78 H. Guo et al.
Fig. 4.3 Changes in the activities of CAT (a), APX (c), POD (e), SOD (g) in the leaves of wheat
at mid-tillering growth stage and changes in the activities of CAT (b), APX (d), POD (f), SOD (h)
in the leaves of wheat at panicle-initiation growth stage. Wheat plants grown in soil with 0, 50, or
400 mg kg−1 Cu, under either ambient CO 2 levels or elevated CO 2 levels ( FACE). Values represent
means ± SD. An asterisk indicates a significant difference between FACE and ambient conditions
( p < 0.05). CAT catalase, APX ascorbate peroxidase, POD peroxidase, SOD superoxide dismutase,
FACE free-air CO 2 enrichment