris and C. braunii were 1.70、1.56 and 1.50 mgO₂ L^-1 h^-1 g^-1, under the condition of light intensity 7, 200 lx and water temperature 28~30℃. Apart from light, temperature and pH, the primary productivity of aquatic macrophytes were influenced by salinity and alkalinity. The salinity that the primary production of P. crispus and Z. palustris were highest are 3 g l-1, the suitable alkalinity of the former was 6.69 mmol L^-1, and that of the latter was 3.82 mmol L^-1. The absorption rates to NH₄-N of P. crispus, Z. palustris, C. demersum and L. minor were similar, and that of to PO₄-P are as follow:Z. palustris > P. crispus > L. minor > C. demersum. The features of Macrophytes in saline water bodies, production of P. crispus and its influence factors and how to avoid the harmful of aquatic macrophytes in fish ponds and the relationship between macrophytes and phytoplankton were discussed.

Key words: aquatic macrophytes, primary production, salinity, alkalinity, nutrients, saline-alkaline ponds