[Responses of soybean to O3, CO2 and their combination]

With cultivar "Zhonghuang 14" as test crop, this paper studied the effects of CO2 and/or O3 on the growth and development of soybean (Glycine max L.) in an open top chamber. The results showed that an increasing CO2 concentration could defer the leaf's O3 injury, and relax the injury degree. After treated with CO2 for 20 days, the stoma resistance and transpiration rate of soybean leaves had little difference with CK. Only when fumed with high concentration CO2 and O3, the stoma became closed, stoma resistance increased, and transpiration rate decreased obviously. Compared with ambient atmospheric CO2 and O3 (CK), doubled CO2 significantly increased the dry matter accumulation and grain yield, reduced the coarse fat and raw protein contents of grain, but the harvest index had no obvious difference; while doubled 03 decreased the dry matter accumulation, grain yield and harvest index of soybean, reduced the coarse fat content, but increased the raw protein content of grain. The interaction of doubled CO2 and O3 had no obvious effects on the dry matter accumulation, grain yield and harvest index of soybean, but reduced the grain raw protein content to a certain extent and increased the coarse fat content obviously.