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    宁夏盐池油蒿叶片水分利用效率的生长季动态变化及对环境因子的响应

    Dynamics of water use efficiency of Artemisia ordosica leaf in growing season in response to environmental factors in Yanchi, Ningxia of northwestern China

      摘要
    • 摘要:
        目的  探明西北半干旱区典型沙生植物油蒿叶片的水分利用效率季节动态及其对环境因子的响应机制，为生态系统过程建模提供重要的生理生态参数。
        方法  本研究于2018年5—9月，使用 LI-6400XT便携式光合仪，测定了油蒿叶片的气孔导度（gs）、净光合速率（Pn）、蒸腾速率（E），并计算得出来叶片水分利用效率（WUE），分析了WUE与土壤含水量（SWC）、叶片表面饱和水汽压差（VPDl）、光合有效辐射（PAR）及叶片表面温度（Tl）的关系。
        结果  油蒿叶片的gs、Pn、E和WUE对SWC、VPDl、PAR和Tl具有一定的响应关系。当SWC ≤ 0.08 m3/m3时，gs、E、Pn、和WUE对VPDl的响应更为敏感；SWC > 0.08 m3/m3时，gs、Pn、E和WUE对PAR与Tl的响应更为敏感。
        结论  本研究结果进一步证明，油蒿在干旱条件下通过气孔的调节来适应环境变化，环境因子通过影响gs，进而影响植物的Pn和E，从而使WUE发生改变，且WUE在干旱时较低，表明土壤干旱胁迫制约油蒿叶片光合作用，从而使叶片水分利用效率受到抑制。因此，得出如下结论：油蒿通过水分资源保存策略来适应干旱环境。

       

      Abstract:
        Objective  We aimed to understand the seasonal dynamics of leaf water use efficiency and its response to environmental factors in Artemisia ordosica, a typical sandy plant in the semi-arid ecosystem of northwestern China for the purpose of ecosystem process modeling.
        Method  The leaf stomatal conductance (gs), net photosynthetic rate (Pn) and transpiration (E) of Artemisia ordosica were measured using Li-6 400 portable photosynthetic analyzer from May to September, 2018. Water use efficiency (WUE, WUE = Pn / E) was analyzed in relation to soil water content (SWC), saturated water vapor pressure deficit (VPD1), photosynthetically active radiation (PAR) and leaf surface temperature (Tl).
        Result  The gs, Pn, E and WUE were more sensitive to VPD1 when SWC ≤ 0.08 m3/m3. When SWC > 0.08 m3/m3, the gs, Pn, E and WUE were more sensitive to the response of PAR and Tl.
        Conclusion  The results of this study further prove that Artemisia ordosica acclimates to drought conditions through changing gs and relative magnitude of Pn and E, and thus changing WUE. And WUE is lower during drought, indicating that soil drought stress restricts leaf photosynthesis and WUE. It is concluded that Artemisia ordosica acclimats to dry environmental conditions through conservative strategy of water resource.

       

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