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A Long Term Affect Of Low SO2(0.857mg/m3) Concentration On The Photosynthetic Energy Transition In Vernicia F

Posted on:2003-03-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:F Y LiaoFull Text:PDF
GTID:1100360062486108Subject:Silviculture
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Vernicia fordii (Oil Tung)is a timber and oil tree with high economic value .occurs originally only in China. It is very sensitive to SOz. There were many reports about severe damage of oil Tung tree plantation by SOz pollution , which lowered down the income of farmers in the mountain area in southern China. Therefore, it is very important to know the mechanism of SOz affecting on oil Tung. SOz pollution is a worldwide environment problem, and has been studied over 100 years. The most studies were focused on the influence of SOz on photosynthetic organ e.g. chloroplast in vitro and fumigating with high concentrations of SOz. Thus, those experiments could not reflect the real state of plant suffering from SOz pollution in nature condition and it was very difficult to find out the mechanism of SOz affecting photosynthesis. In most situations, the research conclusion resulted from disturbed chloroplasts. On the other hand, the studies on photosynthesis mechanism were mainly focused on carbon assimilation, little on photosynthetic energy transition and its mechanism. And the such studies on tress were even lesser. . Thus, it is not only important to find out the effect of SOz on the photosynthetic energy metabolism for photosynthetic theory, but also important for improving the farmer' s income from the Oil Tung growing in the mountain.. The affect of a long -term low concentration SOz, which was 0.8571mg/m3, on the photosynthetic energy transition in Oil Tung was investigated by means of chlorophyll fluorescent technique and leaf 820nm absorbance changing technique and top-open chambers.The results showed that SOz fumigation depressed the growth of oil Tung, diminished the leaves area, shortened the length of leaves and shortened the distance between nearby leaves stipe. After SOz treated for 102 days, the leaf areas of one, two and three years old seedlings were only 67.87 percent, 48.99 percent, 52.84 percent of those of control respectively.The leaf biomasses decreased obviously after SOz fumigation for 102 days, the dry biomasses per cm2of one, two and three years old seedlings were only 84. 35percent, 78.04percent, 79.94percent of those of control respectively. And the fresh biomasses per cm2 were 85.02percent, 76.OOpercent, 74.90 percent of that of control respectively.SOz fumigation shifted the maximal absorbance peak of chlorophyll a from 677. 7 nm to 672. 1 nm and the maximal fluorescence peak of chlorophyll b from 667. 2nm to 669. 7nm. The absorbance peak of chlorophyll b at 665nm vanished by SOz fumigation.The fluorescence peak of carotid at 671. 2nm was enhanced, but the fluorescence peak of carotid at 731. 5nm almost vanished. After SOa treated for 100 days, the contents of total chlorophyll, carotid of one, two and three years old seedlings were 73.31 percent, 72.84 percent , 68.04 percent of those of control respectively .And the contents of carotid (Car) of SQj treated plants s 1. 0725, 1. 3898,0.6232 times those of the control respectively. But the value of Carotid /total chlorophyll (TChl) increased with the fumigation tine prolonging. The value of carotid/total chlorophyll of treatment 1.4031,1.9080,1.0971 times that of the control respectively.S02 decreased the produce of apparent photosynthetic electron transport (ETR), over photochemical quantum yield (Yield), non-photochemical quenching (q? and photochemical quenching (qP). The figures of variable fluorescence (Ft), ETR, Yield were decreased when measured in the air containing 2% of Oxygen. While qP increased in such a condition..S02 fumigation decreased the efficiency of energy transition. Photosynthetic energy transition efficiency, potential activity and electron transition efficiency of PSII were depressed by SOz fumigation. After treated for 100 days, F0/TChl of PSII of one, two and three years old seedlings were 1.6359,1.2938,1.8250 tines of the control respectively, which showed that the energy did not engage in photochemical reaction increased. F.(maximal fluorescence)/TChl of PSII of one, two and three years ol...
Keywords/Search Tags:Sulfur dioxide:energy, Photosystem II(PSII), Photosystem I(PSI), Chlorophyll fluorescence
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