The Research On Rational And Standardized Use Of Two Common Pesticides In Lisusticum Chuanxiong Planting

Chuanxiong crude drug is the rhizoma of Ligusticum chuanxiong Hort., with the function of promoting Qi, activating the circulation of blood, dispelling wind and relieving pain. Nowadays, it is used for the treatment of coronary heart disease, angina and angioneurotic headache etc. In addtion, it is the raw material of health care products, cosmetics, animal feed additives and so on. Chuanxiong crude drug is applied in many aspects. Therefore, its demand is great both at home and abroad.The commodities of Chuanxiong Rhizoma are cultivated, which is a kind of famous-region drugs in SiChuan. Root rot, powdery mildew, grubs and Epinotia leucantha Meyrick are the main diseases and pests in Chuanxiong planting. Local peasants use chemical pesticides to control plant diseases and insect pests. Surveys visits show that thiophanate methyl and chlorpyrifos are the main chemical pesticides.Thiophanate-methyl is a low toxicity fungicide while chlorpyrifos is a moderately toxic organophosphorus pesticides (mites) agent. Both of them are efficient and broad-spectrum. Systematic researches for the effects of different pesticides on the growth and development of Chuanxiong, the dynamic changes of active ingredients, the yield and quality of Chuanxiong rhizoma as well as pesticide dissiparation dynamics and final residue were performed to figure out the issue of dosage, technique and interval of harvest for different pesticides. Main results of the researches were as follows:1This study investigated the effects of different thiophanate-methyl and chlorpyrifos treatments on the growth and development of Chuanxiong for the first time, to provide a theoretical basis for their rational and safe use in the cultivation of Chuanxiong. The high dose-spray treatment resulted in the Chuanxiong leaves SOD activity significantly lower than the usual level. It also led to the MDA content higher than the normal level obviously. The high dose root-zone irrigation treatment caused the Chuanxiong rhizoma SOD activity clearly lower than the normal level. The treatment also could bring about the MDA content higher than the usual level distinctly. Compared with the normal Chuanxiong plant, high dose spray and root-zone irrigation treatment for thiophanate-methyl as well as chlorpyrifos postponed the rapid growth period of agronomic characters. Therefore, the two pesticides high dose treatment went against the growth and development of Chuanxiong. 2The thesis first discussed the influence of different thiophanate-methyl and chlorpyrifos treatments on the dynamic changes of active ingredients in Chuanxiong rhizoma, supplied reference for the determination of reasonable dose and technique. The use of thiophanate-methyl and chlorpyrifos was conductive to the the accumulation of effective constituents. The two pesticides were favorable to the production of high quality Chuanxiong crude drugs.3This paper compared and analyzed the impact of different thiophanate-methyl and chlorpyrifos treatments on the yield and quality of Chuanxiong crude drugs, to lay scientific foundation for how to select the rational applications of two pesticides. Compared with the control (no pesticide), thiophanate-methyl and chlorpyrifos high-dose treatments tended to reduce yield while low-dose treatments were likely to increase yield. The quantity of active ingredients in applying pesticides Chuanxiong rhizoma was higher than the control. Comprehensive analysis indicated that thiophanate-methyl and chlorpyrifos low-dose treatments had good effect on the production of high yield and quality Chuanxiong crude drugs.4The study established HPLC and GC-MS detection methods to detect thiophanate-methyl (containing toxic metabolite carbendazim) and chlorpyrifos residues in Chuanxiong plant and soil for the first time as technical basis for research extending. The detection methods meet the requirement of "Guideline on pesticide residue trials".5This thesis carried out systematic research on thiophanate-methyl and chlorpyrifos dissipation dynamics in Chuanxiong plants and soil. Half-life of two pesticides in Chuanxiong plants and soil was applied to evaluate the use of security. Half-time of thiophanate-methyl (containing toxic metabolite carbendazim) and chlorpyrifos was5.24～12.81d,which were less than30d. The results indicated that two pesticides belong to easily degradable pesticide. In other words, thiophanate-methyl and chlorpyrifos are available to control diseases and insect pests of cultivated Chuanxiong.6This is the first study conducted pre-harvest interval of thiophanate-methyl and chlorpyrifos on Chuanxiong, combined with the maximum residue limit (MRL) to determine its safety interval period. The detection result of thiophanate-methyl (containing toxic metabolite carbendazim) and chlorpyrifos residues in Chuanxiong plants, which were harvested7d,14d and21d before the optimal time for collection, declared that residues of thiophanate-methyl and chlorpyrifos were lower than MRL when they were used21d before the optimal time for collection. It is necessary to make sure the safety of Chuanxiong crude drugs.7Comprehensive analysis of thiophanate-methyl and chlorpyrifos for the effect on Chuanxiong revealed that low-dose spray treatment of70%thiophanate-methyl WP (100g/667m2, added2000ml water) as well as low-dose root-zone irrigation treatment of40%chlorpyrifos EC (100ml/667m2, added2000ml water) ensured the production of " safe, effective,high quality and yield," Chuanxiong rhizoma. Thiophanate-methyl and chlorpyrifos were recommended to use21d before the optimal time for collection.