盐胁迫对芦苇与碱蓬叶绿素荧光特性的影响

[Objective]The aim of this study was to clarify the fluorescence characteristics and photoprotection mechanism of Phragmites australis and Suaeda glauca under salt stress.[Method]The pot experiment was conducted with seedlings.The salt concentrations of 0%(control),0.5%(C1),1%(C2),1.5%(C3),2%(C4),2.5%(C5)and 3.5%(C6)were set to measure the photosynthetic pigment contents and chlorophyll fluorescence parameters of P.australis and S.glauca seedlings,with subsequent analysis of their changes.[Result]The photosynthetic pigment contents and chlorophyll fluorescence parameters of P.australis and S.glauca had different changes under salt stress.Specifically,the photosynthetic pigment contents,actual photosynthetic efficiency[Y(II)],and electron transport rate(ETR)of P.australis leaves decreased with increasing soil salt content.Under the same light intensity,the potential maximum value of electron transport efficiency(ETRmax)of P.australis in control was higher than those in other treatments.The ETRmax of S.glauca in the C1,C2,and C3 treatments increased compared to the control.The maximum photochemical efficiency(Fv/Fm)of S.glauca under C5 and C6 treatments were significantly lower than that of the control.With the increase of salt concentration,the Y(II)and ETR values increased first and then decreased,and both had maximum values at C3 treatment.The photochemical quenching coefficient(qP)of P.australis gradually decreased with the increase of salt concentration,while the non-photochemical quenching coefficient(NPQ)tended to increase and then decreased.Both qP and NPQ values of S.glauca showed a decreasing and then increasing trend with the increase of soil salinity.Under different salt concentrations,NPQ of P.australis was above 0.6,which was higher than that of S.glauca.In conclusion,the imposition of salt stress inhibited the synthesis of photosynthetic pigments,affected photosynthetic electron transport,and lowered light energy conversion efficiency in P.australis seedlings.Conversely,low salinity stress in S.glauca could promote photosynthetic pigment synthesis,facilitate light energy absorption,and enhance electron transport rate.Nevertheless,high concentration of salt stress can inhibit photosynthetic electron transport.P.australis has a stronger ability to dissipate excess light energy as heat to protect photosynthetic structures from damage.