中文摘要：

通过大田试验研究了不同浓度的土壤侵蚀磁性示踪剂对大白菜生理特性及产量、品质的影响。结果表明，在4个浓度（1％、3％、5％、10％）的示踪剂处理下，大白菜叶长、叶宽及产量均明显增大；低浓度（3％-5％）的示踪剂提高了大白菜的株高，促进了根的伸长，显著提高了叶绿索含量（P〈0．05），同时对大白菜净光合速率、蒸腾速率也有促进作用。示踪剂处理使叶片中超氧化物歧化酶（SOD）活性显著降低（P〈0．05），而根系中SOD活性则显著升高（P〈0．05）；示踪剂对过氧化物酶（POD）活性的影响与对SOD活性的影响恰好相反，对过氧化氢酶（CAT）活性影响较小，在低浓度条件下，叶片与根系中POD和CAT保持有较高活性；示踪剂还导致叶片中丙二醛（MDA）含量显著提高（P〈0．05）。同时，示踪剂降低了大白菜可溶性糖含量，但不显著。示踪剂浓度大于5％时显著降低维生素c含量（P〈0．05）。低浓度（1％-3％）处理时有效改善了大白菜品质。总之，低浓度的示踪剂用量对大白菜生长有促进作用，高浓度的示踪剂对大白菜生长有抑制作用。

英文摘要：

In order to determine effects of the magnetic tracer for soil erosion on Chinese cabbage,a field experiment was carried out,with the cabbage exposed to the tracers different in concentration （1% ,3% ,5% and 10% ）. Results show that in all the four treatments, leaf length, leaf width, root length and yield of the plant were all increased significantly. In Treatments 3% and 5% , the tracer improved plant height, chlorophyll content （p 〈 0.05 ） , net photosynthetic rate and transpiration rate as well. The tracer inhibited SOD （Superoxide dismutase） activity in leaves of the plant,but stimulated the activity in roots significantly （p 〈 0.05）, however,its effect on POD （peroxidase） in the plant was just the opposite and its effect on CAT （catalase） activity little. In plants exposed to low concentrations of the tracers, POD activity and CAT activity both remained high in leaves and roots. The tracer also caused increase in MDA （malondialdehyde） content significantly （p 〈0.05） in seedling leaves, but decrease in content of soluble sugar, though not significant. When higher than 5 % , the tracer significantly decreased vitamin C in the plant （p 〈 0.05） ,but when lower than 3 % , it improved quality of the plant effectively. In a word, the tracer low in concentration promotes growth of Chinese cabbage,but when high in concentration, it displays an opposite effect on the plant.