枯草芽孢杆菌防治大豆菌核病效果初报

本文应用枯草芽孢杆菌ZH-2菌株的发酵菌剂,在桦南县进行了生防菌剂防治大豆菌核病的田间防效试验,结果表明生防菌剂100倍稀释液浸种和喷洒处理对大豆菌核病的田间防效达67.9%。     

利用水稻品种抗性遗传多样性持续控制稻瘟病研究进展

利用作物品种抗性的遗传多样性持续控制作物病害是当今植物病害防治研究与应用的热点。对利用水稻品种抗性遗传多样性持续控制稻瘟病研究的原理、现有研究状况和防病机理进行了较系统的评述。     

稻瘟病大发生情况调查分析

从气候条件、品种方面、单一追求高产等因素分析了稻瘟病大发生的主要原因,并针对上述情况提出了积极主动预防稻瘟病,选择抗病力强的品种,强化旱育“三化”栽培技术普及工作等防治措施,为今后水稻发展提出了可行性建议。     

稻瘟病的发病症状与防治

对世界性的重要稻病之一“稻瘟病”的发病症状进行介绍,然后分析了其发病原理及规律,最后对如何防治稻瘟病提出了几点建议。     

丘陵区水稻品种多样性混合间栽控制稻瘟病研究

在对 2个主栽品种 (生产上推广的当家杂交稻组合 )和 2个间栽品种 (优质感瘟 )进行 RGA遗传背景研究的基础上 ,配成 4个混合间栽组合。经在祁东 (丘陵 )小区试验和示范比较 ,结果都表明品种混合间栽后 ,间栽品种叶瘟的防治效果达 48.86 %～ 79.91% ,穗瘟的防治效果达 12 .38%～ 6 3.5 7% ;混合间栽的主栽品种与净栽主栽品种比较 ,叶瘟和穗瘟的病情严重度差异不大。在产量上 ,混合间栽比净栽均表现出不同程度的增产 ,幅度在 1.5 7%～ 12 .71%。基于本研究结果 ,选择抗瘟性遗传背景差异大 ,株高差异突出的品种以 1行优质稻间 5行主栽品种混合栽培 ,能起到控瘟增产的作用。     

抗稻瘟病水稻培育的新进展

本文介绍了美国农业研究中心化学家Leong与同事们研究破解水稻应对不断演变的致病真菌的天然防御能力,取得了重大进展。发现、确认了水稻新的抗性基因,并进行了克隆。同时研发一种新方法,用于水稻和病原菌的操纵基因,培育抗病性敏感的水稻。     

稻瘟病菌培养基筛选试验

稻瘟病[Pyicularia grisea (Cbode) Sacc．]是水稻一种重要病害,该病菌存在较大的种群变异性,不同的生理小种适宜生长的培养条件有较大的差异。为明确福建省水稻稻瘟病菌优势种群的最适培养条件,进行了不同生理小种稻瘟病菌培养基的筛选试验,现将试验结果总结如下：     

Identification of rice blast disease-suppressing bacterial strains from the rhizosphere of rice grown in Pakistan

Sixteen bacterial strains isolated from the roots and rhizosphere of rice plants growing in saline and non-saline soils from the Shorkot area of Pakistan were tested for their ability to promote plant growth and reduce the incidence of rice blast disease. When applied to the soil, many of the isolated rhizobacterial strains increased seedling growth and/or suppressed rice blast disease in greenhouse-grown plants of the cultivars Super Basmati and Azucena, but each cultivar responded to different subsets of the bacteria. In the cv Super Basmati, increased blast resistance was correlated with the production of siderophores by the rhizobacteria. Several strains inhibited the growth of the causative agent of rice blast disease, the fungal pathogen Magnaporthe grisea, in an in vitro dual culture assay. Direct bioantagonism was correlated with disease resistance in Super Basmati, but not in Azucena, and direct antagonism as a cause for the reduced disease incidence is also unlikely since no epiphytic colonisation of leaves was detected. Rhizosphere colonisation by the bacteria in plants grown in sterile sand was correlated with disease resistance in Super Basmati, but not in Azucena. As well as the differences in strains that protected each cv against blast disease, we also found that there were differences in the ability of some strains to protect plants against blast depending on soil type. Hence, there are complex interactions between rhizobacteria and rice plants with respect to biocontrol of rice blast disease, dependent upon both rice cv and soil type. The identity of strains that promoted high levels of disease protection, including three that performed well across all plant cultivars and growth conditions, was determined by 16S rRNA gene sequencing.     

Effects of rice-water chestnut intercropping on rice sheath blight and rice blast diseases

Both sheath blight and blast are important rice diseases worldwide. The exploration of environmentally sound practices to control these diseases will help to reduce fungicide application. Effects of rice (Oryza sativa) intercropping with water chestnut (Eleocharis dulcis) on rice sheath blight and rice blast disease as well as the extracts of different plant parts and root exudates from water chestnut on pathogens of rice sheath blight (Rhizoctonia solani) and rice blast disease (Magnaporthe oryzae) were investigated using pot experiments and bioassay tests. The results from pot tests showed that rice-water chestnut intercropping system suppressed sheath blight and blast and improved land equivalent ratio (LER). The results from bioassay tests indicated that extracts and root exudates from water chestnut had significant effects to inhibit the expansion of these pathogens. The scales of these inhibitions were time and concentration dependent. The antifungal activities of the extracts from aboveground parts and pulp of water chestnut were significantly higher than the extracts from other parts and root exudates. The water extracts of aboveground parts showed the highest antifungal activity on both pathogens according to EC₅₀ values. The antifungal activities of the same extracts from water chestnut on R. solani were significantly higher than on M. oryzae. The result suggests that water chestnut possesses bioactive substances to suppress rice sheath blight disease and rice blast disease. The rice-water chestnut intercropping system can be used as an environment-friendly method for diseases control in rice field.     

Fighting the enemy:How rice survives the blast pathogen's attack

Global food security is threatened by rice blast disease caused by the filamentous fungus Magnaporthe oryzae. An understanding of rice resistance mechanisms is ...     

Genetic diversity of rice blast fungus in northern China

The characterization of population structure ofblast pathogen contributes to the rational de- velopment and the deployment of blast-resis-tant cultivars.To study the population struc- ture of blast pathogen in northern China,DNA fingerprinting of 192 blast isolates col-lected in 8 representative districts in 1996 wasconducted by using Pot 2-PCR method. Sampling sites and number of haplotypeswere listed in Table.DNA isolation,DNAamplification,and gel running were done as     

Production of D-lactic acid by bacterial fermentation of rice

This study describes the synthesis of D-lactic acid from rice by fermentation using microorganisms. Some micro-organisms were found to be active for producing D-lactic acid of high optical purity after an intensive screening test for D-lactic acid bacteria using glucose as substrate. Rice powder was hydrolyzed with a combination of enzymes:α-amylase,β-amylase, and pullulanase, and the resultant rice saccharificate was subjected to the fermentation with the selected D-lactic acid bacteria. After the optimization of this fermentation it has been confirmed that D-lactic acid can be manufactured in a pilot scale.     

枯草芽孢杆菌B215生物学特性及对香蕉枯萎病的生防效果评价

在室内测定菌株B215对香蕉枯萎病菌菌丝生长和孢子萌发都有良好抑制效果的基础上,优化拮抗菌株的最佳培养条件为:在NA培养基上,装液量为50mL/500mL,最适初始pH值为7.0～7.5,初始接菌量为1%,培养温度为28℃,以便更好地应用于田间试验。以此培养条件为依据,开展拮抗菌株的盆栽小苗实验,选用正交试验L8(27)设计,得出菌株B215对香蕉枯萎病菌的最佳防效组合为:在小苗定植前,用活菌培养液750mL/株浸根,可以降低小区香蕉枯萎病发病率。进一步试验验证结果显示:盆栽试验B215对Foc的防效为62.95%。     

浅谈稻瘟病的发生原因及防治对策

针对通河县水稻稻瘟病发生严重的实际情况,阐述了稻瘟病的发生症状,分析了发病原因,并提出了防治对策。     

巨大芽孢杆菌A6对油菜根系分泌物所含有机酸和糖类的趋化性

应用溶液培养方法采集油菜根系分泌物并研究巨大芽孢杆菌A6对分泌物的趋化性。经高效液相色谱测定,发现油菜根系分泌物中含有7种有机酸和10种糖类。有机酸中琥珀酸含量最高达31.4µg/株;糖类中甘露醇含量最高达7.2µg/株。使用烧杯法和平板趋化法分别测定A6对7种有机酸、10种糖类和油菜根系的趋化性。结果表明,A6对6种有机酸有趋化性,其中对苹果酸的趋化性最强;对8种糖类也有趋化性,其中对山梨醇的趋化性最强;A6对油菜根系也有趋化性。     

酸性土壤改良剂与生防制剂协同防控香蕉枯萎病的效果

将酸性土壤改良剂分别与生防制剂结合,通过温室盆栽试验研究其防控香蕉枯萎病的效果。酸性土壤改良剂分别与放线菌菌剂处理(Act A)和生物有机肥处理(BIOA)的协同防效(61.1%和58.3%)均高于单独施用酸性土壤改良剂(ASA)(49.7%)、放线菌菌剂(Act)(55.6%)和生物有机肥(BIO)的处理(52.8%)。至试验结束时,各处理土壤的p H值显著高于对照(CK)(p0.05);Act和BIO处理显著降低了香蕉根际尖孢镰刀菌数量(p0.05);Act A和BIOA处理能显著提高香蕉根际细菌和放线菌数量并降低真菌数量。各处理显著促进香蕉生长,且能提高土壤有机质、有机碳、全氮、速效钾含量和电导率。结果表明,酸性土壤改良剂和生防制剂可有效协同防控香蕉枯萎病。     

Resistance responses of rice to rice blast fungus after seed treatment with the endophytic Achromobacter xylosoxidans AUM54 strains

In the present investigation, we studied resistance imparted by seed treatment with an endophytic strain of Achromobacter xylosoxidans, AUM54, against rice blast caused by Magnaporthe oryzae. In vitro studies showed that A. xylosoxidans AUM54 was able to inhibit mycelial growth of M. oryzae by 11% and was able to increase rice germination and seedling vigor index of rice by 31 and 114%, respectively. AUM54 also showed better survivability in the spermosphere and spermoplane and was able to move systemically through the roots and stem. Among the evaluated carriers, liquid formulation amended with 2% glycerol sustained the maximum bacterial population (7.4 log cfu ml⁻¹) after six-months-storage at room temperature. Plants treated with A. xylosoxidans AUM54 followed by inoculation with M. oryzae showed a significant increase in the activities of defense related enzymes such as polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL) and chitinase. A. xylosoxidans AUM54 treatment was able to reduce blast disease incidence by 39% in treated rice plants. Additionally, inoculation with A. xylosoxidans AUM54 significantly enhanced the growth (3–13% plant height), and yield (11–31%) of inoculated rice plants under no-disease and disease conditions in the greenhouse experiments.     

稻瘟灵与三乙膦酸铝混剂对稻瘟病的防治效果

分别采用孢子萌发法和菌丝生长法测定了三乙膦酸铝与稻瘟灵5种不同质量配比混剂对稻瘟病菌的毒力。结果表明,不同质量配比的三乙膦酸铝与稻瘟灵混剂都有不同程度的增效作用,其中以三乙膦酸铝与稻瘟灵质量比为1：1混剂的增效作用最为显著,其抑制孢子萌发和菌丝生长的共毒系数分别为203．92和190．24。田间试验结果表明,以40％三乙膦酸铝WP与40％稻瘟灵WP质量比为1：1的混剂（1g·L^-1）对稻瘟病的防治效果最佳,达87．20％,分别比40％三乙膦酸铝WP（2．86g·L^-1）和40％稻瘟灵WP（1．25g·L^-1）单用的防治效果提高14．40％和12．28％。