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    干旱环境3种荒漠灌木叶绿素荧光参数动态

    Dynamics of chlorophyll fluorescence parameters under drought condition for three desert shrub species

      摘要
    • 摘要:
        目的  研究荒漠植物生理特征对自然环境波动下的响应过程可以更好地认识和预测气候变化对荒漠生态系统的影响。
        方法  本文研究了宁夏盐池油蒿、沙柳和杨柴3种荒漠灌木优势物种在春季干旱环境下光系统II（PSII）最大光化学效率（Fv/Fm）、实际光化学效率（ΦPSII）和非光化学淬灭（NPQ）对环境因子的响应，旨在探讨荒漠灌木在干旱环境下PSII的光合生理状态以及其保护调节机制。
        结果  结果表明：在水分胁迫下（土壤含水量 < 0.08 m3/m3），3种荒漠灌木Fv/Fm、ΦPSII显著降低，NPQ显著增加（P < 0.01），沙柳Fv/Fm显著低于油蒿并且显著高于杨柴（P < 0.01），杨柴ΦPSII显著低于油蒿和沙柳（P < 0.01）。3种荒漠灌木ΦPSII和NPQ受光合有效辐射（PAR）的影响呈现出明显的日变化，且PAR、空气温度（Ta）、相对湿度 （RH）和饱和水汽压差（VPD）对ΦPSII和NPQ均有影响。研究发现3种荒漠灌木PSII表现出不同受胁程度，其通过自身调节机制增加热耗散比例来抵御干旱下的环境胁迫。油蒿Fv/Fm能通过自身调节恢复到适宜状态值（约0.75），认为其反应中心损伤具有可恢复性。杨柴热耗散的光保护响应机制的敏感性较高，认为其受环境波动的影响较大。
        结论  综上得出油蒿可以作为干旱区植被恢复的首选物种，沙柳其次，杨柴不建议考虑。可见由叶绿素荧光参数变化表征PSII反应中心的活性，可以充分体现荒漠灌木对环境波动的响应策略，可以作为探究干旱半干旱区荒漠植物对环境变化响应的重要手段。

       

      Abstract:
        Objective  Research on the response process of physiological parameters of desert plants to natural environment fluctuations can better understand and predict the impact of climate change on desert ecosystems.
        Method   We conducted in situ field measurements of chlorophyll fluorescence for three desert shrub species (Artemisia ordosica, Salix psammophila and Hedysarum mongolicum) to explore the responses of photosystem II (PSII) maximum quantum yield (Fv / Fm), photochemical efficiency (ΦPSII) and non-photochemical quenching (NPQ) to environmental factors, in order to understand the PSII photosynthetic physiology and its photoprotection mechanism of desert shrubs in arid environment.
        Result  Under water stress (soil water content < 0.08 m3/m3), Fv / Fm and Φ PSII of three kinds of desert shrubs were reduced and NPQ increased (P < 0.01). The Fv / Fm of S. psammophila was lower than that of A. ordosica and higher than H. mongolicum (P < 0.01). The ΦPSII of H. mongolicum was lower than both A. ordosica and S. psammophila (P < 0.01). The ΦPSII and NPQ for three typical desert shrubs presented a clear daily variation with photosynthetic active radiation (PAR), and also were affected by air temperature (Ta), relative humidity (RH) and vapor pressure difference (VPD). Three shrub species resisted drought stress through heat dissipation mechanism, but had different degrees. The Fv / Fm of A. ordosica can be restored to an appropriate value of about 0.75 through self-regulation of heat dissipation, and its reaction center damage was recoverable. H. mongolicum was greatly affected by drought stress, and its photoprotective response of heat dissipation was sensitive.
        Conclusion  A. ordosica can be considered as the first choice for vegetation restoration in arid areas, S. psammophila is the second and H. mongolicum is not recommended. The activity of PSII reaction center is characterized by changes in chlorophyll fluorescence parameters, which can fully reflect the response strategy of desert shrubs to environmental fluctuations, and can be used as an important means to explore the response of desert plants in arid and semi-arid areas to environmental changes.

       

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