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 O-3. Five years of study have shown that the yields of wheat and rice decreased with increasing O-3 concentration. There were significant relationships between the relative yield and AOT40 (accumulated hourly O-3 concentration over 40 ppb) for both winter wheat and rice. Winter wheat was more sensitive to O-3 than rice. O-3-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 O-3 pollution and breeding of O-3 tolerant crops are urgent to guarantee food security in China. (C) 2012 Elsevier Ltd. All rights reserved.