Effects Of Redox Characteristics On The Germination And Growth Of Vallisneria Natans(Lour.) Hara In The Sediment

Lake eutrophication is one of the ecological and environmental problems.Excessive nitrogen and phosphorus have caused a series of problems such as the proliferation of phytoplankton,the deterioration of water environment,the degradation of sediment habitat,resulting in the shrinkage of submerged vegetation and the simplification of vegetation communities.The restoration and reconstruction of aquatic ecosystems have become an urgent problem.As the cornerstone of maintaining the stability of aquatic ecosystems,the restoration of submerged vegetation is the key measure for the restoration of aquatic ecosystem.In this study,Vallisneria natans(Lour.)Hara,the common submerged macrophyte in aquatic ecological system,was selected to explore the influence of ammonia,sulfide,and sediment redox characteristics on the germination and growth of V.natans,the main conclusions of this study were summarized as follows:(1)The germination and growth of V.natans increased firstly and then decreased with the increase of ammonia concentration.At a pH value of about 7,when the concentration of ammonia was 3 mg/L,the germination rate of V natans seeds was biggest(56.33%±3.94%);when the concentration of ammonia was higher than 1 mg/L,the growth of V.natans seedlings was biggest;when the concentration of ammonia was higher than 1 mg/L,the oxidative stress reaction in V.natans seedlings was significantly enhanced,which interfered with the normal growth of seedlings.(2)The germination and growth of V.natans increased at low concentrations and then decreased with the increase of sulfide concentration.At a pH value of about 7,when the concentration of sulfide was 6.72 mg/L,the germination rate of V.natans seeds was biggest(58.33%±2.63%);when the sulfide concentration was higher than 15 mg/L,the growth of V.natans seedlings was inhibited;when the concentration of sulfide was higher than 15 mg/L,the oxidative stress reaction in seedlings was significantly enhanced,interfering with seedling growth.(3)Nitrogen exposure could increase sediment pH,decrease the redox potential,and increase the concentration of NH3 in interstitial water,but significantly reduce the concentration of H2S;The addition of clean soil can increase the redox potential,while the addition of glucose can significantly lower sediment redox potential.When the sediment redox potential was lower than-150 mV,the oxidative stress reaction in V.natans seedlings increased,which interfered with the normal growth of V.natans seedlings;when sediment redox potential was lower than-250 mV,V.natans seeds could not germinate.