Quantifying the effects of ozone on plant reproductive growth and development

Abstract

Tropospheric ozone (O 3 ) is a harmful air pollutant that can negatively impact plant growth and development. Current O 3 concentrations ([O 3 ]) decrease forest productivity and crop yields and future [O 3 ] will likely increase if current emission rates continue. However, the specific effects of elevated [O 3 ] on reproductive development, a critical stage in the plant's lifecycle, have not been quantitatively reviewed. Data from 128 peer-reviewed articles published from 1968 to 2010 describing the effects of O 3 on reproductive growth and development were analysed using metaanalytic techniques. Studies were categorized based on experimental conditions, photosynthetic type, lifecycle, growth habit and flowering class. Current ambient [O 3 ] significantly decreased seed number (À16%), fruit number (À9%) and fruit weight (À22%) compared to charcoal-filtered air. In addition, pollen germination and tube growth were decreased by elevated [O 3 ] compared to charcoal-filtered air. Relative to ambient air, fumigation with [O 3 ] between 70 and 100 ppb decreased yield by 27% and individual seed weight by 18%. Reproductive development of both C 3 and C 4 plants was sensitive to elevated [O 3 ], and lifecycle, flowering class and reproductive growth habit did not significantly affect a plant's response to elevated [O 3 ] for many components of reproductive development. However, elevated [O 3 ] decreased fruit weight and fruit number significantly in indeterminate plants, and had no effect on these parameters in determinate plants. While gaps in knowledge remain about the effects of O 3 on plants with different growth habits, reproductive strategies and photosynthetic types, the evidence strongly suggests that detrimental effects of O 3 on reproductive growth and development are compromising current crop yields and the fitness of native plant species.

Involvement of Phytohormones in Plant Responses to Ozone

“…O 3 caused the reduction and the abortion of bud and flowers (Black et al 2007) and the decrease in fruit weight and fruit number in a significant manner (Leisner and Ainsworth 2012), and in these processes ET could be actively involved (Wilkinson et al 2011). …”

“…Two types of exposure are defined: (1) acute, high concentrations, above 120 ppb for a few hours, as may occur at most polluted sites and (2) chronic, an elevated background concentration with daily peak concentrations in the range of 40-120 ppb over several days in the growing season (Long and Naidu 2002). Chronic exposures to low levels of O 3 result in a (1) decline in photosynthesis, (2) growth inhibition, and (3) premature senescence, normally even without visible damage (Krupa 2003;Leisner and Ainsworth 2012;Vainonen and Kangasjärvi 2015). Conversely, acute exposures, which can occur several times throughout the growing season, lead to the induction of cell death and visible leaf injuries in sensitive plants (Rao et al 2000).…”

Estimating ozone risks using forest monitoring networks—results for science, policy, and society

“…Ozone has been frequently reported to cause severe risks to a variety of targets, including forest vegetation (Leisner and Ainsworth 2012) and human health (WHO 2000). In Europe, the Directive 2008/50/ EC ( /50/EC 2008 sets acceptable limits for ozone concentration and exposure to protect human health and vegetation, for which thresholds are also defined by UNECE (CLRTAP 2004).…”

Impact of Elevated Ozone on Growth, Yield and Nutritional Quality of Two Wheat Species in Northern India

“…O 3 is one of the most damaging tropospheric air pollutants affecting plant growth and productivity (Leisner and Ainsworth, 2012). Concentrations of tropospheric O 3 have increased considerably since the Industrial Revolution, especially during the past 60 years, and are likely to continue to increase by 10-30 parts per billion (ppb) by 2100 if current high emission rates continue in the Northern Hemisphere (The Royal Society, 2008).…”