[Objiective] The effects of paclobutrazol on the physiological characteristics in longan seedlings under acid rain stress were studied to provide a scientific basis for improving the resistance of the longan.[Method] With the different concentrations of paclobutrazol treatment,physiological characteristics of longan seedlings under acid rain stress such as MDA content,electrolyte leakage rate,photosynthetic pigment content,antioxidant enzyme activities were determined.[Result] The results showed that paclobutrazol could decrease the accumulation of MDA and elec trolyte leakage rate,and increase the activities of superoxide,peroxidase and catalase,which could alleviative the peroxidation degree of membrane lipid.Paclobutrazol can retard the degradation of chlorophyll and carotenoid,increase the net photosynthetic rate remarkably,and increase the content of soluble protein and sugar in leaves of longan under acid rain stress.[Conclusion] Physiological effects could be relieved by activating antioxidant enzyme activities and reducing oxidative stress in longan seedlings with paclobutrazol under acid rain stress.The proper concentration of paclobutrazol is about 300 mg/L.%[目的]研究酸雨胁迫下多效唑对龙眼幼苗生理特性的影响,为改善龙眼的抗性提供科学依据.[方法]研究不同浓度多效唑(0、100、200、300、400和500 mg/L)对酸雨胁迫下龙眼幼苗叶片丙二醛含量、电解质渗漏率、光合色素含量、抗氧化酶活性等生理特性的影响.[结果]龙眼幼苗喷施一定浓度多效唑能减少酸雨胁迫时丙二醛的积累和电解质渗漏率;多效唑能够激活龙眼幼苗叶片的SOD、POD和CAT活性,减轻膜脂过氧化作用;多效唑减缓龙眼幼苗叶片叶绿素和类胡萝卜素的分解,降低蒸腾速率,提高气孔导度和净光合速率,提高叶片中可溶性糖和蛋白质含量.[结论]多效唑通过激活龙眼叶片抗氧化酶活性,减轻氧化胁迫,缓解酸雨胁迫下的生理效应;300 mg/L多效唑是缓解龙眼幼苗酸雨胁迫的适宜浓度.
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