【摘要】 以盆栽一年生苦楝(Melia azedarach)为试材,4个p H梯度(5.6(CK)、4.5、3.5和2.5)的模拟酸雨每2 d喷洒叶片1次,探讨处理20、40和60 d对叶片叶绿素(Chl)含量、可溶性蛋白含量、细胞膜透性、MDA含量、抗氧化酶活性等的影响。结果表明:随处理时间的延长,可溶性蛋白含量在p H 4.5下呈先升后降趋势,最大增幅为10.3%,p H 3.5和p H 2.5呈降低趋势,最大降幅为42.9%;质膜透性和MDA含量均显著增加,最大增幅分别为84.6%和145.5%;SOD在p H 4.5下呈升高趋势,p H 3.5下先升高后降低,p H 2.5下呈降低趋势,最大增幅和降幅分别为47.9%和20.9%;CAT在p H 4.5下呈先升后降趋势,p H 3.5和p H 2.5下呈降低趋势,最大增幅和降幅分别为23.0%和27.0%;POD在p H 4.5和p H 3.5下呈升高趋势,p H 2.5呈降低趋势,最大增幅和降幅依次47.1%和17.6%;Chla、Chlb和叶绿素总量减少,最大降幅分别为39.0%、37.0%和38.3%。结合叶片的外观形态、脱落率和株高增量发现,p H 3.5下苦楝叶片变黄,脱落率显著增加(P<0.05),p H 2.5下叶片严重变形,株高显著降低(P<0.05),由此认为,苦楝耐酸雨的阈值大约为p H 3.5。更多还原

【Abstract】 A pot experiment was conducted with 1-year-old Melia azedarach as material. Simulated acid rain of four pH levels( 5.6( CK),4.5,3.5 and 2.5) was sprayed on leaves every two days,and the chlorophyll( Chl) content,soluble protein content,cell membrane permeability,MDA content,antioxidant enzyme activity of leaves were investigated after 20,40 and 60 days of treatment. The results showed that with the extension of treatment time,the soluble protein content decreased firstly and increased afterward at pH 4.5 with a greatest increase of 10.3%,while it decreased at pH 3.5 and pH 2.5 with a sharpest drop of 42.9%. The plasma membrane permeability and MDA content significantly increased up to 84.6% and 145.5%,respectively. SOD activity increased at pH 4.5,while it first increased and then decreased at pH 3.5 and decreased at pH 2.5,with a greatest increase of 47.9% and a sharpest drop of 20.9%. CAT activity appeared in a dropping trend after an initial increase at pH 4.5,and it decreased at pH 3.5 and p H 2.5,with a greatest increase of 23.0% and a sharpest drop of 27.0%. POD activity increased at pH 4.5and pH 3.5,and decreased at pH 2.5,with a greatest increase of 47.1% and a sharpest drop of17.6%. Chla,Chlb and Chl decreased with sharpest drops of 39. 0%,37. 0% and 38. 3%,respectively. Combining the findings on leaf shape,abscission rate and plant height increment,it was found that leaves turned yellow and abscission rate increased significantly at pH 3. 5( P<0.05),while leaves deformed severely and plant height decreased significantly at pH 2.5( P<0.05). Thus,the threshold of M. azedarach to resist acid rain is about pH 3.5.更多还原