Is intraspecific trait differentiation in Parthenium hysterophorus a consequence of hereditary factors and/or phenotypic plasticity?

Of the various strategies adopted by an invasive plant species for expanding its niche breadth,phenotypic differentiation(either due to plasticity and/or adaptive evolution) is proven to be the most successful.Lately,we studied the persistence of substantial morpho-functional variations within the individuals of alien invasive plant,Parthenium hysterophorus in Chandigarh,India,through field surveys.Based on observed differences,the individuals were categorized into two morphotypes,PAand PB.PAhad higher leaf area,leaf biomass,and chlorophyll content as compared with PB.However,PBhad a higher stem circumference,stem specific density,twig dry matter content,profuse branching,bigger canopy,and better reproductive output than PA.To substantiate the persistence of intraspecific variations in P. hysterophorus and to deduce the possible genesis of these variations,we propagated both the morphotypes under experimental conditions in winter and summer.Apart from the key morpho-functional differences observed during the field studies,protein and carbohydrate metabolism were studied in leaves and roots of the propagated plants.Differences in plant metabolism were observed only during the early growth period,whereas the morpho-functional traits varied in the mature flowering plants.The effect of growth season was highly significant on all the studied morpho-functional and biochemical parameters(p ≤0.05).Parent morphotypes(P) and interactions between morphotypes and seasons significantly affected several growth parameters(p ≤0.05).The analyses revealed that the contrasting growth conditions at the time of transplantation and early growth may regulate the phenotype of P. hysterophorus.The pattern of intraspecific variations observed during the study is justified to consider morphotype PAas winter biotype and morphotype PBas summer biotype of P. hysterophorus.The study points towards the role of plasticity or a combination of genetic and environmental(G×E) factors in producing the phenotypic variability observed in the population of P. hysterophorus.

银胶菊(Parthenium hysterophorus)中抗TMV活性成分的分离及活性测定

采用活性跟踪法从银胶菊中分离获得抗病毒活性物质,经质谱和核磁共振分析,确定该物质为小白菊内酯。采用半叶枯斑法和叶圆盘法测定了其对烟草花叶病毒(Tobacco mosaic virus,TMV)的抑制效果,结果表明:0.2 mg/mL的小白菊内酯在混合接种和药液浸泡两种处理中均表现出较好的体外抑制TMV活性,其抑制率分别为69.0%和72.1%;在离体条件下对烟草叶圆盘中的烟草花叶病毒复制也具有良好的抑制效果,抑制率为72.3%。

Predicting suitable habitat of an invasive weed Parthenium hysterophorus under future climate scenarios in Chitwan Annapurna Landscape,Nepal

Chitwan-Annapuma Landscape(CHAL)in central Nepal is known for its rich biodiversity and the landscape is expected to provide corridors for species range shift in response to climate change.Environmental assessments have identified biological invasions and other anthropogenic activities as major threats to the biodiversity in the CHAL.One of the rapidly spreading Invasive Alien Plant species(IAPs)in the CHAL is Parthenium hysterophorus L.,a neotropical invasive weed of global significance.This study aimed to investigate the current and future projected suitable habitat of P.hysterophorus in the CHAL using MaxEnt modelling in three'Representative Concentration Pathways'(RCPs 2.6,4.5 and 8.5)corresponding to different greenhouse gases emissiontrajectories for the year 2050 and 2070.A total of 288species occurrence points,six bioclimatic variablesmean diurnal range,isothermality,annual precipitation,precipitation of driest month,precipitation seasonality,precipitation of driest quarter and two topographic variables(aspect and slope)were selected for MaxEnt modelling.Potential range shift in terms of increase or decline in the suitable habitat areas under the projected scenarios were calculated.Slope and annual precipitation were the most important variables that explained the current distribution of P.hysterophorus.Twenty percent of the total area of CHAL was predicted to be suitable habitat for the growth of P.hysterophorus in the current climatic condition.Highest gain in the suitable habitat of this noxious weed was found under RCP 4.5 scenario in 2050 and 2070.whereas there will be a loss in thesuitable habitat under RCP 8.5 scenario in 2050 and2070.Out of four physiographic regions present in CHAL,three regions-Siwalik,Middle Mountain and High Mountain have suitable habitat for P.hysterophorus under current climatic condition.The mountainous region is likely to be affected more than the Siwalik region by further spread of P.fhysteropfhorus in the future under low(RCP 2.6)to medium(RCP 4.5)emission scenarios.The suitable habitat for this weed is likely to increase in the protected areas of mountain regions(Langtang National Park,Annapurna Conservation Area and Manaslu Conservation Area)in the future.The results have revealed a risk of spreading P.hysterophorus from present localities to non-invaded areas in the current and future climatic condition.Such risk needs to be considered by decision makers and resource managers while planning for effective management of this weed to reduce its ecological and economic impacts in the CHAL.

Distribution pattern and ecological determinants of an invasive plant Parthenium hysterophorus L., in Malakand division of Pakistan

After habitat loss,drastic effects of biological invasion caused by alien invasive species to the native biodiversity have been acknowledged worldwide by the agriculturists,ecologists,and governments as it is more overwhelming than pollution,harvest and disease combined.One such example of biological invasion is P.hysterophorus which is considered to be one of the topmost noxious weeds threatening ecosystems diversity in the world,particularly in Pakistan due to its invasive success and generalist nature.Yet no studies have explored the pattern and determinants of plant biodiversity in the Parthenium dominated landscapes.Here we explored the current distribution pattern of this species with relation to environmental variables in the Malakand division of northern Pakistan.Twenty-three sites dominated by P.hysterophorus were identified through a participatory mapping process combined with traditional ecological knowledge and quantitative inventories were made.In total,we found 62 plant species in 55 genera and 32 families,predominately from Asteraceae,Poaceae,and Solanaceae.Ward’s agglomerative clustering procedure showed three well-differentiated,and ecologically meaningful but overlapping vegetation communities.P.hysterophorus was found to be the leading species with an average Importance value ranging from 33.28%to 65.59%.Based on our criteria,surprisingly we found significantly less to be fully(30%)or partially invaded(21%)than the less invaded(47%)plots,indicating the gradual invasive success of the species across the landscape.Canonical Correspondence Analysis(CCA-ordination)has explained 36.9%of the cumulative variance by the first three axes and identified elevation(r=-0.526),slope(r=0.438)and percent sand(r=-0.474)to be the major environmental factors affecting the distribution of P.hysterophorus and associated vegetation.These results suggested that elevation and percent sand negatively affect Parthenium distribution whereas slope has a positive relationship thereby promoting its populations in the region.The generalist nature of this invasive species is likely to have an overall adverse negative effect on the ecosystem functioning and cannot be ignored.Therefore,quick actions should be taken for the management of this noxious weed to avoid economic consequences and potential threats to fragile ecosystems such as that in Malakand division.

Comparative Efficacy of Weed Control Practices for Parthenium Weed and Sunflower Crop under Varying Tillage Systems

Parthenium poses serious threat to modern crop production system and necessitate evaluating control practices for its effective management.Efficacy of different weed control practices for controlling parthenium was explored in conventional and deep tillage systems in the field conditions.Hand hoeing(20 and 35 days after emergence),S-Metolachlor(pre-emergence herbicide),sorghum straw mulch@5 tons ha-1 and combination of hand hoeing and sorghum straw mulch(hand hoeing at 20 and straw mulch at 35 days after emergence)were used as weed control practice.Weedy check where no weed control measure was applied was also included in this experiment for comparison.Results concluded that the all weed management treatments significantly reduced parthenium density,its fresh and dry biomass during both the years of study as compared to weedy check.Maximum sunflower achene yield was recorded in hand hoeing(20 and 35 days after emergence)in combination with deep tillage.So,mold bold plough used for the purpose of deep tillage should be encouraged for better control of parthenium and higher achene yield of sunflower crop(3293.3 kg ha^(-1) in 2017 and 3221.3 kg ha^(-1) in 2018).Moreover,is also inferred that total dose of herbicide might be reduced by using hoeing and mulching in an integrated way.

Phenolic Acids from <i>Parthenium hysterophorus</i>: Evaluation of Bioconversion Potential as Free Radical Scavengers and Anticancer Agents

Parthenium hysterophorus is a globally recognized invasive alien weed that prominently colonizes grazing areas and cultivated lands causing adverse effect on crop production. Major allelochemicals released from parthenium include sesqueterpene lactones and phenolic acids. Among these the presence of caffeic, vanillic and ferulic acids is of industrial significance as they possess potent free radical scavenging and anticancer activities. This study reports for the first time, high total phenolic acid content (20.82 ± 0.82 mg GAE/g dry sample) in parthenium. The GC-MS analysis indicated the presence of ferulic, p-coumaric, vanillic and gallic acid as major phenolic components. Free radical scavenging activity of the phenolic acids extract gave an EC50 value 130.4 μg/ml when measured using DPPH assay. Anticancer activity of parthenium phenolic extract against A-498 (IC50 0.5237 μg/ml) and MDA-MB231 (IC50 and 0.2685 μg/ml) cancerous cell lines indicated its potential to be used as anticancer agent.

Impact of <i>Parthenium hysterophorus</i>L. Invasion on Species Diversity of Cultivated Fields of Bilaspur (C.G.) India

In present study invasion of Parthenium hysterophorus L. and its impacts on agriculture fields will be done in different cultivated crops in Bilaspur. The present work deals with diversity and distribution of weeds species in cultivated fields of Bilaspur C.G. A total number of 28 species under 27 genera and 16 families was distributed in three study sites (Koni, Sakri & Kota) of cultivated fields in Bilaspur C.G. These study sites were located in different altitudinal zones responding different conditions in the this study. The number of species per sites ranged from 13 to 24. In the Sakri, number of species was ranged from 17 to 27, and the relative density of plant species ranged between 0.77 (Heteropogon contortus, Solanum surratense, Vernonia cinneria and Leucas aspera) and 22.92 (Parthenium hysterophorus). In the Kota, number of species was ranged from 14 to 28, and the relative density of plant species ranged between 0.85 (Ageratum conyzoides, Heteropogon contortus, Triticum aestivum) and 29.06 (Zea mays) and 30.91 (Parthenium hysterophorus). In the Agriculture field, number of species was ranged from 15 to 28, and the relative density of plant species ranged between 0.58 (Leucas aspera) and 26.23 (Triticum aestivum). Present work will give the information that weeds are harmful to herbs, crops and medicinal plants. Parthenium weed can suppress and crowd out other weed species, and could form a single dominant population in the invasion area, causing serious threat to plant community biological diversity.

Distribution and Abundance of <i>Parthenium hysterophorus</i>L. in Metekel Zone, Northwest Ethiopia

Parthenium hysterophorus L. is a harmful invasive weed to plant biodiversity and human health. It is native to American tropics and first introduced to Ethiopia in the 1970s. Today, it is widely distributed across the country and severely affecting the biodiversity, crop, and animal production in the country. In the Metekel Zone, there was no report on its distribution and impacts so far. Therefore, this study was aimed to assess the distribution and abundance of the plant in the zone. The distribution and abundance data of the weed were recorded at five km intervals following all accessible roads of the zone. The result reveals that P. hysterophorus L. was less distributed in the area with a 4.95% frequency. However, it was found abundantly growing at roadsides, wastelands, around habitation, market place, and around Zeghibridge where it can rapidly spread to most economical lands like the arable and grazing lands. Moreover, it has aggressively invaded a nursery site, which enables the weed to enter agricultural fields directly. This suggests that the weed is on a fast move to agricultural lands in the zone. The regular active development activities such as agricultural investment, construction of roads, and factories are presumed to promote its spread. Therefore, a decisive and timely decision is needed to mitigate the weed when it is still sparse and small.

Comparative Efficacy of Common Broad Leaf Herbicides against an Invasive Weed: <i>Parthenium</i><i>hysterophorus</i>L.

Parthenium hysterophorus L. (parthenium weed) is an annual weed that grows rapidly in disturbed land. It is considered as one of the most hazardous weeds in Pakistan as it poses serious health problems to livestock as well as severe allergenic reactions in humans. It has invaded the Punjab and Khyber Pakhtunkhwa provinces and also been spreading in other parts of the country where it poses a risk for the grazing lands, roadsides, forests, wet lands, waste lands and of all types of cropped and non-cropped areas in Pakistan. The present studies were carried out to determine the impact of four locally available broad leaf herbicides viz;Stomp 455 CS (pendimethalin), Buctril Super 60 EC (bromoxynil + MCPA), Vantage 48 SL (glyphosate) and Logran Extra 750 WG (triasulfuron + terbutryn) (@ recommended and ½ of recommended dose) against P. hysterophorus grown in pots at research field of CABI CWA, Rawalpindi. All herbicides were applied at three growth stages (rosette, bolted and flowering). The observations for the mortality of P. hysterophorus were made 2 and 4 weeks after spray. The glyphosate was the most effective and reported 100% mortality of P. hysterophorus plants at flowering stage followed by bromoxynil + MCPA (89%), pendimethalin (80%) and triasulfuron + terbutryn (61%) at recommended dose after 4 weeks of spray. All tested herbicides achieved a mortality between 38% - 86% at rosette while 54% - 96% mortality at bolted stage after 4 weeks. Initially, 2 weeks after spray at flowering stage glyphosate caused 53% wilting followed by 49% (bromoxynil + MCPA), 33% (pendimethalin) and 9% (triasulfuron + terbutryn) at their recommended doses. The results indicated that P. hysterophorus is the most susceptible to glyphosate and bromoxynil + MCPA, both these herbicides are very promising for the wilting and management of parthenium weed.

气候变化下2种银胶菊属入侵植物在中国的潜在适生区分析

结合多个时期CMIP6气候变量数据和两种银胶菊属Parthenium物种在全球的分布数据,运用MaxEnt模型和ArcGIS软件,模拟分析两种银胶菊属植物在中国的潜在适生区。结果表明,各时期模拟预测结果的AUC值均大于0.9,模型预测准确,结果可靠;影响银胶菊P.hysterophorus在中国分布的主导因子依次为最湿季降雨量、最冷季平均温度、温度季节性、等温性,影响灰白银胶菊P.argentatum的主导因子为平均气温日较差、等温性、最干月降雨量、最冷季平均温度。在气候变化影响下,银胶菊的潜在适生区在未来有扩大,灰白银胶菊潜在适生区变化不大;银胶菊潜在适生区迁移方向主要为南北方向,纬度有所变化;当前及未来银胶菊的高适生区主要在华南及西南地区,未来气候下银胶菊在华中、华东、华北都存在适生区。相对于灰白银胶菊,银胶菊在我国的入侵危害更严重,应重点关注其入侵动态,加强监测与防控。

银胶菊中木脂素类成分的研究

研究银胶菊Parthenium hysterophorus Linn.中木脂素类化学成分。采用硅胶、Sephadex LH-20、MCI、ODS和半制备型HPLC等色谱技术,从银胶菊地上部分的95%乙醇提取物中分离得到5个木脂素类化合物(1~5),通过波谱学数据分析,将它们的结构分别鉴定为(7S,8S,7′E)-4,9,9′-三羟基-3,5,7,3′,5′-五甲氧基-8,4′-氧新木脂素-7′-烯(1)、丁香脂素(2)、杜仲树脂酚(3)、松脂素(4)、五味子醇甲(5)。其中,化合物1为新化合物,化合物3~5为首次从银胶菊中分离得到。对所有化合物进行了体外抗神经炎症活性筛选,结果显示,化合物1对LPS激活的BV-2小胶质细胞释放NO具有显著抑制作用,IC_(50)为21.10±1.97μmol/L,其余化合物均无活性,且所有化合物在测试浓度下均不影响细胞的存活率。

银胶菊丙二烯氧化物合成酶的表达纯化及其活性分析

植物来源细胞色素P450的表达和结晶都十分困难,成为成功解析该类蛋白晶体结构的瓶颈。探索了使用大肠杆菌表达系统表达、纯化银胶菊丙二烯氧化物合成酶(allene oxide synthase,AOS)的方法。氨基酸序列比对分析显示,银胶菊AOS缺失N-末端的膜锚定序列和信号肽序列,推测其在大肠杆菌中应表达为水溶性蛋白质。试验中纯化得到的银胶菊AOS是一个分子量为54.5 kD的八聚体分子,均一性好,不含去垢剂,达到毫克量级,适合下一步的晶体培养研究;还原一氧化碳差示光谱显示该酶在450 nm处有特征吸收峰,酶活性测定得到该酶的米氏常数为45.3μmol/L,显示该重组AOS具有很高的酶活性。

外来入侵植物银胶菊水提物对三叶鬼针草和茶条木种子萌发的化感作用

以伴生草本植物三叶鬼针草和能源木本植物茶条木为受试植物,初步研究了外来入侵植物银胶菊根、茎、花水浸提液对二者种子萌发的化感效应。根据发芽率、化感效应敏感指数、发芽速率可以看出,银胶菊不同部位的浸提液在不同浓度下对三叶鬼针草的种子萌发的影响力不同;而对茶条木种子萌发无明显的作用。为选择适宜植物,生物替代防治银胶菊提供依据。

入侵植物银胶菊在不同生境下表型可塑性和构件生物量

研究了入侵植物银胶菊在4种不同小生境间花果期形态特征变化和构件生物量特征。结果显示:在植株密度小但土壤肥沃的小生境中,植株各形态指标如茎长、茎直径和花序直径等都明显高于其它小生境,在生物量结构特征上则表现为总生物量和花果生物量所占比例的升高。随着植株密度的增加以及土壤肥力下降,上述各形态指标都发生了较明显的变化,生物量投资也进行了优化配置,银胶菊表现出了较高的形态可塑性。银胶菊与觅光和竞争相关的几个指标如叶和根的比例都增加,但用于生殖构件的比例却减少了。相关分析显示,银胶菊花果期各构件生物量与高度成正相关,与密度为负相关,并受环境因素的制约。表明,较高的形态可塑性和较强的生殖配置策略可能是银胶菊成功入侵我国的重要特征。

外来入侵植物银胶菊在广西的分布与危害

银胶菊为一种菊科植物,原产中、南美洲。尽管在广西出现的时间不长,但分布范围较广,由路旁向荒地、耕地发展,引起了很大的危害,包括入侵道路旁,阻碍交通、破坏道路环境;入侵放牧地,减少放牧地产草量;入侵耕地,引起农作物减产;且有毒,能引起人的皮炎、鼻炎及哮喘,危害人类健康。在广西发展成为一种重要的外来入侵植物,已引起科学家的注意。该文介绍了银胶菊的生物学特性和在广西的入侵、扩散等情况,提出了防治措施。

几种菊科入侵植物和非入侵植物的化感作用比较

以萝卜为受体,采用培养皿法比较研究了几种菊科入侵种和非入侵种的化感潜力。结果表明:入侵种和非入侵种都具有化感作用,且入侵种在高浓度下的化感抑制作用强度不一定都大于非入侵种。在0.2 g.mL-1浓度时,艾蒿和黄鹌菜的综合化感作用强度分别是小飞蓬的2.5和3.1倍;而紫茎泽兰和银胶菊则是小飞蓬的3.8和3.5倍。而不同植物浸提液对萝卜的不同检测指标影响不同。其中,紫茎泽兰对萝卜种子发芽和幼苗生长的影响主要表现为化感抑制作用。银胶菊和除0.025 g.mL-1外的黄鹌菜各浸提液都使萝卜种子萌发受较强的抑制,且抑制强度随浸提液浓度的升高而增大,而对幼苗生长则表现为"低促高抑"的规律。小飞蓬和苦荬菜对萝卜种子萌发和幼苗根长为抑制作用,但对其苗高和鲜质量为促进作用。除0.025 g.mL-1外,艾蒿对萝卜种子萌发和幼苗根长有较强的抵制,对其苗高和鲜质量则呈"低促高抑"的规律。

外来入侵植物银胶菊不同部位的化感作用

在室内以滤纸为载体用离体生物测定方法测定了银胶菊(Parthenium hysterophorus)根、茎、叶和果实水浸提液对蔬菜萝卜(Raphanus sativus)和杂草马唐(Digitaria sanguinalis)、苘麻(Abutilon theophrasti)种子的化感效应,同时在温室内以土壤为载体测定了银胶菊不同部位干粉对这3种植物种子萌发和幼苗生长的影响。室内生测试验结果表明,银胶菊叶和果实水浸提物对3种受体植物种子的萌发和幼苗生长均有较强的抑制作用,其中受体萝卜和苘麻的敏感性较高,而马唐的敏感性较低。温室盆栽试验也表明,银胶菊叶和果实对受体生长的影响明显高于根和茎,说明叶和果实是集中表现银胶菊化感作用的特定部位。

银胶菊叶和花提取物对南方根结线虫的毒杀活性比较

为进一步明确银胶菊(Parthenium hysterophorus L.)的杀线虫活性,对银胶菊叶和花的不同溶剂提取物、甲醇提取物的不同萃取物以及甲醇提取物碱水层的不同极性组分对南方根结线虫(Meloidogyne incognita Chitwood)的杀虫活性进行了检测,并对不同提取物、萃取物和萃取组分进行了生物碱的定性分析。结果表明:银胶菊叶和花的蒸馏水、甲醇、乙酸乙酯和石油醚提取物的得率分别为24.5%和20.3%、19.6%和10.9%、6.8%和7.7%、2.0%和2.7%,其中,叶和花的蒸馏水和甲醇提取物的杀线虫活性均较强,而石油醚提取物的杀线虫活性最弱。用质量体积分数1.0%和0.5%的叶和花蒸馏水提取物分别处理24和48 h后试虫的校正死亡率均达到100.00%;用质量体积分数1.0%和0.5%的叶和花甲醇提取物处理48 h,试虫的校正死亡率均大于90%。叶和花甲醇提取物的碱水层、三氯甲烷Ⅰ层和Ⅱ层萃取物均具有一定的杀线虫活性,其中,用质量体积分数1.0%的花和叶碱水层萃取物以及花的三氯甲烷Ⅰ层萃取物分别处理48 h,试虫的校正死亡率均为100.00%,而三氯甲烷Ⅱ层萃取物的杀线虫活性最弱。银胶菊叶和花甲醇提取物碱水层的11个不同极性组分(A1～A11)也表现出不同程度的杀线虫活性,其中,用质量体积分数0.2%和0.1%花的A2〔溶剂为V(三氯甲烷)∶V(甲醇)=10∶1〕和A7〔溶剂为V(三氯甲烷)∶V(甲醇)=1∶1〕组分以及叶的A2和A6〔溶剂为V(三氯甲烷)∶V(甲醇)=2∶1〕组分处理48 h后,试虫的校正死亡率均达100.00%,显著高于其他组分。定性实验结果表明:银胶菊叶和花中具有杀线虫活性的提取物、萃取物和萃取组分中均含有生物碱。研究结果说明:银胶菊花的杀线虫活性高于叶片,其毒杀活性不仅与提取部位及溶剂的种类和极性有关,还与提取物浓度及作用时间等因素有关。

外来入侵杂草银胶菊种子萌发特性及无性繁殖能力研究

银胶菊Parthenium hysterophorus L.是一种危害性很强的外来入侵杂草,在我国南方多省均有分布,在山东省莒南县也大面积分布,目前已对发生地生态环境造成巨大影响。文章于2011年采用人工气候箱培养皿法和温室土壤盆栽相结合的方法,研究银胶菊的种子在不同pH、盐浓度、湿度、营养条件、不同埋藏深度等条件下种子萌发特性及其无性繁殖能力,以期为明确其入侵机制和适生环境提供依据。结果表明,银胶菊种子适宜的萌发环境为酸性,pH=6.0时发芽率最好,到pH=8.0时,种子不能萌发;盐对银胶菊种子的萌发影响很大,随着盐浓度的提高,发芽率下降明显,当盐浓度达到0.12 mol·Lˉ1时,种子不再萌发;但不同的营养条件和不同P水平对种子的萌发无显著影响;干旱或水涝均能降低种子发芽率;种子埋藏土层越深,其发芽率越低,土层深度达3.0 cm以上,银胶菊种子几乎无发芽率。银胶菊有较强的无性繁殖能力,根部、基部茎和上部茎等不同部位埋入土壤后均能发芽,基部茎的发芽率最高(为66.7%-88.9%),根部和上部茎发芽率较低(为22.2%-44.4%)。另外,从发芽后的生长来看,茎部(包括基部茎和上部茎)发芽后均能正常生长,但根部发出新芽后逐渐黄化死亡。由此可以看出,银胶菊种子适应力、耐贫瘠能力强,一般的农田、荒地环境均能萌发生长,但盐碱地的环境下不能萌发生长;散落在土壤表层的银胶菊种子萌发率最高,因此,没有人类扰动的荒地、沟渠更适宜其萌发和生长;由于其很强的无性繁殖能力,人工砍伐的防除措施不能将其彻底防除。这些都是银胶菊入侵后,能够在短时间内暴发成灾,且不易彻底防除的原因。

入侵植物银胶菊对不同氮、磷水平的繁殖适应性

通过模拟野外生境,研究了入侵植物银胶菊(Parthenium hysterophorus L.)在不同氮、磷养分水平下的繁殖特征,探讨其对土壤养分增加的繁殖适应性及繁殖能力。结果表明:在一定范围内,随氮水平的增加,银胶菊分枝数、头状花序数、繁殖器官的生物量及其比例、结实率等显著增加;对于磷养分来说,仅株高和种子千粒重明显增加,其余参数未见明显增加。银胶菊主要通过提高种子产量适应氮养分丰富的生境,而通过提高种子质量才能适应磷养分丰富的生境。土壤氮、磷养分的增加,提高了其繁殖能力,使其具有根据环境养分调节繁殖特性的能力,实现对不同养分资源生境的入侵。