Abstract
Elevated tropospheric ozone concentration (O3) increases oxidative stress in vegetation and threatens the stability of crop production. Current O3 pollution in the United States is estimated to decrease the yields of maize (Zea mays) up to 10%, however, many bioenergy feedstocks including switchgrass (Panicum virgatum) have not been studied for response to O3 stress. Using Free Air Concentration Enrichment (FACE) technology, we investigated the impacts of elevated O3 (~100 nmol mol−1) on leaf photosynthetic traits and capacity, chlorophyll fluorescence, the Ball–Woodrow–Berry (BWB) relationship, respiration, leaf structure, biomass and nutrient composition of switchgrass. Elevated O3 concentration reduced net CO2 assimilation rate (A), stomatal conductance (gs), and maximum CO2 saturated photosynthetic capacity (Vmax), but did not affect other functional and structural traits in switchgrass or the macro- (except potassium) and micronutrient content of leaves. These results suggest that switchgrass exhibits a greater O3 tolerance than maize, and provide important fundamental data for evaluating the yield stability of a bioenergy feedstock crop and for exploring O3 sensitivity among bioenergy feedstocks.
Highlights
Obtaining renewable energy from biomass feedstocks is projected to reduce reliance on traditional fossil fuels and emissions of greenhouse gases while benefitting economic growth and energy security [1,2,3]
There was no significant effect of elevated O3 on leaf area, biomass or tiller number in switchgrass after growing in chronic elevated O3 for two months (Table 2)
It is well known that elevated O3 negatively influences the growth, development, production and yield of C3 plants
Summary
Obtaining renewable energy from biomass feedstocks is projected to reduce reliance on traditional fossil fuels and emissions of greenhouse gases while benefitting economic growth and energy security [1,2,3]. Plants 2019, 8, 85 of environmental variables on switchgrass [10,12,13,14,15], the majority of those focusing on switchgrass breeding and management, biomass improvement and enhancement and conversion efficiency of biomass to biofuels [1,3,7,8,9,10,11,16] Another important consideration is the yield stability of bioenergy feedstocks, which can be altered by atmospheric pollutants. We used switchgrass, a promising bioenergy feedstock crop, to investigate the effects of season-long elevated O3 on leaf photosynthetic gas exchange, respiration, chlorophyll fluorescence, leaf structure, biomass and nutrient composition.
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