Measure of multilocus correlation as a new parameter for study of plant pathogen populations

ABSTRACT The measure of multilocus correlation for diallelic loci was developed to augment use of other diversity indices in the study of multilocus structure of populations. This measure provides information not revealed by other parameters for measuring multilocus association and linkage disequilibrium among pairs of loci. Relationships between the measures of multilocus correlation and association and all commonly used indices for diversity within populations are also described. A number of hypothetical examples demonstrate that the measure of multilocus correlation describes unique aspects of multilocus structure of populations compared with the measure of multilocus association and phi coefficient of association. The measure of multilocus correlation can be used for analysis of independence of differentiating characters for a given population-the necessary condition of valid applications of the bootstrap method across differentials. Comparisons of the measures of multilocus correlation and association with the measures of diversity within population show that they reveal different aspects of population structure. As an adjunct to standard diversity indices, the measure of multilocus correlation may reveal subtle differences in diversity within populations even if the standard index fails to distinguish between the populations. A new measure of population uniformity also was developed to characterize another aspect of diversity within populations not detected by standard indices.     

甘肃陇东南紫花苜蓿土壤水分利用程度的评估研究

通过种植试验分析,用数理统计方法模拟了紫花苜蓿生物量累积过程及土壤水分消耗过程,揭示了紫花苜蓿的生物量累积特点及其土壤水分利用规律。发现1年生紫花苜蓿在开花期物质累积以地上为主,干物质上/下比可达2.92;开花以后逐渐以地下部分为主,到收刈期干物质上/下比为0.57。紫花苜蓿的田间贮水量小于粮食作物,耗水量大于粮食作物。紫花苜蓿的土壤利用率大于粮食作物,是小麦的2.1~2.8倍,玉米的2.0~2.5倍。     

施氮量对棉田主要害虫种群动态的影响

通过不同施氮肥量对棉田主要害虫种群动态影响的研究结果表明,在低、中、高3种施氮肥水平处理条件下,随着氮肥量的增加,棉田棉铃虫落卵量增加,棉苗蚜、棉叶螨种群数量减少,发生为害减轻,但棉伏蚜种群数量增加。中等施氮肥条件下,第二、三代棉铃虫幼虫数量高于低和高施氮肥处理,对棉铃虫幼虫的生长发育和存活较为有利。     

黄土高原长期施肥对小麦产量及土壤肥力的影响

重点分析黄土高原长武试验站长期定位施肥试验地2004年长期施肥对小麦产量、肥料利用率及土壤肥力影响的试验结果,表明:单施磷肥和单施氮肥的产量很低,与对照的产量无明显差异,氮磷钾配施与氮磷配施能显著提高小麦的产量。单施磷肥的磷肥利用率最低,为1%;单施氮肥的氮肥利用率为12.5%;氮磷配施的氮、磷肥利用率均较高,磷肥利用率比单施磷肥提高5.7%,氮肥利用率比单施氮肥提高42.1%。氮磷钾配施较氮磷肥配施的氮肥利用率降低了4.5%,而磷肥利用率升高了2.2%,钾肥的利用率不高,仅为7.3%。单施磷肥只增加土壤磷素含量而降低了氮素含量,单施氮肥能增加土壤中氮素的含量,速效磷含量增加了31%,氮磷肥配施增加了土壤中有机质和氮、磷养分含量。氮、磷配施或氮、磷、钾配施是提高黄土高原小麦产量和土壤肥力的有效措施。     

梭梭属不同种源种子品质初评

梭梭属(Haloxylon Bge.)的两个种,主要分布在新疆准噶尔盆地,是优良防风固沙和薪炭树种,被列为国家重点保护植物。国内对两种梭梭的利用和研究,从50年代末就已经开始进行,至今已做了大量的工作,但对其种子特性的研究报道甚少。为了更深入了解梭梭两种植物的种子特性,我们于1987年选用吐鲁番沙漠研究站引种成功的两种梭梭(H.ammodendron、H.Persicum)的种子同原分布区莫索湾沙漠研究站采的种子,对其品质进行了对比试验分析,为梭梭属引种工作中的种源选择及种子保存提供依据。现将结果报道如下。     

吡虫啉胁迫对褐飞虱共生解脂假丝酵母抗性及敏感菌株生长的影响

为明确吡虫啉对褐飞虱共生解脂假丝酵母Candida lipolytica抗性及敏感菌株生长的影响,通过菌株培养、菌落观察和菌丝镜检等方法,比较了褐飞虱共生解脂假丝酵母不同菌株在含不同质量浓度吡虫啉的固体培养基上的菌落数,以及在液体培养基中的生长量差异。结果发现:不同质量浓度吡虫啉对褐飞虱共生解脂假丝酵母敏感和抗性菌株菌落生长均有抑制作用,且吡虫啉浓度越高,抑制作用越强。经500、1 000和2 000 mg/L吡虫啉处理4 d后,敏感菌株的菌落数量分别为对照的46.61%、27.58%和6.25%,均与对照差异显著;500和1 000 mg/L处理组抗性菌株菌落数量与对照无显著差异,而2 000 mg/L处理组与对照差异显著。经吡虫啉处理后,敏感菌株假菌丝形态变得不规则,部分假菌丝不舒展、萎缩或弯曲、顶端出现膨大,酵母出现空泡等,且吡虫啉浓度越高,不规则程度越明显;抗性菌株的假菌丝形态也有类似变化,但与敏感菌株相比,其菌丝体不规则形态的比例明显下降。500 mg/L吡虫啉处理对敏感和抗性菌株的生长量及菌丝干重均无明显影响,1 000和2 000 mg/L吡虫啉对不同菌株前期生长的抑制作用明显,但对后期生长影响不明显。研究表明,吡虫啉对褐飞虱共生解脂假丝酵母抗性菌株生长的影响显著小于对敏感菌株的影响。     

基于MaxEnt模型的柑橘木虱在西南地区潜在分布模拟

本研究应用生态位软件MaxEnt和地理信息系统软件ArcGIS预测柑橘木虱在西南地区的潜在地理分布范围,筛选影响柑橘木虱分布的关键变量。结果表明柑橘木虱在西南地区高适生区主要位于西藏东南部、四川中东部、重庆大部、贵州大部和云南中北部,总面积为52.03万km 2,占西南地区总面积的23.89%。影响柑橘木虱分布的关键变量为最冷月最低温度、最冷季度平均温度、最湿季度降水量、最暖季度降水量、最暖季度平均温度和最暖月最高温度。本研究不仅模拟了柑橘木虱在西南地区的潜在地理分布,更为该虫的分布与环境变量之间关系的研究提供了理论参考。     

甘肃省农村居民环境意识影响因素分析——基于年龄、性别、文化水平群体的分析

环境意识是环境保护的思想基础,其水平的高低直接影响着人们环保行为的自觉程度。因此,甘肃省农村生态环境的保护及改善与农村居民的环境意识水平息息相关,其中,认清甘肃省农村居民的环境意识影响因素,分门别类地开展有针对性的宣传与教育工作,提高相关群体环境保护的意识和能力是关键。文章通过问卷调查法,对甘肃省农村居民的环境意识现状进行了调查与分析,并在此基础上运用综合得分法来分析年龄、性别、文化水平这三个因素对农村居民环境意识的影响,结果显示:居民的环境意识水平随年龄的增长有提高的趋势;男性群体的环境意识水平高于女性群体;环境意识水平随文化水平的提高而提高;环保行为与环保知识掌握程度、环境认知程度存在不一致性。     

Zones of exudation along plant roots and spatial distribution of micro-organisms in the rhizosphere

The use of ¹⁴C-labelling of plants in short-term studies has established that the major zone of release of carbon-containing materials from roots is the zone of elongation. Much of this material is in an insoluble form, comprising sloughed-off root cap cells and polysaccharide material, and remains in the immediate vicinity of the root. Electron microscopy of ultra-thin sections of the root-soil interface of wheat plants has shown that colonisation by micro-organisms of the rhizosphere is relatively sparse in the young parts of roots. In the older parts of roots, evidence was obtained that bacteria lyse the walls of the outer root cells and this is followed by dense colonisation of these moribund outer cells by bacteria.     

柑桔炭疽菌次生分生孢子形成的研究

 分别用不同温度、湿度、pH、光照对柑桔炭疽菌的不同分离系作单因子和复因子试验,结果表明:次生分生孢子形成的最适温度为23~27℃,最适pH值为6~7,在相对湿度为100%时产孢率最高,需要一定的营养。光对次生分生孢子形成的作用受温度影响,当温度在25℃以上产孢率最高的是黑光与黑暗交替和黑光的处理;温度在25℃以下时产孢率最高的是连续24小时的荧光处理。次生分生孢子形成必需要光。复因子试验的结果表明主效因素为温度,产孢率最高的最优组合为全黑暗-015-查彼培养液-pH8-水-25~29℃及先昼后夜-011-1%蛋白胨液-pH6-水-20~23℃。     

Toxicity of the entomopathogenic fungus, Metarhizium anisopliae (Deuteromycotina: Hyphomycetes) to adult females of the blowfly Lucilia sericata (Diptera: Calliphoridae)

The fungus Metarhizium anisopliae (Metchnikoff) (Deuteromycotina: Hyphomycetes) is a natural component of soil flora world-wide and is a causal agent of the green muscardine diseases of insects. The use of this pathogen as a potential biocontrol agent against adult females of the blowfly, Lucilia sericata (Meigen) (Diptera: Calliphoridae) was considered. The blowfly L sericata is an economically important agent of cutaneous myiasis of sheep, particularly in northern Europe. Exposure of flies to suspensions of fungal spores by immersion, topical application or tarsal contact with treated surfaces all resulted in high levels of fatal infection. Spores suspended in silicone oil resulted in higher levels of infection (50-70%) than those formulated in a 0.3 glitre(-1) solution of the detergent Tween 80 (10-20%). Spore concentration had a significant effect on levels of infection of flies, with the highest levels of mortality (64%) resulting from a suspension of 1 x 10(7) conidia ml(-1). The duration of tarsal contact had a significant effect on levels of infection. Mean infection levels of 30% were observed following exposure of free-flying adults to a single spore-treated, 5 x 15 cm2 cloth surface suspended from the roof of a cage (30 cm cube). The implications of the results for the potential use of M anisopliae in the biocontrol of blowflies are discussed.     

Pathomorphological changes in roe deer lungs during ontogenesis of Varestrongylus capreoli (Stroh et Schmid, 1938) Dougherty, 1945

The specification of pathomorphological changes occurring during Varestrongylus capreoli ontogenesis was studied on the basis of different forms of inflammation. The character, course and extent of inflammatory reactions were contingent on the maturity, localization and number of worms. The allergic inflammation accompanying the development of juvenile specimens inside the alveoli was followed by the regeneration of lung tissues providing suitable conditions for further development of the parasite. A prolonged edema occurring during the differentiation of juvenile parasites localized in the bronchioles caused a disposition of the roughen bronchial wall to its miliary necrotic disintegration producing a negative effect on further development of the helminth. The pathomorphological effect of mature productive parasites was characterized by focal changes hatching nodes. Activated epithelial cells of alveoli, phagocytizing disintegrating eggs and not developing 1st-stage larvae together with eosinophilic granulocytes participated in the restoration of the host lung functional ability while tolerating the presence of the parasite. A difficult excretion of sex products from the lungs stimulated the development of proliferative forms of inflammation reducing the number of Varestrongylus specimens.     

麦田小气候对第一代粘虫发生数量影响的研究

麦田小气候因子对粘虫的发生有一定影响。栽培技术及小麦生长情况不同农田小气候特点各有不同,因而影响粘虫发生数量及发育进度的变化很大;禾苗生长愈茂密,小气候相对湿度愈高,温度愈低。此种条件下,粘虫发生数量较大而发育进度较慢。杂草丛生的农田粘虫发生即多,被害严重,这可能也是受小气候因子的影响所致。预测预报时应注意这些规律。     

西北干旱区水资源利用与生态环境重建研究

西北干旱地区是我国西部大开发战略的重点建设区域之一。但是长期以来，由于气候干旱以及在市场经济利益驱动下所形成的人类对水产 过度开发利用，导致了一系列阻碍区域经济发展的严重生态环境问题。水资源的合理利用是干旱区振兴流域经济的主要保证，也是促使生态经济系统向良性方向发展的关键因素。本文从分析西北干旱区内陆河流域水资源系统特征、开发利用现状以及主要的水环境问题出发，得出干旱区生态恢复与重建必须以水资源的合理利用为核心的结论，同时提出了干旱区水资源利用优化途径与生态重建的基本对策。     

Control strategies using systemic fungicides for limiting disease development and resistance buildup: practical implications of a simulation model

A simulation model was used to assess the control efficacy of, and the buildup of resistant populations to, systemic fungicides as affected by preventive vs responsive (curative) treatments with a protectant fungicide, or with a mixture composed of a systemic and a protectant fungicide. The variables introduced in the model were: rate of fungicide weathering, coverage efficacy, and relative fitness of the resistant population of the pathogens. In all simulated epidemics (with different combinations of apparent infection rates, critical disease levels and rates of weathering of the fungicides), preventive treatments, before the critical disease levels were reached, were significantly more effective than responsive (curative) treatments. At low rates of weathering of the protectant fungicide (half-life of the protectant greater than or equal to that of the systemic), the buildup of the resistant population was significantly inhibited when a mixture was used either preventively or responsively. At high rates of weathering of the protectant fungicide (half-life of the protectant less than that of the systemic), both the buildup of the resistant population and the control efficacy were dependent on the control program used and on the different combinations of fungicide weathering, fitness of the resistant population, and coverage efficacy of both the protectant and systemic fungicides.     

西北荒漠绿洲区隔沟交替灌溉对棉花生长及产量与经济效益的影响

2006～2007连续两年在石羊河流域下游民勤县干旱荒漠绿洲区大田试验覆膜条件下隔沟交替灌溉(AFI)和常规沟灌(CFI)对棉花生长、产量及经济效益的影响.结果表明,隔沟交替灌溉方式对棉花株高的生长起到了抑制作用,且结铃率高干常规沟灌处理;在次灌水定额为当地畦灌水平的50%左右时隔沟交替灌溉与常规沟灌处理相比,能够提高棉花的产量和霜前花比例,增加经济效益.在荒漠绿洲区隔沟交替灌溉是一种有效的灌溉方式,可以实现节水优质高效的目标.     

SELECTIVE ACTION OF TRIAZINES FOR CONTROL OF WILD CANARYGRASS IN WHEAT

Summary. The selective action of triazine herbicides for control of wild canarygrass ( Phalaris spp.) in wheat was studied in four field experiments. Canarygrass was controlled by pre- and post-emergence applications of methoprotryne and terbutryne. The phytotoxicity of methoprotryne to wheat was higher than that of terbutryne. Addition of small amounts of simazine to either one of the methylthiotriazines considerably increased damage to wheat. The most resistant stage of wheat after emergence was that of spike initiation, whereas the most sensitive stage was that of earing. Increase of yield as a result of control of canarygrass was higher in semi-dwarf wheat than in normal-height cultivars. Application of 625 g/ha of terbutryne to a semi-dwarf cultivar pre- and post-emergence increased grain yield by 56% and 29%, respectively.
Action selective des triazines pour la lutte contre les Phalaris dans le blé     

准噶尔盆地沙漠增温效应对棉花光合速率、蒸腾速率的影响

沙漠增温效应导致了绿洲不同区域热量资源的分异[1],为了进一步了解沙漠增温效应对绿洲不同区域作物的影响,本文通过在准噶尔盆地沙漠区、距沙漠20 km、70 km区域进行试验,从棉花生理生态的角度分析了准噶尔盆地不同区域的农田小气候、棉花净光合速率(Pn)、蒸腾速率(Tr)的差异。结果表明:(1)准噶尔盆地三个区域之间的光合作用有效辐射差异不大;(2)不同区域的大气温度均呈单峰曲线,距沙漠越近的区域温度越高;(3)不同区域的相对湿度都呈现不断下降的趋势;(4)影响区域间Pn、Tr差异的主要因素是气温的差异。     

两种有机硅助剂对四氯虫酰胺防治菜青虫的增效作用

为明确两种有机硅助剂Silwet 408和Greenwet 7618对四氯虫酰胺防治菜青虫的增效作用,本文采用喷雾法测定四氯虫酰胺以推荐剂量、50%推荐用量分别与Silwet 408和Greenwet 7618的3 000倍稀释液混用对菜青虫的田间防效。结果表明,四氯虫酰胺以50%推荐用量分别与Silwet 408和Greenwet 7618混用,药后3 d对菜青虫的防效均与单独使用推荐剂量的防效无显著差异;药后7 d,50%推荐用量与Greenwet 7618混用对菜青虫的防效与推荐剂量的四氯虫酰胺仍无显著差异,而50%推荐用量与Silwet 408混用的防效显著降低;在药后14 d,所有处理对菜青虫无防治效果。因此,建议在生产上推广50%推荐用量的四氯虫酰胺与Greenwet 7618的3 000倍液混用防治菜青虫。     

吉林省粘虫猖獗世代发生虫源的研究Ⅱ.虫源策源地的探讨

粘虫是吉林省粮食作物上最主要的猖獗性害虫,防治工作上迫切需要中、长期預测方法。为此,作者等研究了吉林省粘虫猖獗世代的虫源,已經查明粘虫在吉林省不能越冬,猖獗世代的虫源是由省外迁入的。通过国內粘虫主要发生地区的发生动态的整理和分析,初步認为吉林省猖獗世代虫源的主要策源地为皖北、苏北、魯南、豫东、豫南、鄂北等粘虫常发生的地区。同时認为不同年度各策源地的发生时期和数量的变化会影响吉林省春季成虫盛发期和数量。一般年分5月末、6月初的成虫与鄂北、豫南、皖北等地区的虫源有关;而6月上旬以后的成虫則与魯南、苏北、豫中的虫源有关。