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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。
In the lower reaches of the Tarim River, four monitoring wells with a groundwater depth> 4 m were selected. Based on the data of groundwater level, the leaf water characteristics and chlorophyll fluorescence characteristics of Populus euphratica under drought stress caused by the descending of groundwater level were investigated and analyzed. The effects of drought stress on PSII photochemical efficiency and energy dissipation of Populus euphratica were analyzed from energy metabolism and conversion perspectives. The results showed that the leaf water potential of Populus euphratica decreased significantly with the increase of drought stress caused by the decline of groundwater level, while the relative water content of leaves was not significantly different (80.38% -86.19%). Under the influence of drought stress , The photosynthetic activity of Populus euphratica decreased significantly and the light saturation point decreased significantly. At the same time, the photosynthetic electron transport rate of Populus euphratica, the actual photochemical efficiency under PSII light and photochemical quenching decreased significantly with the increase of light intensity, The more violent the decline and the greater the decline. Under drought stress, the parameters of non-photochemical quenching and regulated energy dissipation quantum yield of Populus euphratica increased significantly with the increase of light intensity, but the potential maximum photochemical efficiency was in a suitable state (0.80-0.86). Under drought stress, photosynthesis photosynthetic energy use decreased, the ability to tolerate high light intensity weakened, the extent of light trapped light exacerbated. Populus mainly through heat dissipation to alleviate the pressure caused by excess energy. Although PSII of Populus euphratica in the study area has not yet been irreversibly damaged by light, its potential for photoinhibition and the resulting damage to the light system is on the rise.