模拟河岸带夏季水位变化对水蓼生长及其光合荧光特性的影响

Effects of simulated water level changes on the growth and photosynthetic fluorescence characteristics of Polygonum hydropiper in the riparian zone in summer

为探讨河岸带夏季水位频繁波动的变化对河岸带湿地植物产生的胁迫及影响,选择鄱阳湖-乐安河段河岸带湿地优势草本植物水蓼(Polygonum hydropiper)为供试材料,室内采用盆栽实验培养植物,分别设置常规控水对照组、浸润组、半淹组和全淹组4个实验组,并分别置于4个不同钢化玻璃水缸中。通过控制缸中水位模拟鄱阳湖-乐安河段河岸带水位动态变化特征,分别经历"淹水-干旱-常规控水"3个不同阶段,共持续46 d,研究不同水位条件对水蓼生长及其光合荧光特性的影响。各控制组代码分别为对照组(CK)、浸润组(INF)、半淹组(HS)、全淹组(FS)、对照-干旱组(CD)、浸润-干旱组(ID)、半淹-干旱组(HD)和全淹-干旱组(FD)。结果表明,第一阶段水淹胁迫14 d后,与CK组相比,INF组和HS组的净光合速率(Pn)、叶绿素a含量(Chla)、叶绿素总量(Chlt)等参数均显著下降;胞间CO2浓度(Ci)、蒸腾速率(Tr)、稳态下的有效量子产率(Fv/Fm)、光化学淬灭系数(qP)、非光化学淬灭系数(NPQ)等指标均显著上升;而FS组的上述各参数值均下降。同时,水淹胁迫也导致FS组的生物量较CK组显著下降。第二阶段干旱胁迫14 d后,与CK组相比,HD组和FD组的Pn、Gs及生物量等均显著下降,Chla、Chlt上升,而CD组的Fv/Fm、稳态下的最大量子产率(QYmax等荧光参数均显著下降。表明前期水淹并未增加水蓼对后期干旱胁迫的光合生理敏感性。第三阶段常规控水条件恢复14 d后,各处理组的生物量、光合参数、叶绿素荧光参数和叶绿素含量等参数均趋于平稳或恢复到正常水平。水蓼不仅耐水淹且能耐旱,是湿地河岸带或洲滩植被恢复与重建的优选物种。

In order to investigate the effects and stress of the frequent alternate changes of water level in summer on the wetland plants in the riparian zone,we selected Polygonum hydropiper,a dominant herb in the riparian zone of the Poyang Lake and Le’an River as the experimental material.The indoor pot experiment was carried out to simulate the dynamic characteristics of water level in the riparian zone of the Poyang Lake and Le’an River,set up four experimental groups including control group,infiltrating group,half submerged group,and all flooded group,which placed respectively in different tempered glass cylinders at different water conditions and experienced three different stages respectively included"flooding-drought-conventional water control",the whole experiment lasted for 46 days in order to observe the growth and photosynthetic fluorescence characteristics of P.hydropiper under different water level conditions.The codes of each control group were control group(CK),infiltration group(INF),half-flooding group(HS),full flooding group(FS),control-drought group(CD),infiltration-drought group(ID),half-flooding-drought group(HD),and full flooding-drought group(FD)respectively.The results showed that the net photosynthetic rate(Pn),chlorophyll a(Chla),total chlorophyll(Chlt)and other parameters of INF group and HS group decreased significantly,while intercellular CO2 concentration(Ci),transpiration rate(Tr),effective quantum yield at steady state(Fv/Fm),photochemical quenching coefficient(qP),non-photochemical quenching coefficient(NPQ)and other indicators of INF group and HS group increased significantly after 14 days at the first stage of flooding stress compared with CK group,while the above parameters in FS group decreased.At the same time,the biomass of FS group was significantly lower than CK group.At the second stage of drought stress for 14 days,the parameters including Pn,Gs and biomass in HD group and FD group decreased significantly compared with CK group,while Chla and Chlt increased,while Fv/Fm and QYmax and other fluorescence parameters in CD group decreased significantly,which indicated that early flooding did not increase the photosynthetic physiological sensitivity of P.hydropiper to late drought stress.At the end of normal water condition stage,the biomass,photosynthetic parameters,chlorophyll fluorescence parameters and chlorophyll content of all water treatment groups tended to stabilize or return to normal levels.P.hydropiper is not only waterlogged but also drought-tolerant.It is the preferred species for vegetation restoration and reconstruction in wetland riparian zone or beach.