[Effects of increased O 3 concentration on growth, subcellular structure and reactive oxygen metabolism of turf-type Festuca arundinace].

Taking ambient environmental O3 (40 nmol·mol-1 ) as control, the study was conducted to assess the impact of elevated O3 (80 and 160 nmol·mol-1 ) on the growth, subcellular structure and reactive oxygen metabolism of turf-type Festuca arundinace in open top-chambers (OTCs). The results showed that under 14-day fumigation, the height and leaf width of F. arundinace decreased significantly, and the total biomass decreased by 43.7%, and some fully expanded leaves yellowed under 80 nmol·mol-1 O3 . Some visible injury symptoms, brown spots and necrosis appeared in the leaves, the total biomass decreased by 46.2%, and plasma membrane became loose from the cell wall and convoluted, chloroplast and mitochondria were damaged under 160 nmol·mol-1 O3 . The rate of superoxide anion (O2 -· ) production, hydrogen peroxide (H2 O2 ) content, malonaldehyde (MDA) content and the activities of antioxidant enzymes were higher under the increasing O3 concentrations (80 and 160 nmol·mol-1 ) compared with control. Total phenolics and the antioxidant capacity increased at first and then decreased with the rise of O3 concentration. It indicated that O3 has already affected F. arundinace growth and antioxidative metabolism before visible injury symptom appeared. F. arundinace had an adaptive response to elevated O3 , but it could not protect itself from excessive O3 or long-term O3 exposure.