| Cucumber fusarium wilt disease caused by Fusarium oxysporum f. sp. cucumerinum is a worldwide destructive soil borne fungal diseases, occurred in all over china. Wilt can cause cucumber yield decreased by 10 % ~ 30 %, severe up to 80 % to 90 %, which is the most serious disease of cucumber, caused one of the biggest economic loss diseases. With the cucumber planting area has expanded each year, resulting in continuous cropping cucumber fusarium wilt disease cause is increasing. Therefore, in-depth study of the effective prevention and cure methods of cucumber fusarium wilt disease has become an important problem to be resolved at present. At present, chemical control is an important method to control cucumber fusarium wilt, but due to the lack of efficient, low toxicity, no pollution of fungicide, easy cause pesticide residues, harm people’s health. Due to cucumber fusarium wilt as soil-borne diseases, drug treatment is difficult to implement a large area of soil and the cost is higher. With the development of modern society, people pay more attention to the strong demand and protection of the environment for pollution-free food, biological control has aroused great attention. Set low price, suppress plant diseases and insect pests significant effect, while increasing crop yields many positive role in improving the quality of one vermicompost entered people’s field of vision. Screening antagonistic to plant disease microorganisms from vermicompost on plant growth, plays the role of plant diseases and insect pests prevention and control.A total number of 374 bacterial strains were isolated from fresh vermicompost by tube dilution assay. The result of plate test showed that twenty-eight strains had antagonistic activity against cucumber fusarium wilt. According to the results of the suppression assay, strain D2 was selected as one of the best effect. The inhibiting diameter was 28.8 mm and the inhibitory effect is stable.D2 single colonies were round or nearly round, flat, medium in size, smooth surface, opaque. Gram stain was negative. Cell function, it does not produce spores. Scanning electron microscope showed straight rod-shaped bacteria,(0.5~1.0) um×(1.5~4.0) um. Do not grow at 4 ℃, 41 ℃ can be grown. D2 growth in Na Cl was less than 5 %, D2 cannot grow in Na Cl was more than 7 %. D2 does not produce fluorescence, it can make the gelatin liquefaction, degradable starch.Identification of molecular biology of D2, obtain the target fragment size was 1462 bp, the PCR products were sequenced, sequence reported in Genbank sequencing and homology comparison, it was proved for the Burkholderia cenocepacia.The optimal fermentation medium components and the best optimal fermentation conditions for strain D2 were studied. The results were as follows: the medium of fermentation for D2 constituted of 1.5 % of yeast extract, 0.3 % of sucrose, 0.3 % of sodium chloride, 0.5 % of ammonium nitrate. The fermentation conditions were: cultural temperature 30 ℃, optimum initial p H 6.0, inoculation seed liquid 2.0 % and loading liquid 40 mL in 100 flasks.Optimizing conditions of cucumber fusarium wilt treatment trial fermentation broth of D2, D2 diluted 50 times, the preventive effect was 70.48 %, diluted 100 times, the preventive effect was 69.89 %, 150 fold dilution, the preventive effect was 69.58 % and carbendazim prevention effect was 78.09 %. The anti effect of D2 diluted 50 times was lower than carbendazim control effect.D2 fermentation liquid on cucumber fusarium wilt disease prevention trials, D2 fermentation broth diluted 50 times, the control effect reached 77.82 %, diluted 100 times, the control effect is 77.56 %, diluted 150 times, the control effect was 76.52 % and carbendazim prevention effect was 70.59 %. The preventive effect of D2 fermentation broth diluted 50 times was 7.23 percentage points higher than carbendazim control effect. |
PDF Full Text Request