【摘要】 以云南拟单性木兰一年生幼苗在城市污染条件下测定其光合速率及蒸腾速率,同时测定其叶绿素荧光的变化.发现在城市大气污染胁迫下,云南拟单性木兰的光合速率呈现下降趋势,其气孔导度下降最为明显。此外,光合速率及蒸腾速率均随着处理时间的延长而降低。造成光合速率下降的原因可能是二氧化硫等污染所产生的气孔限制因素所致。用NaHSO3溶液拟合大气中SO2的污染,测定云南拟单性木兰的叶绿素荧光变化及细胞膜相对透性的变化,叶绿素荧光的变化出现了类似的变化趋势,而细胞膜相对透性则随处理时间的延长而增高。同时测定胁迫条件下云南拟单性木兰叶绿素变化,叶绿素a、叶绿素b及叶绿素含量都有不同程度的下降,表明大气污染物能够对叶绿素的形成及结构的破坏产生较大的影响。更多还原

【Abstract】 Effects of the air pollution in the urban area on one year Parakmeria yunnanensis seedlings have been studied in the experiment .The results showed that the stomatal behavior has been greatly affected by the pollution stress.The photosynthesis rate and the transpiration rate degraded following the prolong of time under the polluted environment while the internal carbon dioxide concentration increased ,it can be concluded that it is caused mainly by the effects on the stomata. Pollutants such as sulphur dioxide and nitrogen dioxide could greatly reduce the amount of carbon dioxide plants can consume. Sulphur dioxide enters the leaves through tiny apertures called stomata the same way carbon dioxide does and creates a reaction within the leaves that changes the phosphorus and causes the stomata to close. Moreover ,as the competition of carbon dioxide ,the air pollutants retard the diffusion of carbon dioxide in the mesophyll cells ,which directly lead to the decrease of the net photosynthesis rate of the leaves .Variations of the chlorophyll fluorescence parameters indicated that urban air pollutants also have an influence on the PSⅡand cause the decrease of Fv/Fm and Fv/Fo. The experiment in the laboratory has got the similar results with the 0.5mmol/L NaHSO₃ solution treatment. The electrical conductivity increased with the increase of time immersed in the liquid. The total chlorophyll content and the chlorophyll a/b also decreased after immersed in the liquid for some time .It indicated that the air pollutant especially for the sulfur dioxide will do a damage effects on the chlorophyll integrity and its construction . At the same time, the collapse of the cytomembrane cause a large leak of the electrolyte in the cytoplasm. grityand更多还原