| Muskmelon Fusarium wilt, which is caused by soil-borne pathogen Fusarium oxysporum f.sp melonis that infects the crop in the whole growth periods, is always a disaster for farmers all over the world. Since chlamydospores of this pathogen can survive in the soil for many years, Fusarium wilt is difficult to control in field. Traditional non-chemical practices including crop rotation, seedling grafting and field managements have been recommended as alternatives to chemical control of the soil-borne disease in view of protecting environment from chemical pesticide pollution, but these practices are always labor-, time-and cost-consuming. Application of biological organic fertilizers is considered as a new sustainable practice for control of soil borne diseases. This work was aimed to study the effect of different bio-organic fertilizers (BIOs) on the control of muskmelon Fusarium wilt and microflora in rhizosphere soil of continuous cropped muskmelon.Pot experiments showed that application of BIO could significantly increase muskmelon biomass and decrease incidence of the soil born disease. In the fruiting period, the plant fresh weight and dry weight were increased by139%and287%, respectively under the mixed application of BIO1with BIO2, and the disease controlling efficiency reached to92%. This was because application of the bio-organic fertilizers could supply rich organic matter to soil and improve the nutrient release by changing the SMBC and SMBN in rhizosphere soil. Correlation analysis showed that incidence of muskmelon Fusarium wilt had significantly negative correlation with soil pH, the content of SMBC (P>0.01), and, the content of SMBN.Application of BIOs significantly improved microbial composition in rhizosphere soil of muskmelon. By the traditional microbial counting, application of BIOs significantly increased the numbers of rhizosphere bacteria and actinomycetes and decreased counts of fungi and the plant pathogen as compared with CK. When compared with CK in the3th season of the successive application BIOs, the number of fungi was reduced by88.46%, while the numbers of bacteria and actinomyces were increased by10.5times and9.2times, respectively. Denaturing gradient gel electrophoresis analysis showed that application of BIOs also increased bacterial diversity at the DNA level. The differences in bacterial diversity existed between the different treatments.454high-throughput sequencing showed that BIOs could significantly increase genus OTU numbers of Bacillus, Asticcacaulis, Caulobacter, Clostridium, and Phenylobacterium as well as some ecologically functional microbes. The analysis on the endophytic in melon root showed that application of bio-organic fertilizers increased bacteria in roots by2.42～3.27times, Bacillus subtilis by0.92～23.7times, and fungi by85.9%-95.6%, while pathogen in the roots was decreased by85%～98.3%. Application of bio-organic fertilizer could increase root endophytic quantity, and mixed application of BIO1with BIO2had a strongest effect on microbial structure in rhizosphere and within roots.In conclusion, application of BIOs significantly increased the disease controlling efficiency, promoted the growth and improved microflora in the rhizosphere soil of muskmelon. Improvement of the microflora might be a pathway to control soil-borne disease through application of BIOs. Further study should focus on the action mechanisms of functional microbes in the BIOs treatments. |
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