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首页> 外文学位 >Effect of ozone on carbon dioxide assimilation and PSII function in plants with contrasting pollutant sensitivities.
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Effect of ozone on carbon dioxide assimilation and PSII function in plants with contrasting pollutant sensitivities.

机译：臭氧对植物的二氧化碳同化和PSII功能的影响具有相反的污染物敏感性。

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摘要

Ozone is known to be the most widespread phytotoxic air pollutant. Ozone causes visible injury, reductions in photosynthesis, growth, and yield. Plant response to ozone may vary with species, varieties, and physiological age. Comparison between sensitive and tolerant cultivars has a key role in assessing ozone damage, investigating the sites of cellular injury, and identifying ozone tolerance mechanism. The objectives of this study were to investigate the effects of high ozone concentration (200 ppb) as well as ambient ozone concentrations (under field conditions) on net CO2 assimilation and PSII function in plants with different sensitivities to ozone. Two species of plants, tobacco (Nicotiana tabacum L.) and black cherry (Prunus serotina) were studied. Gas exchange analysis and chlorophyll fluorometry were utilized to characterize physiological function.;Two tobacco cultivars, Bel-B and Bel-W3, tolerant and sensitive to ozone, respectively, were grown in a greenhouse supplied with charcoal filtered air and then exposed to 200 ppb ozone for 4hr. Effects on chlorophyll fluorescence, net photosynthesis, and stomatal conductance are described. Quantum yield was calculated from chlorophyll fluorescence and the initial slope of the assimilation-light curve measured by the gas exchange method. Only the sensitive cultivar, Bel-W3, developed visible injury symptoms involving up to 50% of the 5th leaf. The maximum net photosynthetic rate of ozone-treated plants of the tolerant cultivar was reduced 40% compared to control plants immediately after ozone fumigation; however, photosynthesis recovered by 24 hr post fumigation and remained at the same level as control plants. In the sensitive cultivar, on the other hand, ozone exposure reduced maximum net photosynthesis up to 50%, with no recovery, apparently causing permanent damage to the photosystem. Reductions in apparent quantum efficiency, calculated from the assimilation-light curve, differed between cultivars. Bel-B showed an immediate depression of 14% compared to controls, whereas Bel-W3 showed a 27% decline. Electron transport rate (ETR), at saturating light intensity, decreased 58% and 80% immediately after ozone treatment in Bel-B and Bel-W3, respectively. Quantum yield decreased 28% and 36% in Bel-B and Bel-W3, respectively. It can be concluded that ozone caused a greater relative decrease in linear electron transport than maximum net photosynthesis, suggesting greater damage to PSII than the carbon reduction cycle.;Two different sensitivity classes of black cherry, tolerant and sensitive, growing under natural environmental conditions in Giles County, VA were assessed for physiological responses to ambient ozone concentrations. Additional measurements were made at two other sites near Blacksburg. Leaf gas exchange rates and visible foliar injury were determined monthly during the growing seasons of 2000, 2001, and 2002 to characterize the relationship of injury to altered photosynthetic function. Ambient ozone levels were sufficient to induce visible symptoms which were highly correlated with a reduction in PnMAX (maximum net photosynthetic rate under saturating light conditions) and ΦCO 2 (quantum yield for carbon reduction) only in sensitive black cherry. Electron transport rate (ETR) and quantum yield of PSII (ΦPSII) were also reduced in sensitive black cherry. Maximum photochemical efficiency (Fv/Fm) in sensitive trees was severely damaged by ambient ozone. There were positive correlations between increasing cumulative ozone concentration and substantial reductions in PnMAX and in ΦCO2 of sensitive trees compared to tolerant trees. There was a negative correlation between chlorophyll content and percent leaf injury in sensitive black cherry.
机译：臭氧是最广泛的植物毒性空气污染物。臭氧会造成可见的伤害，减少光合作用，生长和产量。植物对臭氧的反应可能随物种，品种和生理年龄而变化。敏感和耐性品种之间的比较在评估臭氧破坏，调查细胞损伤的部位以及确定臭氧耐受机制方面具有关键作用。这项研究的目的是调查高臭氧浓度（200 ppb）和周围臭氧浓度（在田间条件下）对不同臭氧敏感性植物中净CO2同化和PSII功能的影响。研究了两种植物，烟草（Nicotiana tabacum L.）和黑樱桃（Prunus serotina）。利用气体交换分析和叶绿素荧光测定法表征其生理功能。在供应有木炭过滤空气的温室中，分别种植两个对耐臭氧和对臭氧敏感的Bel-B和Bel-W3品种，然后暴露于200 ppb臭氧4小时。描述了对叶绿素荧光，净光合作用和气孔导度的影响。由叶绿素荧光和通过气体交换法测量的同化光曲线的初始斜率计算出量子产率。只有敏感的品种Bel-W3出现可见的伤害症状，涉及高达第五叶的50％。臭氧熏蒸后，耐性品种的臭氧处理植物的最大净光合速率与对照植物相比降低了40％。然而，熏蒸后24小时光合作用恢复，并保持与对照植物相同的水平。另一方面，在敏感品种中，臭氧暴露使最大净光合作用降低了50％，没有恢复，显然对光系统造成了永久性损害。根据同化光度曲线计算得出的表观量子效率的降低因品种而异。与对照组相比，Bel-B立即下降了14％，而Bel-W3下降了27％。在Bel-B和Bel-W3中，臭氧处理后，饱和光强度下的电子传输速率（ETR）分别立即降低了58％和80％。 Bel-B和Bel-W3的量子产率分别下降了28％和36％。可以得出结论，臭氧引起的线性电子传递比最大净光合作用的相对下降更大，表明对PSII的破坏要比碳还原循环更大。两种不同的敏感性黑樱桃，耐性和敏感性，在自然环境条件下生长评估了弗吉尼亚州吉尔斯县对环境臭氧浓度的生理反应。在布莱克斯堡附近的另外两个地点进行了额外的测量。在2000、2001和2002年的生长季节每月测定叶片气体交换速率和可见叶损伤，以表征损伤与光合功能改变的关系。仅在敏感的黑樱桃中，环境中的臭氧水平足以引起可见的症状，这与PnMAX（饱和光条件下的最大净光合速率）和ΦCO2（减少碳的量子产率）的降低高度相关。在敏感的黑樱桃中，电子传递速率（ETR）和PSII的量子产率（ΦPSII）也降低了。敏感树木的最大光化学效率（Fv / Fm）被周围的臭氧严重破坏。与耐受树木相比，敏感树木的累积臭氧浓度增加与PnMAX和ΦCO2的大幅降低之间存在正相关。在敏感的黑樱桃中，叶绿素含量与叶片伤害百分率之间呈负相关。

著录项

  • 作者

    Yun, Myoung Hui.;

  • 作者单位

    Virginia Polytechnic Institute and State University.;

  • 授予单位 Virginia Polytechnic Institute and State University.;
  • 学科 Environmental Sciences.;Biology Plant Physiology.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 105 p.
  • 总页数 105
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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