Major Changes in Fusarium spp. in Wheat in the Netherlands

The re-emergence of fusarium head blight throughout the world and especially in Western Europe prompted a survey of the situation in the Netherlands. To allow for a high throughput screening of large numbers of samples, a diagnostic PCR method was developed to detect the most common species of Fusarium occurring on wheat. Seven primer pairs were tested for their ability to identify isolates of Fusarium avenaceum, F. culmorum, F. graminearum, F. poae, F. proliferatum and Microdochium nivale var. majus and M. nivale var. nivale. Each primer pair only generated a PCR product with the corresponding Fusarium species and all PCR fragments had different molecular sizes. This allowed the generation of these amplicons using a mixture of all seven primer pairs. The robustness of this multiplex PCR encouraged us to screen a large series of isolates collected in 2000 and 2001. In both years 40 fields were sampled leading to a collection of 209 isolates from 2000 and 145 isolates from 2001. The results of the multiplex PCR demonstrated that F. graminearum was the most abundant species in the Fusarium complex on wheat in both years. This is in sharp contrast to reports from the 1980s and early 1990s, which found F. culmorum as the predominant species. Primers derived from the tri7 and tri13 genes, which are implicated in the acetylation and oxygenation of the C-4 atom of the backbone of the trichothecene molecule, were used to discriminate between deoxynivalenol and nivalenol (NIV) producers. The populations of F. culmorum and F. graminearum both showed a slight increase in NIV-producers in 2001.     

真菌甲硫氨酸生物合成途径研究进展

 甲硫氨酸是蛋白质的重要组分,同时还可通过生成S-腺苷甲硫氨酸（SAM）调控细胞内多种生理过程。本文根据酿酒酵母、粗糙脉孢菌和构巢曲霉3种模式真菌中甲硫氨酸生物合成的最新研究进展,勾画出真菌的甲硫氨酸合成途径,综述了该途径中关键酶的生物学功能,探讨了该途径的调控机制,为病原真菌甲硫氨酸合成的研究提供理论基础,同时为新杀菌剂的研发提供新思路。     

我国苜蓿病害研究进展

综述了我国苜蓿主要病害的分布和危害、病原学、发生规律、抗性种质材料的遗传筛选和鉴定及综合防治等方面的主要研究进展,并提出了今后的研究方向和发展目标。     

昆虫组蛋白修饰的研究进展

组蛋白修饰作为表观遗传修饰的一种主要形式,对基因表达和表型调控具有重要作用。组蛋白修饰的N端尾区可通过乙酰化、甲基化、磷酸化等修饰来改变染色质的状态以及调控基因的表达。与脊椎动物相比,昆虫种类繁多,且有变态发育、表型复杂等特征,可以成为探索动物社会行为、发育调控和毒理作用等表观遗传基础的模型。本文总结了昆虫组蛋白修饰的主要类型（乙酰化和甲基化修饰）及修饰酶的研究进展,对染色质免疫共沉淀测序技术（chromatin immunoprecipitation followed by sequencing,ChIP-seq）、染色质转座酶可及性测序技术（assay for transposase-accessible chromatin with high-throughput sequencing,ATAC-seq）、转录组测序技术（RNA-seq）、组蛋白修饰酶功能验证以及Western blot、免疫细胞化学（immunocytochemistry,ICC）、免疫组织化学（immunohistochemistry,IHC）、酶联免疫吸附测定（enzyme linked immunosorbent assay,ELISA）等免疫学方法进行了介绍,并综述了昆虫组蛋白修饰的功能,以期为进一步研究昆虫组蛋白修饰提供借鉴和参考。同时对加强昆虫组蛋白修饰在种群水平、跨代遗传等方面的研究进行了展望。     

中国植物弹状病毒研究进展

弹状病毒含有单链负义RNA基因组,寄主范围比较广泛,能侵染无脊椎动物、脊椎动物以及植物等寄主,对人类的健康、农作物产量和自然生态系统造成严重威胁。植物弹状病毒主要根据复制场所分为细胞质弹状病毒属Cytorhabdovirus和细胞核弹状病毒属Nucleorhabdovirus,其基因组由单股负链RNA组成。此外,Dichorhavirus和Varicosavirus病毒属是两个新鉴定的植物弹状病毒属,其特征是具有二分体基因组。本文着重介绍危害我国农作物的几类植物弹状病毒,对它们的病理学、病害流行、基因组信息以及传播媒介进行概述,为中国植物弹状病毒病害的研究提供理论依据。     

新疆奇台县近42a气候变化特征分析

根据新疆奇台县气象站的气温及降水资料,利用线性趋势函数及M ann-kendall突变检测法分析了该地区近42年的气候变化。结果表明:年平均气温与极端最低气温均呈上升趋势,而极端最高气温呈下降趋势;年降水量呈上升趋势。从季节变化来看,除夏季平均气温呈下降趋势,其它各季平均气温均呈上升趋势,其中以冬季增幅最大,秋季次之;各季降水均呈上升趋势,其中以夏季增幅最大,冬季次之。年平均气温未发生突变,而年降水量在1984年发生由少向多的突变。对气温和降水的异常分析得出,暖温年多发生在上世纪80年代后,冷温年多发生在上世纪60、70年代;多雨年主要在近20年,少雨年则多在上世纪60、70年代。此外,该县近42 a来增暖幅度小于全疆和北疆;增湿幅度大于全疆,小于北疆。     

磴口县农林复合生态系统农田子系统能流分析

采用Odum能流分析理论以及主成分分析法,结合磴口县1992～2008年统计年鉴,选取有机能、无机能、能量总投入和总产出、产投比、能量循环指数和投能结构6个指标,对磴口县农林复合生态系统农田子系统的能流特征进行定性、定量分析.结果表明:该地区有机肥使用量逐年降低,而无机肥却在增加;该系统能量产出大于投入,产投比为:3....     

西安地区丰水年农田深层土壤含水量研究

通过对西安南郊吴家坟、长安区郭杜镇大学城和双竹村附近丰水年(年降雨量883 mm)麦地、玉米地土壤含水量的测定,以及与正常年份该地土壤含水量的对比,研究丰水年该地区农田0~6 m土壤含水量的变化。结果显示,正常年份西安地区麦地0~2 m土层含水量高于12%,2~6 m土层含水量高于13%;丰水年西安地区麦地0~2 m的土壤含水量在18%以上,2~6 m土层含水量达24%以上,远远高于正常年份这一层位的土壤含水量。分析得出,西安地区农田深层土壤含水量高的主要原因是重力水带分布范围大于或等于农作物的强烈耗水层范围。     

Variability in initial spray deposit in apple trees in space and time

Variation in pesticide residues in space and time has not been investigated systematically in spite of the large variability found at single scales (e.g. between trees or orchards). Information on variability at different scales will support the development of sampling methods and more reliable prediction of residues. Experiments were conducted to quantify the spatiotemporal variability in initial spray deposit on apple leaves and fruit using a substitute tracer (zinc EDTA chelate). Five hierarchical spatial scales were defined as (1) between orchards, (2) between plots within an orchard, (3) between trees within a plot, (4) between zones within a tree and (5) between leaves/fruit within a zone. Similarly, two temporal scales were defined as (1) between applications within a single year and (2) between years. The initial zinc concentration was approximately log-normally distributed; the variability in initial deposit concentration was greater on leaves than on fruit. The average initial zinc deposition was significantly greater in the top and outside zones than in the middle zones within individual trees. The most important scale for driving residue variability is the within-zone unit-to-unit variation, contributing to 71 and 49% of the observed variability for leaf and fruit samples respectively. Variability at other scales was related to the variation in the tree architecture. The results indicated that stratified sampling on the basis of within-tree zone structures, with the effort focused on within-zone sampling, should be used for the determination of pesticide residues.     

Progress in research on resistance in arthropods

This is a short review of the history of the extensive research on resistance in the post-DDT era, in relation to advancing experimental technique. The subject began as a serious concern to applied entomologists only, gradually involved other disciplines, notably genetics and biochemistry; and the inherent interest and challenge of the problem attracted the attention of experts in these fields. It will be convenient to divide the 25 years involved into three periods: the years up to 1952, the decade 1953-62 and the decade 1963-72. The various types of investigation can be categorised as: (1) detection and measurement, (2) genetic studies, (3) primary toxicology and (4) biochemical toxicology.     

昆虫紫外视觉研究进展

昆虫在长期进化过程中形成的颜色视觉能力，是其直接获取外界信息的最主要途径之一。其中，紫外视觉在昆虫颜色视觉系统中普遍存在，通过紫外光感受器可以感知并辨别周围环境中光源或物体反射的特定波长紫外光，提高颜色辨别能力。自19世纪80年代证实昆虫具有紫外敏感性以来，陆续发现蜜蜂、蝴蝶、果蝇和蛾类等许多昆虫具有良好的紫外视觉能力，利用颜色、对比度和偏振光等紫外光特性调控昆虫的定向导航、觅食、种内通讯和昼夜节律等行为活动，对于其生存、繁殖和生态适应具有重要意义。此外，紫外敏感视蛋白是昆虫紫外视觉形成过程中的一类重要分子，不仅可以独立介导趋光性等特定波长行为，还可纳入整个颜色视觉系统，与其他视蛋白协同调控昆虫的颜色视觉，从而将紫外光当作一种基本颜色进行辨别。该文系统综述了昆虫紫外视觉的发现、特性、功能和感知机制，鉴于当前国内在相关领域研究的薄弱和局限性，建议今后可在解析植物-害虫-天敌生态系统中的紫外光特性、探究紫外光-B紫外视觉的生态学意义、揭示紫外敏感视蛋白基因的分子进化机制以及阐明昆虫避免或修复紫外光所致视网膜损伤相关适应机制方面进行深入研究。     

Insecticide resistance in Heliothis armigera in Australia

A voluntary insecticide resistance management strategy for the control of H. armigera was implemented in Australia in 1983 after an outbreak of resistance to synthetic pyrethroids. This strategy restricts the use of pyrethroids to three sprays within a 42-day period in summer. The use of endosulfan is also restricted and rotation of other pesticides is encouraged. The effectiveness of the strategy is monitored by tests on larvae collected from two major cotton areas and from unsprayed crops in northern New South Wales. Research is under way to determine the genetic basis of two of the three mechanisms involved in resistance. One genetic component is associated with the mixed-function oxidases. Selection in the field for this semi-dominant gene (or genes) occurs in larvae 4 days or more old. It is not possible to evaluate directly the success of this strategy because there is no control area where it has not been implemented. While the long-term outcome of the strategy is uncertain, it is likely that resistance will increase in frequency.     

Fluctuations in Sunn-pest Populations in South-eastern Anatolia

Sunn pest ( Eurygaster integriceps ) is the most serious and widespread pest of cereals in south-eastern Turkey. It is very important to estimate its spring populations, and the area possibly needing to be treated, a few months before they migrate to the fields. The field populations of the pest and the severity of epidemics can be forecast from the population density of overwintering adults per plant in the overwintering localities. To do this, surveys have been made since 1955 on 25 selected mountain sites. Parallel to these investigations, the population of overwintered adults per m2 in cereal fields has been determined in order to fix the area to be treated, since 1956. A relation can be seen between the population density of overwintered adults per plant and the next season's populations in the infested areas.     

Buried seeds in arable soils in Scotland

Soil from arable areas in Scotland was examined macroscopically for seeds. In terms of the percentage of sites at which they were recorded, Chenopodium album L. (33%), Poa annua L. (22%), Polygonum aviculare L. (41%), Polygonum persicaria L. (39%), Spergula arvensis L. (42%) and Stellaria media (L.) Vill. (44%) were the most common species found. They accounted for 78% of the seeds recovered. There were eighty different species found over the 5 years of the survey. Estimated total weed populations (m^?2) ranged from nil to 170000 with an average of 16000 m^?2 in the top 20 cm of soil.     

中国干旱区的湖泊

湖泊作为地表水的重要载体,参与自然系统的水分循环,这在世界干旱地区显得格外突出和重要.应用浏览软件(Google Earth),对2001-2005年中国干旱区湖泊进行判别,并结合有关实地调查资料得知,我国干旱区有大小湖泊近400个,其中,10 km2以上的有29个,10 km2以下的有334个,在我国3大自然地理区域中位居第二.开展干旱区湖泊的研究,对破解干旱区的气候变化和湖泊演变过程、形成特征,以及湖泊水生生物资源的科学开发利用和保护具有重要的理论和现实意义.     

Phytopathological situation in potato in Belarus1

The control of potato diseases in Ukraine is reviewed. Control of potato blight (Phytophthora infestans) has only been adequate for limited periods in the past (when resistant cultivars were available and when the systemic fungicides were introduced). Currently, the disease is in a new epiphytotic phase and control has failed again, probably connected with the introduction of new mating types and the existence of greater variability. Blight now occurs earlier in the season and in most years (instead of only years when climatic conditions are favourable). Control has now to be essentially preventive, rather than based on forecasting. The importance and control of other potato diseases is also considered (Alternaria spp., Rhizoctonia solani, Geotrichum candidum, Phytophthora erythroseptica, Sclerotinia sclerotiorum, Streptomyces scabies).     

Insecticide resistance in vector mosquitoes in China

Because of their special behaviour, physiology and close relationship with humans, mosquitoes act as one of the most important vectors of human diseases, such as filariasis, Japanese encephalitis, dengue and malaria. The major vector mosquitoes are members of the Culex, Aedes and Anopheles genera. Insecticides play important roles in agricultural production and public health, especially in a country with a huge human population, like China. Large quantities of four classes of insecticides, organochlorines, organophosphates, carbamates and pyrethroids, are applied annually to fields or indoors in China, directly or indirectly bringing heavy selection pressure on vector populations. The seven major species of vector mosquito in China are the Culex pipiens L. complex, C. tritaeniorhynchus Giles, Anopheles sinensis Wied., A. minimus Theobald, A. anthropophagus Xu & Feng, Aedes albopictus (Skuse) and Ae. aegypti L., and all have evolved resistance to all the above types of insecticide except the carbamates. The degree of resistance varies among mosquito species, insecticide classes and regions. This review summarizes the resistance status of these important vector mosquitoes, according to data reported since the 1990s, in order to improve resistance management and epidemic disease control, and to communicate this information from China to the wider community.     

杨凌区浅层土壤水分与深层土壤水分的关系研究

通过测定陕西杨凌区不同灌水条件下冬小麦的土壤水分变化,研究了浅层土壤水分与深层土壤水分的关系。结果表明:土壤含水量随土层深度的加深,呈先上升,后下降,又上升的变化趋势。在自然降水或灌溉条件下,土壤水分的变化程度随土层深度的增加,呈剧烈—缓和—剧烈—缓和的趋势。表层20、30、40、50 cm各土层含水量分别与0~150 cm各土层含水量的相关性较好,并且土层相邻越近,其相关性越好,说明由表层土壤含水量来推算深层土壤含水量是可行的。基于Biswas土壤水分估算模式,由表层30~40 cm的含水量来推算0~100 cm各土层含水量的精度较高,由表层20 cm的含水量来推算100~150 cm各土层含水量的精度较高。总灌水量及灌水次数对含水量的影响,直接影响到估算模式参数的取值及估算精度。     

Chemical Weed Control in Tobacco in Trinidad

Abstract

Ramie, the vegetable fibre, is obtained from the stem of Boehmeria nivea (L.) Gaud, and is used in many textile products. It is grown in tropical, sub-tropical and temperate regions and the main countries where it is grown are China, Brazil and the Philippines. However, it is only a minor crop in terms of world trade. The diseases of ramie are discussed in relation to their occurrence, symptoms and control measures. The major and most widespread diseases are white fungus caused by Rosellinia necatrix, leaf spot caused by Cercosporo spp. and Phyllosticta spp., seedling rot caused by Rhizoctonia solani, cane rot caused by Macrophomina phaseolina and eye rot caused by Myrothecium roridum. A number of diseases of minor importance are also reviewed.