Effects of different concentrations of Cu2＋, Zn2＋ and Mn2＋ in nutrient solution on leaf SOD activity of grafted and own-root cucumber seedlings under low temperature stress

صينى. 探讨Cu2＋、Zn2＋和Mn2＋在黄瓜幼苗抗冷中的作用。以自根和嫁接黄瓜幼苗为试材，研究了用含有不同（Cu2＋+Zn2＋+Mn2＋）整体浓度营养液育苗对幼苗叶片Cu、Zn和Mn含量、低温胁迫下超氧化物歧化酶(SOD)及其同工酶活性和电解质渗漏率的影响。提高营养液（Cu2＋+Zn2＋+Mn2＋）整体浓度，自根黄瓜幼苗叶片Cu、Zn和Mn含量显著增加，低温胁迫下其SOD、Mn-SOD及Cu/Zn-SOD活性均显著增强，且低温胁迫时间越长活性增强越显著，Fe-SOD活性和电解质渗漏率则显著降低；降低营养液（Cu2＋+Zn2＋+Mn2＋）整体浓度培育嫁接黄瓜幼苗的结果则与之相反。Cu、Zn和Mn在黄瓜幼苗抗冷性中具有重要作用。以黑籽南瓜为砧木嫁接的黄瓜，根系吸收Cu2＋、Zn2＋和Mn2＋能力较强是其抗冷性增强的内在因素之一；自根黄瓜幼苗叶片Cu、Zn和Mn含量和SOD活性因营养液（Cu2＋+Zn2＋+Mn2＋）整体浓度升高而升高，从而增强其抗冷性。

إنجليزي. The aim of this study was to investigate the functions of Cu2＋, Zn2＋and Mn2＋ on cold tolerance of cucumber seedling leaves. Studies were made on the leaf contents of Cu, Zn and Mn, activities of superoxide dismutase (SOD) and its isoenzymes, and electrolytic leakages of own-root and grafted cucumber seedlings treated by different concentrations of Cu2＋, Zn2＋and Mn2＋as a whole in nutrient solution under low temperature stress. The leaf contents of Cu, Zn and Mn, the activities of SOD, Mn-SOD and Cu/Zn-SOD of own-root cucumber seedlings treated by high concentrations of Cu2＋, Zn2＋and Mn2＋ as a whole in nutrient solution were higher than those of the control, while the Fe-SOD activity and electrolytic leakages were lower. When grafted cucumber seedlings were treated by low concentrations of Cu2＋, Zn2＋and Mn2＋as a whole in nutrient solution, the results were contrary. It showed that Cu2＋, Zn2＋and Mn2+ played a very important role in cold tolerance of cucumber seedlings. It was proved that the greater absorbability of grafted cucumber seedlings after grafted onto figleaf gourd was one of the important reasons why it could have stronger chilling tolerance than own-root cucumber seedlings. Both the contents of Cu, Zn and Mn in leaves and SOD activity of own-root cucumber seedlings can be increased by elevating the contents of Cu2＋, Zn2＋and Mn2＋as a whole in nutrient solution, consequently their chilling tolerance can be enhanced.