辽宁省甜瓜果腐病病原菌鉴定及生物学特性初探

 由丝核菌引起的甜瓜果腐病是辽宁省近年发生的新病害，在棚室甜瓜生产中发生渐趋严重。根据病原菌形态、致病性、菌丝融合群和rDNA-ITS序列分析，确定其病原菌为茄丝核菌（Rhizoctonia solani），AG-4 HGI融合群。病原菌生物学特性测定结果表明，菌丝生长最适温度28 ℃；最适pH 6.0 ~ 8.0；供试10种培养基中，在甜瓜煎汁培养基中菌丝生长最快；供试9种碳源和10种氮源中，最适碳源为可溶性淀粉，最适氮源为蛋白胨；光照对菌丝生长影响较小。菌核形成最适条件为温度25 ℃，pH 7.0，理查培养基，黑暗条件；以山梨醇为碳源的PA培养基和以KNO₃为氮源的查氏培养基有利于菌核形成。对于病菌菌核萌发胡萝卜煎汁培养基最为适宜；供试9种碳源和10种氮源中，最适碳源为麦芽糖，最适氮源为蛋白胨；菌核萌发最适温度28 ℃，最适pH 5.0 ~ 8.0，黑暗条件利于菌核萌发；菌丝致死温度50 ℃、10 min；菌核致死温度53 ℃、10 min。

Identification and Biological Characteristics of Muskmelon Fruit Rot Pathogen in Liaoning Province

Muskmelon fruit rot caused by Rhizoctonia sp. is a new disease first found in Liaoning Province in recent years. The disease appears more serious on greenhouse muskmelon. The casual agent was identified as AG-4 HGI of Rhizoctonia solani by the studies of the morphology，pathogenicity，anastomosis groups and ribosomal DNA-ITS. The biological characteristics of the results showed that the best mycelium growth was obtained at 28 ℃ and pH 6.0–8.0；The melon juice culture medium was most conducive to mycelium growth in the 10 tested media，The optimum one was soluble starch in the 9 tested carbon sources，the optimum nitrogen source was peptone. The effect of light on the mycelial growth was not evident. The ideal sclerotium generation was at 25 ℃，pH 7.0，in darkness and with Czapek culture medium. The beneficial carbon source for the formation of sclerotia was Sorbitol；The beneficial nitrogen source for the formation of sclerotia was KNO₃. Sclerotium germination was well with carrot juice culture medium；In the 9 tested carbon sources and 10 tested nitrogen sources，sclerotium germination was in favor of malt sugar and peptone；The optimum temperature for sclerotium germination was 25 ℃；The optimum pH is 5.0–8.0；Dark conditions was benefit for sclerotium germination. The mycelial lethal temperature was at 50 ℃ for 10 min. The lethal temperature for sclerotium was at 53 ℃ for 10 min.