76 H. Guo et al.
At panicle-initiation growth stage, the activity of CAT in leaves of wheat grown
on FACE plots with 50 mg kg−1 Cu was 24.8 % higher than that in leaves of wheat
grown on ambient plots, while that was 35.3 % lower in 400 mg kg−1 Cu treatment
group (Fig. 4.3b). No significant changes in the activity of APX in the leaves of
wheat at mid-tillering and panicle-initiation growth stages were observed (Fig. 4.3c,
d). The activity of POD in leaves of wheat grown on FACE plots with 400 mg kg−1
Cu added was lower than that in leaves of wheat grown on ambient plots at mid-
tillering growth stage, as well as panicle-initiation growth stage (Fig. 4.3e, f). In all
Cu treatment groups, the activities of SOD in leaves of wheat grown on FACE plots
were lower than that in leaves of wheat grown on ambient plots (Fig. 4.3g, h). The
changes in the activities of enzymes in the leaves of wheat at mid-tillering and pan-
icle-initiation growth stages in response to Cd treatment are shown in Fig. 4.4. At
mid-tillering growth stage, the activity of CAT in leaves of wheat grown on FACE
plots with added Cd was higher than that in leaves of wheat grown on ambient plots.
Fig. 4.1 Changes in the activities of CAT (a), APX (b), POD (c), SOD (d) in the leaves of rice at
mid-tillering growth stage. Rice 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 cata-
lase, APX ascorbate peroxidase, POD peroxidase, SOD superoxide dismutase, FACE free-air CO 2
enrichment