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With rice (Oryza sativa L.) cultivar 3694 Fan as test material, and by using open top chambers, the effects of different ozone (O3) concentration on the leaf soluble protein content, lipid peroxidation, and antioxidant system were applied. Three treatments were applied, i.e., charcoal-filtered air (CF, 20 nl O3 x L(-1)), non-filtered ambient air (NF, 40 nl O3 x L(-1)), and elevated O3 (EO, 75 nl O3 x L(-1)). The results showed that there were no significant differences in the test variables between treatments CF and NF. Compared with CF, EO induced a significant decrease of soluble protein content and significant increases of H2O2 and ASA contents and SOD, CAT and POD activities. In treatment EO, the SOD, CAT and POD activities increased by 93.7%, 39.9% and 312.4%, respectively, as compared with treatment CF, while the APX activity tended to increase at first and decrease then. MDA content had no significant differences among the treatments, indicating that leaf antioxidant system could significantly prevent the lipid peroxidation induced by elevated O3, and rice cultivar 3694 Fan could resist O3 to some extent.

Assessing and predicting the impacts of ozone (O3) concentration on crop production have been drawing great attention in the scientific community. The ambient O3 concentration above the winter wheat field was observed with ML9810B O3 Analyzer in Jiaxing, Zhejiang Province. The impact of O3 on the wheat leaf photosynthesis was measured in open-top chamber. Based on the observed parameters, a numerical model for simulating the impact of O3 on the winter wheat development and yield was established, by added the effects of O3 on ear photosynthesis and leaf area. The results showed that the model properly simulated the impacts of O3 on wheat growth in field. The relative error of predicted biomass was 10.3%. The accumulated loss of photosynthate was 11.4% and yield loss was 17.8% at ambient O3 concentration in the wheat growth period under sufficient moisture and fertilizer supplies.

In order to understand the possibility of AM in protecting crops from O3 pollution, simulated experiment was carried out to investigate effect of increased atmospheric O3 (0.02 microL x L(-1), 0.1 microL x L(-1) and 0.2 microL x L(-1)) on AM and its function. The results indicate that mycorrhizal colonization was slightly affected by elevated atmospheric O3, but spore and hypahe growth were significantly impacted. Spore number at high O3 level increased I times than that at ambient O3; hypahe length of AM at low and high O3 level decreased 48.7% and 85.6% than that at ambient O3, respectively. Root biomass, nodule number, horsebean pod and grain weight (excluding the treatment-- S + M) significantly decreased with elevated atmospheric O3, but they markedly increased after inoculation with AM fungi. Compared with the uninoculated treatment, nodule number increased by 2-5 times and grain weight of horsebean increased by 3-6 times after inoculation with AM fungi. Relative function of AM was slightly impacted by elevated atmospheric O3. Although indigenous microbes competed with inoculated AM fungi, inoculation with AM fungi could decrease the stress of O3 on plant, which was positive significant to alleviate crop loss resulted from O3 pollution.

Effects of elevated O3 on the yields of rice and winter wheat were studied by using open-top chambers (OTCs). Results showed that compared to the control treatment, 200 ppb, 100 ppb, 50 ppb treatments caused a 80.4%, 58.6% and 10.5% decrease in grain yields per winter wheat plant and a 49.1%, 26.1% and 8.2% decrease in grain yield per rice plant, respectively. According to the dose-response relation educed from OTCs experiment and the monitor data of O3 concentrations in spots, it was estimated that the yield losses of rice and winter wheat resulted by O3 pollution in the Yangtze River Delta region in 1999 were 0.599 million ton and 0.669 million ton, economic losses were 0.539 billion RMB Yuan and 0.936 billion RMB Yuan, respectively.

With rice (Oryza sativa L.) cultivar 3694 Fan as test material, and by using open top chambers, the effects of different ozone (O3) concentration on the leaf soluble protein content, lipid peroxidation, and antioxidant system were applied. Three treatments were applied, i.e., charcoal-filtered air (CF, 20 nl O3·L-1), non-filtered ambient air (NF, 40 nl O3·L-1), and elevated O3 (EO, 75 nl O3·L-1). The results showed that there were no significant differences in the test variables between treatments CF and NF. Compared with CF, EO induced a significant decrease of soluble protein content and significant increases of H2O2 and ASA contents and SOD, CAT and POD activities. In treatment EO, the SOD, CAT and POD activities increased by 93.7%, 39.9% and 312.4%, respectively, as compared with treatment CF, while the APX activity tended to increase at first and decrease then. MDA content had no significant differences among the treatments, indicating that leaf antioxidant system could significantly prevent the lipid peroxidation induced by elevated O3, and rice cultivar 3694 Fan could resist O3 to some extent. [ABSTRACT FROM AUTHOR]