【作者】 李斌；

【导师】 龚国淑； 姚革；

【作者基本信息】 四川农业大学 ， 植物病理学， 2008， 硕士

【摘要】 烟草黑胫病是广泛分布于我国各烟草主产区的重要病害,其病原(Phytophthoranicotianae)可以侵染危害烤烟、晾烟、晒烟、白肋烟、香料烟等所有栽培烟草,破坏力极强。开展烟草黑胫病菌生理小种的鉴定有助于了解其病原的生理分化情况,可为四川烟草品种布局和黑胫病防治提供重要有用的参考。放线菌是一类重要的生防微生物,具有较大的开发利用价值,用放线菌防治烟草黑胫病可避免烟草的农药污染和病菌抗药性等问题,是烟草生产中值得探索的新途径。本研究从四川烟草主产区收集了108份烟草黑胫病标样,采用髓部碟片分离法和组织分离法获得74株黑胫病菌。采用TTZ颜色反应和鉴别寄主法对74个菌株进行了生理小种鉴定,结果表明,四川烟草黑胫病菌存在0号和1号小种,供试菌株中0号小种占28.38%,1号小种占71.62%,属优势小种。两个小种在各采样区均有分布,以1号小种分布最广。采用稀释平板涂布法对采自四川烟草黑胫病发生区的29份根际土进行了分离,共获得239株放线菌。通过平板对峙培养法筛选得到48株对烟草黑胫病菌有拮抗活性的菌株,占筛选菌株的20.1%。根据形态和培养特征,48株拮抗放线菌被鉴定为链霉菌属(Streptomyces)和诺卡氏菌属(Nocardia)。链霉菌属占拮抗菌的97.92%,包括灰褐类群(Griseofuscus)、白孢类群(Albosporus)、淡红紫类群(Lavendulae)、球孢类群(Globisporus)、灰红紫类群(Griseorubroviolaceus)、金色类群(Aureus)、粉红孢类群(Roseosporus)等7类,其中灰褐类群和白孢类群为优势类群,分别占拮抗菌的41.67%和27.08%,其平均抑制率分别为54.73%和46.64%。淡红紫类群拮抗菌数量较少,但平均抑制率最高,为61.83%。对拮抗效果较好的菌株A20-8、A27-12、A30-9和A36-15分别进行了发酵条件优化测定,结果表明,其发酵液拮抗活性最好的发酵条件A20-8为pH7.0～8.0、28℃下培养4d,A27-12为pH8.0、24～28℃下培养8d,A30-19为pH8.0、24℃下培养8d,A36-15为pH8.0、28℃下培养8d。盆栽试验结果表明,4株放线菌对烟草黑胫病均具有不同程度的防治效果,以菌株A30-19效果最好,其防效为78.79%,与58%甲霜灵锰锌800倍液无显著差异,菌株A36-15,A27-12,A20-8对烟草黑胫病的平均防效分别是67.95%、57.41%、50.46%。更多还原

【Abstract】 Tobacco black shank,caused by Phytophthora nicotianae,causes serious damage to cultivated tobacco including flue-cured tobacco,air-cured tobacco,sun-cured tobacco,burley tobacco and oriental tobacco in many parts of China.Identification of physiological race of P. nicotianae can provide an important reference to tobacco varieties arrangement and control of tobacco black shank in Sichuan Province.Actinomyces has immense biocontrol potential to many pathogens.Up to now,many actinomyces isolates have been used to control plant diseases.Using actinomyces to control tobacco black shank is a valuable measure that can avoid chemical pollution and pathogen resistance to fungicides.108 samples of tobacco blank shank were brought from the main planting tobacco areas of Sichuan.74 P.nicotianae isolates were obtained from these disease samples through isolating the samples by tissue isolation method and medulla plate method.The physiologic races were determined by using identification of TTZ color and differential host.According to the differential host,21 isolates were identified to race 0,in proportion of 28.38%,53 isolates s were identified to race 1,in proportion of 71.62%.Both Race 0 and Race 1 existed in all tobacco planting areas of Sichuan,and their distributions were different.However,Race 1 was predominant race type.239 actinomyces strains were isolated from 29 soil samples.Among them,48 isolates showed antagonistic effects against P.nicotianae through plate dual culture,in proportion of 20.1%.Based on the characteristics of morphology and physiology-biochemistry,the antagonists were identified as Streptomyces(47 strains,97.92%) and Nocardia(1 strain).Streptomyces was the dominant genera including Griseofuscus,Albosporus,Lavendulae,Globisporus,Griseorubroviolaceus, Aureus,Roseosporus.Griseofuscus is in proportion of 41.67%and its average inhibition percentage was 54.73%,Albosporus is in proportion of 27.08%and its average inhibition percentage was 46.64%.The highest average inhibition percentage was Lavendulae,61.83%.The fermentation culture conditions of 4 actinomycetes strains were optimized through determining antagonism against P.nicotianae under different days,different pH,and different temperature. Strain A20-8 showed its strong inhibition activity through fermentating 4 days,the initative pH7～8, 28℃.A27-12 was fermentated 8d,pH8,24-28℃.A30-19 was fermentated 4d to 8d,pH8,24℃.A36-15 was fermentated 8d,pH 8,28℃.The results of greenhouse test showed that the 4 actinomycetes had different control effects on curing tobacco blank shank.The strain A30-19 had the best effect,which was 78.79%.And it had no significant difference with 58%Metalaxyl and Mancozeb WP 800 times.Control effect of strain A36-15,A27-12,A20-8 were 67.95%,57.41%, 50.46%,respectively.更多还原