Elevated [CO2] has been shown to protect
growth of wheat against moderately elevated [O3].
To investigate the role of ozone exclusion and detoxification in this
protection, spring wheat (Triticum aestivum
L. cv. Wembley) was grown from seed, in controlled-environment chambers,
under reciprocal combinations of
[CO2] at 350 or 700 μmol mol−1
and [O3] peaking at <5 or 60 nmol mol−1,
respectively. Cumulative ozone dose
to the mesophyll and antioxidant status were determined throughout flag
leaf development. Catalase activity
correlated with rates of photorespiration and declined in response to elevated
[CO2] and/or [O3]. Superoxide
dismutase activity was not significantly affected by either condition.
ascorbate nor glutathione content was
enhanced by elevated [CO2]. In wheat, at moderately
elevated [O3], our results show that stomatal exclusion
a major role in the protective effect of elevated [CO2]
against O3 damage.