To investigate the effects of sediment types on growth and photosynthetic characteristics in emergent plants,the leaf pig-ment contents,chlorophyll fluorescence and gas exchange of three dominant species(Phragmites communis,Typha minina and Acorus calamus) from aquatic vegetation of Lake Chaohu,which were grown in five different sediment types,were examined.The results showed that in the three emergent plant species, the shoot biomass was highest in T.minina, followed by P.communis, and the lowest in A.calamus.The chlorophyll-a content(Chl.a),chlorophyll-b content(Chl.b),carotenoid content(Car),stomatal conductance,intercellular CO₂ concentration,transpiration rate in T.minina were significantly higher than that in A.calamus and in P.communis,net photosynthetic rate,Fv/Fm and ΦPS Ⅱ in T.minina were significantly higher than that in A.calamus.Ac-cording to correlation analysis,the shoot biomass was positively correlated to net photosynthetic rate,while net photosynthetic rate was significantly correlated to stomatal conductance and intercellular CO₂ concentration.Therefore,the results indicated that the high stomatal conductance,pigment content,as well as Fv/Fm and ΦPS Ⅱ in T.minina plants might lead to the high shoot bio-mass and net photosynthetic rate.Compared to the control(the original sediment),using the four sediment treatments(loosen sedi-ments,organic sediments coverage,soil sediments coverage and sand sediments coverage) in varying degrees have increased pig-ment contents(Chl.a,Chl.b,Car and Chl.a/Chl.b),improved the activity of reaction center(Fv/Fm and ΦPS Ⅱ),and en-hanced stomatal conductance and intercellular CO₂ concentration.As a result,the sediments enhanced photosynthetic rate and plant growth,and the loosen sediments and organic sediments coverage had high effects among the four treatments.