| Fusarium disease is a typical, worldwide rhizosphere soil-borne disease which is widely distributed, heavy damaged and controlled difficultly. With the increase of years of continuous cropping, the disease incidence increased significantly, which threaten and impeded seriously the production of cucumber. Using allelopathy to prevent soil-borne diseases is a new ideas and new methods in today's plant protection.we obtained extract solution of parsley seeds by using distilled water, ethanol, acetone as the extraction solvent respectively. Study on the allelopathic effect by growth rate method. and further research the allelopathy mechanism on Fusarium oxysporium f.sp.cucumerinum, and preliminary allelochemicals separation with the strongest allelopathic extracts of parsley seeds, which provided scientic and theoretical foundation for preventing fusarium disease by usingallelopathy .The main results were as follows:1. The parsley seeds extraction with three kinds of solvents (distilled water, ethanol,acetone) had allelopathic effect on Fusarium Oxysporium f. sp. Cucumerinum; and the higher the concentration, the stronger the effect of allelopathy. Allelopathic effect showed the strongest inhibition was 50 mg·ml -1 in the concentration range tested of three parsley seed extractions respectively. After 144 h treatment of 50 mg·ml-1, allelopathic effects of different extractions are different, the extraction from distilled water is 31.07%, ethanol extraction effect is 49.6% and acetone is 57.5%. Allelopathic effect of distilled water extract solution was weaker than the others.2. The mycelium of Fusarium oxysporium f.sp.cucumerinum was thinner and less forked after treated with three parsley seeds extraction (distilled water, ethanol and acetone).The spore formation and spore germination were allelopathic inhibited differently after treated, the inhibition rates of spore formation were 40.32% , 62.26%, 60.42%, and the inhibition rates of spore germination were 13.85%, 27.28%, 28.08%. Through the electron microscopy observed,the structure of membranes of Fusarium oxysporiumf.sp.cucumeris. spores was destructed by three parsley seeds extraction treated, the intracellular structural was disorded and the contents extravasated.After the extract treatment, the activity of the three cell wall-degrading enzymes (pectinase, cellulase,β-glucosidase) secreted by Fusarium was lower than the control. And compared with the control, the contens of the toxins (Fusarium acid) produced by Fusarium were decreased 20.02%, 31.50% and 34.18%.The cell membrane penetrability of Fusarium oxysporium f.sp.cucumerinum was influenced obviously by the extracts of parsley seeds. Compared with the control, its relative electrical conductivity of the plasma membrane increased by 5.54% ,15.57%, 18.90%, and MDA content increased respectively by 7.95%, 26.36%, 35.62%. Soluble protein content decreased 26.62%, 25.27%, 27.45%.compared with the control. Three intracellular protective enzymes (SOD, POD, CAT) activity decreased compared with the control.3. The cucumber seedlings were treated (twice time) by three kinds of the extracts of parsley seeds at the stage of 5cm width of the first true leaf, in order to investigated the physiological mechanism for resistance of Cucumber Fusarium Wilt.Than the material content and enzymic activity about resistance in the cucumber leaf at different times were determined. The results showed that the content of MDA, conductivity were lower than that of the control. The content of MDA in each sampling period were lower than the control from 8.65% to 23.89%, 0.68% to 13.89%, 7.50% to 21.69% treated respectively with distilled water extracts, ethanol extracts and acetone extracts. Conductivity was lower than the control from 0.62% to 9.47%, 0.40% to 11.35%,1.86% to 19.80% dealed with distilled water extracts, ethanol extracts and acetone extracts.The content of soluble sugar, soluble protein were higher than that of the control .The content of soluble sugar were higher than that of the control from 12.21% to 41.50% irrigated with distilled water extracts; 6.28% to 62.25% dealed with ethanol extracts; 23.43% to 54.38% irrigated with acetone extracts; The content of soluble protein were higher than that of control from 0.08% to 25.87% irrigated with distilled water extracts; 0.93% to 23.08% irrigated with ethanol extracts; 2.20 % to 37.67 % irrigated with acetone extracts.The content of superoxide anion and hydrogen peroxide were higher than that of the control at early days and lower at late stage. The content of O2-. were higher than that of the control from -12.50% to 38.52% irrigated with distilled water extracts. -24.41% 6.28% to 109.46% deal with ethanol extracts; -9.65% to 166.10% irrigated with acetone extracts. The content of H2O2 were higher than the control from - 36.38% to 16.26% irrigated with distilled water extracts; -36.38% to 16.26% irrigated with ethanol extracts; -34.27% to 41.36% irrigated with acetone extracts. Activities of protective enzymes in cucumber leaves (POD, SOD, CAT) which dealed with extraction were higher than that of control. Peroxidase activity changes from -1.65% to 32.19% in distilled treatment, from -6.62% to 23.84% in ethanol treatment, and from 1.46% to 34.09 at acetone treatment. Superoxide dismutase activity were higher than that of control, the range from and 9.81% to 47.41% in Distilled water treatment, from 7.23% to 44.31% in the treatment of ethanol, in acetone treatment, from 19.90% to 54.72%. Catalase activity amplitude range from 13.57% to 25.55% treated by distillation, from -12.68% to 59.43% treated by ethanol, from2.07 % to 78.38% treated by acetone.Amplitude of each index are as follows: treated with acetone were larger than treated with ethanol, and treated with ethanol were higher than treated with distilled water.4. The parsley seed extracts was separated by column chromatography, and eight fractions was obtained, the stronger allelopathic inhibition on Fusarium oxysporium f.sp.cucumerinum of fractions was as follows: fraction 3 and fraction 7 of distilled water extracts, which allelopathic effects were 25.29% and 26.84%, fraction 4 and fraction 5 of ethanol extracts, which allelopathic effects were 88.90% and 82.03%, fraction 4 and fraction 5 of acetone extracts, which allelopathic effects were 95.98% and 81.73%.
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