油菜菌核病生防芽孢杆菌的分离鉴定及其脂肽化合物分析

采用平板拮抗筛选,分别从西藏日喀则地区和拉萨地区杂草根围土壤中筛选到2个对油菜菌核病菌有显著拮抗活性的芽孢杆菌菌株RJGP16和YBWC43。通过生理生化鉴定、16S rDNA序列分析和BOX-PCR指纹图谱分析,鉴定菌株RJGP16为萎缩芽孢杆菌Bacillus atrophaeus, 菌株YBWC43为解淀粉芽孢杆菌Bacillus amyloliquefaciens。离体叶片试验结果显示,菌株RJGP16和YBWC43对油菜菌核病菌防治效果分别为50.24%和100.00%。脂肽化合物种类分析显示,菌株RJGP16产生脂肽化合物表面活性素和芬枯草菌素,菌株YBWC43产生杆菌霉素D和芬枯草菌素。表明菌株RJGP16和YBWC43对油菜菌核病的防治效果与其产生的脂肽化合物有关。     

In vitro and in vivo antifungal activity of synthetic pure isothiocyanates against Sclerotinia sclerotiorum

BACKGROUND: Isothiocyanates (ITCs) released by the enzymatic hydrolysis of glucosinolates in the Brassicaceae are potentially useful for controlling fungal pathogens. In vitro activity of pure ITCs against Sclerotinia sclerotiorum (Lib.) de Bary was studied by adding them to glass filters in petri dishes and dissolving them in the growing media. RESULTS: Methyl, allyl and benzyl ITCs were the most fungitoxic of the compounds in bioassays with S. sclerotiorum isolate Ss31. In the volatile phase, mycelial growth was completely inhibited by these three compounds. Aromatic ITCs were less toxic in the petri dishes but were more toxic than aliphatic ITCs when dissolved in the agar. Benzyl ITC exhibited the highest inhibitory effect on sclerotial germination, with an EC₅₀ value of 75.1 µmol L^?1. Butyl and benzyl ITCs reduced apothecial production of S. sclerotiorum by 92.5% at the highest concentration. In in vivo assay, only allyl and 2‐phenylethyl ITCs reduced disease incidence (by 76.7 and 70% respectively) at low concentrations. CONCLUSION: Sclerotinia sclerotiorum in the soil might be suppressed by the higher concentrations of allyl and benzyl ITCs released from decomposition of Brassica juncea, B. carinata, B. nigra and Sinapis spp. Copyright © 2011 Society of Chemical Industry     

Multivariate effects of plant canopy, soil physico-chemistry and microbiology on Sclerotinia stem rot of soybean in relation to crop rotation and urban compost amendment

The effects of canopy, soil physico-chemical and microbiological variables on Sclerotinia stem rot (SSR) on soybean were assessed in two soils (clay loam and sandy loam) using multiple regression and canonical redundancy analysis (RDA) and their partial form to control for the rotation (2 or 3-y-corn/soybean monoculture) and fertilization (mineral/urban compost) or spatial variables effects. The models revealed the minimal sets of variables that best explain the variance of the survival of Sclerotinia sclerotiorum’s sclerotia, carpogenic germination, disease severity and their associations. In clay loam, the 3-y-corn rotation reduced disease severity mainly through the reduction of weed biomass that favoured carpogenic germination. Urban compost has a conducive effect explained by a better soil surface drainage. Additionally, total N was found suppressive to sclerotial survival. In sandy loam, the carpogenic germination was negatively correlated with high C mineralization quotient and aggregate stability but correlated positively with Ca. Sclerotial survival was negatively correlated with pH and Ca, and positively correlated with biological fertility index. Aggregate stability, Ca and pH were associated with the urban compost. The regression and RDA analyses allowed to identify key variables that drived SSR development and explain their relationship with the cultural practices, soil health, as well as the spatial variation of disease variables.     

向日葵菌核病菌核及子囊柄萌发峰期的预测

向日葵菌核病的流行取决于田间菌核量与气候因素的影响。试验研究得知,菌核子囊柄萌发程度在菌核经过一场透雨后与七月底,八月份的降雨量及降雨次数呈正相关,而与此时期的平均温度,降雨间隔期呈负相关。由此建立了预测菌核子囊柄萌发程度的多元回归式为y=65.25—2.58x_1 0.04x_2 2.36x_3-2.10x_4。子囊柄萌发期是进行药剂防治的最有效时期,因此预测子囊柄萌发峰期是防治菌核病的关键。通过多元回归建立预测式为y=76.52-1.38x_1 0.06x_2-1.84x_3-3.86x_4。用上述两式回测前2年的田间实测值其结果与预测值极近。     

利用栽培措施控制油菜菌核病的研究

以2个甘蓝型油菜品种为材料，利用自然鉴定和人工接种方法研究不同播期和不同密度等栽培措施对控制油菜菌核病的作用。结果表明，品种 播期对油菜菌核病的影响均达显著水平，种植密度对油菜菌核病的影响不显著，选用抗（耐）病性品种和适当晚播可有效控制或避开油菜菌核病发生。合理密植可提高油菜产量。     

不同碳氮源对青海春油菜菌核病菌菌丝生长及菌核形成的影响

[目的]探讨油菜菌核病菌在外源营养条件下的生物学特性。[方法]以青海高原春油菜菌核病菌为材料,研究了不同碳源和氮源及不同pH对该病菌菌丝生长和菌核形成的影响。[结果]适宜该菌核病菌菌丝生长和菌核形成的碳源分别为可溶性淀粉和果糖,氮源分别为柠檬酸铵和硫酸铵,碳氮比为30∶1,pH范围为6.0～7.0。[结论]为控制和防治油菜菌核病提供了理论依据。     

油菜菌核病轻发生条件下的空间分布格局与抽样技术

通过田间调查,应用聚集度指标法、Iwao法和Taylor幂函数法,研究油菜菌核病的田间空间分布格局和抽样技术.结果表明,油菜菌核病空间分布型总体上呈聚集分布,但聚集程度不高,少量田块呈随机、均匀分布.轻发生时油菜菌核病的空问分布型倾向随机和均匀分布.抽样数量随着发病程度的加重而递减,最适理论抽样模型为n2=103.33/m-0.86,在茎株发病率为轻发生的10％时,每田的理论抽样样方数为103,即1030株.     

用品种抗性和栽培措施防控油菜菌核病的效应研究

油菜菌核病是霍邱县油菜上主要病害。近2a来,笔者结合油菜品种抗性,利用不同播期、种植密度、施肥等栽培措施,进行了物理方法防控油菜菌核病的效应研究。结果表明:(1)品种抗性对油菜菌核病有很强的抑制作用;(2)适时迟播、合理稀植和施肥,在一定程度上能够减轻油菜菌核病的发生程度。     

施肥对油菜菌核病发生的影响

对5个油菜品种,设氮肥(对照、施氮),磷肥(对照、施磷)和钾肥(对照、施钾)试验,分析了氮磷钾肥对油菜产量和菌核病发生的影响.结果表明,施氮油菜平均增产203.7％,菌核病病情指数平均增加17.7％;施磷油菜平均增产47.2％,菌核病病情指数平均下降31.0％;施钾油菜平均增产30.1％,菌核病病情指数平均下降21.9％.分析认为,施氮因病原菌获得更多的营养物质,以及油菜枝繁叶茂提高田间阴湿度致使油菜病害加重;施磷为油菜抗性生理活动提供了物质基础;施钾通过对植株代谢过程的调控和植物形态学的调节提高了油菜对菌核病的抗性.生产上可以通过调控氮肥施用,合理增施磷钾肥,达到既提高油菜产量又有效减轻菌核病危害的目的.     

核盘菌弱毒现象及其生防潜能的研究进展

核盘菌(Sclerotinia sclerotiorum (Lib.) de Bary)因其缺乏抗性资源、寄主广泛、抗药性等原因,在防治上存在极大困难.核盘菌种内存在明显的致病性分化现象,自然界中存在弱致病力菌株.本文对引起核盘菌致病力衰退的RNA病毒(SsDRV)、单链环状DNA病毒(SsHADV-1)和部分没有定性的双链dsRNA因子等真菌病毒进行了归纳;阐述了真菌病毒在病原菌群体中的传播方式;讨论了如何打破菌丝不亲和带来的界限,使得真菌病毒在菌丝间有效地传播,为探索用于核盘菌的生物防治提供新思路.