Absorption And Physiological Response Of Three Vertical Greening Plant Species To Pollutants

Vertical greening plant is an important part of the urban landscape and plant landscape. The most widely used plants---- Parthenocissus tricuspidata, Jasminum mesnyi, Rosa multiflora were chosed as the subjects. The effect of air pollution on monthly dynamic changes of sulfur contents, total nitrogen and physio-biochemical indices of P. tricuspidata and J. mesnyi in natural state were investigated, and discussions on seasonal variation of leaf sulfur content, heavy metals (zinc, copper, lead, cadmium, chromium) were carried out with three kinds of potted plants in different locations. The absorption capacity, physio-biochemical responses of three plant species were also studied under different stress concentrations of SO2 and NO2. Here are the conclusions below:(1) Sulfur content in leaves under natural conditions was as follows:J. mesnyi>young leaves of P. tricuspidata>mature leaves of P. tricuspidata. The sulfur content in different locations showed a dynamic month change of decrease then increase. The measurement results of different locations showed that industrial and traffic areas were higher than relatively clean areas. The sulfur content of 3 vertical greening plant species under potted conditions was in order of J. mesnyi>P. tricuspidata>R. multiflora. Seasonal changes of sulfur content were consistent with results of natural condition. Sulfur contents of P. tricuspidata and J. mesnyi in different places were closely consistent with air pollution index. Average purification ability of three plant species to SO2 under SO2 stress was as follows:R. multiflora>J. mesnyi>P. tricuspidata. This three vertical plant species can absorb SO2 in atmosphere at a certain extent.(2) The average total nitrogen contents of J. mesnyi, young and mature leaves of P. tricuspidata had no significant difference under natural condition, with similar dynamic monthly change which rised firstly and then declined and rised again in different locations. Under NO2 stress, the absorption of nitrogen was first increased and then decreased with the increase of NO2 concentration. They were species with strong ability of purifying NO2, with average purification rates of more than 60%.(3) The order of content of five heavy mental elements in leaves of three plant species was:Zn>Cu>Pb>Cr>Cd. The absorption and purification abilities of three plants varied by the type of heavy metals. Seasonal changes of Zn and Cr content of three plant species were approximately consistent, with the trend of a decrease-increase-decrease. The Cu content of P. tricuspidata present a downward trend. The Cu accumulation of J. mesnyi and R. multiflora got a up-down trend. There was no significant difference in the Pb and Cd content of P. tricuspidata among the months, but R. multiflora and J. mesny showed a considerable increase in June and then decrease slowly.(4) In natural state, comparisoned to young and mature leaves of P. tricuspidata, the content of total chlorophyll, soluble sugar, soluble protein, ascorbic acid, superoxide dismutase and catalase of J. mesnyi were significantly higher, while free amino acid was on the contrary. MDA of J. mesnyi was considerablely lower than mature leaves of P. tricuspidata. Transport hub areas and industrial areas were inferior to the relatively clean areas in terms of total chlorophyll and soluble protein, but superior to the relatively clean areas in soluble sugar, free amino acid and ascorbic acid. MDA, superoxide dismutase and catalase of young and mature leaves of P. tricuspidata in transport hub areas and industrial areas were higher than that in relatively clean areas. While there were no significant difference in those three indices of J. mesnyi in different sampling locations.From April to September, the dynamic changes of physio-biochemistry indices of P. tricuspidata and J. mesnyi varied according to plant species and different indices.(5) With the increase of SO2 or NO2 stress, the total chlorophyll, soluble sugar, soluble protein, peroxidase, proline of three vertical plant species got up then down trend. But with the increasing concentration of SO2 stress, ascorbic acid, free amino acid, catalase decreased and then increased. Superoxide dismutase present a descending trend and MDA had a down-up-down trend. With the increasing concentration of NO2 stress, superoxide dismutase and catalase declined first and then rised. MDA and free amino acid showed an ascending trend. Soluble protein got down-up-slowly down trend.(6) Using principal component analysis method to analyse the resistance of three vertical plant species. The order of plant resistance under air pollution was:J. mesnyi>mature leaves of P. tricuspidata>young leaves of P. tricuspidata. The resistance to SO2 or to NO2 was all as follows:J. mesnyi>R. multiflora>P. tricuspidata.