紫茎泽兰提取物对3种杂草的化感胁迫作用

为探讨紫茎泽兰(Eupatorium adenophorum)提取物对植物种子萌发和早期幼苗生长的影响及其生理机理,以稗草(Echinochloa crusgalli)、灰绿藜(Chenopodium glaucum)和反枝苋(Amaranthus retroflexus)3种常见的田间杂草为材料,采用根悬空培养等方法,研究了不同浓度紫茎泽兰提取物对3种杂草种子萌发和幼苗生长、根尖组织结构、根系边缘细胞(root border cell,RBC)生理特性和根冠果胶甲基酯酶(pectin methyl esterase,PME)活性的影响。结果发现:紫茎泽兰提取物对3种植物种子萌发均具有明显的抑制作用;1000 mg/L紫茎泽兰提取物处理后,3种杂草幼苗的根尖均有不同程度的伤害,如根尖肿胀、抽缩或变形;根尖表层细胞脱落、内层细胞排列混乱。紫茎泽兰提取物处理能显著抑制3种杂草幼苗根尖RBC的数量(分别比对照降低了44.5%、48.3%和64.0%);诱导RBC凋亡(凋亡率分别达到81.7%、91.3%和97.1%)并显著增加RBC的黏胶层厚度(分别比对照增加了99.0%、65.5%和61.1%)及诱导PME活性升高。这些结果表明:紫茎泽兰提取物抑制了3种杂草根边缘细胞的产生,并诱导了根尖边缘细胞凋亡,因而破坏了根边缘细胞对根尖的保护系统,最终抑制了根系的生长发育。研究为将紫茎泽兰提取物用于植物源除草剂的开发提供了理论依据。     

亚高山地区香芸火绒草挥发油的研究

对甘肃产野生香芸火绒草采用SED和萃取两种方法提取精油和浸膏,测得精油平均得率0．037％,浸膏1．18％,净油53．4％。精油有65种组分,评香鉴定认为,具有醛香、清香、甜香,香气浓强。研究分析表明,该植物可成为一种新的生产天然香精香料的原料来源。     

原产地和入侵地紫茎泽兰对泽兰实蝇的选择性、卵巢蛋白质含量与解毒酶活性的影响

[目的] 紫茎泽兰是我国危害严重的恶性入侵杂草。比较专一性天敌泽兰实蝇对该杂草入侵前后植株的适应性,是揭示外来植物入侵后适应性机制的重要科学问题之一。[方法] 比较泽兰实蝇对原产地和入侵地紫茎泽兰植株的寄主选择性,并测定寄生于2类植株的上泽兰实蝇卵巢蛋白质含量及乙酰胆碱酯酶、羧酸酯酶、谷胱甘肽S-转移酶活性。[结果] 泽兰实蝇对原产地和入侵地紫茎泽兰的选择无显著性差异;寄生在紫茎泽兰入侵地植株上的卵巢蛋白质含量较原产地植株上更高。解毒酶活力比较表明,入侵地紫茎泽兰上泽兰实蝇的羧酸酯酶活性低于原产地上的,但谷胱甘肽S-转移酶（雌虫）活性比较则相反,乙酰胆碱酯酶活性比较均无显著性差异。[结论] 紫茎泽兰入侵后,专一性天敌泽兰实蝇的适应性有所下降,丰富了外来植物入侵机制中天敌逃逸假说的内涵。     

紫茎泽兰化感作用对9种草本植物种子萌发的影响

【背景】紫茎泽兰是一种入侵我国的世界性恶性杂草,给当地的农、林、畜牧业生产造成严重的经济损失,使生态环境面临"绿色灾难"。紫茎泽兰的化感作用是其成功入侵的重要原因,其化感物质对当地植物的生长具有明显的抑制作用。【方法】利用培养皿滤纸法研究了紫茎泽兰叶片水提液对9种草本植物种子萌发的影响,这些植物包括紫茎泽兰入侵早期直接与之竞争的云南草本植物:鲁梅克斯、高丹红、鸭茅(安巴)、苕子、胡枝子,以及为替代控制紫茎泽兰而引进的外来优良牧草:紫花苜蓿(敖汉)、白三叶(海发)、红三叶、黑麦草(速达)。【结果】紫茎泽兰叶片提取液对9种受体植物种子萌发均具有化感作用。低浓度提取液对受体植物的化感作用较弱(对部分植物种子萌发有促进作用);高浓度提取液对受体植物的化感作用较强,且能降低种子发芽率及发芽速率,其中,发芽速率对化感作用更敏感。不同植物对紫茎泽兰化感作用的敏感程度不同,鲁梅克斯、鸭茅和苕子对紫茎泽兰的化感作用较敏感;黑麦草、胡枝子和高丹红最不敏感;紫花苜蓿、红三叶和白三叶对低浓度紫茎泽兰叶片水提液不敏感,对高浓度提取液较敏感。【结论与意义】不同植物种子对紫茎泽兰化感作用的敏感性存在差异,研究结果有利于了解紫茎泽兰成功入侵的机制,并可为筛选具有替代控制潜力的优良牧草奠定基础。     

外来植物紫茎泽兰的入侵机理与控制策略研究进展

为了解析外来恶性杂草紫茎泽兰在中国的入侵扩张机制和控制策略,从其种群形成与扩张的生态适应性及遗传分化特性、对本地植物的竞争替代和可持续控制技术基础3个方面进行了集中研究.对紫茎泽兰的主要研究进展为:(1)入侵中国的紫茎泽兰在核DNA水平上具有丰富的遗传多样性,形成了不同的地理种群,不同环境条件下的隔离是导致遗传分化的主...     

丛枝菌根真菌对紫茎泽兰生长与繁殖的影响

【目的】紫茎泽兰是一种世界性的恶性入侵杂草,侵入我国后迅速扩散至多个省市,严重阻碍了当地农、林、牧业的发展。研究丛枝菌根真菌对紫茎泽兰生长和繁殖的影响,解析土壤中丛枝菌根真菌在紫茎泽兰入侵、传播和扩散过程中的作用,能为开展紫茎泽兰防控工作提供参考。【方法】通过盆栽实验,测定接种丛枝菌根真菌的紫茎泽兰株高、叶片数、总叶面积、节间距、地径,并统计单株花序数、单花序种子量、种子量、种子千粒重、含水率、发芽率、发芽势、发芽指数等。【结果】丛枝菌根真菌对紫茎泽兰的株高、地径有极显著影响(P0.01),接种丛枝菌根真菌后,紫茎泽兰的单株花序数、单花序种子数、总种子量分别增加了5.03、1.51、7.64倍;种子的长度、宽度、含水率、发芽率、发芽势、发芽指数分别增加了15.24%、23.08%、19.46%、29.22%、391.01%、183.56%(P0.05)。【结论】丛枝菌根真菌可显著促进紫茎泽兰生长,控制丛枝菌根真菌的数量可有效抑制紫茎泽兰生长,并抑制紫茎泽兰花序数、种子量及种子的生命力,降低其扩散蔓延速度。     

利用泽兰实蝇控制紫茎泽兰的生防策略研究

本文根据野外泽兰实蝇种群15个世代的调查资料,利用契贝谢夫正交多项式拟合了泽兰实蝇、紫茎泽兰的空间格局。阐明了泽兰实蝇空间格局的序列变化及紫茎泽兰空间格局的特点;揭示了泽兰实蝇空间格局的特点受当地主风及寄主紫茎泽兰空间格局特点的影响;并从最优控制系统的角度对泽兰实蝇-紫茎泽兰系统作了初步探讨。首次提出了最佳释放虫量指标为每条虫占有10条枝条。这些结果为多点释放及定点多次释放泽兰实蝇防治紫茎泽兰这一生防策略提供了理论基础。     

泽兰实蝇雌成虫的寄主选择行为

【背景】泽兰实蝇是紫茎泽兰的专性寄生天敌,已成为控制紫茎泽兰的重要因子。泽兰实蝇的寄主选择力对其控制紫茎泽兰至关重要,但相关报道还很少。【方法】采用"Y"形嗅觉仪在实验室内测定泽兰实蝇雌成虫对寄主植物——紫茎泽兰及其他植物的选择行为,以及紫茎泽兰受重金属胁迫后泽兰实蝇对其选择的变化。【结果】不同日龄的泽兰实蝇雌成虫对紫茎泽兰的选择性不具有显著差异;交配与否对雌成虫的寄主选择没有显著影响;雌成虫对紫茎泽兰的选择显著高于黄蒿、水葫芦和蓝花鼠尾草等非寄主植物;雌成虫对花期及机械损伤的紫茎泽兰选择更显著;紫茎泽兰经重金属镉(Cd)、铅(Pb)和锌(Zn)单一及复合处理后,泽兰实蝇雌成虫对其选择性显著降低。【结论与意义】泽兰实蝇雌成虫的寄主选择性随植物种类、寄主植物(紫茎泽兰)的生育期、健康状况及重金属胁迫而变化,这有助于更好地利用泽兰实蝇控制紫茎泽兰。     

泽兰实蝇雌雄成虫转录组及差异分析

[目的]泽兰实蝇Procecidochares utilis Stone是入侵杂草紫茎泽兰Eupatorium adenophorum Spreng的重要的专食性天敌,已成为控制紫茎泽兰的重要因子.本研究旨在获得泽兰实蝇转录组,并深入研究泽兰实蝇雌雄成虫差异表达基因.[方法]利用Illumina高通量测序技术对泽兰实蝇雌雄成虫进行转录组测序和生物信息分析.[结果]总共获得29 147条unigenes,平均长度为457 bp,同时将所得序列注释到七大数据库进行比对,共获得19 384条unigenes注释结果.分析发现11 331条差异表达基因;与雄成虫相比,雌成虫有2 640条unigenes表达量上调,8 691条unigenes表达量下调.[结论]本研究获得了泽兰实蝇转录组,为今后泽兰实蝇性别相关研究提供了序列支持.     

泽兰实蝇内生殖器官的结构及其发育状况

【背景】泽兰实蝇属双翅目实蝇科,是杂草紫茎泽兰的重要专性天敌。该蝇幼虫可蛀入紫茎泽兰内部形成虫瘿,有效控制紫茎泽兰的扩散,许多国家都利用泽兰实蝇控制紫茎泽兰的危害。【方法】通过光学显微法观察了泽兰实蝇成虫内生殖器官的结构及其发育动态。【结果】雌性泽兰实蝇的内生殖系统主要由卵巢、输卵管、受精囊、雌性附腺等器官组成,雄性生殖系统由精巢、输精管、雄性附腺、射精管组成。在成虫发育过程中,雌虫卵巢的长度在第4日龄时达最大值,宽度在1日龄时达最大值,与其他日龄相比有显著差异,雌性附腺及受精囊的大小在各日龄间无显著差异;雄虫精巢长度在4日龄时达到最大,宽度在2日龄时达最大,且不同日龄间也有显著差异,而雄性附腺的大小在不同龄期间无显著差异。【结论与意义】本文阐明了泽兰实蝇的内生殖系统结构与发育状况,这有助于为提高泽兰实蝇人工繁殖效率及生物防治效果奠定理论基础。     

空心莲子草对南京春季杂草群落组成和物种多样性的影响

空心莲子草(Alternanthera philoxeroides)是目前我国危害最为严重的外来植物之一。利用样方法调查了南京市春季有空心莲子草分布的不同生境下杂草的种类和分布情况,用主成分分析及聚类分析法进行数据处理分析,目的是研究空心莲子草对杂草群落组成和物种多样性的影响。结果表明,南京市春季有空心莲子草分布的样点杂草有36科142种,其中禾本科、菊科、蓼科最多;影响空心莲子草及伴生杂草分布、发生的主要因素是土壤水分条件和人为干扰强度。依据这两个因素的不同,可将样点划分为4个聚类群,比较了各聚类群物种多样性指数,结果显示:各聚类群里随着空心莲子草重要值的升高,Simpson优势度指数也逐步上升,表明空心莲子草的优势度得到加强;Shannon-Weiner指数和Pielou均匀度指数均逐渐下降,说明了群落的物种多样性持续降低,原来的优势种危害加大,空心莲子草的入侵影响群落结构,使物种多样性降低。     

Weed performance in crop rotations with and without leys and at different nitrogen levels

Weed populations were studied from a 26-year-old field experiment in southern Sweden with three different 6-year crop rotations, each with four rates of nitrogen application. The rotations differed in that one had a two-year legume-grass ley, another had a two-year grass ley, and that the third had spring wheat followed by a repeatedly harrowed fallow. The leys and the fallow were followed by turnip rape, winter wheat, oats and barley which was undersown in the two ley rotations. Data on weed biomass, collected in one season, were subjected to multivariate analysis.
Winter turnip rape had the highest weed biomass. However, of the several weed species, only Matricaria perforata Merat was important in wheat (the crop following turnip rape in the rotation). The weed flora did not differ consistently between rotations. We conclude that none of the three rotations had developed any major weed problems under the past weed management regime (herbicides applied to cereal crops).
There was no consistent effect of nitrogen fertilisation on total weed biomass in any of the three rotations. However, when comparing the weed floras in winter wheat, turnip rape and oats, the unfertilised plots differed from the plots receiving nitrogen. In the two latter crops, the abundant, low-growing annual Stellaria media (L.) Vil. performed best in fertilised plots with dense stands. Equisetum arvense L., the most abundant perennial weed, was important only in unfertilised plots.     

安徽沿江圩丘农区夏收作物田杂草群落分布规律的研究

作者创用了七级目测调查取样,进行数量分析的方法,对夏收作物田杂草群落进行分类研究,揭示了安徽沿江圩丘农区夏收作物田杂草群落的分布规律主要受土壤类型和轮作制度制约。看麦娘杂草群落分布于水稻土田,猪殃殃,野燕麦杂草群落分布于丘岗区旱地,卷耳、婆婆纳杂草群落分布于灰潮土旱地。首次提出综合草害指数,用以评定杂草群落类型中每种杂草的危害性,从而,提出了不同土壤类型和轮作制度的田块中恶性杂草的定量化指标与防除策略。     

Steroidal constituents of rice (Rryza sativa) hulls with algicidal and herbicidal activity against blue-green algae and duckweed

Two new compounds, 14-methyl stigmast-9(11)-en-3alpha-ol-3beta-D-glucopyranoside (1) and cholest-11-en-3beta, 6beta, 7alpha, 22beta-tetraol-24-one-3beta-palmitoleate (2), along with the known compound beta-sitosteryl-3beta-D-glucopyranosyl-6'-linoleiate (3), were isolated from the methanolic extract of rice (Oryza sativa) hulls. The structures of the two new compounds were elucidated using one- and two-dimensional NMR in combination with IR, EI/MS, FAB/MS, HR-EI/MS and HR-FAB/MS. In bioassays with blue-green algae, Microcystis aeruginosa UTEX 2388 and duckweed, Lemna paucicostata Hegelm 381, the efficacy of bioactivity of the two new compounds linearly increased as the concentration increased from 0.3 to 300 IgM. Compared with momilactone A, compounds 1 and 2 showed similar and higher inhibitory activities against the growth of M. aeruginosa at a concentration of 300 microM. However, compound 2 was similar to momilactone A in inhibiting L. paucicostata growth at a concentration of 300 microM. As a result, compound 2 appears to have a strong potential for the environmentally friendly control of weed and algae that are harmful to water-logged rice.     

薇甘菊在广东的分布与危害

较全面调查了薇甘菊（Mikania micrantha)在广东省内的分布,生境与危害状况。薇甘菊多集中分布在珠江三角洲一带,生长在路边向阳潮湿的废弃地,垃圾堆放地,受人为干扰较多的农田,菜地,苗圃,果园,园林绿地,人工林,次生林等环境中。分析了薇甘菊的危害特点和生境的气候条件,并对防治措施作了介绍。     

冬小麦播种密度和施肥方式对麦田杂草群落组成及生长的影响

在半湿润地区的土垫旱耕人为土上,以冬小麦品种小偃22为指示作物,通过田间小区试验研究了不同施肥条件下冬小麦田间杂草种群的组成以及在4个生育期(越冬期、返青期、拔节期、成熟期)田间杂草密度和生物量的变化.结果表明:(1)在冬小麦全生育期内共发现以猪殃殃、麦家公、婆婆纳、播娘蒿、泽漆、荠菜等为主的17种杂草,不同生育期杂草的优势种群不同,而且杂草总密度表现为越冬期>返青期>拔节期,生物量表现为拔节期>返青期>越冬期;(2)与不施肥处理(P0N0)比较,单施氮肥增加了杂草密度和生物量,在氮磷配施条件下,氮肥对生物量有极显著影响且随施氮量增加表现为减小趋势,其中PN45处理的杂草生物量最大并比P0N0增加51.8%;施磷对杂草生物量有极显著影响,其中单施磷比P0N0处理增加44.0%,PN135处理比P0N135处理增加24.0%.(3)低密度播种比正常密度播种能显著增加杂草生物量,平均增加幅度达82.9%.结果表明,通过增施氮肥和适当增加种植密度,可在一定程度上控制杂草发生,促进作物良好生长.     

种植制度对江苏省棉田杂草群落影响的研究

 经连续5年对江苏省主棉区水旱轮作及旱连作两种种植制度下的棉田杂草种群密度及草害优势度级数进行定田调查,通过时间和空间上的比较统计分析,研究了棉田杂草群落演替趋势及草害发生规律。研究结果表明,种植制度与江苏省棉田杂草群落的组成和草害发生程度紧密相关。在水旱轮作棉田中,随着棉花(Gossypium hirsutum)种植年数的增加,喜湿性杂草稗草(Echinochloa crusgalli)等优势度值逐渐减少,喜旱性杂草马唐(Digitaria sanguinalis)等优势度值逐渐提高,它们之间存在显著的线性关系。旱连作棉田以喜旱性杂草为主,发生量较大,草害较重,年际间杂草群落变化较小。另外,水旱轮作和旱连作棉田之间的杂草群落结构和种群数量差异显著。而地理区域差异的影响明显小于轮作制度差异导致的影响。     

不同生境和森林内薇甘菊的生存与危害状况

对薇甘菊（Ｍｉｋａｎｉａ ｍｉｃｒａｎｔｈａ Ｈ．Ｂ．Ｋ）在不同生境下生长状况及其对其它植物的危害程度的研究表明,这种热带杂草是喜光、好湿的。薇甘菊伴生物种以藤本植物居多。其中葛藤和五爪金龙出现的频度最大。薇甘菊及其伴生种通过攀爬树冠,形成盖幕作用而对其它植物造成危害。在森林内薇甘菊危害的对象主要是低矮的乔木对高大乔木影响不大。     

Allelopathic effect of Bromus spp. and Lolium spp. shoot extracts on some crops

Allelopathy is an untapped resource for weed control in crops that could give good possibilities for environmentally sound, integrated crop production. Allelopathy is defined as the direct or indirect harmful or beneficial effects of one plant on another through the production of chemical compounds, called allelochemicals, which escape into the environment. Allelochemicals can be produced by weeds and affect crops, and the reverse is also true. Allelopathic interactions include weed-weed, weed-crop, and crop-crop. Allelopathy offers potential for selective biological weed control for instance weed-suppressing crops and the use of plant residues in cropping systems, allelopathic rotational crops, or companion plants with allelopathic potential. Bromus species occur in many habitats in temperate regions of the world, including America, Eurasia, Australia, and Africa. The genus Lolium is one of the most important forage grasses. The weed species usually grow in the same production zones as wheat and are considered weeds since they parasitize wheat fields. Some of the weed species in these two genus have been reported to have allelopathic effect. One of the methods that has been successful in studying allelopathic activity are bioassays. Laboratory experiments were conducted to determine allelopathic effect of watery shoot extracts of four weed species of the Poaceae family, namely Bromus rigidus, Bromus diandrus, Lolium multiflorum and Lolium temulentum on germination and growth of winter wheat (Triticum aestivum L.), spring barley (Hordeum vulgare L.), corn (Zea mays L), perennial ryegrass (Lolium perenne L.), bean (Phaseolus sp.) and sunflower (Helianthus annuus L.) and on each other. The experiment was carried out during the period March 2010 to October 2010. Twenty five seeds were put into one Petri-dish on filter paper, adding 15ml of extract to each in four repeats. The germination took place in a Binder-type thermostat in the dark. The timing of germination was checked in every two days and the rate of growth was estimated after a week, by counting the number of germinated seeds and measuring the length of the radicle and plumule. The measured data was statistically analyzed and the effect of the extracts on germination percentage and seedling length was evaluated.     

Assessing broomrape risk due to weeds in cropping systems with an indicator linked to a simulation model

Integrated crop protection tolerates residual weed floras if they are not harmful for crop production. These weeds can host harmful crop pests, among which parasitic plants such as branched broomrape (Phelipanche ramosa). This holoparasite is responsible for large yield losses in French crops such as oilseed rape. To date, there are no herbicides available to control it. To evaluate ex ante the impact of crop management practices on weed-mediated parasite infection of crops, we developed an indicator calculated from outputs of the weed dynamics model FlorSys. It consists of three components assessing weed impact on (1) stimulation of parasite germination during the whole cropping season, i.e. the potential risk reduction for future crops via a reduction of the parasite seed bank, (2) the stimulation of parasite germination in host crops, i.e. the potential risk increase for the current crop, (3) parasite reproduction on weed plants, i.e. the potential risk increase for future crops. This indicator was then used to predict weed-mediated broomrape risk in cropping systems from six regions from France and one from Spain. Antagonisms and synergies with other indicators of weed-harmfulness for crop production and weed contribution to plant and functional biodiversity were investigated with Pearson correlation analyses. For instance, cropping systems with a high parasite risk also had a high functional biodiversity (e.g. weed-based food offer for bees). Effects of crop management practices on the weed-mediated parasite risk indicator were identified with linear models; regression trees were used to identify the combinations of management practices that maximised or minimised weed-mediated broomrape risk. Parasite risk depended on crop rotation, sowing and harvest dates, tillage, herbicides and mechanical weeding. The lowest risk was observed in fields that were last tilled less than 21 days before sowing, with more than 0.6 herbicides per year (i.e. 3 applications in 5 years) with multiple entry modes into the weeds (e.g. leaves and roots) and the last herbicide sprayed no later than 127 days before harvest. RLQ analyses were used to identify correlations between weed species traits (Q matrix) and simulated parasite risk (R matrix), via simulated weed densities (L matrix). Early summer-emerging weed species increased parasite risk. No other notable correlations were found, indicating that parasite risk results from a weed community of interacting species, and not simply from individual weed species. An advice table was built to summarize and explain the effects of crop management practices on weed-mediated parasite risk.