生物质炭载体联合有益菌防控番茄土传青枯病的效果研究

Effects of Probiotics with Biochar as Carrier Inhibiting Tomato Soil-borne Bacterial Wilt

土传青枯病是由青枯菌(Ralstonia solanacearum)引起的一种细菌性病害。根际有益细菌在青枯病的防控中发挥着重要作用,其在根际有效定殖是发挥生防作用的前提。以玉米秸秆、木块(松木)和稻壳为原料制成的3种生物质炭为有益菌Bacillus amyloliquefaciens T-5的载体,探究生物质炭对有益菌防控番茄土传青枯病效果的影响,并利用室内模拟试验探究生物质炭对青枯菌的吸附、固持以及对根系分泌物的吸附作用,旨在阐述施用生物质炭提升有益菌T-5抑制病原青枯菌能力的可能机制。温室试验结果表明:单独施用3种生物质炭均显著降低青枯病的发病率和根际青枯菌的数量,其中具有高比表面积的木块生物质炭的防控效率达到60.56%。3种生物质炭作为有益菌T-5的载体均能够显著提升有益菌T-5的根际定殖数量及其防病效率,其中木块生物质炭的提升效果最好。与仅接种青枯菌的对照相比,木块生物质炭与有益菌T-5组合处理的根际青枯菌数量降幅达97.42%;与单独有益菌T-5处理相比,有益菌T-5以木块生物质炭为载体使其根际定殖数量提高了5.71倍。进一步研究发现,木块生物质炭能够有效吸附青枯菌,吸附量接近90.00%,且能够有效固持吸附的青枯菌,青枯菌的逃离降低了96.66%。此外,生物质炭不仅可以有效吸附根系分泌物,且有益菌T-5能够有效利用这些根系分泌物并抑制青枯菌的生长。生物质炭作为生防有益菌的载体,促进根际有益菌的定殖能力,并吸附、固持病原菌,有效抑制土传青枯病的发生。

【Objective】Tomato wilt is a kind of destructive soil-borne disease caused by Ralstonia solanacearum.In controlling the disease,rhizosphere probiotic play an important role.They reduce pathogen density and dull disease dynamics via resource competition and competitive exclusion.Their effective colonization in the rhizosphere is the precondition of their wilt controlling effect.As a porous material with adsorptive properties,biochar is used as a promising strategy to improve soil structure and fertility.Moreover,biochar has a great potential to inhibit soil-borne diseases,by transferring root exudates off rhizosphere and providing shelter for probiotics.To improve biocontrol efficiency of the probiotics,it is proposed that biochar is used as a carrier to improve their colonization in rhizosphere.【Method】In this study,wilt controlling effect of the application of biochar and probiotics in combination was evaluated and mechanisms underlying the potential were explored.To the end,a pot experiment was conducted to test three different kinds of biochar(derived from maize straw,pine wood and rice husk,separately)applied together with probiotic Bacillus amyloliquefaciens T-5 in controlling tomato bacterial wilt.And then an in-lab experiment was carried out too to measure efficiencies of the biochars adsorbing of pathogens and tomato root exudates in vitro.In the end,resource competition and direct toxin production of Bacillus amyloliquefaciens T-5 and their effects on pathogens were determined with simulated root exudates.【Result】Among the three kinds of biochar,the one derived from wood biochar is the highest in specific surface area(SSA)and absorption capacity,reaching up to 395.88 mm2 and 116.4 mg·g-1,respectively.The pot experiment showed that the application of biochar,regardless of kind,significantly reduced the incidence of bacterial wilt and pathogen density in rhizosphere.Wood biochar performed the best.When applied alone it decreased the incidence of bacterial wilt by 60.56%,and when applied in combination with probiotic Bacillus amyloliquefaciens T-5,it reduced pathogen density by about 97.42%,while increasing probiotic colonization by about 5.71 times.In exploring mechanisms of such potentials,it was found that 1)Biochar effectively adsorbed pathogen R.solanacearum,and wood biochar was the highest in adsorption capacity,reaching up to 90.00%,and fixing the adsorbed R.solanacearum by 94.66%;2)Biochars absorbed root exudates,which were used by probiotic T-5 as carbon source for growth,thus inhibiting the growth of R.solanacearum.【Conclusion】As a carrier of probiotics,biochar,once applied together with probiotics can significantly decrease incidence of bacterial wilt by adsorbing root exudates probiotics relay as nutrient resources for growth and restricting the mobile ability of pathogen.The findings in this paper explain the mechanism of combined application of biochar and biocontrol bacteria controlling soil-borne tomato bacterial wilt and may serve as a theoretical basis for developing an environment-friendly,high efficiency and stable biocontrol strategy.