关键词: 饱和水汽压差, 液流密度, 侧柏, 冠层气孔导度, 光合有效辐射

Abstract: An experiment was conducted to study the characters of epidermis stomata and leaf tissue structure of Ligustrum obtusifolium seedlings exposed to elevated O₃ concentration (160 nmol·mol^-1) for 136 days in open top chamber (OTC). The results showed that elevated O₃ decreased the stomatal length, width, perimeter and area in adaxial leaves of L. obtusifolium by 12.9%, 8.4%, 8.2%, and 15.0%, respectively, while decreased by 16.8%, 9.8%, 13.3%, and 23.6%, respectively in abaxial leaves. The stomatal aperture decreased by 69.2% in adaxial leaves (P <0.05), and decreased by 39.3% in abaxial leaves (P <0.05). The elevated O₃ concentration did not have significant effect on stomatal density (P >0.05). Under elevated O₃, the thickness of palisade tissue and thickness ratio of palisade tissue to spongy tissue in adaxial leaves increased by 10.2% and 28.9%, respectively, and increased by 7.3% and 295% in abaxial leaves, respectively (P <0.01). The thickness of spongy tissue decreased by 15.1% in adaxial leaves, and decreased by 16.8% in abaxial leaves (P<0.01). The thickness of upper and lower epidermis increased by 18.9% and 23.1% in adaxial leaves, respectively, and increased by 11.5% and 16.0% in abaxial leaves (P<0.05). The leaf thickness increased slightly (P>0.05). These results provided new evidence for the research in the effects of elevated O₃ on leaf tissue structure and function of urban plants under the background of global climate change.

Key words: Platycladus orientalis, photosynthetically active radiation, vapor pressure deficit., sap flow density, canopy stomatal conductance