Abstract: The dynamics of the generation rate of O₂·, the contents of H₂O₂ , MDA, GSH, AsA and the activities of SOD, POD, CAT, GR, APX in the leaves of virus-free Ziziphus jujuba Mill. ‘Junzao’trees were similiar with those in leaves of common‘Junzao’trees. The generation rate of O₂·, the contents of H₂O₂ , MDA, GSH, AsA and activities of SOD, POD, CAT, GR, APX in the leaves of virus-free‘Junzao’trees were lower than those of common‘Junzao’trees in the early period of growth. The differences became significant with the growth of trees. In the later period of growth, most indexs in the leaves of virus-free
‘Junzao’treeswere higher than those of common‘Junzao’trees except the generation rate of O₂·, the concents of H₂O₂ and MDA. However, the content of AsA in the leaves of virus-free‘Junzao’trees was higher than that of common‘Junzao’trees throughout the growth period, and the difference was significant only in later period of growth. The results showed that there were lower reactive oxygen species (ROS) content and stronger ability to clean out the ROS in virus-free‘Junzao’trees than those in common 'Junzao' tree.

Key words: Ziziphus jujuba, Virus-free, ROS metabolism, Protective enzyme