| Ophiopogon japonicus is a well-known traditional Chinese medicine which has a long history and has a significant clinical effect.It has been used as a tonic ingredient in medicine for more than 2000 years and its ingredients also be added to some Chinese patent medicine now.The Chinese Pharmacopoeia discusses its efficacy of good for lungs and heart.In recent years,O.japonicus has begun large-scale cultivation in Sichuan and other places,however,due to the frequent occurrence of diseases and insect pests during the planting process,in order to ensure the yield,farmers often apply a variety of pesticides.At the same time,in order to further increase yield,plant growth regulators are also widely used in the cultivation of O.japonicus.Therefore,this study established a multi-residue analysis method for 108 pesticides in O.japonicus and the risk assessment of pesticide intake was studied.On this basis,this study explored the impact of the use of paclobutrazol on the physiological and biochemical and the active ingredients of O.japonicus.The main conclusions of this article are as follows:1.A robust and high-throughput method was established for simultaneous determination of 108 pesticide residues in O.japonicus with a combination of UPLC-MS/MS and the modified Qu ECh ERS method.The optimized extraction method was: after adding 2 m L of Ophiopogon japonicus sample to 10 m L of water,ultrasonic extraction was performed with 0.75%(v/v)acetonitrile acetate for 15 minutes;150 mg Mg SO4 and 25 mg C18 were used as the dispersive-solid phase extraction sorbent.The method validation showed that over 92% pesticides showed good recoveries between 70-120% and all the pesticides with LOQs ranging from 0.01–50 ng/m L in O.japonicus.The intra-day and inter-day precision of this method was 1.08-11.91% and 1.32-16.16%,respectively.At the meantime,this method showed good linearity(r2>0.9901).The multi-residue method of Ophiopogon japonicus pesticide developed by this research showed good accuracy,precision and repeatability,which not only greatly improves the efficiency of pretreatment,but can be detected within 21 minutes.2.The modified method was applied for the analysis of 60 samples and found that 18% of the samples detected more than 5 pesticides.In the detected pesticides,86% were insecticide and fungicide.The detection rate of paclobutrazol was 100%.Since there is no pesticide residue limit standard in O.japonicus,compared with the MRL in agricultural products specified in GB 2763-2019,the residual amount of paclobutrazol in 6% of the samples exceeded the standard.Intake risk assessment of long-term and short-term consumer exposures for pesticides with a detection rate>10% showed that all the pesticides risks can be accepted.Due to its low toxicity,paclobutrazol did not present a risk of long-term intake.Some pesticides like Fenobucarb,although the detection rate is also high,because of the low residual concentration,there was no risk of dietary intake.The result of Cumulative dietary risk assessment was HI<1,which indicated that there was no risk.But it was not the pesticide which had higher detection rate or larger residues,gave the more contribution of the intake risk.On the contrary,some highly toxic pesticides with a small residue like phorate sulfone and carbofuran should be noted,therefore,such high-toxic pesticides should be avoided as much as possible during the planting process.3.It was found that when concentration of paclobutrazol was 0.3 kg/mu-6 kg/mu,with the concentration increased,the inhibitory effect of paclobutrazol on the plant height of O.japonicus and the promotion of root elongation became stronger,which could inhibit growth by 28% and promote root elongation by 67%.However,when the concentration was 12 kg/mu,the inhibition of plant height and the growth promotion effect of tubers were significantly reduced,and the same trend was shown for tuber weight.Paclobutrazol could cause the cell wall become thick and make the cells smaller and tightly arranged.6 kg/mu of paclobutrazol could cause the separation of the cell wall and the loss of organelles.Paclobutrazol has a good effect of inhibiting the growth of bacteria,and its inhibitory effect is inversely related to the concentration.Flavonoids in O.japonicus were mainly distributed in the epidermis of tuber.Considering the residual concentration after application,the growth promotion effect and the effect on saponin and flavonoids,the application of 0.7 kg/mu or 1.5 kg/mu of paclobutrazol could promote the production while increasing the accumulation of saponin and flavonoids and reducing farmers' cost of pesticide application which could make farmers get the most benefit. |
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