两种杀菌剂对立枯丝核菌(Rhizoctonia solani)生长的抑制作用机理

Inhibiting Mechanism of Two Fungicides on Rhizoctonia solani

为探究代森锰锌和多菌灵两种杀菌剂对引起苗木立枯病的一类病原菌-立枯丝核菌(Rhizoctonia solani J.G.Kühn)的抑菌机理,采用菌物学和生物化学等方法,研究代森锰锌和多菌灵对立枯丝核菌的抑制作用,测定两种杀菌剂对立枯丝核菌的毒力作用,分析抑菌率进而计算出对于该菌的抑菌中浓度(EC_(50)),并从菌株生长和生理代谢两个侧面探讨立枯丝核菌对杀菌剂胁迫的响应。结果表明:代森锰锌的抑菌效果要好于多菌灵,其平均抑菌率最大可以达到90%,根据抑菌回归方程求得代森锰锌EC_(50)浓度为10.23mg·L^(-1),多菌灵EC_(50)浓度为2213.77mg·L^(-1)。在菌株生长方面,两种杀菌剂均能抑制立枯丝核菌的生长。在生理代谢方面,菌株生长必需的碳和磷元素的利用被抑制,PCA分析表明,杀菌剂主要通过抑制菌株营养利用(碳和磷)达到杀菌目的。除此之外,采用药剂抑菌中浓度浸泡方法,利用抑菌中浓度药剂对菌株进行浸泡,研究菌株在药剂胁迫下的抗氧化酶活性和细胞渗透调节物质的含量变化。结果表明:杀菌剂处理组,菌株细胞的渗透调节物质(可溶性蛋白和丙二醛)、抗氧化酶活力(CAT、POD和SOD)均有不同程度的上升,表明菌体受到不同程度的破坏,其中代森锰锌对菌体的胁迫程度要高于多菌灵。综合以上试验结果分析,这可能是代森锰锌和多菌灵对立枯丝核菌(R.solani)的杀菌机理,该结果可为科学防治苗木立枯病提供参考。

In order to study on inhibition o f Rhizoctonia solani by mancozeb and carbendazim, the methods of mycology and biochemistry were used to test the toxicity function on R. solani and analyze the antibacterial rates and bacteriostatic concentration（EC50）. The response of R. solani through growth and physiology to fungicide stress was determined. The effect of mancozeb was better than that of carbendazim. The highest antibacterial rate reached to 90%. The mancozeb＇s EC50 was 10.23 mg·L^-1, and carbendazim＇s EC50 as 2213.77 mg·L^-1by regression equation. In terms of growth, the growth of R. solani could all be inhibited by mancozeb and carbendazim. In the aspect of physiological metabolism, the use of carbon and phosphorus were inhibited. PCA showed that fungicide was mainly through inhibiting the strain nutrition used to achieve sterilization. In addition, with the use of ethephon bacteriostatic concentration method, under the stress of potions, the antioxidant enzyme activity and cell osmotic regulation substances content changes were studied. In the treatment with fungicide, the osmotic regulation substances in strain cell（soluble protein and MDA） and the activity of antioxidant enzyme（CAT, POD and SOD） increased, indicating that the R.solani was damaged, with a better effect of mancozeb than that of carbendazim. The above may be the sterilization mechanism of mancozeb and carbendazim on R. solani, and the results can be used as scientific prevention and control of seedling blight.