Tropospheric O3: A Cause of Concern for Terrestrial Plants
Tropospheric ozone (O3) is a phytotoxic pollutant causing risk to food production, pasture, and forest communities. In the present scenario, unsustainable resource utilization has turned this secondary pollutant into a major component of global climate ch
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Richa Rai, Aditya Abha Singh, S.B. Agrawal, and Madhoolika Agrawal
Abstract
Tropospheric ozone (O3) is a phytotoxic pollutant causing risk to food production, pasture, and forest communities. In the present scenario, unsustainable resource utilization has turned this secondary pollutant into a major component of global climate change. The background levels of O3 are very high, and IPCC projections have shown that it will increase by 20–25 % in 2050 and 40–60 % in 2100, causing severe consequence on global food security. Ozone enters plants through stomata, where it can be dissolved in the apoplastic fluid. Ozone has several potential effects on plants: direct reaction with cell membranes, generation of ROS and H2O2 (which alter cellular function by causing cell death), induction of premature senescence, negative impact on photosynthetic machinery and up- or downregulation of antioxidants, defense reactions, and variations in metabolic pathways. Tropospheric O3 causes changes in tree diameter, wood quality, herbivory pattern, forage quality, and crop yield and quality. In this chapter, we make an attempt to present an overview of O3 concentrations throughout the globe and its impact on agricultural crops, forest, and grassland ecosystems. We summarized the information available on plant responses to O3 at physiological, cellular, and biochemical levels; crop yield; and forest and grassland communities at present concentrations and also under projected future concentrations. Keywords
Tropospheric ozone • IPCC • Photosynthetic machinery • ROS • Crop yield
14.1 R. Rai • A.A. Singh • S.B. Agrawal M. Agrawal (*) Laboratory of Air Pollution and Global Climate Change, Department of Botany, Banaras Hindu University, Varanasi 221005, India e-mail: [email protected]
Introduction
During the last few decades, tropospheric ozone (O3) has become one of the most wide spread toxic pollutants around the globe (IPCC 2013; Booker et al. 2009), negatively affecting the crop
© Springer Science+Business Media Singapore 2016 U. Kulshrestha, P. Saxena (eds.), Plant Responses to Air Pollution, DOI 10.1007/978-981-10-1201-3_14
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productivity and hence a major threat to global food security (Rai and Agrawal 2012). Since the industrial revolution, the global average O3 concentrations have increased from around 20–30 ppb to present-day values of 30–50 ppb with significant variability in its spatial distribution (IPCC 2013). Due to substantial escalation in industrialization and urbanization, ground-level O3 is considerably higher in the Northern Hemisphere than the Southern Hemisphere. Its abundance in mid-latitudes of Northern Hemisphere has increased twice or more since the preindustrial era with present background O3 concentrations ranging from 35 to 50 ppb (Cooper et al. 2010; IPCC 2013). At the global scale, O3 concentrations are higher in Central Europe, Eastern China, and the Eastern USA (Royal Society 2008). In Europe, the highest O3 levels occur in Central and Southern Europe (Royal Society 2008). High levels
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