Impacts Of Radix Isatidis Of Growth, Quality Under Cadmium, Lead Contamination And Control

Chinese traditional medicinal crops are well- known in the world. Unfortunately, they were contaminated by heavy metal due to production places polluted by heavy metal. Heavy metal absorbing abilities varied with various species of Chinese traditional medicinal crops, which contributes to different the contents of heavy metals in these crops. As a result, the contents of heavy metals were up to "Green Trade Standards of Importing & Exporting Medicinal Plants & Preparations" and cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg) and arsenic (As) were detected in some Chinese traditional medicinal crops.Four treatments were carried out based on studying documents and pot experiment: (1) Effect of Cd and Pb on radix isatidis germination (2) Effect of Cd and Pb on radix isatidis seeding (3) Effect of Cd and Pb on radix isatidis growth (4) Effect of Cd and Pb on radix isatidis growth after adding modifiers into soils.Effect of Cd and Pb on radix isatidis germination shows radix isatidis germination contaminted are restrained by cadmium or lead to some extent. Low cadmium concentration (5mg ?l^-1) hastened germination rate, germination index and germination vigor of radix isatidis which are higher than CK. Further, they tend to decrease with increasing cadmium concentration. In contrast, the corresponding indexes are restrained by lead. Also, root length of radix isatidis are retrained by cadmium and lead. Activity of enzyme with maximal concentration of Cd and Pb are higher than CK.Effect of Cd and Pb on radix isatidis growth shows biomass of radix isatidis is affected by Cd or Pb. Low Cd can promote the growth of radix isatidis and biomass are higher than ck with and inverse relationship to high Cd. Under maximal lead content, radix isatidis biomass greatly reduces to 40%. Contaminated by Cd or Pb, active oxygen free radical sharply increase which reduces the activityof root enzyme metabolism.Contents of heavy metal in leaf are different from those in the root of radix isatidis when they are polluted by Cd or Pb, which shows that Cd and Pb contents in the leaf are higher than in the root of radix isatidis and Pb content in the leaf is lower than in the root of radix isatidis. Contents of heavy metal in the leaf and root of radix isatidis are related to available contents of heavy meals in the soil.Effect of Cd and Pb on radix isatidis growth after using modifier shows the application of modifier can increase biomass of radix isatidis and restrain heavy metal content in the radix isatidis.The application of five kinds of modifiers can promote radix isatidis growth in the soils polluted by Cd. In other word, plant height and biomass of radix isatidis are higher than ck. Their amended effect ranks in the following order: attapulgite > silica fertilizer > Calcium magnesium phosphate > malic acid > citric acid. Among of them, attapulgite is the best, which is higher than ck and biomass is 12.02g more than ck.Different from that of Cd, amended effect of Pb ranks in the order: silica fertilizer > attapulgite > Calcium magnesium phosphate > malic acid > citric acid. Impact of different treatments on the form of Cd or Pb shows that the exchangeable Cd and Pb are decreased and carbonate combined Cd and Pb are increased.At present, there are few researches on effect of heavy metals on Chinese traditional medical crops. Also, the report that amendments is used for the lessen of the effect of heavy metals on Chinese traditional medical crops is seldom seen. The study is conducted based on the principle of the application of amendments in crop and vegetable soils to reduce the impact of heavy metals on them. Therefore, further work is still on the way. For instance, the study on how the using of amendments reduce heavy metal in the soils and how its effect on radix isatidis growth should be done when using different levels of amendments.