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题名: 臭氧浓度升高对城市植物生长及生理特性的影响
作者: 杨宁1
学位类别: 博士
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 王效科
关键词: 臭氧,光合特性,生物量分配,吸收通量,植物激素 ; Ozone, photosynthetic performance, assimilate allocation, ozone flux,phytohormone
其他题名: Growth and physiological responses of urban plant to elevated tropospheric ozone concentration
学位专业: 生态学
中文摘要: 城市化和工业化的快速发展对周边乃至区域环境质量造成了严重的负面影 响,尤其是机动车、工业排放等产生的氮氧化物含量的增加,导致对流层臭氧污 染加重,对农田、森林、草地生态系统带来不可逆转的负面影响。城市植物作为 城市结构中自然生产力的主体,在改善空气质量,调节城市微气候等方面具有不 可替代的重要作用,是人与自然和谐发展的桥梁。但目前臭氧现状并不利于城市 植被生态效益的发挥,已在多种植物叶片上发现了明显的臭氧伤害。基于实时监 测结果,2010年至 2014年植物生长季的平均臭氧浓度呈上升趋势:2010年为 67 ppb,2013和 2014年的分别为 74和 76 ppb。因此在臭氧浓度尚未得到有效控 制的情况下,研究绿化植物的形态响应及其引起相应响应的生理机制,将对景观 植物的培育、城市绿化过程中绿化植物的选择具有重要的科学意义和理论依据。 本研究采用开顶式气室对北京常见的景观绿化植物(黄栌、月季、串红、万 寿菊、矮牵牛、圆叶牵牛)进行田间原位臭氧熏蒸实验。通过测量供试植物色素 含量、光合生理、植物激素以及适应策略对臭氧胁迫的响应,探讨臭氧浓度升高 造成叶色变化的机理;明确造成生长响应差异的光合机制;探明造成不同植物氧 化伤害的内源激素变化以及不同供试植物适应臭氧胁迫的策略响应,为城市绿化 过程中绿化植物的选择提供基础数据,并为进一步培育耐 O3品种提供理论依据, 以期在臭氧浓度得不到有效控制的前提下最大程度保证城市化的可持续性。主要 研究结果如下: (1)叶片伤害:臭氧浓度升高对供试植物叶片叶脉间区域造成了明显的臭 氧伤害,伤害特征因植物种类的不同存在差异:黄栌叶脉间出现褐色斑点,随时 间延长,斑点融合、扩大、干枯;圆叶牵牛叶片则是出现白色斑点,逐渐融合形 成白色斑块,最终干枯;万寿菊和矮牵牛叶片则表现出黄化程度加剧。 以万寿菊为例定量分析了臭氧伤害程度和臭氧暴露之间的关系,受害叶片比 例以及叶片受害程度随暴露时间的延长而加剧,与臭氧累积值(AOT40)之间呈 显著正相关关系(P < 0.05)。但 NF+60和 NF+120处理下万寿菊首次出现臭氧 症状时的 AOT40值并不一致(NF+60,8.6 ppm∙h;NF+120,6.4 ppm∙h),意味 着臭氧伤害的形成除与 AOT40有关外,可能还受臭氧峰值及其频率的影响。 (2)生长特性:臭氧胁迫对植物横向生长的影响大于纵向生长:黄栌、月 季、串红、万寿菊基径增长量的降低幅度分别为 19.1-32.4%,15.3-29.4%, 12.8-22.9%,和 7.2-46.8%;株高生长因植物种类表现出不一致的规律,但其受抑 程度小于基径。臭氧浓度升高推迟了花期长的植物达到最大花径所需要的时间, 因植物种类可延长 4-15天不等。花径与花生物量之间存在明显正相关关系(万 寿菊:P = 0.0089;矮牵牛:P = 0.0521),故而推测臭氧主要通过影响花径大小 抑制花生物量的形成。 (3)生物量及其分配:臭氧浓度升高抑制了敏感植物生物量的形成(黄栌: 14.3-43.8%,串红:2.7-3.4%,万寿菊:8.3-40.4%,矮牵牛:10.6-34.1%),同时 改变了内在冠根比大的植物的生物量分配,且内在冠根比越大,生物量越趋于分 配于地上部。 (4)光合生理特性:基于生物量响应,黄栌和万寿菊被归为臭氧敏感品种, 源于其各时期光合性能明显受抑;月季被归为耐臭氧品种,源于其前期较高的光 合性能。引起敏感植物光合性能下降的因素因植物种类不同存在差异:CO2由气 室向羧化位点的扩散过程受抑是造成黄栌光合性能下降的主要原因;万寿菊叶片 光合性能下降则是由于其光反应和暗反应过程均受到抑制。而月季表现出较高的 光合速率是由于其具有高效的暗反应过程。 (5)激素响应:臭氧浓度升高对供试植物造成了细胞水平上的氧化伤害, 一方面促进了丙二醛的累积,并加剧了其累积的程度;另一方面加速了生长旺盛 期可溶性蛋白的降解。但造成相似氧化伤害的激素响应因植物种类不同而存在差 异:万寿菊氧化伤害的形成主要是由于茉莉酸含量降低造成的保护功能下降;矮 牵牛氧化伤害的形成则是由于水杨酸累积引起的直接伤害;圆叶牵牛氧化伤害的 形成既有水杨酸累积的直接伤害又源于茉莉酸保护功能的下降。 (6)策略响应:植物可通过改变自身生理特性以适应高浓度臭氧环境,如 气孔大小调节以及抗氧化物质的合成:臭氧浓度升高降低了黄栌(臭氧敏感品种)、 月季(耐臭氧品种)以及万寿菊(臭氧敏感品种)的气孔导度,三种供试植物分 别下降了 32.3-56.0%、8.8-31.4%和 26.4-64.1%,但臭氧吸收通量却明显增加了 147.0-317.6%、162.9-189.0%和 104.8-145.6%,这主要是由于臭氧吸收通量的决 定因子是外界臭氧浓度(两者具有明显的正相关关系),而与气孔导度没有相关 性;臭氧浓度升高促进了月季和万寿菊叶片 ASA合成,与月季不同的是万寿菊 叶片氧化还原状态降低,即氧化态转化为还原态 ASA的过程受到抑制,这可能 是其不同于月季臭氧抗性的主要原因。臭氧处理后无论是耐臭氧的月季还是臭氧 敏感的黄栌和万寿菊,与 ASA反应后残留臭氧量明显高于对照处理。意味着单 一的 ASA体系并不能解释不同植物之间的臭氧抗性差异,需进一步量化其他抗 氧化指标与臭氧之间的关系。 因此,基于叶片和生物量响应,月季被归为耐臭氧品种,可优先选作高浓度 臭氧环境中的城市绿化树种。月季叶片具有高效的生物化学过程以确保其光合同 化能力不受影响,因此可作为培育抗臭氧品种的参考植物。
英文摘要: Rapid development of urbanization and industrilization gave rise to severely adverse impact on local air quality, which even spread out the larger region in all directions. In particular, the increase in NOx concentration generated from motor vehicle and industry resulted in increase of tropospheric ozone (O3) concentration, leading to inevitably negative effect on crops, forest and grassland (semi-natural vegetation). As the main body of natural productivity in urban system, urban plants play irreplaceable role in improving air quality, adjusting urban microclimate and so forth, whereas, current O3 concentration is bad for these ecological benefits, mean O3 concentration during plants‘ growing season from 2010 to 2014 was on the increase based on the real-time monitoring: 2010, 67 ppb; 2013, 74 ppb; 2014, 76 ppb, and severe O3 injury has already appeared. Therefore, it is necessary to comprehend morphological responses and physiological mechanisms of urban plants in face of rising O3 concentration, which will provide theoretical foundation for selecting and breeding O3-resistant species, evaluating landscaping and greening effect. In this study, open-top chambers (OTC) field experiment was conducted to investigate the O3 effect on ornamental plants (Cotinus coggygria, Rosa chinensis, Salvia splendens, Tagetes erecta, Petunia hybrida, Pharbitis purpurea) widely-used in Beijing by exposig them to three O3 levels: non-filtered air (NF), NF+60 and NF+120. During their own growing season, growth characteristics, leaf pigments, photosynthetic performance, oxidative damage, phytohormones and resistance strategies were determined to explore the mechanisms causing variation of leaf color, understand photosynthetic mechanism leading to growth difference, ascertain the endogenetic phytohormones responses resulting in various oxidative damage and find out the difference in resistance strategies among tested plant species. Theses results will be the theoretical foundation for selecting plants in urban landscape construction and breeding O3-resistant species. The following are the main consequences: (1) Leaf injury. Increased O3 concentrtion resulted in obviously intervenal injury to Cotinus coggygria, Tagetes erecta, Petunia hybrida, Pharbitis purpurea, and injury symptoms showed the difference among plant species. For Cotinus coggygria, brown stains appeared between veins, gradually covered and formed patches, finally withered. Pharbitis purpurea exhibited similar injury process to Cotinus coggygria, only except that white stains insteaded of brown ones. For Tagetes erecta and Petunia hybrida, yellowing occurred between the veins. Tagetes erecta was taken as example to analyze the quantitative relationship between injury degree and O3 exposure. Percentage of injured leaves and leaf injury index increased as exposure duration, showing positive correlation with AOT40 (P < 0.05). Whereas, O3 injury occurred firstly with different AOT40 under NF+60 (8.6 ppm∙h) and NF+120 treatments (6.4 ppm∙h), suggesting that except for AOT40, peak O3 concentration and its frenquency may also contribute to O3 injury. (2) Growth characteristics. Increased O3 concentration inhibited the radical growth of Cotinus coggygria, Rosa chinensis, Salvia splendens and Tagetes erecta, expressed as increment of stem diameter with 19.1-32.4%, 15.3-29.4%, 12.8-22.9% and 7.2-46.8% reduction, respectively. There‘s difference in response trend of plant height among tested plant species, showing positive response to elevated O3 or less inhibition than stem diameter. Elevated O3 retarded the timing of maximum flower diameter of flower plants with longer flower period, 4 to 15 days as species. There‘s consistent response to elevated O3 between flower biomass and flower diameter, and obviously positive correlation existed between them (P=0.0089 for Tagetes erecta; P=0.0521 for Petunia hybrida), suggesting that decrease of flower biomass may be attributed to inhibition of flower diameter when exposed elevated O3 concentration. (3) Plant biomass and allocation. Increased O3 concentration inhibited biomass formation of sensitive species (Cotinus coggygria, 14.3-43.8%; Salvia splendens, 2.7-3.4%; Tagetes erecta, 8.3-40.4%; Petunia hybrida, 10.6-34.1% ), and also altered the biomass allocation of species with higher inner shoot to root ratio. The higher shoot to root ratio is, the more allocation to shoot (P = 0.0202). (4) Photosynthetic performance. Based on biomass response, Cotinus coggygria and Tagetes erecta were regarded as O3-sensitive species, while Rosa chinensis was categorized into O3-resistant one. For O3-sensitive species, reasons of decrease in photosynthetic performance were ascribed to mesophyllic limitation—CO2 diffusion from substomatal chamber to carboxylation site (Cotinus coggygria), or impairement of both photochemical and biochemical processes (Tagetes erecta); for Rosa chinensis, higher-efficient biochemical process contributed to betterphotosynthetic performance. (5) Endogenous phytohormones response. O3 damage to Tagetes erecta, Petunia hybrida and Pharbitis purpurea also took place at the cellular level, expressed as accelerated and aggravated MDA accumulation, and accelerated protein degradation. There‘s distinct phytohormone responses causing ozixdative injury among plant species. For Tagetes erecta, protection capability of jasmonic acid (JA) was weakened; for Petunia hybrida, direct damage from salicylic acid (SA) accumulation was enhanced; for Pharbitis purpurea, both above occurred. (6) Adaptive strategies. Plants can adapt to elevated O3 environment by adusting stomata or synthesizing antioxidants. Increased O3 concentration decreased stomatal conductance, with reduction of 32.3-56.0% for Cotinus coggygria, 8.8-31.4% for Rosa chinensis and 26.4-64.1% for Tagetes erecta,while O3 flux increased by 147.0-317.6%, 162.9-189.0% and 104.8-145.6%, respectively. That‘s because O3 concentration, not stomatal conductance was the determinant factor (remarkably positive correlation existed between O3 flux and O3 concentration), suggesting that O3-induced stomatal closure could not control O3 amount into leaves effectively, and may be not an effective approach to reducing O3 injury. Increased O3 concentration facilitated to synthesize ASA of Rosa chinensis and Tagetes erecta, while for the latter, conversion process from oxidized to reduced ASA was inhibited, which may contribute to the difference in O3 sensitivity from Rosa chinensis. Based on residual O3 amount after reacting with ASA, potential of reactive oxygen species formation of both O3-resistant and O3-sensitive species was enhanced, indicating that ASA consideration alone cannot interpret the different O3 responses, and the relationship between O3 and other antioxidants should be further quatified. In conclusion, Rosa chinensis could be classified as O3-resistant species based on leaf morphology and biomass responses, and be selected preferentially for urban greening. Rosa chinensis may be further used as a reference due to its efficiently biochemical process when breeding O3-resistant species.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38730
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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作者单位: 1.中国科学院生态环境研究中心

Recommended Citation:
杨宁. 臭氧浓度升高对城市植物生长及生理特性的影响[D]. 北京. 中国科学院大学. 2017.
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