辣椒青枯病拮抗菌株的筛选及田间防效的测定

Screening for Biocontrol Agents Against Ralstonia solanacearum

用抑菌圈 定殖力双重测定法筛选出 6个定殖密度大于 1 0 5 cfu/ g根 ,抑菌能力亦较强 ,同时又极易于人工培养的菌株 ,作为青枯病的潜在生防菌株。温室试验 ,防病效果分别达83 4% (J2 )、91 6 % (J3 )、5 8 4% (FH1 7)、75 0 % (BB1 1 )、6 6 6 % (BT4)和 41 6 % (BT6 ) ,增产效果为 2 1 3 %～ 1 1 0 1 % ,其中以J3增产效果最为显著 ,BB1 1次之。 1 996年在南京和淮阴两地的辣椒青枯病小区进行试验 ,移栽 40d后各菌株平均防效分别为 :6 6 0 % (J2 )、6 1 6 % (J3 )、5 8 2 % (FH1 7)、6 2 4% (BB1 1 )、72 8% (BT4)和 3 7 1 % (BT6 ) ;平均增产效果为 45 7% (J2 )、76 5 % (J3 )、3 2 4% (FH1 7)、78 5 % (BB1 1 )、2 9 3 % (BT4)和 1 9 0 % (BT6 )。

Cayenne pepper bacterial wilt, caused by Ralstonia solanacearum, is one of the most important diseases in China. Biocontrol is considered to be the most environment safe and efficacious approaches to control the disease. In this study, screening for potential biocontrol agents against the disease was performed based on abilities to inhibit the pathogen in vitro and to colonize host roots in planta. 6 bacterial strains (Corynebacterium sp.BT6, Bacillus spp.FH17, BB11, Escherichia sp.BT4, Serratia sp.J2, and Pseudomonas sp.J3) were selected. All strains exhibited pathogen inhibiting zone diameters larger than 1cm on artificial media and root colonizing population counts higher than 1×10 5cfu/g root 30d after root dipping and planting. The disease controlling efficacy of these strains was assayed both in the greenhouse and in field plots. In greenhouse experiments, the roots of seedlings were dipped in cell suspensions before planting in soils containing R.solanacearum. The disease incidence 40d after treatment was reduced by 42% to 92%, and the yield 71d after treatment was increased by 21% to 110%. Field plot experiments were completed under natural condition without inoculation of the pathogen in Qixia of Nanjing, and Huaiyin of Jiangsu, on cultivars Daguozaofeng and Sujiao 2, respectively. On average, the disease incidence 40d after treatment was reduced by 37% to 73%, and the yield at ripeness was increased by 19% to 79%. All strains tested except the BT6 showed high disease controlling efficacy and yield increasing potential.