| Banana is one of the important fruits in the world and food crops in developing countries,which has important economic value and edible value.In the past 20 years,with the widespread planting of bananas,Banana Fusarium wilt has become the biggest factor in restricting the development of the banana industry.Banana Fusarium wilt is a kind of soil falciparum disease in the vascular bundle caused by Fusarium oxysporum f.sp.cunbense(FOC).At present,there is no cost-effective method for preventing and controlling Banana Fusarium wilt.Disease suppressive soil refers to a type of soil that has an inhibitory effect on soil-borne crop diseases.Its principle is to inhibit the growth of soil-borne pathogens through a special and stable microbial community structure in the soil.Disease suppressing soil has the advantages of good inhibition effect,strong durability,environmental protection and no pollution.Therefore,exploring the construction of disease suppressing soil is an effective way to prevent and control Banana Fusarium wilt.In this study,rapeseed cake fertilizer was prepared by decomposing and fermenting rapeseed cake as the raw material,and rapeseed cake fertilizer was used as experimental fertilizer.Banana Fusarium wilt soil was used as test soil,the susceptible variety “Baxi Banana”and the resistant variety “ Nan Tian Huang ” is a test variety for pot experiment of rapeseed cake fertilizer to prevent and control banana wilt.Fluorescent quantitative PCR technology and Illumina Miseq high-throughput sequencing technology were used to compare and analyze microorganisms in potted soil with good prevention and control effects and potted soil bwith serious disease to find out the differences in the types of microorganisms between disease suppressive soil and diseased soil,which can reveal the microbiological principles of disease suppressing soils.In order to provide a research basis for the future construction of Banana Fusarium wilt disease suppressing soils.This study obtained the following results:(1)It was clarified that the isolated Bacillus subtilis and Bacillus amyloliquefaciens could be used in the fermentation of rapeseed cake;In the plate bacteriostatic experiment of rapeseed cake fertilizer,it was found that the main substances that inhibited the microorganisms in the rapeseed cake fertilizer.By analyzing the microorganisms in rapeseed cake fertilizer,the results showed that the rapeseed cake fertilizer contained more bacteria and rich species,while the fungus content was less and the species was single.(2)In order to show the control effect intuitively,this study used fluorescence quantitative PCR technology to detect the number of FOC4 spores in the soil.In order to make the inspection more standardized and accurate,the standard linear fragments were quantified by DNA concentration,frozen and dried to prepare standard products,which had the advantages of strong stability,easy storage for a long time and avoiding experimental errors.The standard curve meets the basic requirements of fluorescence quantitative experiments.Therefore,the standard can be used for soil FOC4 spore count detection.(3)In this study,two pot experiments were carried out.The results showed that the application of rapeseed cake fertilizer as base fertilizer and top dressing,combined with planting the disease resistant variety “Nan Tian Huang”,has a good control effect on Banana Fusarium wilt.The first pot experiment was a pre-test without repeating.The planting variety was “Nan Tian Huang”,and the incidence rate was only 8.33% after 60 days of planting;the second was a regular random block arrangement pot experiment,the results showed that “Nan Tian Huang” cooperated the control effect of applying rapeseed cake fertilizer was better than that of the susceptible variety “Baxi Banana”;The analysis of the soil in the “Nan Tian Huang” experimental group found that after 4 months of treatment,the incidence of wilt in the CN treatment group applying rapeseed cake fertilizer was 63.33% lower than YN control group.By detecting the amount of FOC4 in the potting soil,it was found that the number of FOC4 spores in the CN treatment group was decreased by 2 orders of magnitude compared with the YN control group,and the physical and chemical properties of the soil in the CN treatment group were superior to the YN control group.Therefore,the application of rapeseed cake fertilizer made the soil in the CN treatment group disease inhibiting effect,while the soil in the YN control group had no disease inhibiting effect.(4)The microbial metagenome sequencing analysis of potting soil and diseased soil with good prevention and control results showed that in terms of bacteria,the relative abundance and diversity of soil bacterial communities with good disease prevention effects were greater than those of diseased soils.At genus level,the relative abundances of Acinetobacter,Aquabacterium,Thermonas,Rhodanobacter,Pseudomonas and Ottowia in the good control effect soil were significantly higher than those in diseased soil,while those of Acinetobacter,Bryobacter and Acidipila were higher than those in diseased soil.In terms of fungi,the relative abundance of diseased soil fungi was higher than that of good control effect soil,but the community diversity of diseased soil fungi was lower than that of good control effect soil.In the top 10 species with the highest abundance at the genus level,fungi that could not be classified accounted for the majority,while Trichoderma and Fusarium that could be classified accounted for the majority in diseased soil,while Trichosporon and Xeromyces accounted for the majority in good control effect soil.In addition,other bacteria in the diseased soil should be more than the soil with good disease prevention effect.In conclusion,the application of rapeseed cake fertilizer as base fertilizer and after manuring changed the soil physical and chemical properties,soil environment and soil microbial population structure,which was beneficial to inhibit the formation of Banana Fusarium wilt disease microbial flora in the soil,as to effectively delay and reduce the occurrence of Banana Fusarium wilt,so that the original diseased soil was transformed into disease suppressive soil. |
