Screening And Iditification Of Herbicidal Activities From 15 Plant Agricultural By-products

Agricultural by-products are non-primary products produced during the production or processing of agricultural products.In this research,agricultural product by-product powders of rice bran,soybean meal,rice straw,rape cake,sesame cake,peanut cake powder,corn stover,cottonseed hull,rice husk,longan shell,banana peel,orange peel,grapefruit peel,potato dregs,and distiller's grains were selected to study.Then screening out the by-products of higher herbicidal activity and identificating of herbicidal compounds,determinating of herbicidal activity and physicochemical mechanisms.The main research results obtained in this study are as follows:Extracting 15 agricultural product by-product powders such as rice bran,soybean meal,rice straw,canola cake,sesame cake,peanut cake powder,corn stover,cottonseed hull,rice husk,longan shell,banana peel,orange peel,grapefruit peel,potato dregs,distiller's grains with anhydrous ethanol.The herbicidal activity of these ethanol extracts was tested by seed germination method using Echinochloa crusgalli(L.)Beauv.,Euphorbia lathyris,Lindernia procumbens(Krock.)Philcox and Cyperus difformis as test materials.The results show that the inhibition rates of ethanol extraction from cottonseed hull,rapeseed cake and grapefruit peel to Echinochloa crusgalli(L.)Beauv roots were 87.07%,70.82% and 66.52%,respectively,the inhibition rates of Echinochloa crusgalli(L.)Beauv.buds were 76.54%,69.27%,and 67.87%,respectively.And the inhibition rate of ethanol seed extract of cottonseed hull on the roots and shoots of Lindernia procumbens(Krock.)Philcox was 75.05% and 50.33%,respectively.The cottonseed hull,rapeseed cake and grapefruit peel ethanol extract had significant differences in the inhibition of Echinochloa crusgalli(L.)Beauv roots,Echinochloa crusgalli(L.)Beauv buds and Lindernia procumbens(Krock.)Philcox roots and shoots.The inhibition experiments on the roots and shoots of the four weeds of other agricultural product by-product ethanol extracts were not significantly different from the blank controls.The solvent of four different polarities of absolute ethanol,n-butanol,petroleum etherand ethyl acetate was selected,and the cottonseed hull powder was extracted by Soxhlet extraction.The extracts were treated with 5 concentrations of 1,2,4,8,and 16 g/L.And the stem and leaf spray method was used to apply the uniform at the three-leaf stage of Echinochloa crusgalli(L.)Beauv.Bioassay of herbicidal activity of four different polar solvent extracts of absolute ethanol,n-butanol,petroleum ether and ethyl acetate has been done,to further judge its herbicidal potential.The results showed that the absolute ethanol extract,n-butanol extract,ethyl acetate extract and petroleum ether extract have an IC50 of3.38,6.66,39.3 and 19.7 g/L,respectively to Echinochloa crusgalli(L.)Beauv.and It indicated that the ethanol extract of cottonseed hull had the highest herbicidal activity.The anhydrous ethanol extract was diluted with acetone,and the chemical composition analysis was carried out by gas chromatography-mass spectrometer(Gas Chromatography-Mass Spectrometer),Mass spectra of nine compounds were obtained,and were searched by NIST05,NIST05 s and WILLEY 73 mass spectrometry databases,combined with artificial spectrum analysis,literature collation and compared with standards.Then the extract was found to mainly contain glycerin,tricyclohexyl-3-ene-6-octanone,4-vinyl-2-methoxyphenol,(o-methylphenol)-2-bromo-2chloro-acetyl ester,tetradecanoic acid,ethyl myristate,palmitic acid,isoamyl octanoate and linoleic acid.Each compound standard was dissolved in acetone,added to Tween-80,and diluted with water to a concentration of 0.5,1,2,4,and 8 mg/L.(The volume fraction of acetone after dilution is not higher than 2%,and the volume fraction of Tween-80 is 0.8%)Taking Echinochloa crusgalli(L.)Beauv.as the test object,the stem and leaf spray method was used,and the uniform application was carried out in the three-leaf stage of Echinochloa crusgalli(L.)Beauv.The results showed that four compounds of linoleic acid,isoamyl octanoate,4-vinyl-2-methoxyphenol and(o-methylphenol)-2-bromo-2-chloro-acetyl ester have certain herbicidal activity,in which linoleic acid is the most active,its IC50 value is 14.5 mg / L.