玉米大斑病菌人工接种方法研究

 The efficient and accurate method of inoculating Exserohilum turcicum on maize is most important for studying the corn leaf blight. In this study, four approaches including spore suspension spraying, inoculation with grinding infected maize leaves, inoculation liquid inoculum into the leaf whorl and inoculation with inoculated sorghum seeds were compared with natural induction in fields during different growth stages of maize in the greenhouse and field. The results showed that disease incidence of all varieties tested were up to 100% by inoculating with inoculated sorghum seeds during the booting stage (11 to 12 leaf stages). This method will not only guarantee the enough pathogen inocula but also be easy to use, and could be an effective way for disease resistance identification in field and greenhouse.      

Miniaturized methods for testing the toxicity of pesticides to microorganisms

A minialurized method of determining the toxicity of pesticides to large numbers or soil mitroorganisms is described. Bacteria. actinomycetes, yeasts, fungi and algae can be used as test organisms. A modification of the method allows determination of minimum inhibitory concentrations of pesticides to specific microorganisms. Some results obtained with herbicides are presented. Microméthodex pour éprauver la toxicité des pesticides vis-á-vis des micro-organismes Une micromethode pour determiner la toxicité des pesticides vis-á-vis de nombreux micro-organismes du sol est décrite. Des bactéries. des actinomycetes, des levures. des champignons et des algues peuvent ëtre utilisés comme organismes-tesis. Une modifitation de la méthode permel les determinations des concentrations minimales inhibitrices des pesticides vis-á-vis des micro-organismes specifiques. Quelques resultats obtenus avec des herbicides sont présentés. Miniaturisierte Methoden zur Prüf'ung der Toxizitüt von Pflan- zenhehandlumgsmit teln auf Mikraorganismen Es wird einc miniaturisierte Methode zur BestimmungderToxi- zität von Pfianzenbehandlungsmitteln für groβe Zablen von Bodenmikroorganismen beschrieben, Als Testorganismen können Bakterien. Actinomyceten. Hefen, Pilze und Algen benutzi werden. Eine Modifizierung der Methode gestattet die Bestimmung der Minimum-Hemmkonzentration von Pflanzen- behandlungsmitteln auf spezielle Mikroorganismen. Einige Ergebnisse, die mit Herbiziden erarbeitel wurden. sind darge-stellt.     

玉米纹枯病的发生特点及综防策略

玉米在我省已经成为粮、饲、经兼具的重要作物。近年,随着玉米种植密度的增加,施肥水平的进一步提高,以及玉米生长盛期适逢阴雨天气,田间湿度大,为玉米纹枯病的发生和流行创造了条件,菌源不断累积,发病有逐年加重趋势,已经成为影响玉米生产的主要病害,常发区产量损失达     

小麦纹枯病的发生与防治技术

小麦纹枯病(Pellicularia gramineum Ikata et Matsmura)是一种土传病害.在我国各麦区均有发生.近年来,该病在我市发生逐年加重,特别是小麦-水稻、小麦-玉米连作田发病面积大、为害重.一般田块病株率40%～70%,减产10%～20%.重病地病株率100%,减产达30%以上.目前小麦纹枯病已上升为我市春季麦田一大病害,成为制约小麦高产稳产的重要因素.因此,认识和掌握小麦纹枯病的发病因素及防治对策,对提高小麦的产量,增加农民的经济效益有着重要的意义.     

作物土传病害的危害及防治技术

近20年来,保护地在中国有了较大的发展,而保护地的发展和作物的连年栽培,导致土传病害和根结线虫发生越来越重,连续栽培3~5年后,作物产量和品质受到严重的影响,已成为生产中的突出问题。本文简述了我国重要作物如玉米、小麦、棉花、大豆、油菜的土传病害种类,以及高附加值作物黄瓜、番茄、茄子、辣椒、瓜类等作物的土传病害种类和20年来的变化。介绍了土传病害的防治方法,如农业防治包括轮作、抗性品种、嫁接、有机质补充、生物熏蒸、厌氧消毒;物理防治技术如太阳能消毒、蒸汽消毒、热水消毒、火焰消毒;化学防治技术如氯化苦、棉隆、威百亩、二甲基二硫、异硫氰酸烯丙酯、硫酰氟;生物防治技术如木霉、枯草芽胞杆菌、荧光假单胞菌、植物促生菌,以及预防为主的综合防治技术。种子、种苗消毒技术在本文中也进行了介绍。     

人工接种对新月弯孢菌侵染玉米籽粒的影响

研究了人工接种不同接种时期和方法对新月弯孢菌侵染玉米籽粒的影响,结果表明:玉米弯孢叶斑病菌可以侵染玉米果穗籽粒,使玉米籽粒产生褐色病斑。伤口接种法能使玉米果穗100%发病;花丝通道接种也可导致果穗发病,但其发病频率很低;而花丝喷雾接种和苞叶喷雾接种病菌不能成功侵染玉米果穗籽粒;吐丝后10 d和乳熟期接种只能引起接种点籽粒发病,病菌扩展不好;但籽粒形成期接种的玉米果穗籽粒不仅接种点发病,而且其周围的籽粒也感染了病菌,病菌扩展情况较好。试验明确,玉米籽粒形成期采用伤口接种是使玉米籽粒发生弯孢叶斑病的一种较为理想的人工接种方法。     

玉米禾谷镰孢茎腐病和穗腐病抗性鉴定接种方法的比较

田间采用不同人工接种鉴定方法对92份玉米种质同步进行玉米禾谷镰孢茎腐病和穗腐病抗性评价与筛选, 明确了东北春玉米产区玉米禾谷镰孢茎腐病?穗腐病抗性鉴定的最佳接种方法:茎节注射法在玉米禾谷镰孢茎腐病抗性精准鉴定中可更好地评价玉米种质的抗病性, 综合考虑接种方法的实用性和可操作性, 菌土覆盖法对大体量的规模化种质进行田间抗病性鉴定更具有优势; 双牙签法对玉米穗腐病抗性鉴定中在种质接种后发病的严重度?田间进行接种的可操作性和实用性等方面均优于花丝通道法?同时筛选出对玉米禾谷镰孢茎腐病抗性稳定的种质52份, 对穗腐病抗性稳定的种质66份, 对2种病害均表现稳定抗性的兼抗种质33份?     

甘薯根腐病抗病性室内鉴定方法的研究

将PDA 平面培养的甘薯根腐病菌研磨成浆,按一定比例加入蛭石中,接菌最适浓度为每200 g蛭石加1/ 2 培养皿菌浆,随后栽入薯苗,在25 ℃下培养25 ～30 d 后检查。以薯苗叶片枯黄程度及根部黑根死根多少划分病级,以病级平均数确定品种抗性,同时对抗感品种接种根腐病菌后过氧化物酶活性进行测定。试验证明,上述方法可以简便、快速、准确地测定品种对根腐病的抗性,同时也证明过氧化物酶活性作为量化分级标准的可行性。     

甘薯根腐病抗病性室内鉴定方法的研究

将PDA 平面培养的甘薯根腐病菌研磨成浆,按一定比例加入蛭石中,接菌最适浓度为每200 g蛭石加1/ 2 培养皿菌浆,随后栽入薯苗,在25 ℃下培养25 ～30 d 后检查。以薯苗叶片枯黄程度及根部黑根死根多少划分病级,以病级平均数确定品种抗性,同时对抗感品种接种根腐病菌后过氧化物酶活性进行测定。试验证明,上述方法可以简便、快速、准确地测定品种对根腐病的抗性,同时也证明过氧化物酶活性作为量化分级标准的可行性。     

Chemical control of soil-borne pathogens in tuff medium for strawberry cultivation

The phytopathogenic fungi Fusarium oxysporum f. sp. lycopersici and Rhizoctonia solani were completely eradicated after exposure for 30 min to a 0.4-0.5 % aqueous solution by weight of formaldehyde. With metham-sodium, higher concentrations or longer exposures were needed to obtain similar results. When tested in tuff (a granular plant growth medium of volcanic rock origin), the toxicity of formaldehyde was lower and that of metham-sodium was higher, compared with the corresponding toxicities in aqueous solutions. Both fungicides eradicated the two fungi, as well as Pythium myriotilum, when tested under practical conditions in vertical aluminium tubes filled with tuff. No detrimental effect could be observed on strawberry plants subsequently grown in these columns.     

Crab apple blossoms as a model for research on biological control of fire blight

ABSTRACT Nonseasonal availability of pomaceous flowers could improve laboratory detection and prefield testing of biocontrol agents for fire blight of pear and apple. Crab apple was selected as a model because of its high flower productivity on 1-year-old wood, high susceptibility to fire blight, and availability from nurseries. Cultivars Manchurian and Snowdrift were manipulated to bloom once by transferring dormant nursery trees from a cold room to a greenhouse and a second time by defoliating trees and applying 1% cytokinin and 0.1% gibberellins to the buds with a brush. Different sets of trees were induced at different times to bloom, so that flowers were produced 12 months in the year. When known bacterial antagonists (Erwinia herbicola strain C9-1 and Pseudomonas fluorescens strain A506) were applied alone or in combination to the stigmas of detached crab apple blossoms prior to inoculation with the pathogen (E. amylovora strain Ea153), population interactions over time were comparable to those reported in previous studies involving pear or apple. In a subsequent series of experiments, the relative effects of 12 bacterial strains on stigmatic populations of strain Ea153 were similar for detached blossoms of crab apple in the laboratory, blossoms of intact crab apple trees in the greenhouse, and blossoms of pear and apple in the field. Additionally, when stigmas of detached crab apple blossoms were inoculated with antagonists (strains C9-1 and A506) and the pathogen, and later subjected to a 24-h wetting period, bacterial populations in the flower hypanthium increased and disease was suppressed. These studies indicate that crab apple blossoms can serve as a suitable model for year-round evaluation and study of biocontrol agents for fire blight.     

两种人工接种方法鉴定RNA干涉介导的转基因玉米对矮花叶病的抗性

本研究采用两种人工接种方法,以玉米成株期病情指数为指标,鉴定了63个转基因玉米株系的田间抗病性。结果表明,T4代转化株系‘47’和‘13h2-3’的抗病性达R抗级,超过抗病对照‘H9-21’。有82.5%(52/63)的转基因株系抗病性比未转化对照显著提高,表明用反向重复的RNA干涉表达载体转化玉米,可获得转基因抗病毒材料,且干涉片段适度延长可增加获得抗病材料的几率。另外,本文通过两种病毒接种方法的比较,发现采用玻璃纤维刷苗床穿刺接种比常规石英砂摩擦接种具有更小的误差。     

Symptoms and signs of banded leaf and sheath blight of maize

Apart from the development of lesions with characteristic bands on leaves and sheaths, some rarely observed symptoms and signs of the disease incited byRhizoctonia solani Kühn f. sp.sasakii Exner in maize (Zea mays) were recorded. The occurrence of stalk lesions (rind spotting), stalk breakage, clumping and caking of styles (silk fibers), horseshoe-shaped lesions with banding on caryopses; and sclerotial formation on styles, glumes, cupules and caryopses, are described for the first time. The blemishes on the caryopses are sufficient for diagnosis of the disease, as kernel rots incited by other fungi do not produce such disfiguration.     

The undiscovered potential of dehydroproline as a fire blight control option

The non‐protein amino acid 3,4‐dehydro‐l ‐proline (DHP) significantly reduced the incidence of fire blight infection on immature pear fruits infected with wildtype Erwinia amylovora. DHP also inhibited biofilm formation in both streptomycin‐sensitive and ‐resistant strains of E. amylovora and induced dispersal of preformed biofilms in the streptomycin‐sensitive strain. The investigations shed light on the hitherto undiscovered ability of DHP to inhibit bacterial biofilms and its potential as a chemical control option for fire blight.     

Improved method for assaying maize plant resistance to maize rough dwarf disease by artificial inoculation and real-time RT-PCR

The study of maize rough dwarf disease (MRDD) and breeding for resistance requires inoculation of maize plants by means of planthoppers. The plant age, insect density and inoculation duration are main factors in the success of maize rough dwarf disease inoculation. These parameters were tested using a susceptible maize inbred line Ye478. Using one or two-leaf plants, 15 planthoppers per plant and a five day inoculation duration, the line Ye478 was the most susceptible with 100% diseased plants; F112132 was moderately susceptible with 60% diseased plants and 90110 and F022411 were resistant without any disease. The results were consistent with those from six years of field studies. Using enzyme-linked immunosorbent assay (ELISA) and real-time quantitative RT-PCR, rice black-streaked dwarf virus was detected in severely diseased plants. The plants were rated from 0 to 3 according to their symptoms at the time of flowering. Plants scoring 0, 1 and 2 could not be distinguished by ELISA, only by real-time quantitative RT-PCR. All of the plants with a score of 3 were positive by ELISA and real-time quantitative RT-PCR. The significant differences in the average viral contents in plants with different symptom ratings could be distinguished by using real-time RT-PCR.     

玉米纹枯病研究进展

玉米纹枯病已成为我国玉米生产上一种重要病害,且有逐年加重的趋势。本文系统介绍了玉米纹枯病症状、病原菌、致病机理、发病规律、防治措施以及玉米纹枯病抗性遗传等方面的研究进展,并从实际出发,提出了抗玉米纹枯病育种的分子标记辅助选择策略。     

苹果3种常见潜叶蛾的识别与防治

本文描述了苹果上常见的3种潜叶蛾金纹细蛾（Phyllonorycter ringoniella)、旋纹潜蛾（Leucoptera malifoliella）和银纹潜叶蛾（Lyonetia prunifoliella）的鉴别特征,附有识别特征图,并依据生物学特性提出防治措施。     

Node inoculation: A quick and easy technique to screen pigeonpea for resistance to Phytophthora blight

The petiole on pigeonpea was removed for easy, precise inoculation of node with Phytophthora drechsleri f. sp. cajani. After node inoculation, 96.0% plants were infected compared with 89.0% after stem-cut inoculation. Among various nodes inoculated on 30-day-old plants, the 5th node had the greatest relative susceptibility (90.0%), followed by the 3rd node (78.0%). This technique was validated on different cultivars (ICP 7119, Bahar, MA 6 and MAL 13), and 586 lines were successfully screened in the field, confirming the rapidity and effectiveness of the technique for resistance screening.     

不同侵染时期对小麦赤霉病发生和籽粒中DON积累的影响

为明确不同侵染时期对小麦赤霉病发生和籽粒中DON的积累情况,在2015年和2016年于河南省焦作市温县黄庄镇西虢村田间进行小麦(‘豫保1号’和‘周麦18’)不同生育期接种对病穗率、病情指数、病粒率和籽粒中DON毒素积累的影响试验。结果表明:小麦赤霉病菌在抽穗盛期(DAA=-6,Zadoks=55～57)至灌浆中期(DAA=14或15,Zadoks=75)都能侵染麦穗,但在始花期前3～4 d的齐穗期(DAA=-3或-4,Zadoks=59)至始花期后4 d的灌浆初期(DAA=4,Zadoks=71)处理的病穗率、病情指数和病粒率显著高于其他处理(P0.05),其中盛花末期(DAA=1,Zadoks=69)处理的侵染率最高,为小麦赤霉病菌侵染发病的关键生育期。此外,在套袋保湿2 d的条件下赤霉病菌在小麦始花期前6 d的抽穗盛期(DAA=-6,Zadoks=55～57)和始花期后10 d的乳熟期(DAA=10,Zadoks=73)也能有较高的侵染率。在籽粒中DON积累方面,‘豫保1号’所有处理的籽粒中DON含量与病穗率、病情指数和病粒率的趋势一致,都是盛花末期(DAA=1,Zadoks=69)处理的籽粒中DON含量最高(P0.05),且间隔时间离盛花末期(Zadoks=69)越近籽粒中DON含量越高;而‘周麦18’齐穗期(DAA=-4,Zadoks=59)至灌浆中期(DAA=14,Zadoks=75)处理的没有显著性差异,说明小麦赤霉病菌在始花期后14 d的灌浆中期侵染也能引起籽粒中DON的大量积累。     

3种地膜在不同覆膜方式下的控草效果及对玉米生长发育的影响

在陇东旱塬区杂草严重发生条件下,试验测定了3种地膜在不同覆膜方式下的控草效果及对玉米生长发育的影响。结果表明,化学除草地膜和黑色地膜以全膜双垄沟播、半膜平作和半膜垄作方式覆膜,对阔叶杂草的株防效和鲜重防效均在93%以上,对禾本科杂草的株防效和鲜重防效均在76%以上;白色地膜以半膜垄作和半膜平作方式覆膜对阔叶杂草有一定的控制作用,但对禾本科杂草作用微弱或无效,以全膜双垄沟播方式覆膜可引起杂草大量发生。化学除草地膜和黑色地膜以全膜双垄沟播方式覆膜,均可明显改善玉米主要农艺性状,显著提高玉米产量及效益,玉米产量较半膜垄作分别增产22.17%和24.78%、较半膜平作分别增产9.23%和5.74%,纯收益较半膜垄作分别增加3 553.13元/hm~2和3 828.78元/hm~2、较半膜平作分别增加1 343.46元/hm~2和736.30元/hm~2;白色地膜以全膜双垄沟播、半膜平作和半膜垄作方式覆膜,玉米主要农艺性状、产量及经济效益均较覆盖化学除草地膜和黑色地膜有明显下降。因此,在杂草严重或较重发生的地区,推荐采取化学除草地膜和黑色地膜全膜双垄沟播方式覆膜。