| Potted cuttings of four cultivars of four years of Osmanthus fragrans of 'Rixianggui', 'Susheng jingui','Zaoyingui' and'Zaohonggui' with similar growth conditions,canopy diameter about 60cm,base diameter about 1.5cm were treated by dust and fumigated by sulfur dioxide(2.5mg/m3,5mg/m3,7.5mg/m3) and nitrogen dioxide(1.2mg/m3,2.4mg/m3,3.6mg/m3) in a special designed fumigation equipment to compare the anti-pollution capacity of the four cultivars.The damage,injured symptom,sensitivity and time of injured symptom came out were investigated and analysed.The dynamic changes of content of chlorophyll,activities of SOD,POD and CAT,content of MDA and proline which closely related to plant resistance were tested.The relationships of physiological and biochemical response between pollutan concentrations,processing time and plant resistance were analysed.The main results are as the followings.1.The four cultivars of Osmanthus fragrans's leaves had no obvious injury symptom by dust,the physiological resistance indicators were waved at the level of check and had no significant difference.It shown that the four cultivars treated by dust had no significant effect.2.The four cultivars of Osmanthus fragrans's overall injury symptom first to appear in the upper part of the cuttings fumigated by sulfur dioxide and first to appear in the lower part fumigated by nitrogen dioxide.The injury symptom of single leaf had a certain similarity fumigated by SO2 and NO2.Irregular dark brown necrotic spot with clear boundaries between the nerves was the typical injury symptom.But the necrotic spots color of 'Rixianggui' was brown when fumigated by NO2.The four cultivars had a comparatively different sensitivity to SO2 and NO2,the time of injured symptom came out in high concentrations had significant difference.'Zaohonggui' has high resistance;injured symptom came out at 12th day.'Rixianggui' has middling resistance;injured symptom came out at 9th day.'Susheng jingui'and 'Zaoyingui'wre most sensitive,injured symptom came out at 6th day.3.The content of chlorophyll first increasing then decreasing when the four cultivars fumigated by SO2 and 'Rixianggui'and'Sushengjingui' fumigated by NO2.The content of chlorophyll first decreasing then came back when 'Zaohonggui'and'Zaoyingui' fumigated by NO2.When the four cultivars fumigated by SO2 and low concentration of NO2 the chlorophyll a/b ratio all decreased,'Zaohonggui'and 'Rixianggui" fumigated by NO2 the chlorophyll a/b ratio higher than CK,"Sushengjingui' and'Zaoyingui" fumigated by high concentration of NO2 the chlorophyll a/b ratio also higher than CK.4.The four cultivars' SOD and POD activity with the increase in processing time were first increased and then decreased,the decline of SOD and POD activity with different cultivars of the same treat have different time and amplitude.The increase rate amplitude of 'Zaohonggui' to CK was significantly higher than that of 'Sushengjingui' and'Zaoyingui'.CAT activity under the two gases fumigate was fallen,and with the increasing of concentration and time the extension of the decrease in activity increased, decrease amplitude between the cultivars were obviously different,'Zaohonggui' never drop more than 20%,'Zaoyingui'and 'Sushengjingui' decrease more than 50%when fumigated by high concentration,between cultivars had decrease amplitude significant differences,decline was negative correlated with the resistance.5.Fumigated by SO2 and NO2,the four cultivars' MDA content were increased,the MDA content increased slowly in the fist six days.With the extension of fumigation time and concentration,MDA content increased gradually,the degree of membrane lipid peroxidation increases.' The increase MDA content of resistant cultivars were significantly less than the sensitive cultivars.6.The proline content of four cultivars increased,with the increasing of concentration and fumigates time,the accumulation also increased.The proline content of resistant varietiy of 'Zaohonggui' keepd a long increase time and large increase amplitude,and in a small decline beyond the injuries range.In contrast,weak resistant varietiy 'Zaoyingui' increases smaller and the content was decreased at later period.When the content was decreased,the injury symptom appeared.7.Comprehensive evaluation of the resistance of the four cultivars to SO2 and NO2 made by subordination value,The resistance of the four cultivars from strong to weak is as the followings:'Zaohonggui'＞'Rixianggui'＞'Susheng jingui'＞'Zaoyingui'.Correlation analysis result of subordination value and indexes shows that POD activity,MDA content and the Pro content very significantly correlation with comprehensivee assessment(P＜0.01),These three indicators can be used as key determination indicators of resistance of Osmanthus fragrans cultivars.CAT and SOD activity between the comprehensive evaluation of the results,there was a significant correlation(P＜0.05),these three indicators can be measured as four cultivars of Osmanthus fragrans reliable indicator of resistance.8.The resistance order made by comprehensive analysis of observed symptom from four cultivars of Osmanthus fragrans and comprehensive analysis of physiological resistance indexes were exactly the same.It shown that by using high concentrations of polluted gas to fumigate plants and observing their injury symptom and injury symptom appeared time to evaluate their resistance which simple operation,save time and manpower,resulting in accurate and reliable,is a simple and effective method for screening of resistant plants.9.'Zaohonggui' and 'Rixianggui' fumigated by different concentrations of SO2 and NO2 both have shown strong resistance,they can growth normally in severe pollution regions.Even 'Sushengjingui'and'Zaoyingui' fumigated by high concentration pollution gases had not growth as well as medium and low concentrations,but also shown strong resistance,they can growth normally in slight pollution regions.The selected four cultivars of Osmanthus fragrans in this test have very high capacity of anti-air pollution in modern urban environment,they were extremely worthy of promotion and application as excellent trees to make landscape fragrant,green and beauty.
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