| Artemisia annua Linn.Common name Artemisia annua etc.is a family of herbaceous Heron class herbs.A.annua L.is a short daylight plant,resistance to barren,waterlogging,drought and disease resistance.A.annua L.distributed throughout the country,habitat adaptability,mainly in the wilderness,hillside,roadside,river bank.The chemical substances released from A.annua L.are readily degradable in the environment and have low toxicity to humans and animals,providing a scientific basis for the development of bio-herbicides from new natural sources with a view to addressing the environmental pollution caused by the extensive use of chemical herbicides.In order to clarify the role of A.annua L.extract in weed control,in this paper,A.annua L.was extracted and isolation,and herbicidal activity and herbicide mechanism of extracts were determined systematically.Single factor test was used to clear the collection time and sampling sites and extraction method of A.annua L.herbicidal active substances.The activity of ethanol extracts from leaves of A.annua L.on different weeds was systematically studied.Radish seeds as indicator receptor,from the effect of ethanol extract of the leaves of A.annua L.on germination physiology aspect of radish,herbicidal mechanism of the ethanol extract of the leaves of A.annua L.is discussed.Radish seeds as indicator receptor,the ethanol extract of A.annua L.leaves was separated and purification by system solvent separation method and column chromatography.The flow with high rate of herbicidal activity was determined by GC-MS.Main active compounds in A.annua L..The following are the main results of this study:1.The effects of extraction methods,harvesting sites and time on the herbicidal activity of A.annua L.extract were determined by single factor test.The results showed that the optimal extraction conditions of A.annua L.were the leaves of A.annua L.in June with 80% ethanol at the ultrasonic power of 800 w and the ultrasonic time of 30 mins.The ratio of material to liquid was 1:20,30 mins,the filtrate after filtration,the second to the residue by adding 300 mL 80% ethanol stirring for 6h after ultrasonic extraction 30 mins,filter the filter after the filtrate,the third time to add 300 mL 80% ethanol stirring 6h after ultrasonic extraction 30 mins,after filtration filtrate.The inhibitory rates of buds and root length of radish extract were 82.05% and 82.21%,respectively.The ED50 is 0.75mg/mL,the ED90 of radish seed germination was 1.4 mg/mL.2.The effects of ethanol extract of A.annua L.on seed germination of different weeds were studied by using bioassay using redroot pigweed(Amaranthus retroflexus L.),velvetleaf(Abutilon theophrasti Medic.),green bristlegrass(Setaria viridis(L.)Beauv.)and barnyardgrass(Echinochloa crusgalli(L.)Beauv.)as the recipient plants.There are different degrees of inhibition to the germination on redroot pigweed,velvetleaf,green bristlegrass and barnyardgrass.The order of the leaf ethanol extract of Artemisia annua L.inhibiting germination of weed seeds at the concentration of 5.0mg/mL: redroot pigweed>velvetleaf>green bristlegrass>barnyardgrass,germination inhibition rate on redroot pigweed,velvetleaf,green bristlegrass and barnyardgrass was 90.09%,85.79%,85.46% and 14.23% respectively.3.The results showed that: the effects of ethanol extract of A.annua L.at 5kg/hm2 on different weeds were studied by using laboratory bioassay,using redroot pigweed,velvetleaf,green bristlegrass and barnyardgrass as the recipient plants.Artemisia leaves ethanol extract on the soil treatment of weed soil activity from strong to weak order : redroot pigweed>velvetleaf>green bristlegrass>barnyardgrass.The plant activity of redroot pigweed,velvetleaf,green bristlegrass and barnyardgrass was 47.50%,43.94%,25.86% and 22.97% respectively,and the fresh weight activity was 49.59%,26.50%,21.05% and 20.50%.4.The effects of ethanol extract of A.annua L.on seed germination of different crops were studied The results showed that the ethanol extract of A.annua L.did not inhibit the germination of soybean,maize,wheat and mung bean.Ethanol extract of A.annua L.at 5.0 mg/mL had a slight inhibitory effect on the germination of red bean,inhibition rate was 9.26%,and had a severe inhibitory effect on the germination of sorghum germination,the inhibition rate was 86.36%.5.The herbicidal mechanism of ethanol extracts from leaves of A.annua L.was studied in terms of the effect of ethanol extracts from leaves of A.annua L.on the germination physiology of radish.The water absorption of radish seeds decreased significantly after ethanol extract treatment at 1.0 mg/mL,2.0 mg/mL and 3.0 mg/mL,and the water absorption was decreased with the increase of the concentration of the extract.The content of soluble sugar,soluble protein and starch content in radish seed decreased.The ethanol extract of A.annua L.could inhibit the germination of radish seeds by affecting the germination physiology of radish.6.By system solvent separation,the inhibition rate of petroleum ether at 0.2mg/ml on seed germination was the highest,was 90.91%,higher than ethyl acetate and n-butanol phase,germination inhibition rate was 50.22% and 19.18% respectively.The extraction of ethanol from leaves of A.annua L.was carried out by column chromatography with petroleum ether,ethyl acetate and n-butanol as eluent,a total of 33 streams were obtained.The biological activity was used to track the strain with the strongest herbicidal activity.The results showed that inhibition rate of Sample No.6 at 0.01mg/mL on the germination,bud length,root length and SE was 60.23%,65.78%,71.67% and 65.90% respectively.7.The ethanol extracts of A.annua L.were identified by GC-MS as: plant alcohol,dihydrochemicol lactone,diethyl phthalate,long leaf aldehyde,artemisinin,(Z,Z)-9,12-octadecadienoic acid,cyclododecane,linolenol,octadecanoic acid,eicosanoic acid,heptadecanoic acid,1-chlorododecane,1-chloroundeca Alkanes and other organic compounds such as terpenes,esters,alkanes,organic acids and the like. |
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