[Effects of high concentration ozone on soybean growth and grain yield]

By using open top chambers (OTCs), soybean plants were grown in pots, and exposed to charcoal-filtered air ([O3] < 10 microg x kg(-1)) and elevated O3 (80 microg x kg(-1)) after anthesis, aimed to investigate the responses of soybean' s agronomic characters, leaf area, chlorophyll content, antioxidant system, and grain yield to elevated O3. Under elevated O3, the leaf area and chlorophyll content decreased significantly (P < 0.05), and the leaf catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activities had a significant increase (P < 0.01) first but a gradual decrease then, compared with those under charcoal-filtered air. Elevated O3 decreased the leaf soluble protein and ascorbate content (AsA) contents while increased the leaf malonaldehyde (MDA) content (P < 0.05), suggesting that the leaf membrane lipid peroxidation was accelerated. The dry mass per plant, effective pod number, grain number, 100-grains weight, and grain yield under elevated O3 had somewhat decreased, among which, grain yield decreased significantly, with the decrement reached to 47% (P < 0.01).