The Effect Of Alkaline Fertilizer On Suppressing Banana Fusarium Wilt Disease And Its Mechanism Study

The long-term irrational application of chemical fertilizers has caused the acidification of the banana plantation in China.Under the acidic environment,the soil microorganisms under the pressure of natural selection community development,pathogenic fungi that Fusarium oxysporum f.sp.race 4(FOC4)a large number of breeding and growth,resulting in severe banana Fusarium wilt disease.Previous investigations have shown that alkaline fertilizer could suppress banana Fusarium wilt disease by improving soil pH value and banana wilt disease incidence is negatively correlated with soil pH value.For systematically researching the mechanism of alkaline fertilizer suppressing banana wilt disease.The study passed the banana field test,pot experiment and indoor culture test,based on study of alkaline fertilizer reclaiming soil acidity and controlling banana wilt disease,field experiment,pot experiment and indoor culture test were applied to reveal the mechanism of alkaline fertilizer controlling banana wilt disease.In this paper,we looked closely at the effects of alkaline fertilizer on soil pH value,the out break of banana wilt disease,the reproduce of Fusarium oxysporum f.sp.,and the soil microbial community structure in undisturbed soils.We also discussed the relationships among alkaline fertilizers,soil pH,soil potential biological control bacterial flora and soil pathogen and their effects on the incidence of banana wilt disease.The main findings are as follows:(1)The application of alkaline fertilizers had significantly increased the soil pH value.The pH values of the alkaline fertilizer treatment field conditions,the undisturbed soil culture conditions and potted conditions were 0.71,0.42 and 0.64 pH units higher than that of the conventional fertilizer treatment,respectively,and the application of alkaline Fertilizers increased soil nutrient availability.(2)Alkaline fertilizer has effect on suppressing banana Fusarium wilt disease,application of alkaline fertilizers in fields could delayed the onset of banana Fusarium wilt disease by 15 days,and the disease index and incidence rate drop by 69%and 45%respectively.In the pot experiment,the alkaline fertilizer delayed onset for 17 days,and the disease index and incidence decreased by 62%and 40%separately,The incidence of alkaline fertilizer treatment was in line with the common fertilizer treatment(22%)delayed by 40 days.(3)FOC4 can germinate,grow and produce new spores(sporulation)in 9 pH acid base buffers.However,strong acid(pH3,pH4)and strong alkaline(pH10,pH11)conditions can significantly inhibit the sporulation of FOC4.Acidic conditions(pH 4)to neutral conditions(pH 7)are suitable for the germination,growth and sporulation of FOC4,whereas alkaline conditions(above pH 8)are not suitable for its germination,growth and sporulation.The germination rate,colony diameter,and sporulation mean values in pH8and pH9 acid-base buffers were 61%,3.19 cm,and 20.7×10~5cfu/ml,respectively,and the average values for pH5 and pH6 were 16%,3.44 cm,and 8.6×10~5cfu/ml,respectively.It can be seen that basic conditions are the necessary conditions to inhibit the germination,growth,and production of new spores of FOC4.(4)Undisturbed soil culture experiment result indicated that the number of bacteria,actinomyces,Pseudomonas and Bacillus in soil,treatment with alkaline fertilizer increased67%,117%,112%and 89%,as well as bacteria/fungi and actinomyces/fungi increased 55%and 100%,and the number of fungi in soil have no significant difference.In conclusion,the application of alkaline fertilizer in the undisturbed soil can significantly change the soil microbial community structure.(5)Under the conditions of pot culture,the number of soil bacteria,actinomycetes,Pseudomonas and Bacillus,increased by 86%,70%,28%and 52%respectively,while the number of fungi and Fusarium in soil decreased by 30%and 39%respectively,and the ratio of bacteria/fungi,actinomycetes/fungi ratio increased by 1.68 times and 1.45 times respectively,that is,the application of alkaline fertilizer in the potted soil can also significantly change the soil microbial community structure,obviously increase the number of FOC4 antagonistic groups,and reduce the fungi that are beneficial to the occurrence of banana Fusarium wilt disease.(6)Alkaline fertilizers can not only replace normal fertilizers,provide sufficient nutrients for bananas,but also have the functions of treating acid,improving the property of soil and suppressing diseases.