Effect Of Induced Resistance Of Banana Roots To Fusarium Wilt Disease By Compound Microbial Agents In Hydroponic Culture

Banana wilt disease is an important soil-borne destructive disease,in order to study the induction resistance ability of compound antagonistic microbial agent on banana wilt disease.For avoid not easy to observe the root on soil and other undesirable factors,this experiment uses advanced hydroponic system for intuitive and clear observe root growth,and explore the change of banana root vitality and defensive enzyme activity,and other biological signal changes,so as to promote crop growth,improve the banana resistance to wilt disease.Inoculated the banana wilt pathogen(Fusarium oxysporium f.sp.cubense race 4)with 1×106 cfu/mL concentration after culturing banana in hydroponic system 5 days.The root was observed and measuring the root vitality,enzyme activity,etc.on 0th,3rd,5th,9th and 14th days.The experimental research results are as follows:(1)Establishing the method of inducing banana root resistance to wilt disease by antagonistic microbial under hydroponic conditions.In hydroponic conditions,the Brazilian banana(Susceptible varieties),Nantian Huang(resistant varieties)roots were inoculated fermentation liquid of HW05 with spore concentration of 1×107 cfu/mL,and the compound microbial fertilizer L41(5 billion/g spore of Bacillus amyloliquefaciens,Bacillus subtilis,Trichoderma viride)which was diluted 600 times.(2)Using TTC method to determine the vitality of root system,it was found that the root vitality of the banana inoculated with compound microbial fertilizer L41 and the fermentation broth of HW05 were significantly higher than that of the control treatment.The experimental results indicating that the Biocontrol microbial could induce bananas to against the pathogens.First inoculation compound microbial fertilizer L41 and fermentation liquid of HW05 and after inoculation pathogen 5 days,the root vitality of Brazilian banana(Susceptible varieties)reached the highest level,and was 3.2 and 2.4 times of the control treatment,respectively.The disease index of banana has increased with time.The disease index of Brazilian banana reached 5.1,and 5 level.The disease prevention effect of compound microbial fertilizer L41 and HW05 fermentation liquid were 55%and 65.7%,respectively.It is shown that the compound microbial fertilizer L41 and HW05 could help banana to resist the pathogen of banana wilt disease and prevention disease.(3)Root performance of the treated plants after Foc 4 colonization on banana roots.The root length statistical analysis of Nantian yellow and Brazilian banana of three treatments were process after inoculation pathogens 0 days,3 days,5 days,7 days,14 days.The results showed that the root length of the differently treatments plant was obviously different,the root system of the treated plant with compound microbial fertilizer L41 or HW05 was strong and the side root was more,and the root system of the treated plant with water showed that the root system was weak and short.When first inoculation compound microbial fertilizer L41 and fermentation liquid of HW05 and after inoculation pathogen 5 days,the root length Nantian yellow(disease-resistant varieties)which inoculation complex microbial fertilizer L41 and fermentation liquid of HW05 were 1.4 times and 2.1 times than the control treatment,respectively.The result indicating that the compound microbial fertilizer L41 and HW05 have PGPR effect,and them could starting the defense mechanism and promote the growth of the root system at the same time.(4)In order to verify the defensive effect of PGPR,the phenylalanine deaminase PAL,oxidase POD and catalase CAT of each treatment plant root system were detected after pathogen colonization on root system.The results showed that the content of POD,CAT,PAL of treatment plant was significantly higher than control plant.The enzyme activity of Brazilian banana(diseased species)reached the peak after inoculation pathogen 5 days,and PAL activity of treatment plant with microbial fertilizer L41 and fermentation liquid of HW05 were 3.1 times and 2.9 times than the control treatment,respectively.POD,CAT,PAL are related to the defense mechanism,and the result indicating that the plant under the threat of disease invasion,the compound microbial fertilizer L41 and fermentation liquid of HW05 could induce plants to produce a large number of enzymes which related to the defense mechanism to prevent banana wilt disease.