Rich-chromium pumpkin and common pumpkin were used to study the changes of antioxidant enzyme activity, chlorophyll content and soluble protein content under the stress of Cr6+ through nutrient solution culture. The subcellular distribution of chromium was studied too. The results showed that with the increase of Cr6+ concentration, the activities of superoxide dismutase (SOD) varied little, but peroxidase (POD) varied obviously. The chlorophyll content and soluble protein content increased first but then decreased. In contrast, the activity of actalase (CAT) decreased steadily. These changes differed between rich-chromium pumpkin and common pumpkin. Chromium accumulated mainly in cell wall and in soluble fraction. The distribution ratio of chromium in cell organs was higher in common pumpkin than in rich-chromium pumpkin.

In order to discuss whether Cr would be absorbed by Pumpkin leaf and be transported to other parts of the plant,the isotope(()~(51)Cr) feeding and pot-cultivation experiment was performed.The result showed that()~(51)Cr could be absorbed and transported through leaves.Pumpkin absorbed and transported more()~(51)Cr during the fruit stage than the seedling stage.10 days after the application of()~(51)Cr,the activity of()~(51)Cr were counted.It is found that during the seedling stage the activities in the unlabelled leaves were the highest,while during fruit stage those in stems were the highest.In addition,the specific activities in the roots were higher than that in other parts of pumpkin during flowering and seedling stage.The specific activities of different parts of leaves and stems were relevant with the distance of tagged leaves.The distribution ratio of()~(51)Cr in pumpkin fruits reached 9%,which indicated that Cr could be absorbed through leaves and transported to pumpkin fruit.

采用51Cr同位素标记法检测富铬南瓜品种‘永安2号’在不同发育时期对51Cr的吸收和分配的结果表明:苗期(8片叶),南瓜地上各部分51Cr放射性强度的相对比例分别为:叶64.4%,茎30.2%,花5.4%,主要分布在距根部较近的叶片和茎中,幼叶中含量很低;幼果期分别为:果肉51.1%,叶片41.6%,茎4.8%,花2.4%,主要分布在果肉和中部叶片中。