【作者】 倪桂花；

【导师】 陈厚德；

【作者基本信息】 扬州大学 ， 农业昆虫与害虫防治， 2002， 硕士

【摘要】 实验研究了9种除草剂、14种杀虫（螨）剂对小麦纹枯病菌（Rhizoctonia cerealis Vander Hoeven）菌丝生长、菌核形成、致病力及病菌活体外三种细胞壁降解酶（果胶酶、半纤维素酶和纤维素酶）活性的影响。结果表明： 23种供试药剂在试验浓度下对小麦纹枯病菌菌丝的生长均有不同程度的抑制作用，其抑制率随浓度的增加而增加，但药剂间抑制率的差异较大，在50mg/L浓度下，骠马（94.4％）、功夫（96.0％）、敌杀死（98.6％）、啶虫脒（95.7％）、高效氯氰菊酯（93.2％）、百树（96.9％）和扑虱蚜（90.8％）对菌丝生长的抑制率均超过了常用杀菌剂井冈霉素的抑制率（86.28％）；而亿力、百草敌、久效磷和氧化乐果等在此浓度下基本上不抑制其线性生长。有的药剂，如扑虱蚜、辛硫磷还能影响菌落的形态和色泽。 毒力测定发现不同药剂的EC₅₀值有较大的差异。其中EC₅₀值较低的有骠马（7.03mg/L）、功夫（10.99mg/L）、敌杀死（9.54mg/L）、啶虫脒（8.19mg/L）、百树（6.75mg/L）和扑虱蚜（2.96mg/L），有的药剂在田间实际使用浓度下，其理论抑制率甚至超过了井冈霉素的理论抑制值（88.6％），如骠马、丁草胺、辛硫磷等。 显微观察表明，50mg/L药剂处理后的菌丝形态可发生不同程度的变化：异常缢缩、膨大、扭曲、分枝频繁，集结程度和畸形程度较高。显微测量表明，药剂处理后的菌丝分枝间距多数明显缩短，如骠马、啶虫脒、高效氯氰菊酯等；而氧化乐果、敌百虫处理可使菌丝分枝间距略有加长。 多数药剂在50mg/L的浓度下，能较高程度的抑制菌核形成的数目，如功夫、敌杀死等。 药剂处理后小麦纹枯病菌在活体外仍能产生果胶酶、半纤维素酶和纤维素酶，但这三种酶的活性受到不同程度的影响。与对照相比，多数药剂处理后能促进半纤维素酶的活性，同时药剂对果胶酶活性的影响不如对其它两种酶活性的影响明显。 盆栽接种试验表明，50mg/L的骠马、功夫、百树、扑虱蚜能很好的抑制病原菌的侵染能力，其抑制程度高达40％以上，三氯杀螨醇和久效磷基本上不影响其侵染能力，而氧化乐果和麦乐宁略能增加其侵染能力。 将含药50mg/L处理形成的菌落转移到无药的PSA平皿后，其菌丝生长、菌核形成和病原菌的侵染力都能得到较好的恢复。 通过定期取样观察表明，与对照相比，有些药剂，如骠马、功夫等处理后的扬州大学硕士学位论文菌丝延迟了侵入小麦叶鞘细胞的时间，而且不能很好的进一步侵入其它邻近细胞. 本文首次利用嵌入法接种小麦纹枯病菌，并与常规的外贴法进行了比较，结果表明，利用嵌入法接种，小麦植株间发病迅速、整齐一致，且操作方便，尤其适用于苗期接种。更多还原

【Abstract】 The effects of nine herbicides and 14 insecticides on mycelia growth, sclerotia forming, pathogenicity and the activities of three cell wall-degrading enzymes (pectinase, cellulase, hemicellulase) in vitro of Rhizoctonia cerealis were studied.The results indicated that all 23 pesticides tested had inhibition effects on the mycelia growth with defferent degrees, and the inhibition increased with concentration, but with pesticides. At the concentration of 50mg/L, the inhibitions of fenoxaprop, cyflithrin, deilamethrin, acetaniprid, alphamethrin, cyflithrinand pushiya were higher than that of jingangmycin( 86.28%); whereas tribenuron, dicamba, monocrotophos and omethoate were of little inhibition at the same concentration; some pesticides ,for example pushiya and phoxim ,could also affect the colony shape and color of R. cerealis.Toxicity test showed that the EC50 varied with pesticides. The EC50 of fenoxaprop, deilamethrin, acetaniprid, cyflithrin and pushiya was lower than l0mg/L. At the recommended field rate, the theory inhibition of fenoxaprop, butachlor, mailening, phoxim and chlorpyrifos even exceeded that of jinggangmycin (88.6%) .Microscopic observation indicated that the shape of treated mycelia deformed in varying degrees, including unusual constriction, intumescent, contortion, branching frequently, more intertwining and deformation. Microscopic measurment indicated that the intervals of mycelia branches were shortened significantly when treated with fenoxaprop, cyflithrin, deilamethrin and so on. However the intervals became slight longer when treated with omethoate and trichlorphon.The numbers of sclerotia decreased significantly when treated with pesticides at the concentration of 50mg/L.Pectinase, cellulase and hemicellulase were also produced in vitro from R.cerealis after treatment, but their activities were affected with various degrees. Compared with the control, majority treatments could promote the activity of hemicellulase, and the effect on the activity of pectinase was less than that of other two enzymes.Inoculating experiment with potted plants showed that fenoxaprop, cyflithrin, cyflithrin, pushiyacould inhibited the pathogenicity of R.cerealis at the concentration of 50mg/L, and the inhibition reached 40% or more. No effects wre found with dicofol andmonocrotophos, whereas omethoate and mailening enhanced the pathogenicity slightly.When subcultured the colonies formed on treated medium with concentration of 50mg/L , the effects on mycelia growth sclerotia forming and pathogenicity of R. cerealis relented.Periodic sampling observation indicated that,during the invading of mycelia into boot cellulars , the time of invading was delayed in some treatments when compared with control, and they could not further more penetrated and expanded vicinity cellulars after invading.Insertion method was applied first time for inoculating R. cerealis , and compared with mycelia plugs clasp stem method. The results showed that: the disease appeared faster and more uniformly with insertion method. With its convenient to operate, insertion method is suitable for R. cerealis inoculating, especially for seedling inoculation.更多还原