外来入侵植物长芒苋在中国不同地区的表型变异与环境适应性

长芒苋(Amaranthus palmeri)是近年来入侵我国的超级杂草,已在我国从南到北的多个点定殖,一旦大面积扩散势必会对农业生产和生物多样性保护等构成极大威胁。长芒苋在我国入侵点的纬度跨度大于其原产地北美洲的分布,探明其在我国不同纬度的地理种群的环境适应机制,对评估扩散潜能、建立早期监测预警等防控措施具有重要意义。本研究在同质种植园实验条件下,通过测定长芒苋不同纬度地理种群的生活史、形态及生物量等11个性状指标来分析其在我国的表型变异与环境适应性。结果表明,在同质园条件下,长芒苋不同地理种群间株高等7个表型性状指标差异不显著,而开花和发芽时间、花序长以及比叶鲜重4个指标具有显著差异(p<0.01),且它们的表型变异随年平均温度(纬度)线性增加或降低。开花时间随纬度的升高而缩短,发芽时间、花序长和比叶鲜重随纬度的升高而增加。基于长芒苋不同纬度地理种群间表型性状的异同,我们推断表型可塑性促进了其在我国不同地理环境中的定殖,表型变异(如高纬度种群开花时间提前)可促进其环境适应性进化,拓展其在我国的适生性分布区,增强其向原产地适应环境梯度之外地区入侵和扩散蔓延的潜力。     

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。     

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...     

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。     

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。     

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...     

中国南方喀斯特外来入侵植物的分布格局及预测分析

分析中国南方喀斯特地区外来入侵植物的地理分布格局并预测其潜在分布区，对区域尺度上外来入侵植物的防控和管理具有重要意义。本研究基于中国南方喀斯特地区记录的327种外来入侵植物的精准地理分布数据，使用物种丰富度算法分析了该地区外来入侵植物的地理分布格局，并评估了其对本地植物多样性保护的影响，然后采用MaxEnt模型预测了外来入侵植物在中国南方喀斯特地区的潜在分布区及其变化趋势。结果表明：（1）中国南方喀斯特地区外来入侵植物的入侵风险区主要分布在北部、西南部和东南部，尤其以广西省的西部和东北部最为严重；（2）在入侵风险区中，有53.15%的区域也是本地植物的保护优先区，主要分布在喀斯特地区的南部；（3）中国南方喀斯特地区的西南部与交通要道沿线是外来入侵植物的重要潜在分布区，未来面临较高入侵风险。中国南方喀斯特地区的南部是外来入侵植物的重点防控和监测的优先管理区域，未来还是外来入侵植物的高适宜潜在分布区，需及时采取措施对入侵风险区的外来入侵植物进行防治以防止其进一步扩散。     

重要检疫性杂草长芒苋的分子检测

为实现检疫性杂草长芒苋(Amaranthus palmeri)的有效检测,本研究基于苋属植物可溶性淀粉合成酶I基因(SSSI),建立了一种序列特异性PCR方法,可实现从众多苋属种子中检测出长芒苋。结果显示,该方法特异性强、简便快捷,可为口岸检疫鉴定工作提供有效的技术支持。     

金佛山自然保护区外来入侵植物初步研究

对金佛山自然保护区外来入侵植物的种类、来源地、入侵机制、危害和防除措施进行了研究。结果表明,金佛山外来入侵植物共有33种,全部为草本,大部分原产美洲和非洲。这些植物一旦随人类活动传入,则能依靠自身强大的繁殖能力、生态适应能力和传播能力以及对本地环境条件的适应性等,在本地自然繁衍和扩散,给金佛山的生态系统和农林业生产带来了一定的危害。对入侵植物进行防控的同时,还应该注意积极利用。     

云南省六个国家级自然保护区外来入侵草本植物与本地植物的关系

为明确不同自然保护区外来入侵草本植物及其与本地植物多样性之间的关系,以我国生物多样性丰富的云南省为研究对象,于2014年对云南省6个国家级自然保护区的82个1 m2小样方(78个100 m2大样方)中外来入侵草本植物和本地植物物种丰富度和密度进行调查,并分析外来入侵草本植物物种丰富度与本地草本植物物种丰富度、外来入侵草本植物密度与本地草本植物密度的关系及对不同自然保护区外来入侵草本植物物种丰富度的差异进行分析。结果显示,共调查发现22种外来入侵草本植物,其中纳板河流域国家级自然保护区种类最多,达14种,金平分水岭国家级自然保护区仅有2种;6个国家级自然保护区本地草本植物的物种丰富度与外来入侵草本植物的物种丰富度之间、本地草本植物密度与外来入侵草本植物密度之间均呈现正、负2种相关关系,其中哀牢山国家级自然保护区本地草本植物的物种丰富度与外来入侵草本植物物种丰富度呈显著负相关,其它5个国家级自然保护区的相关性均不显著。简单回归分析表明自然保护区外来入侵草本植物物种丰富度与本地草本植物物种丰富度、本地草本植物盖度、本地乔灌木物种丰富度呈显著负相关,多元回归分析结果表明乔灌木物种丰富度和经纬度是造成不同自然保护区外来入侵草本植物物种多样性差异的主要原因。     

进境美国高粱携带杂草种子萌发率测定

收集并整理2014~2016年从黄埔和南沙口岸进境美国高粱中截获的杂草种子,对截获频次进行统计,并对截获频次较高的9种检疫性杂草、14种非检疫性杂草进行萌发试验,结果表明,供试杂草种子几乎均能萌发,且萌发率较高,如长芒苋和裂叶牵牛萌发率达58%以上、糙果苋19.17%、假高粱和豚草的萌发率也达到7.50%和5.00%。因此要重视美国高粱中携带的杂草种子检疫以及杂草监测工作,防止这些杂草种子的定殖传播。     

不同环境因素对节节麦萌发的影响

节节麦Aegilops tauschii Coss.是麦田难治杂草,研究环境条件对节节麦发芽的影响对预测其适生区域及综合治理有重要意义。以采自陕西、山东和河南的3个节节麦种群为对象,通过室内和室外萌发试验研究了水势、pH、盐分和播种深度与节节麦萌发的关系。结果表明,3个节节麦种群在不同的环境条件下表现出相似的萌发及出苗特性,其萌发对水势敏感,发芽率随水势的下降而降低,当渗透势小于-1.0 MPa时,种子不萌发;节节麦萌发对pH要求不高,在pH 3～10条件下发芽率均超过70%;其萌发具有一定的耐盐性,盐浓度为0 mmol/L时,发芽率最高,盐浓度大于420 mmol/L时,节节麦不能萌发;节节麦出苗率随播种深度的增加而降低,播种在土壤表面时,出苗率最高,播种深度大于10 cm时,未发现节节麦出苗。3个节节麦种群发芽对上述不同环境因子的反应差异不显著。     

Effect of environmental conditions on Alopecurus myosuroides germination. I. Effect of temperature and light

Summary Control of Alopecurus myosuroides with a minimum amount of herbicide may be improved by models describing the impact of cropping system effects on the weed's demography. In order to develop the submodel relating the weed seedbank to the emerged seedlings, a series of laboratory experiments was set up to analyse and quangify the effects on A. myosuroides germination of temperature, storage location, seed age and light incidence for various seed populations. The minimum temperature requirement for germination was estimated at 0 °C, and it did not depend on seed population or weight. In the subsequent experiments, a four-parameter non-linear equation depending on accumulated day-degrees was fitted to the observed germination data, resulting in the estimation of parameters quangifying germination proportion and rate. Storage location had little influence on germination. Germination proportion and rate increased with seed age and were higher in light than in darkness. The later the germinating seeds were submitted to light, the less was their germination stimulated. These observations were synthesized by a series of equations quangifying the relative variation in germination parameters as a function of storage and light conditions, independent of seed population.     

Factors affecting seed germination and emergence of Aegilops tauschii

Information on seed germination and emergence ecology of Aegilops tauschii is scant, despite it being a widespread invasive weed in China. We conducted this study to determine the effects of various factors on seed germination and seedling emergence in three A. tauschii populations. Seeds germinated across a wide range of temperatures (5–35°C), with germination of over 90% at 15–20°C. Germination was completely inhibited when dry seeds were exposed to a temperature of 160°C for 5 min; a similar response was observed for pre-soaked seeds at 100°C. Light was neither required for nor inhibited germination. Germination was not significantly affected by pH. Aegilops tauschii was relatively tolerant to low osmotic potential and high salt stress: over 80% of seeds germinated at −0.3 MPa, and all three populations germinated in the presence of 400 mM salt (NaCl) although salt tolerance varied among the populations. Seeds buried at depths of 1–3 cm emerged well, but emergence was completely inhibited at depths greater than 8 cm. The addition of maize straw caused a linear reduction in seedling emergence, although the rate of reduction varied among the populations. The results of this study have contributed to understanding the requirements of A. tauschii germination and emergence and optimising an integrated management system for this weed in Huang–Huai–Hai Plain of China. In addition, our study provides data for development of models to predict the geographical distribution of this weed.     

Germination behaviour of two morphologically different types of seed of Cassia tora at different temperatures

The effect of temperature on the germination response of two categories of morphologically different seeds of Cassia tora L. was investigated. Germination response of dormant seeds (category A with closed ultraastructures) was not affected by temperature, as 96% of the seeds germinated at all temperatures on scarification. On the other hand, non-dormant seeds (category B with open ultrastructures) were temperature sensitive and germinated best at 32°C. However, storage affected the germination responses of both types. While the category A seeds lost moisture gradually with storage time and retained viability for a longer period, i.e. 2 years, the moisture loss in category B seeds was noted only after 2 years and the seed viability was retained for only 1 year. The production of two morphologically and physiologically distinct types of seed simultaneously by C. tora is probably an ecological adaptation for progressive emergence of the species over long periods in the field.     

Seed germination response to temperature for a range of international populations of Conyza canadensis

Conyza canadensis is a surface‐germinating ruderal facultative winter annual with recruitment that is highly susceptible to changes in microsite conditions. A key adaptive characteristic for a facultative winter annual species, like C. canadensis, is germination response to temperature. The objective of this study was to determine the germination response to temperature for C. canadensis seed sourced from regions around the world with differing climates and, by doing so, gain insight into the role that seed germination biology plays in the adaptiveness and weediness of facultative winter annual weeds. Seed was sourced from populations in Málaga, Spain, Hertfordshire, UK, Shiraz, Iran and southern Ontario, Canada, and grown out in a common garden under controlled conditions to produce seed for this study. These seeds were then subjected to temperatures from 6.5 to 20°C at 1.5°C increments using a thermogradient plate. Cumulative daily germination counts for 30 days were recorded. Results indicated that temperature and source location had a significant effect on germination response. Estimated base germination temperature ranges were significantly different among the populations [Ontario (8–9.5°C), Iran (9.5–11°C), Spain (12.5–14°C), UK (11–12.5°C)], as were accumulated growing degree days (GDDs; d°C) required to reach 50% germination. For three of the four populations, estimated base germination temperature range values were below those previously reported in the literature. These differences are most likely rapid evolutionary adaptations to local climate and highlight the potential C. canadensis has to be problematic as a native and invasive species.     

Influence of hairy vetch seed germination and maturation on weediness in subsequent crops

Hairy vetch is a widely adopted cover crop in the United States. However, hairy vetch can become weedy in subsequent crops as seeds germinate after the cover crop growing season, which is largely attributed to seed dormancy. We conducted two field experiments to determine seed germination, viability and seed production phenology of two common hairy vetch cultivars in Blacksburg and Blackstone, Virginia, US. ‘Groff’ and ‘Purple Bounty’ seed were sown in October 2015 and May 2016 and germination was tracked until June 2017. Subsequently, ungerminated seeds were tested for viability. Both cultivars had <2% germination after the initial germination period, and <1% of seed recovered was still viable at the end of the experiments. We also conducted experiments to determine when these cultivars produce viable seed. Hairy vetch seeds were counted and tested for germination in the spring. Both cultivars produced seed beginning in late‐May, but most seed were not viable until mid‐June in Virginia. Our results indicate that seed dormancy is not the primary cause of hairy vetch weediness in subsequent crops as nearly all germination, 99% of the total germinated seed, occurred during the cover crop growing season. Also, if complete termination occurs before mid‐June in Virginia, it is unlikely viable seed will be added to the seed bank. To better utilise this cover crop species, cultivar selection and proper termination are important to prevent weediness.     

Germination behaviour in seeds of Diplotaxis erucoides and D. virgata

The seed germination behaviour of four populations each of Diplotaxis erucoides (L.) DC. and D. virgata (Cav.) DC, two weedy Brassicaceae species widely distributed in the Mediterranean region, was studied under controlled light, temperature and moisture conditions. Germination rates in D. virgata were generally higher at alternating (25/15^C) and low (15^C) temperatures, whereas in D. erucoides optimal germination rates were achieved at higher temperatures (25^C). No correlation between seed weight and germination was found in either species. In D. virgata, the geographic origin of the seed had an important effect on germination percentage. Great germination variability was found among the populations and even among seeds belonging to the same population. In this species, the application of gibberellic acid stimulated germination, especially in the populations with higher dormancy levels. Dormancy was found in mature D. virgata seeds but not in those of D. erucoides. In both species, germination percentages decreased after a certain period of storage at low temperatures. This period varied depending on the species and the population considered.