University of Illinois at Urbana-Champaign Urbana, Illinois
Body of Abstract: Tropospheric ozone (O3) is a damaging and widespread air pollutant that is detrimental to human and ecosystem health worldwide. Current background O3 concentration is estimated to decrease the yields of maize (Zea mays) up to 10% in the United States and reduce global crop yield (maize, soybean, rice and wheat combined) by 227 Tg annually, which portends a significant threat to future global food and energy security. However, it is unclear how other bioenergy feedstocks, including miscanthus (Miscanthus × giganteus), sorghum (Sorghum bicolor) and switchgrass (Panicum virgatum), respond to O3 stress, or whether these species share a similar O3 sensitivity as maize. Using the unique capabilities of Free Air Concentration Enrichment (FACE) technology, which provides elevated concentrations of O3 (100 nL L-1) in open-air plots at the field scale, we examined the photosynthetic and biomass response of diverse genotypes of maize, miscanthus, sorghum and switchgrass to elevated O3 in 2018, 2019 and 2020. Elevated O3 concentration reduced net CO2 assimilation in maize and photosynthetic capacity in sorghum and maize, but did not alter leaf photosynthesis in most of genotypes in miscanthus and switchgrass. In addition, elevated O3 had no effect on plant biomass in miscanthus, sorghum and switchgrass. This information could aid in optimal placement of diverse C4 bioenergy feedstocks across a polluted landscape.