| Object:Ligusticum chuanxiong Hort., a kind of Chinese medicinal materials, was named as’" blood medicine with Qi" by TCM experts. Ligusticum chuanxiong Hort. with the efficacy of activatingblood, promoting Qi, dispelling wind and relieving pain, is commonly used to treat kinds of pain syndrome caused by stagnation of blood stasis, and gynecological disease,. In recent years, because the content of Cd was out of standard, Ligusticum chuanxiong Hort. were destroyed by customs many times. The problem of high-content of Cd seriously impacts the safety of patients and exports for foreign exchange, and reports about solving this were not be found so far. On the basis of preliminary study, a study of improving cultivation methods and enhancing pH value of acid soil was set to reduce content of Cd of Ligusticum chuanxiong Hort. On the other hand, a comparative study was carried out to compare with the improvement effect of quicklime application by applying Sulphur to reduce soil pH value, and content of active-state Cd in soil and Cd in Ligusticum chuanxiong Hort. were detected. The quality of Ligusticum chuanxiong Hort. which were be improved by quicklime application was detected to determine whether or not meet the standard of Chinese Pharmacopoeia. Then, a tentative exploration was set to explore the growth stage of Ligusticum chuanxiong Hort. with highest Cd-enrichment capacity, in order, finally, tofurther reduce the Cd content of Ligusticum chuanxiong Hort by reduce sources of cadmiumduring the growth stage.Method:On the basis of preliminary study, afield experiment was carried out on a representative acidic soil of the plant base of Ligusticum chuanxiong Hort. in Aoping town of Penzhou, Sichuan province. First, randomized block which applied with different quicklime application rate before planting Ligusticum chuanxiong Hort was designed, and the soil was turned up after applying. Quicklime application rate:750 kg/hm2(P1),1150kg/hm2(P2),1500 kg/hm2(P3) and PCK(blank group). Ligusticum chuanxiong Hort. and soil samples were collected and produced monthly during the growth stage of Ligusticum chuanxiong Hort.,7 times in total. Secondly, content of active-state Cd in soil and Cd in Ligusticum chuanxiong Hort. collected in harvesting time before and after taking measures was detected. The relationship of quicklime application rate, soil pH value and content of active-state Cd in soil and Cd in Ligusticum chuanxiong Hort. was analyzed. Third, water, ash content, extractium and assay of ferulic acid of Ligusticum chuanxiong Hort. was tested following the methods stipulated by Chinese Pharmacopoeia. Forth, the Cd content of soil and Ligusticum chuanxiong Hort. sampled collected monthly during the growth stage was tested to count the enrichment coefficient. Dynamic change of enrichment coefficient and effect of quicklime application on that was analyzed.Results:(1) Cd content of Ligusticum chuanxiong Hort., collected in harvesting time after quicklime application, was 1.96 mg/kg (PCK),1.42 mg/kg (P1),1.48 mg/kg (P2) and 1.06 mg/kg (P3), respectively.A highly significant negative correlation was found between the Cd content in Ligusticum chuanxiong Hort. and quicklime application rate (P=0.008). The percent contents of active-state Cd in soil of tested groups started getting below those of blank group in the third month after quicklime application. The percent contents of active-state Cd in soil showed a regular trend which was decreased firstly and increased subsequently, and the regular trend was distinctly be found in the group with high quicklime application rate. A negative correlation was found between the percent contents of active-state Cd in soil and quicklime application rate. The second month after quicklime application, compared with the blank group, soil pH value increased rapidly in tested groups, high pH value decreased in the 2-4 month, and then tend to stabilize. A positive negative correlation was found between soil pH value and quicklime application rate.(2) In the contrast test, Cd content in Ligusticum chuanxiong Hort was 0.433 mg/kg, 0.740 mg/kg,0.749 mg/kg,0.760 mg/kg and 0.769 mg/kg, and the percent contents of active-state Cd in soil was 24.02%,23.80%,25.01%,26.92% and 27.03%with 0,245, 231 and 2432kg/hm2 Sulphur application rate, respectively. Positive correlation was found between Cd content of in Ligusticum chuanxiong Hort. and Sulphur application rate, and also be found between the percent contents of active-state Cd in soil and Sulphur application rate.(3) After quicklime application, test results of Ligusticum chuanxiong Hort. sample collected in harvesting time were summarized as follows:Water content was 10.2%(PCK),11.3%(P1),11.0%(P2) and 10.7%(P3); Total ash was 3.94%(PCK). 3.85%(P1),3.87%(P2) and 3.85%(P3); Acid-insoluble ash was 0.47%(PCK), 0.52%(Pl),0.49%(P2) and 0.55%(P3); Extraxtum was 28.8%(PCK),32.3%(P1), 31.1%(P2) and 31.7%(P3); Assay of ferulic acid was 0.23%(PCK),0.23%(P1), 0.24%(P2) and 0.28%(P3). All test results met the criteria of Chinese Pharmacopoeia (Version 2010).(4) The highest Cd content of Ligusticum chuanxiong Hort. and enrichment coefficient was found in the first month of growth stage. The root of Ligusticum chuanxiong Hort. was just growing and alive during the first month, therefore, the reason for the high Cd content need to be further studied. The second month after quicklime application, enrichment coefficient started reducing, and a negative correlation was found between enrichment coefficient and quicklime application rate.Conclusion:(1) Quicklime application could reduce the percent contents of active-state Cd in soil by increase the acid soil pH values, and as a result, significantly reduce Cd content in Ligusticum chuanxiong Hort., and a significant negative correlation was found between application rate and Cd content in the application rate range of 750-1500kg/hm2. In field condition, percent contents of active-state Cd in soil could be affected by environmental factors, on the basis of that, the effect of high quicklime application rate on Cd content of Ligusticum chuanxiong Hort., soil pH value and percent contents of active-state Cd in soil was more stabilized and efficacious.(2) The percent contents of active-state Cd in soil could be enhanced by Sulphur application, as a result, Cd content of Ligusticum chuanxiong Hort. was significant enhanced, and the higher Sulphur application rate was, the more significant change was. Cd content of Ligusticum chuanxiong Hort. and percent contents of active-state Cd in soil was sensitive to the change of soil pH value. Ligusticum chuanxiong Hort. was selective about soil conditioner. Sulphur was unfit to improve soil of planting Ligusticum chuanxiong Hort.(3) After quicklime application, soil pH value enhanced to 5.51～5.y2,which was contained within the pH value range of the experiment areas investigated in previous study.All test results about Ligusticum chuanxiong Hort. met the criteria of Chinese Pharmacopoeia (Version 2010).(4) The stage with the highest concentrating capability of cadmium can not be found in growth cycle of Ligusticum chuanxiong Hort. In order to control the cadmium content of Ligusticum chuanxiong, the Cd content and pH value of soil need to be control during whole growth cycle of Ligusticum chuanxiong Hort.; quicklime can effectively reduce the accumulation of cadmium in the Ligusticum chuanxiong Hort., but had no significant effect on the Cd enrichment stage of Ligusticum chuanxiong Hort.. |
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