Effects Of Waterlogging Stress On The Photosynthetic Characteristics Of Ternstroemia Gymnanthera

Ternstroemia gymnanthera,Theaceae,Ternstroemia,is an excellent everygreen and foliage species,and has strong appreciation.In order to explore the effect of waterlogging stress to Ternstroemia gymnanthera,First-year seedlings were used as materies to placed in the waterlogging environment to study its dynamic change of photosynthetic characteristics.The conclusions were as follows.?1?Compared with the control groups,Fo was increased,and other parameters such as the maximum net photosynthetic rate,stomatal conductance,intercellular CO₂ concentration,efficiency of water application,Fv/Fo,Fv/Fm,? PSII,ETR and chlorophyll content were decresed.And the deeper waterlogging stress group was more obvious.?2?under normal circumstances,daily variation of the maximum net photosynthetic rate,intercellular CO₂ concentration and stomatal conductance all showed double peak shape,which at around 9:00 in the morning and 15:00 in the afternoon reached the peak.Stomatal limitation of the differert degree of waterlogging stress groups was higher than the control group every time in the day,but the other photosynthetic gas parameters were quite the contrary.?3?The initial quantum efficiency and the maximum net photosynthetic rate Pnmax were reduced significantly with the degree of waterlogging stress increased.The dark respiration rate Rd was increased gradually,and the photosynthesis was restrained.The fitting effect of the rectangular hyperbola model for light response process of Ternstroemia gymnanthera was better than that of the other two models.Compared with the differert degree of waterlogging stress groups,photosynthetic parameters of the control group which fitted by mathematical model were more accurate.?4?The main photosynthetic indexes impacted Ternstroemia gymnanthera were Chl,Gs,?PSII,and ETR.?5?The phenomenon of leaves bladed wilting edge,turning to yellow or red color and falling off,plant drooping,and even the whole plant death happened after long time waterlogging stress.Seedlings in the lighter waterlogging stress group could conduct self adjusting to resist outside bad environment in the first 7 days.But,this ability gradually declined or disappeared after that.The phenomenon became more obvious after 14 days.Apparent deathplants could still be raised after 35 days.Seedlings in the deeper waterlogging stress group didn't show self adjusting phenomenon obviously.When experiment continued to 35 days,plants died in a certain number,and the death was irreversible.Adverse effects of Ternstroemia gymnanthera's photosynthetic characteristics produced in the differert degree of waterlogging stress,were similar with Acer palmatum and Cerasus yedoensis.The seedlings' characteristics of the waterlogging tolerance were not strong.