【作者】 朱蕾；

【导师】 陈垣；

【作者基本信息】 甘肃农业大学 ， 作物栽培学与耕作学， 2010， 硕士

【摘要】 近年来,甘肃道地产区黄芪根腐病普遍发生,并有逐年加重趋势。本研究对甘肃渭源县种植的蒙古黄芪根腐病病原物进行系统研究,研究结果归纳如下：1.通过对根腐病不同病级病株发病部位分离纯化和致病性测定,结果表明,从根腐病发病部位共获得6种分离物,主要致病菌为尖孢镰刀菌(Fusarium oxysporum Schiecht.)和腐皮镰孢菌(F.solani(Mart.)Sacc),两者均可在不同生长期1-4级病株发病部位分离获得,分离频率分别为15.8%-38.1%和25.0%-42.1%。刺伤黄芪幼根接种致病菌后,根腐病发病率均显著提高,尖孢镰刀菌致病力最强。相同培养条件下各级苗栽病斑基本稳定在初始水平,0级苗始终无病斑产生。以上说明环境因素及苗栽质量和完整性是决定黄芪根腐病发生的重要因素,伤口有助于病原菌的侵染。2.生物学特性研究表明,尖孢镰刀菌菌株致死温度为60℃,菌丝适宜在连续光照下15℃-30℃生长,生长最适温度25℃,最适pH=6,最佳碳、氮源分别为蔗糖和硝酸钠；产孢量在黑暗25℃-35℃下较高,最适产孢pH=5,以蔗糖和葡萄糖为碳源的产孢量相对较高,最佳产孢氮源为硝酸钠。腐皮镰刀菌菌株致死温度为65℃,菌丝适合在光照下20℃-30℃生长,最适温度25℃,生长最适pH=8,最佳碳、氮源分别为蔗糖和硝酸铵;产孢量在黑暗20℃-35℃下较高,最适产孢pH=7,麦芽糖作为碳源产孢量相对较高,最佳产孢氮源为硝酸铵。说明两种病原菌的生长特性存在差异。3.采用含毒介质法药剂测定结果表明,1.25 mg/mL甲基托布津对尖孢镰刀菌和腐皮镰刀菌均有显著的抑制效果,菌落直径分别为1.8 cm和1.9 cm,抑制率分别达85.3%和84.4%。2.00mg/mL甲霜灵锰锌的抑菌效果次之。甲霜灵锰锌、甲基托布津、多菌灵和康地蕾得对尖孢镰刀菌抑制的ECso值分别为0.9623 mg/mL.0.6599 mg/mL. 2.4997 mg/mL和3.2462 mg/mL.对腐皮镰刀菌抑制的EC50值分别为：0.6161mg/mL、0.5643 mg/mL、2.3442 mg/mL和3.6828mg/mL。4种药剂对两种病原菌的毒力依次为甲基托布津>甲霜灵锰锌>多菌灵>康地蕾得。4.田间药剂防治表明,移栽时蘸根,10d后喷施药剂,20 d后黄芪地上部分接菌裂区部分植株叶片萎蔫甚至发黄脱落,而不接菌部分地上部分性状相对良好。接菌部分根腐病发病率63.3%-90.0%,病情指数30%-44.2%,防效11.5%-15.4%,800倍液甲基托布津防治最有效,500倍液康地蕾得次之。而不接菌裂区发病率20.0%-66.7%,病情指数13.3%-31%,防效46.2.5%-73.1%,800倍液甲基托布津和500倍液甲霜灵锰锌防治效果最好,400倍液多菌灵次之。说明接种根腐病病原菌后发病率和发病程度显著提高,而防治效果显著减弱。更多还原

【Abstract】 In recent years, astragalus root rot is widespread in the genuine producing aera. The root rot pathogens from A. membranaceus planted Weiyuan county were studied in this paper. The results show as follows:1. Isolation, identification and pathogenicity tests of the pathogens from A. membranaceus root rot in Weiyuan county were conducted. The result showed that 6 kinds of fungus were isolated from the biennial root rot plants. The major pathogens were F. oxysporum Schiecht. and F. solani (Mart.) Sacc., which could be isolated in different stages of growth by 15.8%-38.1% and 25.0%-42.1%, respectively. The root rot incidence after inoculating pathogens by goring radicles was significantly higher than that by non-goring. The F. oxysporum showed strongly nosopoietic ability. The root rot spots would not develop under culture conditions and the health seedlings always grow well without spots. All above reveals that the climate, environment factors and the seedlings are the major factors causing root rot and the wound is helpful for the pathogens to infect. It suggests that it should ensure the seedling quality, prevent the wound in the standardization operation and integrate stubble change with medicament early application so as to synthetically control the root rot.2. Biological characteristics study showed that LT of F. oxysporum is 60℃. The mycelia growed well under continuous light at 15℃-30℃, with the optimum temperature of 25℃and optimum pH=6. The best carbon and nitrogen sources were sucrose and sodium nitrate. The sporulation produced higher in the dark under 25℃-35℃and pH=5, especially using sucrose and glucose as carbon source. The best nitrogen source for the sporulation is sodium nitrate. The LT of Fusarium was 65℃and the mycelia are suitable under light at 20℃-30℃with the optimum temperature of 25℃and pH=8. The best carbon and nitrogen sources were sucrose and ammonium nitrate. The spores were highly yielded in the dark under 20℃-35℃and pH=7, using ammonium nitrate as nitrogen source. All these reveal that the growth characteristics of pathogens are quite different.3. Toxic pharmaceutical test showed that 1.25 mg/mL of thiophanate methyl had significantly inhibitory effect on F. oxysporum and Fusarium fungi with 1.8 cm and 1.9 cm in colony diameter and 85.3% and 84.4% of the inhibition rates. The inhibitory effect of 2.00 mg/mL metalaxyl mancozeb was the second. The EC50 of Metalaxyl mancozeb, thiophanate methyl, carbendazim and Kangdileide for F. oxysporum were 0.9623 mg/mL, 0.6599 mg/mL,2.4997 mg/mL and 3.2462 mg/mL, respectively. The EC50 for Fusarium were 0.6161mg/mL,0.5643 mg/mL,2.3442 mg/mL and 3.6828mg/mL. Toxicity of the two pathogens were ranged in thiophanate-methyl> metalaxyl mancozeb> carbendazim> Kangdileide.4. Field medicament selection showed that after 20 d following inoculation when transplant and spray application when growed for 10 days, the aerial parts of astragalus showed some wilting even yellow leaves falling off, however, these symptoms were not happened in the non-inoculated plants. Under inoculation, The root rot incidence ranged from 63.3% to 90.0% and disease index ranged from 30% to 44.2%, but the control effect varied in 11.5%-15.4%.800 dilution of thiophanate-methyl was the most effective in prevention and treatment,500 dilution of Kangdileide followed. However, under non-inoculation, the fissure incidence ranged from 20.0% to 66.7%, disease index ranged from 13.3% to 31% , but the control effect varied from 46.2.5% to 73.1% ,800 dilution of thiophanate methyl and 500 dilution of mancozeb metalaxyl had excellent control effect on carbendazim, and the effect of 400 dilution followed. It shows severity incidence of root rot after pathogen inoculation as compared with the control.更多还原