中文摘要：

以一年生龙眼小苗为材料，研究了La3＋对龙眼叶片活性氧代谢和抗氧化系统的影响，探讨La3＋提高植物抗逆境能力作用机制。龙眼小苗喷施10，20，30，40，50mg·L-1的La（NO3）3两次，通过检测叶片的自由基含量、抗氧化酶活性和抗氧化物质含量来分析La3＋提高龙眼抗氧化的作用。结果表明：20—30mg·L-1 La3＋处理可明显清除龙眼叶片的·O2-和H2O2，减少MDA生成量；显著提高叶片SOD和CAT酶活性，降低POD活性，提高AsA-GSH循环运行效率及相关代谢酶APX，MDAR，DHAR和GR的活性，保证AsA和GSH再生，显示稀土离子La3＋对龙眼抗性具有显著的正调节作用。

英文摘要：

The effects of La3 ＋ on active oxygen metab- olism and antioxygen system of leaf of one year old longan were studied to investigate the mechanism of enhancing tolerance to negative environment of plant treated by La3＋ The longan leaves were treated by 10, 20, 30, 40, 50 mg-L-1 La（NO3）3 for two times, and the contents of free radicals and antioxidant, activities of antioxidase were determined to analyze the role of La3＋ on stress tolerance of longan. The results showed that the treatments of La3＋ ranged from the concentrations of 20 to 30 mg·L-1 scavenged ·O2- and H2O2 markedly, reduced MDA content, signifi- cantly increased activity of SOD and CAT, decreased POD activity, and ensured the regeneration of AsA and GSH by increasing operation efficiency of AsA- GSH cycle and activities of corresponding enzymes of APX, MDAR, DHAR and GR, which suggested the significant influence of rare earth element La3＋ on the resistance of longan.