| Cucumber wilt are worldwide rhizosphere soil-borne diseases that it caused byFusarium oxysporum f.sp. cucumerinum. It have been brought huge economic lossesattributed to the incidence rate of10～30%in total of the cucumber yield. Chemicalagent prevention will bring the3R questions and environment pollution. The grafting wasable to fundamental in control of fusarium wilt, but complicated technologies wererelatively difficult and poor management system after grafting, the cucumber quality willdecline and lead to difficult to promote after grafting. Fusarium oxysporum attenuatedstrains induced resistance prevention has become a new disease control measures.The study on Fusarium oxysporum f.sp. cucumerinum （Foc） treated with parsleyacetone, ethanol and distilled water extracts from fresh roots, rhizosphere soil and seeds,respectively. The extracts will effect at one generation, continuous several generationsand subculture more generations in medium conditions. We measured the pathogen’scolony diameter and field pathogenicity among different treatment for each generation.The aim is to screening attenuated strains of Foc. Furthermore, in order to figure outattenuate mechanism of parsley different extracts from fresh roots, rhizosphere soil, andseeds onFoc, the pathogen’s fusarium acid content and its enzyme activity ofCWDEs fordifferent treatment each generation were determined. Finally, study on attenuated strainsof Foc induced resistance on cucumber wilt. The key results were as follows:1. Different treatment showed the1stgeneration colony diameter of Foc had thestrongest inhibitive effect, and following inhibition weaken with the increase of thesubculture generations. There are no significantly differences between colony diameter oftreatment and control after treated with50mg·mL-1concentration parsley acetone,ethanol, and distilled water extracts from fresh roots, rhizosphere soil, seeds onegeneration, respectively. Three parsley extracts from fresh roots, rhizosphere soil andseeds had attenuation effect on virulence of Foc, disease index of all of the differenttreatment were first reduce, then increase with the increase subculture generations.Different treatment strain was inoculated to the6thgeneration, the disease index ofparsley acetone, ethanol, and distilled water extracts from fresh roots was27.5,29.2, and28.3, respectively. The disease index of parsley acetone, ethanol, and distilled water extracts from rhizosphere soil was28.3,27.5, and28.3, respectively. The disease index ofparsley acetone, ethanol, and distilled water extracts from seeds was29.2,28.3, and28.3,respectively. The study failed to screened attenuated strains of Foc in treated with threeparsley extracts from fresh roots, rhizosphere soil, and seeds one generation2. Both acetone and ethanol extracts have allelopathy inhibition on subculture1～5generations of Foc colonies, but distilled water extracts had an inhibiting or promotingeffect on1～5generations of Foc colonies after treated with50mg·mL-1concentration ofacetone, ethanol, and distilled water extracts from parsley fresh roots, rhizosphere soiland seeds each generations, respectively. Three parsley extracts from fresh roots,rhizosphere soil and seeds have an attenuation effect on virulence of subculture1～5generations with Foc, disease index of the different treatment showed gradually decreasewith the increase of subculture generations. Different treatment strain was inoculated tothe5thgeneration, the pathogenicity of acetone extracts treatment from parsley fresh rootswas0, the pathogenicity of ethanol extracts treatment from parsley rhizosphere soil andseeds were6.7%,3.3%, respectively. The study have been screened3attenuated strainswith Foc by treated with three extracts from parsley fresh roots, rhizosphere soil, andseeds continuous5generations.3.50mg·mL-1concentration of acetone, ethanol, and distilled water extracts fromparsley fresh roots, rhizosphere soil, seeds one generation processing have an attenuationeffect on fusarium acid content of the1～6generations of Foc. The inhibiting ability ofdifferent extracts treatment to pectinase and cellulose secreted with Foc showed reducegradually with the increase subculture generations. Fusarium acid content and celluloseactivity were secreted by different treatment Foc and its virulence showed highlysignificant positive correlation by treated with extracts from parsley fresh roots,rhizosphere soil, and seeds one generation. The continuous processing with50mg·mL-1concentration of acetone, ethanol, and distilled water extracts from parsley fresh roots,rhizosphere soil, seeds had an attenuation effect on fusarium acid content and CWDEsactivity. They significantly inhibit the secretion of fusarium acid of1～5generation withFoc, reduce the accumulation of pectinase, cellulose and β-glucosidase enzyme activity.There is a highly significant positive correlation between the virulence at differenttreatment with Foc and fusarium acid content, cellulose activity, and β-glucosidaseactivity after treated with parsley extracts from fresh roots, rhizosphere soil, and seedscontinuous5generations.4. Three attenuated strain of FOC-RA-5, FOC-SE-5, and FOC-RSE-5had a goodgenetic stability in virulence. Attenuated strain of FOC-RA-5can significantly stimulated the cucumber against fusarium wilt. It attribute to a low incidence of Foc compared tocontrols. Induced method of root-soaking and radicle-dipping superior to root-irrigation,injection, and foliar spraying, were the best induced method. and relative control effect oftwo methods was still more than50%after challenge inoculation15d. The higher theconcentration of inducer, the more relatively control effect. The best concentration ofinducer was1.0×107个·ml-1treatment. The moderate concentration of challenge disposalhad the best of relative control effect, and the best concentration of challence disposalwas1.0×106个·ml-1treatment. Cucumber plant was induced by attenuated strainFOC-RA-5, the relative control effect was firstly increased and then decreased with theextension of induction period, and the interval period of72h treatment had a maximumrelatively control effect, was the best interval period. In addition, cucumber seedlings cansignificantly improve the induced resistance disease by repeatedly inducing treatment,and3times induced processing account to more than83%during the entire investigation,was considerd as the best induced inoculums frequency. |
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