Effects of elevated O3 concentration on winter wheat and rice yields in the Yangtze River Delta, China

The effects of a continuing rise of ambient ozone on crop yield will seriously threaten food security in China. In the Yangtze River Delta, a rapidly developing and seriously air polluted region in China, innovative open-top chambers have been established to fumigate winter wheat and rice in situ with elevated O3. Five years of study have shown that the yields of wheat and rice decreased with increasing O3 concentration. There were significant relationships between the relative yield and AOT40 (accumulated hourly O3 concentration over 40 ppb) for both winter wheat and rice. Winter wheat was more sensitive to O3 than rice. O3-induced yield declines were attributed primarily to 1000-grain weight and harvest index for winter wheat, and attributed primarily to grain number per panicle and harvest index for rice. Control of ambient O3 pollution and breeding of O3 tolerant crops are urgent to guarantee food security in China.

► The wheat and rice response to ozone had been investigated for five years in China.
► There were significant relationships between relative crop yields and AOT40 dose.
► O3-induced wheat yield loss was primarily due to 1000-grain weight and harvest index.
► O3-induced rice yield loss was primarily due to grains per panicle and harvest index.
► Wheat and rice in this study are more sensitive to O3 than previous investigations.