Abstract: Based on a Free-Air Ozone Concentration Enrichment facility, we studied the responses of bacterial communities in the rhizosphere of four wheat cultivars-Yangmai 15, Yangmai 16, Yangfumai 2, Yannong 19 (Y15, Y16, Y2, Y19) to elevated O₃ at jointing and ripening stages. Denaturing gradient gel electrophoresis (DGGE) and realtime quantitative PCR were conducted to reveal community structure and abundance of rhizosphere soil bacteria. The results showed that the elevation of O₃ concentration significantly reduced the rhizosphere bacterial abundance of cultivar Y2 at the jointing stage, but had no significant effects on the rhizosphere bacterial abundance of four wheat cultivars at the ripening stage. Diversity index and principal component analyses indicated that the rhizosphere bacterial diversities and community structures of wheat cultivars Y15 and Y2 were obviously changed respectively at the jointing and ripening stages under the treatment of elevated O₃ compared with the control. The results suggested that elevated O₃ might have a longer effect on the rhizosphere bacterial community of wheat cultivar Y2 than on the other wheat cultivars, which would cause a cumulative effect.

Key words: wheat, environmental temperature, seed vigor, seed development