Study On Ligusticum Wallichii Relaxation Effect On Rice Injury Caused By Pretilachlor And Its Preparation

Take traditional chinese medicinal Ligusticum wallichii as object of study,several extraction methods were compared on the extraction efficiency of its volatile oil.Then,based on determination of phytotoxicity of rice seeding caused by pretilachlor,relaxation effect of Ligusticum wallichii on pretilachlor caused phytotoxicity was studied.At last,formula screening of Ligusticum wallichii extraction was conducted.Results were showed as follows:There was certain difference on extraction efficiency of different extraction methods.When solvent extraction method was employed,choosing different extraction solvent may affect the extraction efficiency,among which acetone had best extraction efficiency of 5.24%.When Soxhlet extraction method was employed and extraction solvent was petroleum ether,the extraction efficiency reached 5.54%;When supercritical fluid extraction method was employed,the extraction efficiency was 5.62%.Thus,the best method for extraction of Ligusticum wallichii volatile oil was supercritical fluid extraction method,secondly Soxhlet extraction method with petroleum ether as extraction solvent.Phytotoxicity of rice seeding caused by pretilachlor was determined.Inhibition of rice seeding growth enhanced with increase of pretilachlor concentration.When pretilachlor concentration was used at recommended dose,inhibition ratio on root length,plant height and fresh weight of rice seeding(Z17)were 51.95%、61.51%、48.76%,respectively;and inhibition ratio on root length,plant height and fresh weight of rice seeding(Y9)were 52.14%、57.12%、41.12%,respectively.When no safener was applied,root length,plant height and fresh weight of rice seeding(indica type rice Z17)in pretilachlor treatment were only 26.24%、39.95%、40.27% of control,and growth of rice was seriously inhibited.When dose of Ligusticum wallichii extraction were 3-4fold of pretilachlor dose,root length,plant height and fresh weight of rice seeding were recovered to 90.92-96.15%、94.19-94.60%、92.36-93.92% of control,respectively;Relaxation effect of higher or lower Ligusticum wallichii extraction dose was weaker.With no safener application,root length,plant height and fresh weight of rice seeding(japonica rice Y9)in pretilachlor treatment were only 26.24%、39.95%、40.27% of control;While dose of Ligusticum wallichii extraction were 3-4fold of pretilachlor dose,root length,plant height and fresh weight of rice seeding were recovered to 96.04-96.83%、92.40-93.45%、93.42-95.89% of control,respectively.Thus,Ligusticum wallichii extraction with suitable concentration could effectively relax the phytotoxicity caused by pretilachlor.The optimal formulation of 15% Ligusticum wallichii EW was screened out with single-factor attempting method: Ligusticum wallichii extraction 15%,emulsifier 8%,cyclohexanone 15%,glycerol 1.0%,xanthan gum 0.8% and water.The results showed that thermal stability,cold storage stability,freeze-thaw stability and emulsion stability all fulfilled the requirements,and the producing technology was very simple.Indoor bioassay showed that 15% Ligusticum wallichii EW had perfect effect on rice phytotoxicity.When dose of 15% Ligusticum wallichii EW was 2-5fold of pretilachlor,root length of rice seeding was recovered to 77.24%~91.47% of control,plangt height of rice seeding was recovered to 84.14%~90.27%,fresh weight of rice seeding was recovered to 86.43%~91.37% of control.