两株解淀粉芽胞杆菌对西瓜枯萎病的防治作用及其相关生防因子检测

本试验从西瓜枯萎病生物防治实际需要出发，检测了两株解淀粉芽胞杆菌TR2和CE对西瓜枯萎病的防治作用及其相关的生防因子。平板对峙试验显示生防菌TR2和CE对西瓜枯萎病尖孢镰刀菌Xg-1、Xg-2和腐皮镰刀菌Xg-3的生长有较强的抑制作用，其中TR2对Xg-1的抑菌效果最好，抑菌带宽度为4.7 mm，CE对Xg-3的抑菌效果最好，抑菌带宽度为5.0 mm，抑菌圈边缘菌丝出现变细、扭曲、个别细胞膨大成球形等畸形现象。幼苗接种试验表明生防菌TR2和CE对西瓜枯萎病的发生具有防治效果，其中TR2对Xg-1在第15 d时防病效果最好，病情指数明显降低，其防治效果达到60%；TR2和CE对Xg-3在第3 d时表现很好的防病效果，发病率和病情指数都明显低于对照，防治效果可达63.6%。采用结晶紫染色、钼锑抗比色法、四苯硼钠法和透明圈检测等方法检测TR2和CE的相关生防因子，发现TR2和CE均可以形成生物膜、分解有机磷、无机磷和钾矿石，并且具备产生蛋白酶、淀粉酶和纤维素酶的能力。采用水培法发现TR2和CE的解磷解钾能力可以促进西瓜幼苗根和茎的生长。结果表明生防菌TR2和CE可以控制西瓜枯萎病的发生、形成生物膜在西瓜根系定殖，促进西瓜幼苗生长，是具有开发潜力的生防菌株。

Control Effects and Related Biocontrol Factors Detection of Two Bacillus amyloliquefaciens Strains on Watermelon Fusarium Wilt

Control effects of two Bacillus strains TR2 and CE on watermelon Fusarium wilt were investigated and their related biocontrol factors were detected. Plate confrontation tests showed that the two Bacillus strains had growth inhibitory effects on watermelon Fusarium wilt strain Xg-1, Xg-2 and Xg-3. Strain TR2 showed the best inhibitory effect on Xg-1with the width of inhibition zone of 4.7 mm. Strain CE showed the best inhibitory effect on Xg-3 with the width of inhibition zone of 5.0 mm. Mycelial deformation such as being thinner, distorted, and some cells expanded into spherical shapes could be observed along the edge of inhibition zones. Watermelon seedling inoculation test showed that watermelon Fusarium wilt could be controlled by strains TR2 and CE. The control effect of TR2 on pathogen Xg-1 reached to 60% with the disease index decreased significantly on the fifteenth day. On the third day, CE had the best control efficacy of 63.6%. Related biocontrol factors of TR2 and CE were detected by crystal violet staining, molybdenum antimony colorimetric, 4 benzene boron sodium assay and transparent circle detection. Both TR2 and CE had the ability of forming biofilm, decomposing of organic phosphorus, inorganic phosphorus and potassium ore, producing protease, amylase and cellulase. Tested Hydroponic culture experiment demonstrated that TR2 and CE could promote the root and stem growth of watermelon seedlings due to their phosphate and potassium solubilizing capacity. The above results indicated that TR2 and CE could control watermelon Fusarium wilt disease, form biofilm and colonize around plant root, and promote the growth of watermelon seedlings, which have the potential to be developed as biocontrol agents.