基于种子发芽率评估长芒苋在我国不同纬度地区的入侵风险

外来入侵植物长芒苋Amaranthus palmeri已经传入我国多个地区,定量评估其入侵风险对制定高效防控措施具有重要意义。外来植物入侵风险应该是由传入后能发芽并完成生活史的繁殖体如种子的量决定的,但已开展的适生区预测等风险评估通常忽略了该因素。基于此,本研究先通过同质园试验, 比较了采自我国不同纬度的11个长芒苋种群与来自原产地美国种群的种子发芽率,分析了种群间发芽率的差异及其与纬度的相关性;然后,通过一年内连续多次在不同纬度地区的交互种植试验,分析了不同纬度种群间种子的发芽率和完成生活史的入侵窗口期差异,并判断是否发生了本地适应;最后,根据发芽率和入侵窗口期评估了长芒苋在我国不同纬度地区的入侵风险。同质园试验表明,种子发芽率与种群所处纬度显著正相关(P<0.05),发芽率随纬度升高而增高。交互种植试验表明,不同种群发芽率的差异是由于本地适应导致的,长芒苋在我国的入侵窗口期随纬度升高而缩短。基于不同种群种子发芽率和入侵窗口期的纬度差异,我们判断长芒苋在我国中低纬度至中高纬度区域内入侵风险较高,应该重点防控。长芒苋在高纬度和低纬度地区的入侵风险相对较低。但长芒苋种子萌发的本地适应可能会增加其在高、低纬度地区的入侵风险。因此,亟须加强对已传入种群的监测预警与早期防控力度,抑制其繁殖增长和进一步的扩散蔓延。     

影响长芒苋种子萌发因素的研究

长芒苋是我国1985年发现的外来入侵植物,明确长芒苋种子萌发特性,将为其有效防控提供数据支撑.采用室内生物测定方法,对温度、光照、水势、发芽深度等影响长芒苋萌发的关键因子进行研究.结果表明,变温处理可有效提高长芒苋种子的发芽势和萌发率,最适萌发温度为35℃/15℃变温处理;在35℃/15℃培养条件下,光照对长芒苋种子的...     

靶标基因突变导致入侵性杂草长芒苋对咪唑乙烟酸产生抗性

长芒苋Amaranthus palmeri生长迅速,适应性广,繁殖系数高,具有很强的竞争性,已在我国多地定植,对作物产量及生态环境构成潜在威胁.一旦其对除草剂产生抗性,将大大增加治理难度.本试验研究了采自不同地点的长芒苋种群对除草剂咪唑乙烟酸的抗性水平和抗性机理.整株生物测定得出,长芒苋疑似抗性种群和敏感种群对咪唑乙烟...     

ITS序列及其SNP位点在外来入侵杂草长芒苋、西部苋和糙果苋物种鉴定中的应用

对于以种子形态为物种主要识别依据的口岸部门,外来入侵杂草长芒苋、西部苋和糙果苋一直是鉴定的难点。本文对34种苋属植物的ITS序列和26SrDNA进行分析,通过SNP变异位点及特异性引物,借助PCR-RFLP方法,对长芒苋、西部苋与糙果苋进行快速、准确的分类鉴定。ITS序列分析表明,长芒苋种内变异小,种间变异显著,可与其他苋属植物明显区分。西部苋与糙果苋之间ITS序列差异小,需依据SNP位点来区别。     

基于4种生态位模型的长芒苋潜在适生区预测

恶性入侵杂草长芒苋Amaranthus palmeri S.Watson对农业生产和生物多样性造成严重威胁。预测其潜在适生区对粮食安全和生物多样性保护至关重要。不同模型由于算法不同对长芒苋潜在适生区的预测结果存在差异。本研究综合4种生态位模型(MaxEnt、GARP、BIOCLIM和DOMAIN)预测长芒苋在我国的潜在适生区以提高预测准确性。结果表明,4种模型的平均AUC值均大于0.85。MaxEnt和DOMAIN的平均Kappa值大于0.81;BIOCLIM和GARP的平均Kappa值大于0.69。MaxEnt的预测精度和稳定性要略胜一筹。BIOCLIM和MaxEnt的预测结果较为收敛,DOMAIN和GARP预测的适生区范围较广,由此预测的长芒苋潜在适生区分别占我国陆地总面积的20.66%和32.38%,48.39%和49.76%。综合预测结果,长芒苋在我国的适生区主要集中在中东部地区,西北和东北地区则是长芒苋存在的边缘环境地区。     

表型可塑性与外来入侵植物的适应性

表型可塑性是生物体在不同环境中表现不同特征和特性的能力,在生物中普遍存在这种现象.在外来入侵植物入侵过程中,表型可塑性强的入侵植物具有强大的适应性,可以促使其成功入侵.外来入侵植物的表型可塑性通过在定殖与种群建立过程中的前适应机制和潜伏与扩散传播过程中的后适应机制拓宽了生态幅,作用于进化和自然选择的速度,从而增强了外来入侵植物的入侵性.本文介绍了表型可塑性的概念与研究进展,重点阐述了外来入侵植物表型可塑性适应意义的主要理论及其研究方法,并对该领域研究进行了展望.     

利用双重数字PCR检测进口美国大豆中长芒苋的EPSPS基因拷贝数

长芒苋是一种原产北美洲的雌雄异株杂草.在美国,一些长芒苋种群已经对草甘膦产生了抗药性.EPSPS基因拷贝数的增加是长芒苋产生抗药性的主要原因.本文建立了双重数字PCR检测长芒苋EPSPS基因拷贝数的方法,对进口美国大豆中携带的8个长芒苋样品进行检测,发现3个样品的EPSPS相对拷贝数较低,5个样品EPSPS相对拷贝数大...     

红火蚁入侵的种群生物学与行为遗传学

红火蚁是广布性以及入侵危害性最强的昆虫类群之一。它有很多的生物学特性适合其入侵、定殖以及扩散。该类害虫在入侵时以及入侵后在种群生物学和行为遗传学上发生了一系列的变异,使其成为一种入侵成功的外来生物。     

进境粮谷中携带苋属检疫性杂草籽风传播扩散距离的预测

风媒传播是外来杂草传播扩散的主要途径之一。我国进口粮谷中经常携带大量苋属杂草种子,这些种子质量轻,在卸货、运输等过程中存在风传播扩散风险。本文以3种重要苋属检疫性杂草,即长芒苋、西部苋和糙果苋种子为材料,通过测定其在可能撒漏高度范围和撒漏点风速范围内的垂直沉降速度和水平扩散距离,预测苋属3种检疫性杂草在装卸及运输过程中风传播扩散范围。结果表明在风速为35 m/s,种子释放高度为35 m时,长芒苋、西部苋和糙果苋3种杂草种子的最远扩散距离分别为57.75 m、111.68 m和114.33 m。     

外来入侵杂草长芒苋

长芒苋(Amaranthus palmeri S.Watson)是20世纪80年代中期传人我国的一种新植物,为中国苋属异株亚属一新归化物种.近年来长芒苋在北京市不断扩展蔓延.本文对长芒苋的形态特征、生物学特性、分布、危害及其防除作一简要介绍.     

STUDIES ON WEED SPECIES OF THE GENUS POLYGONUM L.

Summary. Seeds of Polygonam persiaria were collected from seven localities during 1962. In 1963 plants of these seven populations were grown in the field and sampled at regular intervals over the period 21st June to 13th August. At all samplings there were differences between populations in total dry weight, in leaf area index and in total nitrogen content, and populations also differed in the date of flowering. The populations also differed significantly in relative growth rate, leaf area ratio, net assimilation rate and relative nitrogen absorption rate. The variations in net assimilation rate did not appear to be closely associated with variations in leaf area index. Certain growth attributes were correlated with the latitude of origin, and it is tentatively suggested that the populations may represent genetically distinct latitudinal ecotypes.
Études sur des espèces de mauvaises herbes du genre Polygonum L.     

Variation and heritability of morphological and physiological traits among Leymus chinensis genotypes under different environmental conditions

Intraspecific trait variation and heritability in different environmental conditions not only suggest a potential for an evolutionary response but also have important ecological consequences at the population, community, and ecosystem levels. However, the contribution of quantitative trait variation within a grassland species to evolutionary responses or ecological consequences is seldom documented. Leymus chinensis is an important dominant species in semi-arid grasslands of China, which has seriously suffered from drought and high temperature stresses in recent decades. In the present study, we measured variation and heritability of 10 quantitative traits, namely the number of tillers, maximum shoot height, number of rhizomes, maximum rhizome length, rhizome mass, aboveground mass, root mass, maximum net photosynthetic rate(Pmax), specific leaf area(SLA), and leaf length to leaf width ratio(LL/LW), for 10 genotypes of L. chinensis under one non-stress(Ck) condition and three environmental stress conditions(i.e., drought(Dr), high temperature(Ht), and both drought and high temperature(DrHt)). Result indicated that(1) the interaction of genotype and environmental condition(G×E) was significant for 6 traits but not significant for the other 4 traits as shown by two-way analysis of variance(ANOVA), suggesting that different selection forces were placed for different traits on the factors dominating phenotypic responses to different environmental conditions. Moreover, these significant G×E effects on traits indicated significantly different phenotypic adaptive responses among L. chinensis genotypes to different environmental conditions. Additionally, individuals could be grouped according to environmental condition rather than genotype as shown by canonical discriminant analysis, indicating that environmental condition played a more important role in affecting phenotypic variation than genotype;(2) by one-way ANOVA, significant differences among L. chinensis genotypes were found in all 10 traits under Ck and Dr conditions, in 8 traits under Dr Ht condition and only in 4 traits under Ht condition; and(3) all 10 traits showed relatively low or non-measurable broad-sense heritability(H_2) under stress conditions. However, the lowest H_2 value for most traits did not occur under DrHt condition, which supported the hypothesis of 'unfavorable conditions have unpredictable effects' rather than 'unfavorable conditions decrease heritability'. Results from our experiment might aid to improve predictions on the potential impacts of climate changes on L. chinensis and eventually species conservation and ecosystem restoration.     

Genetic and morphologic diversity of <Emphasis Type="Italic">Echinochloa crus-galli</Emphasis> populations from different origins

Echinochloa crus-galli (L.) P. Beauv. (barnyardgrass) is an annual weed that is native to Asia and found throughout the world. The broad ecological tolerance and competitive ability of E. crus-galli makes it the most important weed species in rice. Genetic studies of plants are becoming increasingly common because reliable information is necessary to better understand population dynamics, occurrence of herbicide resistance, and demographic data. Echinochloa crus-galli populations from 34 different locations in Turkey were compared with respect to morphological differences and genetic variation. For morphological variation, five seeds of each population were sown in pots and grown in a screenhouse using a randomized block design. Morphological parameters such as germination speed, flowering time, leaf area, plant height, spikelet length, above-ground biomass, root dry weight and number of seeds were measured. Distinct differences among populations with respect to hierarchical cluster analysis were observed. Genetic variations among populations were performed using random amplified polymorphic DNA (RAPD) markers. The seven RAPD primers amplified 55 bands whose molecular weight varied between 200 and 4000 bp. The percentage of polymorphic bands was 74.54%. Results showed high morphological and genetic variability among individual genotypes within geographic locations. Phenotypic and genetic variability among E. crus-galli populations would be influenced by agricultural practices, crop characteristics, geographic location and herbicide pressure. Differences between weed populations may affect response to chemical or biological control.     

Potential allelopathic effects of Suregada multiflorum and the influence of soil type on its residue's efficacy

This experiment was conducted to determine the potential allelopathic effects of the aqueous extracts and dried leaf powder of Suregada multiflorum and to find the herbicidal effects of its granule on the weed species, barnyardgrass (Echinochloa crus‐galli) and slender amaranth (Amaranthus viridis), in various growth media (germination paper, sand, and soil). Observations in this study demonstrated that the potential and magnitude of their inhibitory effects varied among the plant parts. The leaves and branches possessed the strongest inhibition levels, followed by the bark. The aqueous extract from the leaves of S. multiflorum had a remarkably stronger inhibitory effect on the germination and growth of slender amaranth, compared with barnyardgrass; when applied at the concentration of 100 g L^–1, it completely inhibited the germination and initial seedling growth of slender amaranth. In addition, all the treatments of the dried leaf powder had stronger inhibition effects than the aqueous extract. Interestingly, the inhibitory effects of the dried leaf granule of S. multiflorum were stronger than the effects of the dried leaf powder at equal rates. The degree of inhibitory effect of the S. multiflorum granule, applied in various growing media, can be classified in order of decreasing inhibition as germination paper = sand > clay soil. The present study indicates that the S. multiflorum granule product that was developed in this research has the potential to provide a powerful organic herbicide for controlling slender amaranth.     

STUDIES ON WEED SPECIES OF THE GENUS POLYGONUM L.

Summary. Seeds of Polygonum persicaria from several sources, or from plants subjected to in lain treatments, were chilled for varying periods and incubated for a 3-week germination test period. Populations differed widely in seed weight and to some extent in the response to different periods of chilling. No relationship between this response and the climate of the locality of origin could be found. There was much variation in seed weight and germination behaviour between individual plants within populations. A total of four polymorphic seed categories were observed. The proportions of seeds in the two main categories varied widely between and within populations, and were affected by certain environmental factors. These factors also appeared to affect the degree of inter-plant variation in seed shape and germination behaviour.
Travaux sur les espàes indésirables du genre Polygonum L. V. Variations dans le poids des semences, leur comportement à la germination et leur polymorphisme chez P. persicaria L.     

Intraspecific variation in Capsella bursa-pastoris in plant quality traits for insect herbivores

The arable plant Capsella bursa‐pastoris is phenotypically variable in many life history traits, particularly time from germination to flowering. The hypothesis was investigated that, associated with this variation, there are differences in traits that influence plant quality for insect herbivores. Significant within‐species variation was found in plant growth, leaf surface characteristics and tissue nutrient composition among 21 accessions of Capsella. Short flowering time plants exhibited slow vegetative growth, relatively large shoot nitrogen content, high leaf hair densities and differences in phloem composition, compared with long flowering time plants. Insect herbivore response to distinctive trait combinations was assessed on a subset of seven accessions using the phloem‐feeding aphids Aphis fabae and Myzus persicae. Variation in aphid performance was small but significant, with 15–25% fewer nymphs produced on plant variants that exhibited greater tissue water content and low tissue C:N ratio (A. fabae) or on variants with less phloem nitrogen (M. persicae). The differential responses exhibited by the two aphid species to the test accessions confirmed that quantifying intraspecific plant variation is a necessary first step in understanding plant functional diversity and its impact on consumers in arable systems.     

STUDIES ON WEED SPECIES OF THE GENUS POLYGONUM L.

Summary. Seeds of Polygonum lapathifolium were collected from eight localities during 1962. Plants of these populations were grown in the field and sampled at fortnightly intervals during June and July 1964. There were significant differences between populations in dry weight, leaf area index and nitrogen content at all samplings, and populations also differed in date of flowering and in certain morphological feature. Smooth curves were fitted to some of the growth data, and an account of the fitting procedure is given. For comparison, certain growth functions were calculated from the smooth curves as well as from the observed data. The populations differed in relative growth rate, net assimilation rate, relative nitrogen absorption rate and in certain other calculated functions, A number of growth attributes were significantly correlated with the latitude, longitude or length of the growing season of the locality of origin, and it is tentatively suggested that the populations represent climatic ecotypes.
Études sur des espèces de mauvaises herbes du genre Polygonum L. II. Variations physiologiques dans P. lapathifolium L.     

探索促进寄生蜂生殖力的蜜源植物共性特征

通过布局合适的蜜源植物,以提高农田生态系统的害虫防控服务,已成为一种常用的生境管理技术。然而,如何筛选理想的蜜源植物是保护生物防治中迫切需要解决的现实问题。本研究通过室内试验构建蜜源植物对寄生蜂寄生能力影响的数据库,分析了不同蜜源植物的效应值与寄生蜂和蜜源植物关键生态特征的相关性。结果表明,花序类型是筛选蜜源植物的最重要特征,其中复伞形花序植物的花对寄生蜂寄生能力的促进作用最显著,而花单生、头状花序和穗状花序植物的对寄生蜂寄生能力的促进作用不明显。赤眼蜂等微小型寄生蜂的生殖潜力的高低对其取食蜜源植物后的寄生能力影响不显著。寄生蜂的寄主类型、种群类型等不会影响蜜源植物对赤眼蜂的寄生能力。     

Differences intraspecifiques chez Convolvulus arvensis L.*

Intra-specific differences in Convolvulus arvensis Convolvulus arvensis plants from French and Spanish populations were grown under uniform conditions in Madrid. Observations were made on seed weight, chromosome number, leaf shape and flowering habit. In addition, soluble seed proteins were examined by electrophoresis. The results were used to establish a pattern of intraspecific variation which was related to the geographic origin of the plants. It is suggested that this variation may affect the efficacy of herbicides used in the control of C. arvensis.