Localization of metabolic sites of action of herbicides

Time- and concentration-course studies were conducted to determine the effect of thirteen herbicides on photosynthesis, respiration, RNA synthesis, protein synthesis, and lipid synthesis using isolated single leaf cells. Each herbicide was from a different chemical class. Appropriate ¹⁴C-substrates and product purification procedures were used for each process prior to liquid scintillation counting. The most sensitive metabolic site of inhibition was photosynthesis for atrazine, bromacil, dichlobenil, monuron, and paraquat; RNA synthesis for dalapon and dinoseb; protein synthesis for chlorpropham; and lipid synthesis for CDAA, chloramben, 2,4-D, EPTC, and trifluralin. However, with several herbicides, one or more process was almost as sensitive as the one mentioned above. All herbicides inhibited more than one process, and the most sensitive site of inhibition may not be the same process that was inhibited the greatest at the maximum concentration and maximum exposure time used. Therefore, a concept of metabolic sites of action, rather than a primary site of action, appears to be more meaningful for herbicides.     

百合地下害虫主要种类调查及生物（源）农药筛选

调查了甘肃省临洮县为害百合的地下害虫种类, 并以主要发生为害种类为供试对象, 采用拌土法测定了几种生物（源）农药对主要害虫的室内毒力和致死中时。调查发现小云斑鳃金龟Polyphylla gracilicornis、棕色鳃金龟Holotrichia titanis为主要发生及为害种类, 不同时间发生种类存在差异, 9月份以小云斑鳃金龟幼虫发生为害为主, 发生量占地下害虫总数的66.16%, 平均种群密度为10.48头/m2, 10月份, 则以棕色鳃金龟幼虫发生为主, 发生量占地下害虫总数的96.86%, 平均种群密度为7.79头/m2, 主要取食百合根系和鳞茎, 造成根系数量减少, 鳞茎出现不规则褐色缺口或凹陷斑。药剂筛选结果表明, 1.8%阿维菌素乳油、200亿孢子/g球孢白僵菌粉剂对两种蛴螬均具有较高的杀虫活性和速效性, 药后7 d时, 校正死亡率在82.22%以上, 对小云斑鳃金龟幼虫和棕色鳃金龟幼虫的LC50分别为0.161、0.060 mg/g和5.558×107、0.362×107孢子/g, LT50分别为2.237 d（2.2 mg/g）、1.393 d（2.2 mg/g）和6.645 d（40.0×107孢子/g）、4.940 d（2.0×107孢子/g）, 这两种生物（源）农药对两种蛴螬的LC50和LT50值均略大于两种化学农药25%二嗪磷乳油、40%辛硫磷乳油处理的, 且对小云斑鳃金龟幼虫的杀虫活性均低于对棕色鳃金龟幼虫的杀虫活性, 致死中时则长于对棕色鳃金龟幼虫的致死中时。     

土壤环境因素对棉花黄萎病菌微菌核存活的影响

 试验研究了土壤温度、湿度、pH值和有机质对棉花黄萎病菌微菌核存活的影响。结果表明:40、30和0℃对微菌核土壤存活影响较大,10和20℃影响较小,尤其以10℃影响最小;土壤含水量越高,对微菌核存活影响越大,在含水量低于15%时,对存活影响较小,尤其以5%的含水量影响最小,表明微菌核对土壤干旱逆境具有较强的抵抗能力;pH值低于5.5或高于8.5的土壤条件对微菌核存活影响较大,pH值为6.5~7.5影响较小;土壤有机质含量越高,微菌核存活率越低,含量低,存活率高。本研究结果表明,只要改善和控制棉花黄萎病菌土壤存活的生态条件,就可以有效地减少土壤存活菌量,达到控制病害发生与发展的目的。     

Evaluation of Likelihood of Co-Occurrence of Erwinia amylovora with Mature Fruit of Winter Pear

ABSTRACT Phytosanitary concerns about fire blight prohibit export of U.S.-grown pears to some countries without this disease. To examine these concerns, we evaluated the potential for co-occurrence of Erwinia amylovora with mature, symptomless winter pear fruit by inoculation experiments and by survey of commercial orchards. Immature pear and apple fruit were inoculated in orchards with E. amylovora strain 153N as resuspended lyophilized cells or as ooze from diseased tissues. Regardless of inoculum source, population size of Ea153N on fruit declined by an order of magnitude every 3 to 4 days during the first 2 weeks after inoculation; at 56 days after inoculation, Ea153N was not detected, except on 1 of 450 fruit with 4 colony forming units (CFU). After inoculation of flowers, calyx-end survival of Ea153N on pear and apple fruit declined from high populations at petal fall to a few cells at harvest, with no detection of the pathogen after a 7-week cold storage. Migration of Ea153N into symptomless pear fruit from diseased branches was evaluated by enrichment assay and nested polymerase chain reaction of internal fruit core tissues; these assays failed to detect the pathogen in healthy fruit from diseased trees. At harvest, E. amylovora could not be detected on 5,599 of 5,600 fruit of d'Anjou pear sampled from commercial orchards in major production areas of the Pacific Northwest; one fruit yielded 32 CFU of the pathogen. Postharvest, mature pear fruit contaminated with Ea153N and subsequently wounded required a dose of >10,000 cells at the wound site to allow for persistence of the pathogen through a 7-week-cold storage. We conclude that epiphytic E. amylovora shows similar survival characteristics on both pear and apple fruit, this pathogen is not an endophyte within mature symptomless pear fruit, its presence is exceptionally rare on commercially produced fruit, and that epiphytic survival of E. amylovora through a postharvest chilling period is unlikely given the unrealistically high population size required for persistence.     

十种藓类植物茎的比较解剖学观察

利用石蜡切片的方法 ,对十种藓类植物 ,钝叶蓑藓 (Macromitriumjaponicum Doz.et.Molk .)、疏齿墙藓〔 Tortulanorvegica(Web .)Wahl.exLindb .〕、岸生连轴藓〔 Schistidiumrivularis(Brid .)Podp .〕、树形疣灯藓〔Trachycystisussuriensis(MaacketRegel )T .Kop .〕、齿边缩叶藓〔 Ptychomitriumdentatum(Mitt.)Jaeg .〕、山羽藓〔 Abietinellaabietina(Hedw .)Fleisch〕、东亚万年藓 ( Climaciumjaponicum Lindb .)鼠尾藓〔 Myurocladamaximowiczii(Borszcz)SteeretSchof.〕、卷叶凤尾藓 (FissidensdubiusP .Beauv .)及二形凤尾藓 (FissidensgeminiflorusDoz .etMolk .)的茎横切面的解剖观察结果表明 :茎的形状、中轴细胞的有无、形状及所占的比例、外皮部厚壁细胞的层数等特征因种类不同而有明显差异 ,可以作为分类依据之一。外皮部厚壁细胞的层数可能与藓类植物的生境有关。     

嘧啶胺类杀菌剂的作用机制

本文介绍了几种嘧啶类杀菌新品种（ｐｙｒｉｍｎｅｔｈａｎｉｌ，嘧菌胺ｍｅｐａｎｉｐｙｒｉｍ，ｃｙｐｒｏｄｉｎｅｌ）的作用机制，该类药剂在离体条件下对病菌的抗菌性很弱，但用于寄主植物上却表现很好的防治效果，该类药剂能抑制病菌甲硫氨酸的生物合成和细胞壁降解酶的分泌，从而影响病菌侵入寄主植物。     

极旱环境中两种梭梭蒸腾的生理生态学特点

白梭梭(Haloxylon persicum)和梭梭(H.ammodendron)是我国干旱荒漠区的优良固沙植物,列入我国第一批保护植物,白梭梭主要分布在新疆北部的古尔班通古特沙漠,梭梭除了分布在新疆外,还分布在青海、甘肃、内蒙古等地,对于它们的生物生态学特性的研究,国内已先后做过不少工作,关于生理方面的研究也有报导。本项工作是从水分生理观点着手,结合     

甘肃省重点城市环境管理地理信息系统开发研究

探讨了采用GIS软件ArcView的开发语言Avenue所开发的甘肃省重点城市环境管理地理信息系统的分析与设计、功能结构和系统应用等。该系统将为城市环境管理提供高效、科学的信息支持,从而提高城市环境管理与治理的水平。     

杀虫剂混合使用的增效作用评判分析

用共毒因子重新评价共毒系数大于100的281个混配组合,发现有29.18%的混配组合没有增效作用。根据单剂的LC-P线和共毒因子公式,求出混剂的期望死亡率和"相加作用区间"(期望死亡率±20%期望死亡率),根据混剂的实测死亡率求出95%置信区间,画出期望LC-P线及"相加作用区间"和实测LC-P线及"95%置信区间",发现当共毒系数大于100、共毒因子小于20时,实测LC-P线和期望LC-P线彼此交缠,期望LC-P线的"相加作用区间"和实测LC-P线的"95%置信区间"能高度重叠,表明两条LC-P线之间没有毒力差异;当共毒系数大于100、共毒因子大于20,或者共毒系数小于100、共毒因子小于-20时,实测LC-P线的"95%置信区间"和期望LC-P线的"相加作用区间"只有少量重叠或完全不重叠,体现出了实测LC-P线和期望LC-P线对供试害虫的毒力差异。因此,为了获得有稳定增效作用的混配组合,共毒系数须大于100,同时共毒因子也要大于20。     

蠋蝽成虫对草地贪夜蛾不同龄期幼虫的捕食能力

为了探究蠋蝽Arma chinensis(Fallou)对草地贪夜蛾Spodoptera frugiperda(J.E.Smith)的生防潜力,在室内条件下测定了蠋蝽成虫对草地贪夜蛾3、4、5龄幼虫的捕食能力。结果表明:雌性成虫对草地贪夜蛾3、4、5龄幼虫的日最大捕食量分别为59.7、23.4、9.0头;瞬时攻击率分别为1.081±0.133、1.247±0.116、0.984±0.159;处理时间分别为(0.017±0.001)、(0.043±0.002)、(0.111±0.014)d。雄性成虫对草地贪夜蛾3、4、5龄幼虫的日最大捕食量分别为58.9、22.5、8.3头;瞬时攻击率分别为0.964±0.118、1.248±0.095、1.025±0.183;处理时间分别为(0.017±0.002)、(0.044±0.002)、(0.121±0.015)d。蠋蝽成虫对草地贪夜蛾3、4、5龄幼虫都能捕食,对3龄幼虫捕食量最大,最喜欢捕食4～5龄幼虫,雌雄成虫都对4龄幼虫的瞬时攻击率最高。试验证实蠋蝽对草地贪夜蛾具有较好的控害效果,可用于对草地贪夜蛾的防控实践。     

Mode of action of etoxazole

The mode of action of the 2,4-diphenyl-1,3-oxazoline acaricide/insecticide etoxazole has been argued to be moulting inhibition, but experimental results supporting this hypothesis are lacking. This study investigated the effect of etoxazole on chitin biosynthesis in the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). Etoxazole induced moulting defects in fall armyworm larvae similar, if not identical, to those caused by benzoylphenylureas, a well-known class of insecticidal chitin biosynthesis inhibitors. Furthermore, in contrast to untreated larvae, the chitin content in the integuments of larvae several days after treatment did not differ from that in freshly ecdysed individuals, thus suggesting strong chitin biosynthesis inhibition in vivo. A more detailed investigation of the inhibitory potential by incubating cultured integument pieces from larvae of S. frugiperda with [14C]N-acetyl-D-glucosamine, a radiolabelled chitin precursor, revealed I50 values of 2.95 and 0.071 microM for etoxazole and triflumuron respectively. The incorporation of radiolabel into potassium hydroxide-resistant material was inhibited by etoxazole in a dose-dependent manner. Based on these results, it is concluded that the acaricidal and insecticidal mode of action of etoxazole is chitin biosynthesis inhibition.     

图们江干流区间流域径流变化特征

以图们江干流区间为研究对象，应用Mann-Kendall非参数检验法分析干流区间4个水文站点径流年际与年内变化趋势。在此基础上，采用R/S分析方法分析年径流、季节径流和月径流变化趋势在未来的可持续性，利用Mann-Kendall突变检验方法分析各水文站点年径流、季节径流和月径流发生突变的年份。结果表明：图们江干流区间各水文站径流年际和年内变化趋势均与干流径流变化趋势一致，呈下降趋势，非汛期径流下降的贡献主要来自春季和冬季径流的下降；Hurst指数表明，上游径流变化趋势的持续性最强，下游的持续性相对较弱；1985年是图们江干流区间年径流发生突变的年份，且降水量也发生了变化，可以推测降水量可能是径流不断减少的重要因素。     

陕北地区水资源可持续利用评价

以水资源复合系统为基础,建立了陕北地区水资源可持续利用评价指标体系,应用模糊综合评判方法和人工神经网络方法对该地区1996~2005年的水资源可持续利用水平进行了定量评价。结果表明:陕北地区除本身干旱缺水以外,水污染、生态环境恶化、用水效率低和经济水平不高是影响该区水资源可持续利用的主要因素;1996~2005延安市和榆林市的水资源可持续利用水平均处于较弱和中等之间,且呈上升趋势,提高陕北地区水资源可持续利用水平有很大潜力。     

Systems of designation of pathotypes of plant pathogens12

A variety of systems of designation has evolved to name pathotypes of plant pathogens. The systems were evaluated to determine those best suited for particular purposes. Virulence and avirulence/virulence formulae of pathotypes have advantage over the use of consecutive numbers or letters given in chronological order of pathotype discovery. As soon as pathotype information exceeds a certain level of complexity, mathematical codes are most advantageous, in particular two codes, octal notation and coded triplets. A more universal adoption of the most appropriate codes is recommended to ease communication and comparisons of results.     

定西地区农业生态经济系统的结构和功能分析

分析了定西地区农业生态经济系统的结构和功能 ,发现水资源时空分布不均 ,种群结构比较单一 ,产业结构不合理 ,使得系统生产能力很低 ,N、P、K不平衡 ,经济效益低下。据此从农业可持续发展的角度出发 ,提出了优化农业生态经济系统结构和提高其功能的对策和建议。     

Determination of the products of surface-induced hydrolysis of organophosphorus pesticides

A procedure which enables the identification of the hydrolysis products of a number of phosphoric and phosphorothioic esters was developed. This procedure, which includes thin-layer chromatography (t.l.c.), gas chromatography and u.v. spectroscopy, has been used to demonstrate that surface hydrolysis on kaolinite is a general property of bioactive phosphoric and phosphorothioic esters. The path of hydrolysis was shown to be the breakage of the P? O A or P? SA bond, where A is the electron attracting moiety of the organic molecule.     

厚朴病虫害种类的初步调查

采用标准地法和线路调查法,对湖北恩施市新塘乡双河厚朴基地的厚朴病虫害进行了系统调查,记录主要虫害13种,其中叶部害虫9种,枝干害虫2种,根部害虫2种。厚朴主要病害5种。藤壶蚧、厚朴枝角叶蜂和厚朴新丽斑蚜为湖北省首次报道,小绿叶蝉为厚朴新寄主记录种。同时记录了藤壶蚧的天敌6种,其中寄生小蜂2种,瓢虫4种;厚朴新丽斑蚜的天敌昆虫8种。对藤壶蚧、厚朴枝角叶蜂和厚朴苗木根腐病等重要病虫害的发生规律进行了初步调查,同时提出了防治建议。     

新疆地衣植物研究历史回顾

本文根据作者１９８５年以来在新疆地衣的研究工作，特别是１９９１年申请到国家自然科学基金课题以后所作的研究工作的基础上，比较前人所做的工作而写出的回顾型论文。标本采集点共计４０个，包括阿尔泰山、天山、昆仑山等山脉，共采集六千多号标本，经过处理鉴定初步定名地衣植物有２６９种，２６５种隶属于８目，３０科，８５属，另半知菌类４属，４种。新疆地区已定名地衣种，主要系泛北极植物区系成分，包括欧、亚森林植物亚区     

禾谷类作物細菌性褐条病病原菌的鉴定

 禾谷类作物细菌性褐条病是我国局部地区禾谷类作物生产上的一种重要病害。通过对几种有关细菌的致病性,细菌学性状和DNA中G+C含量的比较研究,认为发生在我国的水稻细菌性褐条病是由Pseudomonas avenae Manns引起的,供试的黍、粟和稗细菌性褐条病菌都属于P.avenae;小麦上的细菌性褐条病是由Pseudo-monas syringae的一个致病变种引起的。此外,还从看麦娘上分离到一种国内尚无报道的水稻细菌性鞘褐腐病菌Pseudomonas fuscovaginae Tanil et al.。     

甲基硫菌灵标样的制备

本文介绍了用进口甲基硫菌灵样品，采用溶剂萃取，高速离心，重结晶，高效液相色谱，红外光谱等分析方法进行系统分离与鉴定，得到其标样的方法。