PARENT SESSION
Organized Oral Session 1: Understanding the impacts of oxidative stress in plants: From molecules to ecosystems
Organizer(s): HS Neufeld and N Grulke
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 510a, Level 5, Palais des congrès de Montréal
Atmospheric oxidative stresses: Trends and prospects.
Cape, John*,1, 1 Centre for Ecology & Hydrology, Edinburgh, UK
ABSTRACT- The evidence for an increase in background ground-level ozone concentrations in the northern hemisphere will be presented, and discussed in the context of recent modelling studies that show large increases in ground-level ozone over the next 50 years. In terms of potential effects on plants, the changing seasonal patterns of ozone will be discussed in relation to the most sensitive stages of plant growth and development. The concentration of O3 is the most obvious evidence of the oxidising capacity of the troposphere, but its formation is the result of complex chemical reactions of nitrogen oxides and volatile organic compounds (VOCs), which are driven by sunlight and involve a range of highly reactive free-radicals. Little is known of the potential direct effects of radicals such as the hydroxyl (OH), hydroperoxyl (HO2) and organic peroxy radicals (RO2) on vegetation. Possible reactions, and the extent to which they might occur in controlled experiments, are discussed, along with their sources (e.g. the reaction of O3 with biogenic hydrocarbons). Given this introduction, the possible interactions of ozone with climate change are discussed in terms of (1) changes in chemical processes caused by increases in temperature, humidity and VOC concentrations; (2) changes in O3 removal rates, and consequences for ground-level concentrations; and (3) changes in plant physiology that influence the response to O3.
Key words: ozone, free radicals, climate change