3种蓼属植物对遮阴的光合生理响应及耐阴性评价OA

[Objective]The study aims to investigate the effects of shading treatments on the growth and photosynthetic physiology of three Polygonum species,and screen for Polygonum species with strong shade tol-erance,to provide a theoretical basis for their development and application in landscaping.[Method]Using P.capitatum,P.chinense,and P.odoratum as experimental materials,a pot experiment was conducted with five treatments(full sunlight as control(CK),30％,50％,70％,90％ shading degree)to determine the morphologi-cal and photosynthetic indicators of the plants under different treatments.The negative Shade tolerance of the three plants was comprehensively evaluated through principal component analysis and membership function analysis.[Result]As shading degree increased,leaf area and plant height of the three Polygonum species gener-ally increased,while stem diameter overall decreased.The chlorophyll content increased,but the chlorophyll a/b ratio decreased.The carotenoid content in P.capitatum first increased and then decreased,whereas it generally increased in P.chinense and P.odoratum.As shading degree increased,the light saturation point(LSP)of P.capitatum first rose and then fell,while the LSP of P.chinense and P.odoratum steadily declined.All three spe-cies showed reduced light compensation point(LCP)and dark respiration rate(Rd),whereas the apparent quan-tum yield(AQY)and maximum net photosynthetic rate(Pnmax)first increased before decreasing.Under various shading treatments,the maximum fluorescence(Fm),PS Ⅱ maximum photochemical efficiency(Fv/Fm),PS Ⅱpotential activity(Fv/Fo),and electron transport quantum yield(φEo)of the three Polygonum species were sig-nificantly higher than those of the control(CK),while the initial fluorescence(Fo)and heat dissipation quantum ratio(φDo)were lower than those of CK.Comprehensive evaluation ranked shade tolerance of the three species as:P.chinense＞P.odoratum＞P.capitatum.[Conclusion]All three Polygonum species exhibit low light adapt-ability,but the extent of this adaptability differs among them.P.chinense demonstrates the strongest shade toler-ance,while P.capitatum exhibits the weakest.