Effects Of Sulfur Dioxide Stress On The Physiological And Biochemical Indexes Of Fifteen Ornamental Tree Species

Sulfur dioxide is one of the primary pollutant in urban environments, it usually leads to the afforestation plant changes in morphology, structure and physiological metabolism. Two-year-old cutted branches of fifteen ornamental tree species were fumigated by sulfur dioxide at different concentrations level and with different treatments time. The purpose is to test the dynamic changes of chlorophyll(Chl) a, b, t contents, pH of the cellular juice, plasma membrane permeability(PMP) and malondialdhyde(MDA), proline(Pro), soluble sugar(SS), soluble protein(SP) contents in the leaves, and to evaluate the main resistive indexes of tree varieties comprehensively by mathematical methods such as correlation analysis, cluster analysis and principal component analysis. Then systematic discussed each tree specie, reaction to sulfur dioxide and further explored the injury mechanisms of sulfur dioxide. The main results are as follows:1. Physiological and biochemical indexes of 15 kinds of common cultural ornamental tree leaves which fumigated with different SO2 concentrations were determined in this experiment. The results showed that: the physiological and biochemical indexes in leaves of most species all showed a regulated change. Chlorophyll content of most species had a significant descend at first day, and then ascended along with the prolongation of stress time and the increase of the SO2 concentration; the Chla/b and Pro content also went up and down; PMP, SS, SP and MDA content were increased in general, but the cellular juice pH was reduced. It revealed that most species had the same physiological response, while a small number of species may has its unique physical conditioning under SO2 stress.2. By studying the correlation regression analysis between chlorophyll content and each other index, the results showed that: physiological and biochemical indices of most species had a low correlation with chlorophyll content, Although the changes of physiological and biochemical indices of most species had certain laws, the range was inconsistency, and the changes of each index were not shown correspondence. After SO2 treatment, it was Amygdalus davidiana which was positive with chlorophyll content and Pro, SS, and Berberis thunbergii'Atropurpurea'with chlorophyll and MDA, and Koelreuteria paniculata which had significant positive with SS.3. By comprehensive evaluation the physiological and biochemical indices of different tree species with principal component analysis, the results showed that There were many factors that had effects on the SO2 resistant mechanism, so it should be had a comprehensive evaluation based on the changes of resistant indices. Different tree species had different adaptability, and the magistral physiological factors were also not the same. So it should be comprehensively considered the changes of each physiological and biochemical index, and found out the evaluation index of magistral factors.The Chl content and relative water content of Amygdalus triloba, Forsythia suspensa, Paeonia suffruticosa, Euonymus phellomanus had the highest score under SO2 stress, and the chla/b, PMP of Acer truncatum, the MDA content of Syringa oblata, Buxus microphylla, the celluar juice pH and nucleic acid of Koelreuteria paniculata, the SP content of Platanus orientalis, Fraxinus pennsylvanica var. lanceolata and the SS content score of Amygdalus davidiana, Sorbaria kirilowii also had the highest score.4. Principal component analysis was used to comprehensive evaluation of the resistance of twelve ornamental tree species under SO2 stress. The sulfur dioxide resistance of the twelve tree species from strong to weak is as the followings: Amygdalus trilobaï¹¥Koelreuteria paniculataï¹¥Forsythia suspensaï¹¥Syringa oblataï¹¥Paeonia suffruticosaï¹¥Acer truncatumï¹¥Platanus orientalisï¹¥Euonymus phellomanusï¹¥Sorbaria kirilowiiï¹¥Amygdalus davidianaï¹¥Fraxinus pennsylvanica var. lanceolataï¹¥Buxus microphylla.5. Twelve species was classified by cluster analysis, the results showed that Amygdalus triloba, Sorbaria kirilowii, Amygdalus davidiana, Forsythia suspensa, Syringa oblata, Platanus orientalis, Euonymus phellomanus and Buxus microphylla were the same category; Paeonia suffruticosa, Fraxinus pennsylvanica var. lanceolata and Acer truncatum were a category and Koelreuteria paniculata was another. Every similar species had a certain common characteristics, while there was also a phenomenon that many indices had a larger change. This showed that each species had a large difference on one index, so it was unilateral to sort the SO2 resistant of each tree species only according to one single index, it must be considered more factors to make the results more accurate.