Has the sensitivity of soybean cultivars to ozone pollution increased with time? An analysis of published dose-response data.

Stephanie A Osborne,Elizabeth A Ainsworth,Lisa Emberson,Felicity Hayes,Patrick Büker,Gina Mills

doi:10.1111/gcb.13318

Stephanie A Osborne, Elizabeth A Ainsworth + Show 4 more

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https://doi.org/10.1111/gcb.13318

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Abstract

The rising trend in concentrations of ground-level ozone (O3 ) - a common air pollutant and phytotoxin - currently being experienced in some world regions represents a threat to agricultural yield. Soybean (Glycine max (L.) Merr.) is an O3 -sensitive crop species and is experiencing increasing global demand as a dietary protein source and constituent of livestock feed. In this study, we collate O3 exposure-yield data for 49 soybean cultivars, from 28 experimental studies published between 1982 and 2014, to produce an updated dose-response function for soybean. Different cultivars were seen to vary considerably in their sensitivity to O3 , with estimated yield loss due to O3 ranging from 13.3% for the least sensitive cultivar to 37.9% for the most sensitive, at a 7-h mean O3 concentration (M7) of 55ppb - a level frequently observed in regions of the USA, India and China in recent years. The year of cultivar release, country of data collection and type of O3 exposure used were all important explanatory variables in a multivariate regression model describing soybean yield response to O3 . The data show that the O3 sensitivity of soybean cultivars increased by an average of 32.5% between 1960 and 2000, suggesting that selective breeding strategies targeting high yield and high stomatal conductance may have inadvertently selected for greater O3 sensitivity over time. Higher sensitivity was observed in data from India and China compared to the USA, although it is difficult to determine whether this effect is the result of differential cultivar physiology, or related to local environmental factors such as co-occurring pollutants. Gaining further understanding of the underlying mechanisms that govern the sensitivity of soybean cultivars to O3 will be important in shaping future strategies for breeding O3 -tolerant cultivars.

Highlights

Ensuring that the rising global population has access to a sufficient and stable food supply is a key international priority for the 21st century
The dose–response relationship presented in this manuscript is linear, with 100% relative yield occurring at a theoretical background O3 M7 value of zero
This is in contrast to the Mills et al (2007) function which is based on the AOT40 metric and assumes that O3 concentrations below 40 ppb are not contributing to effects

Summary

Introduction

Ensuring that the rising global population has access to a sufficient and stable food supply is a key international priority for the 21st century. A further threat to agricultural yield comes from rising concentrations of ground-level ozone (O3) (Fuhrer, 2009) – a common air pollutant and phytotoxin (Krupa et al, 2001). The global surface background concentration of O3 more than doubled between the early 1900s and the end of the 20th century (Hough & Derwent, 1990; Parrish et al, 2014), most likely as a result of rising anthropogenic emissions of O3 precursor compounds from fossil fuel combustion, biomass burning and paddy field cultivation (Brasseur et al, 2001). Establishing a thorough understanding of crop and cultivar responses to O3, and the incorporation of these responses into crop production models, is needed to quantify the potential impact of O3 on food supply in different world regions

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