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题名: 干旱胁迫下大气臭氧浓度升高对元宝枫生长和生理影响
作者: 李丽
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 王效科
关键词: 臭氧, 干旱, 元宝枫, 生理生化, 气体交换, 生物量, 生长 ; O3, drought stress, Acer truncatum, physiology and biochemistry, gas exchange, biomass, growth
其他题名: The effects of elevated ozone on growth and physiology of Acer truncatum under drought stress in a surburb of Beijing, China
学位专业: 生态学
中文摘要:       臭氧(O3)是一种具有强氧化性的二次污染物, 不断升高的近地层O3浓度严重威胁着全球生态系统安全, 导致粮食减产, 森林和草地大规模退化。在北京郊区和城区已经观察到大量植物叶片O3受害症状。同时, 干旱也是威胁我国北方树木生长的重要因子, 缺水地区林木生长会受到 O3和干旱的复合影响。针对于O3和干旱胁迫同时存在对树木生理响应的研究存在大量空白, 且结果差异很大。我们于2012-2013年生长季在北京市昌平区通过采用开顶式气室(OTC)对我国北方典型树种-元宝枫进行了干旱背景下O3浓度升高熏蒸实验, 结合室内分析测定数据, 对O3和干旱共同作用对元宝枫幼苗生长和水分利用的影响进行了研究, 主要结果如下:
    (1) 叶片受害症状随O3熏蒸时间的延长具有明显的累积效应。O3处理导致元宝枫植株成熟叶片的上表面叶脉两侧逐渐出现了褐色褪绿斑点, 随着O3熏蒸时间的加长, 受害症状面积不断增大, 叶片出现早衰凋落。单独O3处理和O3和干旱共同处理后叶片出现受害症状的AOT40累积量分别为39.9 ppm h和51 ppm h, 与亚洲相似树种进行对比的结果表明元宝枫是一种对O3不敏感或者O3抗性较强的树种。
    (2) O3胁迫下, 元宝枫幼苗叶片出现比叶重、叶面积、叶绿素a、叶绿素b和类胡萝卜素含量显著下降, 叶片元素N和C含量下降, 叶片中C/N比升高。叶片同位素13C/12C值升高, 叶片水分利用效率提高。O3浓度升高后叶片ABA含量显著升高, 说明O3浓度升高加速了叶片衰老和脱落。O3浓度升高和干旱处理后叶片MDA含量均显著升高, 说明处理造成了叶片膜质过氧化。同时O3浓度升高和干旱处理后叶片脯氨酸含量显著升高, 可溶性蛋白含量减少。O3和干旱处理后叶片光合值、气孔导度和蒸腾量显著下降, 造成光合值下降的主要原因在不同时期不同, O3处理在前期是气孔限制, 末期是非气孔限制。Vcmax和Jmax的比值保持一致, 因此说明RUBP再生能力并没有受到O3胁迫影响, RUBP羧化过程与光驱动的电子传递过程之间存在很好的偶联关系。树干液流值的下降随O3处理时间的增加而加剧。
     (3) O3 和干旱共同处理后, 显著的交互作用表明干旱对于O3对叶片的伤害有一定的保护作用, 干旱减缓了叶片受害症状, 减缓了叶片LMA、老叶叶面积、叶绿素a、叶绿素b、类胡萝卜素含量、叶片元素N和C含量以及树干液流累积量在O3处理后的下降。交互作用结果也表明干旱也对O3造成的叶片ABA含量升高有一定的抑制作用。但是在叶片光合和植株生长并未发现显著交互作用, 由于碳固定减少, 共同处理对13C/12C值的影响表现为协同交互作用, 含量显著高于单独O3浓度升高和干旱处理, 说明进入叶片的CO2量更少, 叶片受到的胁迫更强。同时也表明共同处理后13C/12C值的升高表明处理后叶片水分胁迫加剧,水分利用效率提高。共同处理后总生物量下降量比单独O3和干旱处理分别增加了8.6%和34.4%。这些数据表明干旱仅能缓解叶片尺度上部分O3的伤害, 由于C固定的减少, 当把植株作为整体进行考虑时, 干旱并不能缓解臭氧对元宝枫幼苗的胁迫作用, 反而造成更多的生物量下降。
英文摘要:     Ozone (O3), the most important phytotoxic pollutant threatening the safety of ecosystem, causes crop yield losses, forests and grassland degeneration worldwide. Foliar injuries of trees have been found widespread in and around Beijing now.
    Besides O3, drought is also an important factor limiting the growth of the forest in north China especially trees are often subject to periodic drought during summer. Drought incidence in summer can coincide with episodes of elevated O3 concentrations, which are high enough to cause plant injury and growth reduction. Many investigations had focused on interactions to determine possible ways in which drought would affect O3 effects on injury and growth. However, the results varied and there were still no determined conclusions. So far, no research about A. truncatum Bunge response to O3 has been reported, especially interactions with drought stress. In the study, A two-year experiment exposing Acer truncatum Bunge seedlings to elevated O3 concentrations above ambient air and drought stress was carried out using open-top chambers (OTCs) in a suburb of Beijing in north China from 2012 to 2013. The main results were detailed as follows:
    (1) O3 fumigation had significantly accumulation effects on foliar injury. Visible foliar injury typically progressed on upper leaf surfaces of A. truncatum with chlorotic stippling, reddening, and premature leaf senescence. O3-like symptoms first appeared on August 8th under individual O3 treatments, when AOT40 was 39.9 ppm h (since April 28th, 2013). Seedlings under elevated O3 and drought combined treatments displayed foliar injury later on September 2nd when AOT40 was 51 ppm h (since April 28th, 2013). Visible symptoms were typically punctate purple-red stipples on the interveinal areas of upper leaf surfaces. Compared the AOT40 threshold for onset of the first foliar injury symptom, we found that A.truncatum is an O3 insensitive or tolerant species.
    (2) Individual elevated O3 treatments significantly decreased leaf mass per area, leaf area, leaf photosynthetic pigments, elemental nitrogen (N) and carbon (C), soluble protein contents as well as stem sap flow. The leaf C/N ratio, isotope 13C/12C, leaf abscisic acid (ABA), malondialdehyde (MDA), proline contents were significantly increased under elevated O3 treatments. Leaf net photosynthesis rates (Asat), stomatal conductance (Gs) and evaporation rates (E) were also reduced by elevated O3, the Asat reduction was due to stomatal limitation at first then changed to non-stomatal limitation at the end of experiment. Although Vcmax (maximum velocity of carboxylation of Rubisco) and Jmax (maximum electron flow through photosysytem II) were both decreased under elevated O3 treatments, the ratio of Vcmax and Jmax kept almost the same which indicated that plants preserved a close functional balance to regenerate RuBP and in adjusting the photosynthetic apparatus to finish the allocation of the optimal utilization of available resources.
    (3) Significant interactions were detected on leaf LMA, old leaf area, leaf photosynthetic pigments, leaf elemental nitrogen (N) and carbon (C), sap flow accumulation and leaf ABA contents, which all showed that drought could protect the above mentioned indexes of leaf scale from O3 damage. However, no significant interaction were found in leaf Asat and growth, due to limited carbon fixation, the significant interaction on total biomass showed that the interaction induced 8.6%和34.4% more reductions than individual O3 and drought treatments. These data suggest that when the whole plant was considered that drought under the conditions of this experiment did not protect the Shantung maple seedlings from the effects of O3.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36878
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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Recommended Citation:
李丽. 干旱胁迫下大气臭氧浓度升高对元宝枫生长和生理影响[D]. 北京. 中国科学院研究生院. 2016.
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