Closing the global ozone yield gap: Quantification and cobenefits for multistress tolerance

Abstract

Increasing both crop productivity and the tolerance of crops to abiotic and biotic stresses is a major challenge for global food security in our rapidly changing climate. For the first time, we show how the spatial variation and severity of tropospheric ozone effects on yield compare with effects of other stresses on a global scale, and discuss mitigating actions against the negative effects of ozone. We show that the sensitivity to ozone declines in the order soybean > wheat > maize > rice, with genotypic variation in response being most pronounced for soybean and rice. Based on stomatal uptake, we estimate that ozone (mean of 2010-2012) reduces global yield annually by 12.4%, 7.1%, 4.4% and 6.1% for soybean, wheat, rice and maize, respectively (the "ozone yield gaps"), adding up to 227 Tg of lost yield. Our modelling shows that the highest ozone-induced production losses for soybean are in North and South America whilst for wheat they are in India and China, for rice in parts of India, Bangladesh, China and Indonesia, and for maize in China and the United States. Crucially, we also show that the same areas are often also at risk of high losses from pests and diseases, heat stress and to a lesser extent aridity and nutrient stress. In a solution-focussed analysis of these results, we provide a crop ideotype with tolerance of multiple stresses (including ozone) and describe how ozone effects could be included in crop breeding programmes. We also discuss altered crop management approaches that could be applied to reduce ozone impacts in the shorter term. Given the severity of ozone effects on staple food crops in areas of the world that are also challenged by other stresses, we recommend increased attention to the benefits that could be gained from addressing the ozone yield gap.

Tropospheric ozone pollution reduces the yield of African crops

“…In the near future, this could include selection of existing cultivars that may be more resistant to the local pollution climate, but in the longer term selective breeding could be used to increase the prevalence of traits or genes associated with ozone resistance. An ideotype for an ozone‐tolerant crop has been suggested, which includes target traits of increased water‐use efficiency, low stomatal conductance, high antioxidant capacity and balanced redox homeostasis and programmed cell‐death pathways, as ozone sensitivity can be a consequence of some traits identified when developing high‐yielding varieties (Mills, Sharps, Simpson, Pleijel, Frei, et al, ). Studies have identified some genetic loci associated with ozone resistance and/or susceptibility in wheat and rice (e.g.…”

“…Analysis of compiled data sets from many experiments has shown a wide range in ozone sensitivity between different crops, based on ozone concentration (Mills et al, ; Mills & Harmens, ; Mills, Sharps, Simpson, Pleijel, Broberg, et al, ). Model‐based studies using dose‐response functions from such data sets have indicated potential crop yield reductions due to ozone across wide regions of the world (Avnery, Mauzerall, Liu, & Horowitz, ; Mills, Pleijel, et al, ; Mills, Sharps, Simpson, Pleijel, Broberg, et al, ; Mills, Sharps, Simpson, Pleijel, Frei, et al, ; Van Dingenen et al, ). Experimental investigations have shown impacts of ambient ozone concentrations on a wide range of crop species in Europe and the USA by comparing responses of plants in filtered air to those in non‐filtered air (De Temmerman, Legrand, & Vandermeiren, ; Marzuoli, Finco, Chiesa, & Gerosa, ; Pleijel, Broberg, Uddling, & Mills, ).…”

Tropospheric Ozone Assessment Report: Present-day tropospheric ozone distribution and trends relevant to vegetation

“…Thus, much of the ozone data are from the NH mid-high latitudes of the developed world (20 to 60° N), with very limited data available for rapidly developing countries of Africa, South America, and parts of SAS/SEA. TOAR has strong representation in areas of NAM and EUR predicted to have high ozone impacts on crops (Avnery et al, 2011;Van Dingenen et al, 2009;Mills et al, submitted) and biodiversity (Fuhrer et al, 2016) such as central states of the USA and Mediterranean areas. However, other areas predicted from modelling to have high impacts of ozone on vegetation such as northern areas of India and the northern plains of China (e.g.…”

“…Avnery et al, 2011;Van Dingenen et al, 2009) or stomatal ozone uptake (e.g. Mills et al, 2018;Mills et al, submitted). For perennial vegetation, there is good representation of data in mid-latitudes of the Northern Hemisphere where grassland and forested areas provide grazing, harvestable biomass and other ecosystem services.…”

A Stratospheric Intrusion-Influenced Ozone Pollution Episode Associated with an Intense Horizontal-Trough Event

“…Tropospheric ozone is an important greenhouse gas contributing to global warming [1,2] and also a main pollutant harmful to human health and crop productivity [3,4]. A significant decrease of ozone concentrations has been observed in the eastern United States and parts of Europe due to precursor emission controls [2,5,6].…”