干旱复水下北京地区刺槐与油松叶绿素荧光特性研究

Chlorophyll fluorescence characteristics of Robinia pseudoacacia and Pinus tabulaeformis under drought stress and rehydration in Beijing area

以北京地区典型落叶阔叶树种刺槐(Robinia pseudoacacia)和常绿针叶树种油松(Pinus tabulaeformis)的3 a生盆栽幼树为研究对象,通过人工控水模拟生长季初期自然干旱和旱后复水事件,分析区域典型树种应对干旱胁迫及旱后修复的叶绿素荧光特性。结果发现:(1)干旱胁迫下刺槐快速叶绿素荧光诱导动力学曲线(OJIP)形状发生明显改变。与对照处理相比,干旱胁迫处理下刺槐初始荧光(F_(o))、J点(V_(J))和I点(V_(I))的相对可变荧光强度显著上升12.95%(P<0.05),油松暗适应下最大荧光(F_(m))显著降低了24.66%。(2)干旱胁迫处理下刺槐光合系统Ⅱ(PSⅡ)光化学性能参数、PSⅡ反应中心活性参数、能量分配比率均出现显著下降(36.01%~61.73%,P<0.05);而油松幼树则无显著变化。干旱胁迫对刺槐OJIP曲线、PSII受体侧性能等荧光参数的影响程度均显著大于油松(P<0.01)。(3)刺槐在干旱初期显著增加了用于热耗散的量子比率(φ_(Do))20.25%,并下调量子产额(φ_(Eo))43.88%(P<0.05),而油松则于干旱末期在减小其单位激发态面积捕获光能的同时充分利用电子传递链中能量,其单位激发态面积传递到电子链末端的能量(RE_(o)/CS_(o))显著减小29.99%(P<0.05)。(4)两种盆栽幼树叶绿素荧光参数在复水处理阶段均可恢复至对照水平,部分参数出现超补偿效应。综上,初步确定土壤水分8.40%±2.03%为刺槐幼树叶绿素荧光参数的突变节点,刺槐光合能力受土壤水分的影响程度大于油松。

Three-year-old potted saplings trees of typical deciduous broad leaved tree species Robinia pseudoacacia and evergreen coniferous tree species Pinus tabulaeformis in Beijing were taken as research objects.The chlorophyll fluorescence characteristics of typical tree species in the region in response to drought stress and restoration after drought were analyzed through artificial water control to simulate natural drought in the early growing season and rehydration events after drought.The results showed that:(1)The rapid chlorophyll fluorescence induction kinetics curve(OJIP)of R.pseudoacacia changed obviously under drought stress.Compared with the control treatment,the minimal fluorescence intensity(F_(o)),the relative variable fluorescence intensity at the J step(V_(J))and at the I step(V_(I))of R.pseudoacacia were significantly increased by 12.95%(P<0.05)under drought stress,and the maximal fluorescence intensity(F_(m))of P.tabulaeformis significantly decreased by 24.66%.(2)The photochemical performances and reaction center activities in photosynthetic system Ⅱ(PSⅡ)and the ratios of capture energy allocation of R.pseudoacacia decreased significantly under drought stress(36.01%~61.73%,P<0.05),whereas those were not found in P.tabulaeformis under drought stress.The effects of water stress on OJIP curve,PSII receptor side and its performance parameters of potted R.pseudoacacia saplings were significantly greater than those of P.tabulaiformis(P<0.01).(3)The quantum yield of dissipatea(φ_(Do))of R.pseudoacacia significantly increased by 20.25%at the beginning of drought,and the transport quantum yield for electron transport(φ_(Eo))decreased by 43.88%(P<0.05),while the energy in electron transport chain of P.tabulaeformis was fully utilized at the end of drought while decreasing the trapped energy flux per excited cross section.The reduction of end acceptors at PSI electron acceptor side per excited cross section(RE o/CS_(o))significantly decreased by 29.99%(P<0.05).(4)Chlorophyll fluorescence parameters of the two kinds of potted saplings was restored to the control level in the rehydration stage,and some parameters showed overcompensation effect.In conclusion,the 8.40%±2.03%of soil moisture was the mutation node of chlorophyll fluorescence parameters of R.pseudoacacia saplings,and the photosynthetic capacity of R.pseudoacacia saplings were more affected by soil moisture variation than that of P.tabulaeformis.