Study On The Allelopathic Effects And Eco-physiological Mechanism Between Microcystis Aeruginosa And Potamogeton Malaianus,Ceratophyllum Demersum

Restoration of submerged macrophytes is the key of aquatic vegetation reconstruction and restoration of eutrophication of water, so recent years the field of theoretical and technological research has been receiving world-wide concern.Cyanobacteria allelopathy is one ecological factors of impact of submerged macrophyte recovery. In this paper, we selected Dianchi cyanobacteria--Microcystis aeruginosa and two kind of submerged plants --Potamogeton malaianus and Ceratophyllum demersum for materials, researched mutual allelopathic effects of two kind of submerged plants and Microcystis aeruginosa by additional assays and coexistence assays, furthermore with different congcentrations of Microcystis aeruginosa allelopathy effects on two submerged plants, Comparison of the different algae density to two kind of submerged plants influence difference, Defined the role of inhibition or promotion of algal cell density threshold value. Discusses allelopathy mechanism of cyanobacteria on aquatic plants. At the same time research allelopathy of submerged plants on Microcystis aeruginosa.(1) Allelopathic effects of extracellular material substance and intracellular substances of Microcystis aeruginosa on seed germination of Potamogeton malaianus were significantly different .which in low algal cell density(2×106个/ml) extracellular material substance of Microcystis aeruginosa can promote seed germination of Potamogeton malaianus,and in high algal cell density(16.7×106个/ml) can inhibit seed germination of Potamogeton malaianus; density of algal cells of various intracellular substances have no significant effect on seed germination.of Potamogeton malaianus.(2) Allelopathic effects of extracellular material substance and intracellular substances of Microcystis aeruginosa on seedlings of Potamogeton malaianus were significantly different .which in low algal cell density(2×106个/ml) extracellular material substance and intracellular substances of Microcystis aeruginosa can promote fresh weight and shoot height of seedlings of Potamogeton malaianus, and in high algal cell density(13.3×106个/ml) can obvious inhibit fresh weight,shoot height,root length,chlorophyll contents and chlorophyll Fv/Fm of seedlings of Potamogeton malaianus.and allelopathic effects of extracellular material substance is bigger than intracellular substances of Microcystis aeruginosa.(3) There is mutual allelopathic effects and significant density effect in Potamogeton malaianus co-cultivated with Microcystis aeruginosa: 1±0.1g/L Potamogeton malaianus performed significant growth inhibiting on Microcystis aeruginosa in low algal cell density(2×106个/ml),and The higher density (3.1×106个/ ml) of Microcystis aeruginosa is not only not been significantly affected, and can inhibit seedling growth of Potamogeton malaianus, and even death.(4) The allelopathic effects of Potamogeton malaianus seedling planting water on Microcystis aeruginosa was different,with initial density increased less of a sense of inhibition. 15±0.5g/L Potamogeton malaianus seedling planting water performed significant growth inhibiting on Microcystis aeruginosa in low algal cell density(3.6×106个/ml),but no effects were observed in low algal cell density(5.3×106个/ml).(5) Allelopathic effects of extracellular material substance and intracellular substances of Microcystis aeruginosa on Ceratophyllum demersum were significantly different.and extracellular material substance is bigger than intracellular substances. .which in high algal cell density(13.3×106个/ml) can obvious inhibit fresh weight,shoot height,chlorophyll contents and chlorophyll Fv/Fm of Ceratophyllum demersum . intracellular substances of Microcystis aeruginosa with the performed significant growth inhibiting on Ceratophyllum demersum in highest algal cell density 18.9×106个/ml.(6) There is mutual allelopathic effects and significant density effect in Ceratophyllum demersum co-cultivated with Microcystis aeruginosa: 5±0.5g/L Ceratophyllum demersum performed significant growth inhibiting on Microcystis aeruginosa in low algal cell density(4×106个/ml), at the same time can promote growth on Ceratophyllum demersum. and The higher density (19.2×106个/ ml) of Microcystis aeruginosa can inhibit seedling growth of Ceratophyllum demersum, and even death.(7) The allelopathic effects of Ceratophyllum demersum seedling planting water on Microcystis aeruginosa was different,with initial density increased less of a sense of inhibition. 5±0.5g/L Ceratophyllum demersum seedling planting water performed significant growth inhibiting on Microcystis aeruginosa in low algal cell density(4×106个/ml),but when the Planting density come up to 20±0.5g/L, Ceratophyllum demersum seedling planting water performed significant growth inhibiting on Microcystis aeruginosa density come up to 10.2×106个/ml.The research results reveal allelopathic effects between algae and higher aquatic plants and its mechanism provides a theoretical basis, At the same time as the algae of eutrophic water body restoration of submerged plant species selection, planting conditions to provide a theoretical basis and practical guidance.