Effects Of Bio-Organic Fertilizer Application On The Control Of Fusarium Oxyporium Wilt Disease And Rhizosphere Microflora Of Watermelon

Watermelon Fusarium wilt disease, caused by soil-borne pathogen Fusarium oxysporium f.sp. nevium, is one of the most prevalent diseases, which typically occurs in watermelon fields with continuous cropping obstacle. Biological control has become the most important way to control the soil-borne plant diseases. To provide the proper organic carrier and nutrients to the antagonists and subsequently to facilitate the conlonization of soil and plant roots by the antagonists, a new bio-organic fertilizer (BIO) enriched with the antagonists was produced by the secondary fermentation of organic fertilizer (OF).Pot experiments and laboratory analysis were conducted to investigate the effects of nursery application of bio-organic fertilizer (BIO) on the growth and rhizosphere microflora of watermelon. The following results were obtained:The shoot dry-weights of watermelon plants by the application of BIO were2.59and2.15times higher and the root dry-weights of watermelon plants in BIO were2.14and1.56times higher than the OF and the CF, respectively. The length, surface area, total volume, tips and average dia of roots were significantly higher by the application of BIO than OF and the CF. After four continuous cropping seasons, the wilt disease incidence of watermelon plants was significantly decreased by the application of BIO, and the best biocontrol effect of63%was determined with the application of BIO both in nursery and transplanted soil (BB) as compared with the treatment applied with chemical fertilizer both in nursery and transplanted soil (CC). The numbers of bacteria, actinomycetes and Panibacillus polymyxa were increased during four continuous cropping seasons. This decrease emergence in BB treatment was slow, while in the CC treatment this decrease emergence was quick. While the numbers of fungi and Fusarium oxysporum were increased, however, this increase in BB treatment was slower than other treatments. Changes of microbial diversity were observed in watermelon rhizosphere soil in different treatments detected by DGGE methods. There were more bacteria and fewer fungi in BIO treatments than CC. The BB relative abundance of all bacterial was more compared with CC detected by454sequencing methods. The results revealed that the BIO can reduce the Fusarium wilt incidence of watermelon by regulating microflora in the rhizosphere soil.