不同水氮梯度下典型挺水植物叶绿素荧光的响应特性

Chlorophyll Fluorescence Response Characteristics of Typical Emergent Plants Under Different Total Nitrogen Gradient

叶绿素荧光测量分析可以揭示植物叶片光化学效率的变化,已越来越多地应用于植物生态监测。以再生水为主要补给水源的北京门城湖湿地公园为研究区,选取典型湿地挺水植物芦苇(Phragmites australis)、香蒲(Typha angustifolia)和茭白(Zizania latifolia)为研究对象,通过野外测量叶片尺度的叶绿素荧光参数和室内测定对应样点的水体总氮含量指标,研究了再生水补给条件下,不同水氮梯度植物叶绿素荧光的响应特性。结果表明,3种典型挺水植物的初始荧光(Fo)与最大荧光(Fm)随着水体总氮含量的增加呈现上升的趋势;PSII的量子效率(F_v/F_m)与实际量子效率(ΦPSII)受水氮含量的影响先升高,达到15–20 mg·L^(–1)区间时,则与之持平;光化学淬灭(qP)参数则呈现先升高后降低的变化趋势,而非光化学淬灭(NPQ)参数的变化没有明显的规律。当水氮含量为15–20 mg·L^(–1)时,光化学反应减弱,光合作用出现抑制。不同类型植物的荧光参数也有所不同,处于生长期(6月)植物的光合作用显著强于生长成熟期(9月)。

Measurements and analysis of chlorophyll fluorescence can reflect changes in plant leaf photochemical efficiency and have been increasingly used in plant ecological monitoring. This study used the Mencheng Lake wetland park, supplied with reclaimed water, as a study area, and Phragmites australis, Typha angustifolia and Zizania latifolia as typical emergent plants. We studied the chlorophyll fluorescence response characteristics of plants under different total nitrogen gradient by measuring leaf-scale chlorophyll fluorescence parameters outdoors and the corresponding water total nitrogen content indoors. Minimal fluorescence （Fo） and maximal fluorescence （Fm） were increased and nitrogen content in water was elevated. Maximum quantum efficiency of photochemistry in photosystem II in the dark （Fv/Fm） and quantum efficiency of PSll （ΦPSll） affected by nitrogen increased at first and then plateaued when nitrogen content reached the 15 to 20 mg·L–1 interval. Photochemical quenching （qP） tended to decrease after the first increase, but nonphotochemical quenching （NPQ） changed without obvious regularity. When water total nitrogen content was at the 15–20 mg·L–1 level, photochemical reaction was abated and photosynthesis was inhibited. Also, fluorescence parameters of different types of emergent plants were not the same; photosynthesis was significantly stronger in the growth stage （June） than the mature stage （September）.