摘要
选取塔里木河下游4处地下水位埋深>4 m的监测井位,结合地下水位数据,调查并分析了在地下水位下降引发的干旱胁迫下,胡杨(Populus euphratica)的叶片水分特征及叶绿素荧光特性,从能量代谢与转换角度分析了干旱胁迫对胡杨的PSII光化学效率和激能耗散的影响。结果表明:随着地下水位下降引发的干旱胁迫程度的加剧,胡杨的叶水势显著降低,而叶片相对水分含量差异不显著,总体处于适宜状态(80.38%–86.19%);在干旱胁迫的影响下,胡杨的综合光合活性明显降低,叶片光饱和点显著下降;同时胡杨的光合作用电子传递速率、PSII光下实际光化学效率以及光化学猝灭均随着光强的增大而显著降低,且干旱胁迫越剧烈,下降幅度越大;干旱胁迫下,胡杨的非光化学猝灭和调节性能量耗散量子产量等参数则随着光强的增大显著升高,但是其潜在最大光化学效率却处于适宜状态(0.80–0.86)。说明干旱胁迫下,胡杨的光合作用光能利用份额下降,耐受高光强的能力减弱,捕获的光能过剩程度加剧。胡杨主要通过热耗散来缓解光能过剩带来的压力。虽然研究区胡杨的PSII尚未发生不可逆的光损伤,但是其发生光抑制以及由此带来的光系统损伤的潜在危险在增加。
We selected 4 survey plots with groundwater depths 4 m near ecological monitoring wells in the Tarim River to investigate leaf water potential,leaf relative water content,and chlorophyll fluorescence characteristics of Populus euphratica under drought stress induced by decreased groundwater level.We analyzed the impact of drought stress on photosystem II photochemical efficiency and excited energy dissipation in terms of energy metabolism and conversion.The leaf water potential of P.euphratica significantly decreased with increasing drought stress induced by increasing groundwater depth,with no significant differences in leaf relative water content,which maintained optimal values（80.38%–86.19%）.Under drought stress,synthetically photosynthetic activity and the leaf light saturation point of P.eu-phratica significantly decreased,and photosynthetic electron transportation rate,actual photochemical efficiency of pho-tosystem II in the light and photochemical quenching of P.euphratica decreased with increasing photosynthetic active radiation.Greater decreases occurred with more severe drought stress.The non-photochemical quenching and the yield for dissipation by downregulation of P.euphratica under drought stress significantly increased with increasing photosyn-thetic active radiation,and the maximal photochemical efficiency was maintained at an optimal value（0.80–0.86）.In-creasing drought stress would result in significantly decreased share of photosynthetic solar energy utilization,whereas the ability to withstand high light intensity decreased,which would result in greater excess of excited energy.P.euphratica can release the stress resulting from excess excited energy by heat dissipation,which plays an important role in the process of energy metabolism on the photosystem of P.euphratica.Although the photosystem II of P.euphratica under drought stress in the lower reaches of the Tarim River has not yet been irreversibly damaged because of light inhibition,the potential crisis of light injury induced b
出处
《植物学报》
CAS
CSCD
北大核心
2011年第4期413-424,共12页
Chinese Bulletin of Botany
基金
国家自然科学基金(No.40871059,No.91025025)
“西部之光”人才培养计划(No.0871031,No.RCPY200801,No.XBBS-200810)
关键词
电子传递速率
叶水势
光抑制
光化学效率
光化学猝灭
electron transportation rate
leaf water potential
light inhibition
photochemical efficiency
photochemical quenching
