【作者】 张广志；

【导师】 文成敬；

【作者基本信息】 四川农业大学 ， 植物病理学， 2005， 硕士

【摘要】 从雅安郊区玉米纹枯病发病叶鞘分离的病原菌,经菌丝融合群鉴定属立枯丝核菌(Rhizoctonia solaM)AG-1-IA。从雅安郊区大田玉米根际土壤中分离木霉菌株18个,其中哈茨木霉3株;康氏木霉2株;绿色木霉2株;钩状木霉1株;长枝木霉1株:深绿木霉2株;黄绿木霉7株,为该地区土壤玉米根际土壤中木霉的优势种群。实验室提供菌株2个,分别属绿色木霉和康氏木霉。对该20个菌株的生长速度、对峙培养、代谢产物的抑菌效果、重寄生等作用机制进行初步研究,以筛选好的生防菌株用于田间防效试验。 木霉生长速度测定结果表明,多数木霉菌株都生长迅速,为空间和营养资源的强竞争者。对峙培养中,所有菌株对立枯丝核菌均有一定程度上的抑制作用,其中T7、T11、T14和T16处理的抑菌率在80%以上。难挥发性代谢产物的抑菌效果显著,抑菌率在80%以上的有6个菌株,分别为T5、T13、T9、T8、T10、T18,但其抑菌活性物质热稳定性不高,;而挥发性代谢产物抑菌效果较差。光学显微镜观察表明,多数木霉菌株通过缠绕、附着和穿透等方式寄生立枯丝核菌,并有溶菌现象。 筛选出生防活性好的菌株T1、T7、T13麦麸培养物做进一步的田间防效试验,结果表明,供试菌株T13、T1和T7的防病效果显著,防效依次为68.52%、64.48%、62.75,明显高于井冈霉素500倍一次的防效,较好地控制了玉米纹枯病的发生,降低产量的损失。然而T13发酵滤液的防效低于井冈霉素,仅为40.07%,但T13处理的病情指数仍大大低于对照。 菌株T1、T7、T11和T13被筛选以研究其对玉米生长调节作用、抗性诱导作用及根际竞争,以全面把握木霉对玉米纹枯病的生防作用机制。结果表明低浓度的木霉发酵滤液能促进种子萌发,并刺激种子胚根、胚芽的伸长,而高浓度的发酵液反而有较强的抑制作用。此外,木霉菌剂还促进玉米植株的生长,并诱导玉米产生对病原菌的抗性,其中T7处理诱导抗性最高,相对病斑面积仅为6.74%,明显小于对照。通过对木霉菌株T1、T7、T11和T13在玉米根际竞争的研究,结果表明,木霉菌株T1、T7、T11和T13均能沿玉米根系迅速生长,其根际竞争指数分别为3.5442、3.8071、4.2354、2.6265;对照处理各深度均无木霉发现;适量浓度的土壤杀菌剂PCNB的施入,有助于增强木霉的根际竞争能力。更多还原

【Abstract】 According to the test of anastomosis groups of Rhizoctonia solani, the pathogen of maize sheath blight, which was isolated from diseased sheath of maize in suburb of Yaan, Sichuan, was grouped into Rhizoctonia solani AG-1-IA. 18 Trichoderma isolates were isolated from the maize rhizosphere soil in suburb of Yaan and identified. There were 3 isolates of T. harzianum, 2 isolates of T.koningii,2 isolates of T.viride,1 isolate of T.hamatum,1 isolate of T. longibrachiatum, 2 isolates of T. aureaoviride,7 isolates of T.aureoviride respectively. Among them T. aureoviride was the dominant species. 2 strains were provided by Lab. of Plant Pathology, one was T. viride, the other one was T. koningii. The strains that possessed stronger potential ability for plant disease biocontrol were selected through dual culture on PDA plates, effects of metabolites and mycoparasitism for field experiment.The test of hyphal growth rate showed that most of Trichoderma strains grew rapidly, and were the stronger competitor for space and nutrition resource. The result of the dual culture showed the inhibition rates of hypaal growth of all Trichoderma isolates against R. solani were 38. 50%~ 84.98%, T7, T11,T14 and T16 showed higher inhibition rates than 80.00%. The non-volatile substances of the isolates tested had obvious inhibition to hyphal growth of R. solani, among them T5, T13, T9, T8, T10 andT18 showed higher inhibition rates than 80%. But antimicrobial substances were not heat stable, when the filtrates were autoclaved at 121°C, inhibition activities against R. solani were decreased. The volatile substances showed lower inhibitions to R. solani. Microscopic observation illustrated that Trichoderma isolates parasitized R. solani by coiling, or penetrating into the hyphae. The infected pathogen hyphae were distorted , contracted or broken.T1,T7, T13 were selected for field experiment. The result of field experiment showed that the efficacies of solid culture of T8,T13 and T2 against maize sheath blight were 62. 75%, 64. 48%, 68. 52%, respectively, thatwere better than that of Validamycin(40. 07%). However, the efficacies of fluid ferment filtrate of isolate T13 was only 49.68%, lower than those of the solid culture. After application of solid culture of T8,T13 and T2 yields significantly increased respectively for 29. 77%, 43. 37% and 54.21T1,T7, T11 and T13 were selected to mensurate the effect of increase growth of plants, induction of resistance and rhizosphere competence. Proper consistence of ferment filtrate of T1,T7, T11 and T13 enhanced the germination rates , stimulate growth of radicel and embryo of maize. Otherwise, Trichoderma strains stimulate plant growth, and induced resistance reactions in the host plant, among them the relative lesion area of T7 was only 6.74%, much smaller than that of control. Rhizosphere competence of Trichoderma spp. were meatured. The result showed T1.T7,T11 and T13 grow readily along with the developing root system of maize, which rhizosphere competence index were 3. 544, 3. 807, 4. 235, 2. 627 respectively. And proper consistence of PCNB may enable Trichoderma isolates T7 and T13 to grow more readily.更多还原