Abstract: 【Objective】The aim of this study is to investigate the functions of Cu2＋, Zn2＋and Mn2 on cold tolerance of cucumber seedlings. 【Method】The contents of Cu, Zn and Mn and the changes of Superoxide Dismutase(SOD) and its isoenzymes activities and electrolytic leakages of own-root and grafted cucumber seedlings leaves cultivated by different concentrations of Cu2＋, Zn2＋and Mn2＋under low temperature were studied. 【Result】The contents of Cu, Zn and Mn ,the activities of SOD, Mn-SOD and Cu/Zn-SOD of own-root cucumber seedling leaves cultivated by high concentrations of Cu2＋, Zn2＋and Mn2＋ in nutrient solution were higher than the control, while the Fe-SOD activity and electrolytic leakages were lower; When grafted cucumber seedlings were cultivated by low concentrations of Cu2＋, Zn2＋and Mn2＋in nutrient solution, the results were contrary.【Conclusion】The functions of Cu2＋, Zn2＋and Mn2 on cold tolerance of cucumber seedlings were very important. And it was proved that the roots of grafted cucumber seedlings which could absorb more Cu, Zn and Mn after grafted by figleaf gourd was one of the reasons that the grafted cucumber seedlings could have more chilling tolerance than own-root cucumber seedlings. The contents of Cu, Zn and Mn and SOD activity of own-root cucumber seedlings both could be enhanced by increasing the contents of Cu2＋,Zn2＋and Mn2＋in nutrient solution, so that the chilling tolerance also could been enhanced.

Key words: Grafted cucumber, Own-root cucumber, Microelement, Low temperature stress, SOD, Electrolytic leakage