4种幼树对二氧化硫胁迫的抗性生理响应

利用密闭环境控制室熏气处理,研究了不同浓度（自然状态和0.5、1.5、3.0 mg·L^-1）SO₂对盆栽巨桉、天竺桂、西蒙得木和茶树幼树叶片渗透调节物质含量、抗氧化系统保护酶活性和丙二醛含量的影响,并就各树种对SO₂的抗性进行综合评价。结果显示:（1）SO₂对4个树种叶片伤害程度表现为天竺桂<西蒙得木<巨桉<茶树。（2）SO₂胁迫显著增加了巨桉和西蒙得木叶片可溶性蛋白（SP）、可溶性糖（SS）和游离脯氨酸（Pro）3种渗透调节物质含量;SO₂胁迫对天竺桂叶片SP和SS含量无显著影响,且对Pro含量的促进作用也是在处理30 d后才体现出来;SO₂胁迫对茶树叶片SP含量无显著影响,使SS含量显著降低,而使Pro含量显著增加。（3）SO₂胁迫总体使巨桉和天竺桂抗氧化系统保护酶——超氧化物酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性和丙二醛（MDA）含量增加,但西蒙得木各指标表现不同,而使茶树抗氧化系统保护酶活性和丙二醛含量则全面下降。（4）巨桉、天竺桂、西蒙得木、茶树的最大净吸收S量依次为1.17、1.32、2.04、0.95 g·kg^-1。（5）通过隶属函数法综合7个生理指标得到的SO₂抗性综合排序为天竺桂>西蒙得木>巨桉>茶树,与叶片伤害程度表现一致。研究表明,植物抗氧化保护酶系统在4个树种抵抗SO₂胁迫调节机制中具有重要作用,其中天竺桂超高的基础POD活性可能是其抵抗SO₂伤害的关键机制之一。

Resistant Physiological Responses of Four Species Young Trees to Sulfur Dioxide Stress

Resistance physiological indexes such as soluble proteins(SP),soluble sugars(SS),free proline(Pro),superoxide dismutase (SOD),peroxidase (POD),catalase (CAT) and malondialdehyde (MDA) of four species of samplings:Eucalyptus grandis (Eg),Cinnamomum pedunculatum (Cp),Simmondisa chinensis (Sc) and Camellia sinensis (Cs) were measured after fumigation of different levels of SO₂ in sealed environmental control chambers.Four levels of SO₂ treatments:control (natural concentration),M1 (0.5 mg·L^-1),M2 (1.5 mg·L^-1),and M3 (3.0 mg·L^-1) were set in the present study.The results showed that:(1)The order of the extent of injury of SO₂ on leaves is:Cp2 treatment significantly increased the concentrations of SP,SS,and Pro in leaves of Eg and Sc.There was no significant effect of SO₂ stress on SP and SS of Cp.The stimulated effect of SO₂ stress on Pro of Cp appeared only on 30 d of treatment.The responses of SS (no obvious effect),SP (significant depress effect),and Pro (significant stimulate effect) of Cs to SO₂ stress were different.(3)On the whole,SO₂ stress significantly increased the activities of antioxidant system enzymes (SOD,POD and CAT),and the content of MDA in leaves of Eg and Cp.There were different responses of SOD,POD,CAT and MDA to SO₂ stress of Sc.However,under SO₂ stress,the activities of antioxidant system enzyme activities and MDA content were overall declined significantly.(4)The maximum absorption of S element of Eg,Cp,Sc and Cs were 1.17,1.32,2.04,0.95 g·kg^-1,respectively.(5)The order of the comprehensive resistance calculated based on membership function was Cp>Sc>Eg>Cs,which was consistent with the results of injury of leaves.This study suggests that the antioxidant system enzymes play a important role in resistance of SO₂ stress for the four species of young trees and the extremely high level of basic POD activity in Cp may be one of the key mechanisms of resistance of SO₂ stress.