【摘要】 杉木幼苗用 PEG6 0 0 0渗透胁迫 (- 1.5MPa,- 2 .5MPa) ,在 4 8h内其叶片中 H2 O2 含量和MDA含量明显增加 ,H2 O2 含量从 35.5μmol.g-1分别增加到 4 3.0 μmol.g-1和 4 8.0 μmol.g-1;MDA含量从 170 .5μmol.mg-1分别增加到 349.5μmol.mg-1和 36 5.2 μmol.mg-1,其变化与胁迫强度成正比 ;4 8h后 H2 O2 含量下降 ,但 MDA含量继续增加。与此同时 SOD和 POD活性随胁迫强度加大和胁迫时间的延长而下降 ,在 - 1.5MPa和 - 2 .5MPa下渗透胁迫 72 h,SOD活性从 6 1.8U.mg-1.min-1分别下降到 4 4 .5、39.7U.mg-1.min-1,而 POD活性从 34.8U.mg-1.min-1下降到 6 .2 U.mg-1.min-1。CAT活性在 - 1.5MPa和 - 2 .5MPa胁迫 2 4 h,分别下降了 13.5%和 2 3.8% ,随后升高。表明杉木叶片在渗透胁迫下的膜脂过氧化是由氧自由基引起的。用 Ca Cl2 溶液 (7mmol.L-1)喷布幼苗叶片 ,H2 O2 和 MDA的含量在渗透胁迫下增加的速率明显降低 ,SOD、POD和 CAT活性下降的速率也明显缓慢 ,而且对 CAT活性的回升有促进作用。说明 Ca2 + 处理在渗透胁迫下对杉木叶片的膜系统有一定的保护作用 ,可能有助于提高杉木幼苗的抗旱能力更多还原

【Abstract】 The effects of osmotic stress induced by PEG ( 1.5 MPa,-2.5 MPa) on hydrogen peroxide (H 2O 2) content,membrane lipid peroxidation and activities of superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT) in levies of Chinese fir ( Cunninghamia lanceolata ) were studied. The results showed that malondialdehyde (MDA) content increased and activities of SOD and POD decreased with osmotic stress time (24,48,72 h) and osmotic stress strength (-1.5 MPa,-2.5 MPa),but H 2O 2 content increased for 48 h then fell and CAT activity decreased for 24 h then raised under osmotic stress (-2.5 MPa). When seedlings were sprayed with CaCl 2 (7 mmol·L -1 ) solution,raising rates of contents of H 2O 2 and MDA,and decreasing rates of activities of SOD and POD obviously slowed down,respectively. CAT activity quickly raised after it decreasing under osmotic stress,when seedlings were sprayed with CaCl 2 solution.更多还原