Paper Reviewed
Novriyanti, E., Mao, Q., Agathokleous, E., Watanabe, M., Hashidoku, Y. and Koike, T. 2021. Elevated CO2 offsets the alteration of foliar chemicals (n-icosane, geranyl acetate, and elixene) induced by elevated O3 in three taxa of O3-tolerant eucalypts. Journal of Forestry Research 32: 789-803.

Writing as background for their work Novriyanti et al. (2021) state that "high CO2 may offset [negative] O3-induced effects by providing excess carbon to produce secondary metabolites or by inducing stomatal closure." And so it was that this team of researchers set out to investigate if this is indeed the case for three eucalyptus species, Eucalyptus globulus, Eucalyptus grandis and Eucalyptus camaldulensis x Eucalyptus deglupta.

The experiment was performed at the experimental nursery of the Field Science Center of Hokkaido University, Sapporo, Japan. Five-month-old seedlings of each eucalyptus species were grown for four months under one of two ozone concentrations (ambient at less than 10 nmol mol^-1 O3 or elevated at 60 nmol mol^-1 O3 for 7 hours during the daytime) and one of two CO2 concentrations (ambient at 370 ppm or elevated at 600 ppm during daytime hours only).

Gas chromatography of leaf extracts revealed, in the authors' words, "the effect of elevated O3 and the countering effect of high CO2 on compounds in leaf epicuticular wax and essential oils, i.e., n-icosane, geranyl acetate and elixene, compounds known as a first-line defense against [abiotic stress]." And so it was that the negative effects of elevated ozone on leaf physiology observed by Novriyanti et al. were "offset by elevated CO2."