Elevated Ozone Concentration Reduces Photosynthetic Carbon Gain but Does Not Alter Leaf Structural Traits, Nutrient Composition or Biomass in Switchgrass
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.
Origin : Publisher files allowed on an open archive
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