[Responses of winter wheat seedling growth and allelochemical content to elevated CO2 and O3 concentrations]

By using open-top chamber (OTC), a pot experiment was conducted to study the effects of elevated CO2 (550 microL x L(-1)), O3 (60 microL x L(-1)), and their interaction (CO2 550 microL x L(-1) plus O3 60 microL x L(-1)) on the seedling dry mass and allelochemical DIMBOA content of seven winter spring cultivars. Under elevated CO2, there existed significant differences in the shoot dry mass and DIMBOA content among the test wheat cultivars. As compared with the control (CO2 370 microL x L(-1); O3 40 microL x L(-1)), the shoot and root dry mass of cultivar Bima-1 under elevated CO2 increased by 36.8% and 24.7%, respectively, and the DIMBOA content increased by 5.7%-184.6%. Elevated O3 decreased the seedling dry mass except for Bima-1 and Shan-139, but increased the DIMBOA content of all the cultivars, with an increment of 0.5-3 folds. Under the interaction of elevated CO2 and O3, the root dry mass of all cultivars decreased, and the shoot dry mass, root dry mass, and DIMBOA content of Changwu-134 had the greatest decrement of 8.2%, 27.9%, and 35.5%, respectively. In contrast to the decrease of the DIMBOA content of Changwu-134, Yuanfeng-175 and Lankao-217, the DIMBOA content of Shan-139 increased by 84.6%. The cluster analysis indicated that both the treatments and the cultivars had significant effects on the DIMBOA content, the cultivars Shan-139, Lankao-217, and Changwu-134 under the elevated CO2 or O3 could be grouped together, whereas the DIMBOA content of Shan-139 in all treatments increased. These findings suggested that DIMBOA could be used as a specific indicator for resistance breeding under climate change, especially under elevated O3 and CO2.