中文摘要：

活性氧（ROS）与抗氧化系统在古树衰老与延缓过程中起着重要作用。以黄帝陵、嵩阳书院、岱庙的不同树龄侧柏（20～3000a）针叶为试材，对生长季中（8月份）和生长季末（11月份）侧柏针叶ROS（O2^-、H2O2、·OH）含量、MDA摩尔质量分数、抗氧化物酶（SOD、POD、CAT、GR、APX）活性及抗氧化物（AsA、GSH）质量分数的动态变化进行了研究。结果表明：在ROS与MDA积累方面，3个地点的侧柏在生长季中和生长季末针叶ROS、MDA基本上随树龄的增长而呈现出先增加后降低的趋势，但均高于20a侧柏；季末各地侧柏ROS积累均高于季中，但不同地点含量存在一定差异。在ROS清除方面，抗氧化酶（SOD、POD、CAT）与ROS积累存在一定负相关性，20a和3000a侧柏的活性高于其他树龄古侧柏；GR、APX酶活性及抗氧化物AsA与GSH质量分数大部分随树龄的增长而呈现出增加的趋势。结果说明，古侧柏可通过较高水平的ROS清除系统使细胞免受或减轻伤害。

英文摘要：

Reactive Oxygen Species （ROS） and anti-oxidative systems play crucial roles in prompting and delaying senescence of ancient trees. In this study, Contents of ROS （O2^-、H2O2 and·OH） and malonldialdehyde （ MDA）, activities of anti-oxidative enzymes （SOD, POD, CAT, GR and APX） and antioxidants （AsA and GSH） were determined in the leaves of Platyeladus orientalis of different ages collected from Yellow Emperor, Songyang Academy and Dai Temple Both in the middle of growing season and at the end of growing season. Results showed that the accumulation of ROS and MDA in P. orientalis in the three experimental sites had a tendency of first increasing and then decreasing with increasing tree age at the two stages of growing season, whereas the contents of ROS and MDA in the trees over 100 years old were higher than those in the 20-year-old trees. The accumulation of ROS at the end of growing season were all higher than that in the middle of growing season, but there were certain differences in the contents of ROS and MDA at different sites. On the other hand, the activities of anti-oxidative enzymes （SOD, POD and CAT） were negatively correlated with the accumulation of ROS to some extent, and the activities in the 20-year-old and 3 000-year-old trees were higher than other trees of different years old. The activities of GSH and APX and antioxidants （ AsA and GSH） in most trees of different years old increased with increasing tree age. The results suggest that the elimination system of ROS largely produced in the old trees of P. orientalis can protect the cells from being damaged.