分离土壤棉花黄萎病菌选择性培养基的筛选

SCREENING THE SELECTIVE MEDIUM FOR ISOLATING Verticillium dahliae OF COTTON FROM NATURALLY INFESTED SOIL

采用土壤检测稀释法、水筛法和不同土样接种量 ,对 5种土壤浸提液改良培养基进行了比较研究。结果表明 ,土壤水筛法对土壤棉花黄萎病菌的检测效果优于稀释法 ,其菌落检测数增加 4～ 10倍。培养基每皿 0 .2 5 g土样接种量的检测效果高于 0 .5 g和 1g。 5种测试培养基中 ,培养基 D对分离土壤棉花黄萎病菌的选择性表现最好 ,其土壤接种体检测回收率达 6 3.5 %～ 83.3% .培养基 D的组份为 :土壤浸提液 2 5 ml,KH2 PO41.5 g,K2 HPO44 g,尿酸钠 0 .2 g,半乳糖醛酸钠 (果胶 ) 1g,山梨糖 1g,Dox盐 2 ml,Tergitol NP- 10 1ml,PCNB0 .1g,琼脂 17g,蒸馏水 10 0 0 ml,p H6 .4～ 6 .7。每 10 0 0ml融化培养基倒皿前加抗菌素液 5 0 ml (含氯霉素 0 .0 5 g,链霉素 0 .0 5 g,青霉素 - G盐 0 .0 5 g)。

The effect of soil wet-sieving,soil dilution analysis methods and the amount of soil inoculated to plate on detection efficiency of Verticillium dahliae of cotton in naturally infested soil was investigated by using five media based on modified soil extract agar.Results showed that soil wet-sieving method was generally more effctive in detecting V. dahliae and gave 4-10 times higher counts than soil dilution method;and more colony counts were detected when 0.25 g soil was added to the plate than when 0.5 g or 1 g soil was used.Among the five media tested in experiments,the medium D was the best,and the recovering rate reached to 63.5%-83.3%.The medium consisted of following chemicals:25 ml soil extract,1.5 g KH\-2PO\-4,4 g K\-2HPO\-4,0.2 g sodium urate,1 g sodium galacturonic acid(sodium pectate),1 g sorbose,2 ml Dox salt,1 ml Tergitol NP-10,17 g agar,and 0.1 g PCNB in 1 liter of medium(pH adjusted to 6.4～6.7).When the basal medium was melted and held at 45℃,1 000 ml medium was added with 50 ml of antibiotic solution containing 0.05 g chloramphenicol,0.05 g streptomycin and 0.05 g penicillin,respectively.