| Long-term overuse of chemical fertilizers during China's banana production has caused soil acidification in banana plantation.Then problems such as imbalance of soil nutrient,deterioration of soil microbial community structure and wide spread of banana wilt disease have been caused by the soil acidification.The present study has proposed a viewpoint of “coupling utilization of alkaline fertilizer and biocontrol actinomycete and fungal agents to control Fusarium wilt of banana'' in order to provide a reliable theoretical and practical basis to promot the application of alkaline fertilizers and biocontrol agents controlling banana Fusarium wilt.A pot experiment was conducted in three different types of soil and hydroponics,matrix culture,soil pot tirls and field experiment were also conducted to study the effectiveness and mechanism of the coupling application of alkaline fertilizer and actinomycetes agent and the application of biocontrol fungal agents on the controlling of banana Fusarium wilt disease.The main results were as follows:1.Alkaline fertilizer is a functional fertilizer which can improve soil acidity in addition to supply nutrients such as N,P,K,Mg and the necessary trace element during banana growth and it is able to replace conventional fertilizers in banana cultivation.Compared with conventional fertilizer(CCF,CK),the banana biomass of single application of alkaline fertilizer and combination of alkaline fertilizer with actinomycete agents increased by 25.81%?62.4% in the acid soil with years of banana planting history(A),acid soil with no history of banana planting(B)and slightly alkaline banana orchard soil.Application of alkaline fertilizer also significantly increased soil p H value,the soil p H was 0.44,0.17,0.33 units higher than conventional fertilizer(CCF,CK).2.Compared with CCF(CK),application of alkaline fertilizer combined with biocontrol actinomycetes agents(AF+Act)could significantly decrease the disease incidence and disease index by 14.34% and 20.96%;41.7% and 46.71%;38.95% and 33.21%,respectively in three types of soil.3.Utilization of alkaline fertilizer combined with biocontrol actinomycetes agents would optimize soil microbial structure.Compared with CCF treatment(CK),soil bacteria and actinomyces numbers of AF+Act increased by 36.99%?301.31% and 13.02%?171.05%,respectively,while the fungi and Foc numbers decreased by 42.26%?63.63% and 28.89%?34.85%,respectively.AF+Act treatment significantly increased soil urease,sucrase,phosphatase and dehydrogenase activities.AF+Act treatment also increased soil Nmin,available phosphorus,exchangeable calcium,available iron and effective zinc content.The results also showed that soil p H,bacteria and actinomycetes numbers,urease activity,soil Nmin,available iron,available zinc content were significantly negatively correlated disease index,while the number of Foc was significantly positively correlated with disease index.4.Under hydroponic,substrate culture,soil culture and field conditions,application of compound fungal biocontrol agents(NFP and NFPT)would significantly increase banana biomass or banana yield and reduce disease incidence and disease index.Compared with CK,under hydroponic conditions,the disease index of NFP and NFPT treatment reduced by 57.89%?63.16%;under substrate culture and soil culture conditions,the disease index of NFP and NFPT treatment decreased by 38.24%?58.82% and 43.18%?47.73%,respectively;under field condition,the disease incidence of NFP and NFPT treatment decreased by 48.37% and 18.25% and the disease index decreased by 49.66% and 25.13%,respectively.The total yield of NFP and NFPT treatment increased by 52.35%?139.96.5.Application of compound fungal biocontrol agents(NFP and NFPT)induced systemic resistance in banana which was reflected by the significantly decrease of malondialdehyde content of banana leaves or roots and increase of the soluble protein content,POD activity and CAT activity in banana.Under soil and field conditions,NFP and NFPT treatment significantly increased soil urease,invertase,phosphatase,and catalase activities.The results showed that soil urease,sucrase and catalase activity were significantly negatively correlated with banana disease index.6.Application of compound fungal biocontrol agents(NFP and NFPT)had increased the richness and diversity of bacterial and fungal communities and altered the structure of bacteria and fungal communities.Then the other antagonistic species in indigenous beneficial microorganisms were stimulated.As the result a number of pathogens were significantly reduced and the soil microbial structure and function were reshaped.Therefore,the resistance of bananas to the banana fusarium wilt disease was enhanced.The high-throughput sequencing results of 16 Sr RNA and ITS regions showed that the composition of bacteria and fungi in each treatement was similar.The bacteria had the highest relative abundance of Proteobacteria,followed by Actinobacteria and Chloroflexi.The Ascomycota,Zygomycota,Basidiomycota were the 3 most abundant fungal phyla across all samples rank in order.However,there are differences in the relative abundance of certain genera between treatments.NFP and NFPT treatments improved the relative abundance of Marmoricola,Nocardioides,Devosia,Mizugakiibacter,Nitrospira and Gibellulopsis.While CK had higher relative abundance of Streptomyces,Pedomicrobium,Aspergillus,Calcarisporiella and Chaetomium.The results of q PCR analysis of the pathogen showed that NFP and NFPT treatments significantly reduced the copies of pathogen.The results showed that the relative abundance of some potential biocontrol genera such as Marmoricola,Nocardioides,Mizugakiibacter,Acidobacterium,Gliomastix,Lophiostoma,Acrostalagmus,Stachybotrys and Gibellulopsis was significantly negatively correlated with the disease index of banana wilt. |
PDF Full Text Request