塔里木河下游干旱胁迫下的胡杨叶绿素荧光特性研究

Chlorophyll Fluorescence Characteristic of Populus euphratica under Drought Stress in the Lower Reaches of Tarim River

结合塔里木河下游典型监测断面和地下水位埋深的监测数据,测量了不同地下水位处胡杨的叶绿素荧光参数、水势及土壤含水量,探讨了不同地下水位埋深条件下胡杨的叶绿素荧光特性。结果显示,随着地下水位埋深加大,胡杨受到的干旱胁迫加剧,胡杨叶片光适应下的实际光化学量子产量、电子传输速率和光化学猝灭、相对叶绿素含量普遍下降,且下降幅度随地下水位埋深加大而增加;非光化学猝灭和调节性能量耗散量子产量随光合有效辐射增大而显著升高;潜在最大光化学量子产量总体处于适宜状态,表明胡杨在地下水位埋深4～8m左右时,尚能通过自身能力进行调节,光系统Ⅱ未发生不可逆转的因干旱胁迫造成的损伤。

In two typical monitoring sections in the lower reaches of Tarim River,soil water content,leaf water potential and chlorophyll fluorescence parameter of Populus euphratica near four ecological monitoring wells with different groundwater level were measured.The results showed that the deeper groundwater level,the fiercer drought stress imposed to Populus euphratica,and series of chlorophyll fluorescence parameters of Populus euphratica,such as photochemical quantum yield of PS Ⅱ in the light（Yield）,electron transport rate（ETR）,photochemistry quenching（qP）and relative chlorophyll content and so on,decreased evidently with the decrease of groundwater level,and there was greater decrease of chlorophyll fluorescence parameters near the monitoring well with deeper groundwater level.Non-photochemistry quenching（qN,NPQ）and the Yield for dissipation by downregulation（YNPQ）,as an available chlorophyll fluorescence parameter to weigh the self-protective capability of PSⅡ,increased remarkably with photosynthetic active radiation（PAR）.The potential maximum quantum yields（Fv/Fm）of all Populus euphratica samples maintained optimum values,indicating that Populus euphratica in the lower reaches of the Tarim River could well maintain their biological functions of PSⅡ at range 4—8 m of groundwater level.Irreversible damage from photo-inhibition did not yet occur in the PSⅡ of those Populus euphratica owing to good adaptability and drought tolerance although drought stress occurred actually.