尼雅河下游沙漠沙、土样品矿物全量、微量元素分析及其分布规律

本文收集了尼雅河下游沙漠沙、土样品的矿物全量及微量元素分析资料,并对其进行了整理和分析,得出了矿物全量及微量元素在不同类型的沙、土样品中的分布规律。而且还通过引入一系列的氧化物比值来更进一步揭示不同类型样品中氧化物含量的变化及其反映的环境特征。同时,本文对沙、土样品中氧化物、微量元素含量的分布特征产生的原因给予了一定的阐述。     

The Prediction of Weed Infestations: Concepts and Approaches

The role of studies on the population biology of weed species is examined and the utility of such studies in the design of weed management systems assessed. It is argued that the development of predictive models of the population behaviour of weed species is likely to be crucial to the critical evaluation of weed control programmes in the future. Illustrations are given of the dynamics of herbicide resistance in Senecio vulgaris and of the calculation of infestation rates of Agropyron repens under differing control managements.     

甲氰菊酯和螺螨酯对二斑叶螨实验种群的亚致死效应

在室内研究了甲氰菊酯和螺螨酯亚致死剂量对二斑叶螨实验种群成螨和卵的影响。结果表明,甲氰菊酯亚致死剂量LC10处理成螨后,二斑叶螨的卵期、幼螨期、若螨期、成螨期及寿命均显著缩短,处理卵后各发育历期均显著低于对照;亚致死剂量LC20处理成螨后二斑叶螨的卵期、若螨期、成螨期及寿命均显著缩短,处理卵后各发育历期均低于对照,处理后F1代种群的内禀增长率rm由0.191 9增至0.193 4～0.205 9,对种群有刺激增殖作用。螺螨酯亚致死剂量LC10处理成螨后,卵期、若螨期显著延期长,处理卵后卵期、若螨期、产卵前期均长于对照;亚致死剂量LC20处理成螨后卵期、幼螨期显著延长,处理卵后卵期、若螨期、产卵前期均长于对照,螺螨酯两亚致死剂量处理成螨和卵后成螨期和寿命均缩短,处理后F1代种群的内禀增长率rm由0.191 9降低至0.149 9～0.150 8,对种群有抑制作用。     

药剂诱导稻飞虱再猖獗及科学用药

稻飞虱是典型的再猖獗型重大害虫。害虫再猖獗包括生态再猖獗和生理再猖獗,前者主要由药剂杀伤天敌使天敌功能崩溃引起,后者指药剂刺激害虫生殖导致害虫增殖倍数显著增加。刺激稻飞虱生殖的药剂包括大部分有机磷、菊酯类、氨基甲酸酯类杀虫剂,及一些除草剂和杀菌剂(如井冈霉素、多菌灵)等。通过蛋白质组学、转录组学、基因表达谱分析及基因沉默试验证实化学药剂刺激稻飞虱生殖主要涉及与生殖和代谢相关基因的上调表达,但同一药剂对稻飞虱组团物种产生物种间基因功能生态位分离。这就需要在深入理解化学农药对生态系统中组团物种的正负效应和生殖影响的基础上进行精准用药技术设计。本文综述了一些农药对稻田害虫天敌行为、生殖、捕食功能及稻飞虱生殖影响的机理,并基于同种药剂对稻飞虱组团内不同物种生殖的相反效应,提出稻飞虱多物种共存时的科学用药技术。     

不同种群小菜蛾乙酰胆碱酯酶性质研究

小菜蛾乙酰胆碱酯酶(AChE)的性质研究表明,不同种群小菜蛾成虫与幼虫AChE活性相比,差异极显著,成虫是幼虫的5～7倍;武汉种群小菜蛾成虫和幼虫AChE与底物的亲和力最小。小菜蛾谷胱甘肽鄄S鄄转移酶(GST)的性质研究表明,宣化、武汉、云南3个田间种群GST活性较高,明显高于台湾敏感品系;北京种群GST活性较低,与台湾敏感品系近似。此研究为进一步分析小菜蛾不同种群、不同虫态抗药性差异提供了依据。     

二甲苯对锦鲤鱼肝脏抗氧化酶的影响

采用暴露试验方法,研究了不同浓度二甲苯对锦鲤鱼肝脏组织中超氧化物歧化酶和过氧化氢酶的影响。结果表明,不同浓度组二甲苯在暴露期间对锦鲤鱼肝脏SOD活性的影响较小,只有在个别浓度和个别时间段下发生了显著诱导或抑制作用;锦鲤鱼暴露于二甲苯时对CAT活性影响主要表现为诱导作用,但CAT对1/16 96hLC50浓度二甲苯反应较滞后;随着暴露时间的延长,试验15 d后,CAT活性随着暴露浓度的降低而整体呈下降趋势;试验中CAT活性的变化与SOD活性的变化具有一定的同步性：在3 d和15 d时,1/4 96hLC50浓度组的SOD活性受到诱导,CAT活性也受到诱导;在12 d时,1/8 96hLC50浓度组的SOD活性受到抑制,CAT活性也受到抑制。在本次暴露试验中,CAT活性对二甲苯较敏感,从分子水平上反映了污染物对鱼体肝细胞的损伤,也反映了环境中氧化作用的存在,因此,可以考虑其作为水环境中二甲苯早期污染的生物监测指标。     

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。     

西藏一江两河地区荒漠化控制研究

由于人口密度增大,人类活动强度增加,西藏—江两河地区荒漠化的进程在不断加快,沙地面积在不断扩大。该区域控制荒漠化的主要途径是：保护自然植被、改变向荒山要粮的传统思路和强化对沙化石质化低质草地的改造。据此本项研究提出了该地区荒漠化控制措施是：进行农业景观结构调整,不提倡开荒要粮,而是以推广农业新技术为主的方法提高现有农田单产水平;用封育和恢复植被相结合的方法改造沙化石质化低质草场;推广以能源改造为中心的新技术。这样才能有效地遏止荒漠化进程。     

定西地区农业发展潜力分析及开发对策研究

定西地区的农业自然资源具有多样性,这为多样化的农业发展提供了有利条件。尽管该区农业发展比较落后,但仍具有很大的发展潜力,主要表现在作物生产、水资源开发利用、生物资源开发、农业产业化发展、生态农业发展五个方面,其中挖掘生物资源开发潜力是定西地区实现农业跨越式发展的突破口所在。     

Weeds resistant to chlorsulfuron and atrazine from the north-east grain region of Australia

The resistance of weeds to triazine and sulfonylurea herbicides has been recorded in several countries. The extent of the problem in the north-east grain region of Australia is uncertain. In an initial study, resistance to chlorsulfuron and atrazine in 15 weed species was investigated. The study showed that at least six of them have evolved resistance to one or other of these herbicides. Two collections of Rapistvum rugosum L., three of Sisymbrium orientale L., five of Sonchus oleraceus L., one of Fallopia convolvulus (L.) A. Love and one of Sisymbrium rhellungii O. Schultz were resistant to the recommended rate of chlorsulfuron (15 g a.i. ha^-1). Resistance to chlorsulfuron was not discovered in three collections of Sisymbrium L., two of Brassica tournefortii Gouan. three of Emex australis Steinh. and 11 of Phalaris paradoxa L. Two collections of Urochtoa panicoides Beauv. were resistant, and three collections possibly resistant, to the recommended rate of atrazine(1.8 kg a.i. ha^-1). Resistance to atrazine was not found in 12 collections of Hibiscus urionum L., nine of Salvia reflexa L., two of Parthenium hysterophorus L., two of Amaranthus viridis L. and 14 of Echinochloa colona (L) Link. The resistance status of four weeds ( R. rugosum. F. convolvulus, S. thellungii and U. panicoides was confirmed using a multiple dose-response screen and is the first report of resistance for these species. Herbicide usage records show that resistance has developed after 3-10 years of selection with chlorsulfuron and 2-15 years of selection with atrazine, with no correlation between the frequency of use and the degree of resistance for any of the species where eight or more collections were made.     

基于GIS的北京地区未来10年土壤水力侵蚀演化趋势探讨

本文是基于永定河上游北京典型段的土壤水力侵蚀深度、降雨强度、地表径流深度、土层有效厚度、土粒平均粒径、植被覆盖度等数据图层 ,利用 GIS、SPSS软件包 ,通过建立水力侵蚀遥感信息模型 ,制作了北京地区土壤水力侵蚀深度图和抗侵蚀年限图 ,依据将近论古的原则及作者的北京地区未来 1 0年环境演化趋势预测结果 ,探讨了未来 1 0年水力侵蚀演化趋势。这可以为该地区未来土地利用和泥石流分布规律研究提供理论指导     

Quantitative evolution of aggressiveness of powdery mildew under two-cultivar barley mixtures

The effects of cultivar mixtures on the evolution of aggressiveness of barley powdery mildew ( Blumeria graminis f.sp . hordei ) were modelled. It was found that the rate and direction of evolution of pathogen aggressiveness in a race-non-specific system and value at equilibrium, depends on initial resistance levels, proportions of component cultivars, autodeposition rates, the relative magnitude of the benefit of autoinfection, and the cost of alloinfection of spores. In the model, mixing cultivars in any proportions tended to reduce the aggressiveness of pathogens at equilibrium compared with pure stands, but this effect decreased when two mixture components were extremely unbalanced in proportion. Under low and medium autodeposition rates, the best control of the evolution of the pathogen was achieved by mixing two components in roughly equal proportions. The magnitude of aggressiveness at equilibrium increased as autodeposition rates increased. Though the level of initial resistance of mixture components did not have an impact on the aggressiveness of pathogens at equilibrium, it strongly influenced the transient values of aggressiveness and therefore the total amount of disease caused over an evolutionary period. The cost to the pathogen of alloinfection and benefit of autoinfection per se did not affect the final level of aggressiveness, but did affect the time to reach equilibrium. However, the ratio of the cost to the benefit did influence the final aggressiveness of the pathogen.     

植物检疫性有害生物名单相互关系研究

植物检疫性有害生物名单对植物检疫工作具有指导意义。本文概述了我国植物检疫性有害生物名单的发展历程及框架体系,介绍了部分植物检疫工作发达国家现有名单情况。对进境植物检疫性有害生物名录、全国农业植物检疫性有害生物名单、全国林业检疫性有害生物名单以及外来入侵物种名单内容间的关系进行比较研究。我国各名单存在交叉的有害生物50种(属)。探讨了名单不足之处,提出使名单内容科学合理的建设性意见。     

基于ESDA分析的关中城市群县域经济空间分异研究

通过ESDA分析,对关中城市群43个县域2009年的经济总体实力、民生建设水平和经济发展速度进行了分析,揭示了县域尺度上关中城市群经济空间的分异规律,研究表明:1)在经济总体空间格局上,关中城市群在经济总体实力、民生建设水平中存在着全局空间正相关,经济发展速度存在着较弱的空间负相关;2)在经济局部空间格局上,关中城市群的经济总体水平呈现南北两极分化格局,并以西安为核心呈圈级结构,民生建设水平冷点区集中分布在中部,经济发展速度热点区多分布在经济总体实力较低区域;3)关中城市群各县域经济总体实力、民生建设水平和经济发展速度在空间分布上呈现出一定的差异性,主要与各区经济基础、经济区位以及区域发展政策有关。     

天水地区农业生态气候资源量化与评价

根据天水地区7个气象台站多年平均气候资料和23个点的订正资料，采用农业生态气候适宜度的动态模型，对天水地区农业生态气候资源进行了量化分析和分类评价。农业生态气候的资源指数、效能指数和利用系数计算结果表明：自南向北、从东到西资源指数Cr、效能指数Ce和利用系数K大致呈递减态势，其中资源指数Cr的最高值出现在天水南部的党川附近，Cr值为6．5，最低值出现在榆盘附近，Cr值为4．4；效能指数Ce的最高值出现在麦积区附近，Ce值为3．8，最低值出现在王铺、沿安等山区，Ce值为1．6；利用系数K的最高值也出现在麦积区附近，K值为0．7，最低值也出现在王铺、沿安等山区，K值为0．3。这一变化基本反映了农业生态气候的地域分异特征。通过对多年逐月平均效能指数的模糊动态聚类，划分出天水农业生态气候资源的5个类型区，并进行了相应评价，结果表明天水农业生态气候的资源潜力、匹配状况和利用程度具有明显的区域分布特征，进而在此基础上提出了开发利用农业生态气候资源的若干建议。     

基于Copula函数的河北省夏大豆干旱风险特征研究

干旱是河北省夏大豆生育期内的主要农业气象灾害之一。选用1991—2020年河北省夏大豆种植区97个气象站的气温、降水、日照时数、风速等资料，以作物水分亏缺距平指数划分干旱等级，基于游程理论提取干旱事件的历时和烈度，采用Copula函数分析干旱事件的同现重现期，以及干旱事件同现重现期与大豆单产之间的关系。结果表明：（1）该区干旱历时、干旱烈度的高值区位于邢台、邯郸，干旱频次的高值区位于石家庄西部、保定西部、廊坊北部，说明高频次的区域不一定是长历时、强烈度干旱过程的分布区域。（2）河北省夏大豆干旱历时以威布尔分布和对数正态分布为主，而干旱烈度以广义极值分布和对数正态分布为主。（3）Frank-Copula函数为河北夏大豆干旱历时和干旱烈度的最优联合分布函数。（4）时长为3旬的干旱事件重现期最小，重旱的高风险区主要分布在廊坊、保定、石家庄中西部、沧州中东部、衡水、邢台、邯郸；时长为11旬的各等级干旱仅邯郸中东部为相对高风险区，其它大部地区为低风险区，即时长为11旬的干旱事件出现的可能性较小。（5）大豆单产与干旱时长、干旱烈度的相关系数75%的站点通过了P<0.05的显著性检验,与重现期的相关系数所有站点均通过了P<0.05的显著性检验，甚至1个站点通过了P<0.001的显著性检验,说明重现期更能反映干旱事件对产量的影响，长历时、高烈度干旱事件的重现期低值区为干旱的高风险区。     

不同形态氮素营养对水稻抗旱性影响的研究

采用溶液培养方法,在不同水分胁迫强度下,分析不同氮素形态(铵态氮、硝态氮、铵硝混合态氮)对水稻生长状况与水分关系的影响.结果表明:在轻度水分胁迫(5%PEG,约相当于-0.05 MPa)条件下,供铵和供铵硝混合态氮水稻生物量高于正常水分条件下的相应供氮形态处理,说明适度水分胁迫可以刺激这2种供氮形态水稻的生长;在重度水分胁迫(10%PEG,约相当于-0.15 MPa)条件下,仅供铵态氮水稻生物量高于正常水分条件下的相应供氮形态处理.此外,在水分胁迫条件下,供铵态氮水稻根系总长、根表面积和根系体积受水分胁迫影响不明显.重度水分胁迫条件下,供铵态氮水稻单位茎截面积的伤流液流速、水分利用率等都显著高于其他供氮形态水稻.因此,与其他氮素形态相比,供应铵态氮可以增强水稻在干旱环境下的生长.     

Root exudates associated with the resistance of four chickpea cultivars (Cicer arietinum) to two races of Fusarium oxysporum f.sp. ciceri

The germination of race 1 spores of Fusarium oxysporum f. sp. ciceri was significantly inhibited by the root exudate of the wilt-resistant chickpea cvs CPS1 and WR315 compared to untreated spores and spores treated with root exudates from susceptible cultivars. The effect was concentration dependent, such that the exudate from 1 g of root in 2 ml of water almost completely inhibited spore germination, whereas the exudate from 1 g of root in 20 ml water did not do so. The inhibitory effects of the active exudates were negated when the apolar components of the exudates were removed by extraction with ethyl acetate. The root exudates of the susceptible cv. JG62 and the late wilting cv. H208 did not inhibit germination. The hyphal growth of germinated spores was also strongly inhibited by the concentrated exudates of CPS1 and WR315, and diluted exudates were less potent. The highest concentration of the exudate of the susceptible cv. JG62 showed some inhibition of hyphal growth, whereas none of the exudates of H208 were found to contain any antifungal activity. The effect of the exudates on the spores of race 2 was similar to that reported for race 1, except that the water-soluble components of the crude root exudate of WR315 after ethyl acetate extraction were also found to inhibit germination significantly. Overall, the spores of race 2 appeared to be more susceptible to the effects of the exudates. The ethyl acetate fractions of the root exudates of CPS1 and WR315 strongly inhibited germination and hyphal growth of both race 1 and race 2, the effect being concentration dependent. The results suggest that the resistance of chickpeas to vascular wilt depends, at least in part, upon the antifungal activity of the root exudates. Differences in the expression of resistance in the field could depend upon the concentration or rate of production of constitutive antifungal components by the root.     

黄土高原不同轮作次序对土壤有机质和有效态微量元素分布的影响

对长武县十里铺村长期定位试验旱地土壤,用重铬酸钾容量法对土壤有机质进行测定,用DTPA浸提-原子吸收法对有效态微量元素进行测定,研究不同轮作次序对土壤有机质和有效态微量元素分布的影响。结果表明,土壤有效态微量元素的分布除受微量元素总量的影响外,还与作物的轮作次序有关。不同轮作次序土壤有机质均呈现先减小后增大的趋势,有效铁由上到下持续增加,有效锰和有效锌呈现上高下低的趋势,有效铜的分布趋势是由上到下先增加后缓慢减少。粮草轮作体系80~100 cm土层有机质含量在11.08~11.89 g·kg~(-1)之间,粮豆轮作体系该土层含量为11.04~11.72 g·kg~(-1)之间。粮草轮作系统中3年小麦的土壤有效铁和有效锰含量较低,种植苜蓿和马铃薯可以提高土壤有效锰含量,连续种植小麦和连续种植苜蓿土壤有效锌和有效铜含量出现下降的趋势。粮豆轮作系统中小麦+糜子茬口土壤有效铁含量较高,小麦茬口的土壤有效锰含量最低,比小麦+糜子茬口和豌豆茬口的含量平均低7.73%~30.55%。粮草轮作系统中土壤有效态微量元素的含量高于粮豆轮作系统,在80 cm以上土层,两个轮作系统中土壤有效态微量元素的含量差异较大,在该土层以下,两个系统间的差异减小。     

Pathogenicity and ultrastructural pathology of Eimeria debliecki (Douwes, 1921) in experimentally infected pigs

It was confirmed, after experimental infection of 24 weaned pigs with different doses (200,000 and 4 mil.) of Eimeria debliecki oocysts that the developmental cycle of E. debliecki occurs in the anterior jejunum and after a high dose of oocysts also in the duodenum and anterior parts of the middle jejunum. Pathological changes characterized by a light atrophy of the villi, scarcely dispersed minute erosions of the epithelium in upper parts of the mucosa and an inflammatory response in the propria of the anterior jejunum were found in the area of the largest occurrence of developmental stages of E. debliecki (from 50 cm to 100 cm from the pylorus). An inflammatory infiltrate in the propria of the anterior jejunum from 3 DPI to 5 DPI contained a conspicuously large number of plasma cells with Russell bodies. Cellular changes were detected only in enterocytes with developmental stages of E. debliecki. Changes of the microvillous zone were observed in infected enterocytes; dilated mitochondria, free ribosomes and an increased number of residual bodies were found in the cytoplasm of enterocytes. The degree of the cellular changes of enterocytes was dependent on the maturity of the developmental stage of E. debliecki. Based on pathological changes observed by the use of light and electron microscopy, the coccidium E. debliecki is considered to be pathogenic for weaned pigs in spite it does not provoke a clinical infection.