4株菌根辅助细菌对苗木猝倒病菌的抑制作用

菌根辅助细菌（MHB）对植物具有促生作用，为探讨MHB对土传病原真菌的生防功能，采用离体平板对峙和活体接种的方法测定了4株MHB对土传病原真菌的抑制作用。结果表明：在离体平板对峙测定中，蜡状芽孢杆菌（Bacillus cereus）HB12、HB59菌株和短小芽孢杆菌（B. pumilus）HR10菌株对苗木猝倒病病原丝核菌（Rhizoctonia sp.）有较为明显的抑制作用，其中短小芽孢杆菌HR10对丝核菌的抑制作用最强，抑菌率达85.58 %；蜡状芽孢杆菌HB12和HB59、短小芽孢杆菌HR10、藤黄微球菌（Micrococcus luteus）HR15对苗木猝倒病病原尖孢镰刀菌（Fusarium oxysporum）均无抑制作用。将筛选获得的短小芽孢杆菌HR10进行活体松苗接种，结果显示，经HR10菌株处理后的黑松苗木其猝倒病的发病率仅为15 %，病死率也低至10 %，而单接种病原丝核菌的对照黑松苗木的发病率则高达80 %，病死率为65 %。说明菌根辅助细菌（MHB）除对植物具有促生作用外，对某些植物土传病害也具有一定的抑制作用。

Inhibition of mycorrhizal helper bacteria against damping-off disease of Pinus thunbergii

Mycorrhizal helper bacteria(MHB)has effect on promoting the plant growth.In order to discuss its biocontrol function to soilborne fungus pathogen,we used the plate confrontation in vitro and in vivo inoculation methods to assay the inhibition effect to soilborne fungus of 4 MHB isolates.The result showed that,in plate confrontation in vitro experiment,Bacillus cereus HB12,HB59 isolates and B.pumilus HR10 isolate had the obvious inhibition effect on Rhizoctonia sp,which caused the seedling damping-off disease.In these isolates,B.pumilus HR10 isolate had the strongest inhibition effect,with 85.58 % inhibition rate.B.cereus HB12,HB59 isolates,B.pumilus HR10 isolate,and Micrococcus luteus HR15 isolate all had no inhibition effect on seedling damping-off pathogen Fusarium oxysporum.Then the screened B.pumilus HR10 isolate was chosen for in vivo inoculation test,the result indicated HR10 had the better biocontrol function to P.thunbergii damping-off disease with only 15 % disease incidence and 10 % mortality after inoculation,while the control had 80 % disease incidence and 65 % mortality,with just inoculate Rhizoctonia sp..Based on the above results,MHB not only had the growth-promoting effect on plant,but also had biocontrol function to some kind of plant soilborne fungus pathogen.So it could serve as a valuable reference for further investigation on tree nursery management practice.