魏子上,陳新微,楊殿林,皇甫超河**

(1.農(nóng)業(yè)部環(huán)境保護(hù)科研監(jiān)測(cè)所 天津 300191;2.沈陽(yáng)農(nóng)業(yè)大學(xué)植物保護(hù)學(xué)院 沈陽(yáng) 110866)

遼寧地區(qū)兩種菊科入侵植物與本地植物光合特性比較*

魏子上1,2,陳新微1,2,楊殿林1,皇甫超河1,2**

(1.農(nóng)業(yè)部環(huán)境保護(hù)科研監(jiān)測(cè)所 天津 300191;2.沈陽(yáng)農(nóng)業(yè)大學(xué)植物保護(hù)學(xué)院 沈陽(yáng) 110866)

為明確外來(lái)植物生理生態(tài)學(xué)性狀及其與其強(qiáng)入侵性的關(guān)系,本研究采用野外原位氣體交換參數(shù)測(cè)定的方法,分析了菊科入侵植物豚草、三裂葉豚草與其共生本地植物紫菀光合特性和葉片性狀的差異。結(jié)果表明,豚草、三裂葉豚草、紫菀3種植物的光飽和點(diǎn)(LSP)均高于800 μmol·m-2·s-1,且兩種入侵植物的LSP顯著高于紫菀,表觀量子效率(AQY)則顯著低于紫菀;3種植物的最大凈光合速率(Pnmax)大小順序?yàn)殡嗖?三裂葉豚草>紫菀,其中,豚草和三裂葉豚草的Pnmax分別比紫菀高出151.28%、82.80%,且差異顯著。兩種入侵植物的比葉面積(SLA)、葉片的單位質(zhì)量氮含量(Nmass)、葉片單位質(zhì)量磷含量(Pmass)、光合能量利用效率(PEUE)、光合氮利用效率(PNUE)均顯著高于紫菀,但3者葉片單位質(zhì)量建成成本(CCmass)差異不顯著。綜上所述,遼寧的兩種菊科入侵植物相對(duì)于本地共生種來(lái)說(shuō)有著較高的氣體交換參數(shù)和葉片特性指標(biāo),且其光合特性和葉片特性也存在著密切的聯(lián)系,表現(xiàn)在這些菊科入侵植物有著更高的Pnmax、PNUE、PEUE和水分利用效率(WUE)等光合特性指標(biāo)和能量利用指標(biāo),使得入侵植物能夠更有效地捕獲和利用環(huán)境資源,成為其得以成功入侵的原因之一。

菊科入侵植物;光合特性;最大凈光合速率;葉片特性;資源利用效率

在經(jīng)濟(jì)全球變化日益加速的背景下,生物入侵已對(duì)入侵區(qū)的生態(tài)環(huán)境、農(nóng)林業(yè)經(jīng)濟(jì)和人民健康造成了嚴(yán)重的威脅和損害,成為21世紀(jì)最矚目的全球性環(huán)境問(wèn)題之一[1-3]。入侵植物通常生長(zhǎng)快速,且具有生態(tài)適應(yīng)能力強(qiáng)、繁殖能力強(qiáng)和傳播能力強(qiáng)的特點(diǎn)[4],并以此排擠本地植物。入侵種入侵到某一個(gè)地區(qū)后開(kāi)始擴(kuò)散建立自己的種群,然而并不是所有的本地植物都被競(jìng)爭(zhēng)或排擠下去,對(duì)比入侵種和當(dāng)?shù)貎?yōu)勢(shì)伴生種群的生理生態(tài)特性差異可以作為探求入侵種入侵機(jī)制的突破口。除了生長(zhǎng)速度,與入侵植物強(qiáng)大競(jìng)爭(zhēng)能力相關(guān)的指標(biāo)還包括高光合速率,低建成成本(construction costs,CC)以及高總?cè)~面積[5]。比葉面積(specific leaf area,SLA)又是表征葉片建成成本的間接指標(biāo)[5-6]。較低的建成成本(也即高比葉面積)意味著較高的植物碳同化產(chǎn)物利用效率以及較高的光合氮素利用效率[7-8](photosynthetic nitrogen-use efficiency,PNUE),而這又有助于植物快速生長(zhǎng)[6],使得入侵種能夠獲得生長(zhǎng)優(yōu)勢(shì)[9-10]。例如,Baruch和Goldstein[11]在夏威夷州采集了30種入侵植物和34種本地植物,通過(guò)對(duì)比其葉片重要的功能特性例如比葉面積、葉片建成成本、葉片氮含量等和光合特性如葉片同化速率,研究發(fā)現(xiàn)入侵種較本地種都有著比較高的比葉面積、同化速率,但有著比較低的葉片建成成本。Alpert等[12]、王睿芳等[13]提出類(lèi)似研究應(yīng)該比較親緣關(guān)系比較近的入侵種和本地種,例如同科或是同屬的植物。王俊峰等[14]研究發(fā)現(xiàn)飛機(jī)草(Chromolaena odorata)和其同科蘭花菊三七(Gynura japonica)兩種植物適應(yīng)光環(huán)境的策略有明顯不同,相比本地植物飛機(jī)草有著較高的光能利用效率。王曉紅等[15]通過(guò)研究入侵植物小飛蓬(Conyza canadensis)及其主要伴生植物山苦荬(Ixeris chinensis)和鴨跖草(Commelina communis)的光合特性發(fā)現(xiàn),小飛蓬具有較高的光合速率和物質(zhì)積累能力,較高的生產(chǎn)力是其成功入侵的重要因素之一。

我國(guó)最常見(jiàn)的入侵植物來(lái)自菊科、禾本科和十字花科[1],其中菊科植物是入侵種類(lèi)最多的類(lèi)群之一[16]。豚草(Ambrosia artemisiifolia)是原產(chǎn)于北美的一年生惡性雜草,屬于菊科向日葵族豚草屬,是世界公認(rèn)的惡性入侵雜草[17],其花粉是過(guò)敏性鼻炎、枯草熱和季節(jié)性哮喘等疾病的重要過(guò)敏原,嚴(yán)重威脅人類(lèi)健康[18]。三裂葉豚草(Ambrosia trifida)同樣也是原產(chǎn)于北美的一年生惡性雜草,于20世紀(jì)40年代傳入我國(guó)東北,現(xiàn)在已成為我國(guó)北方最主要的惡性入侵雜草之一[19]。該入侵種能在入侵地形成單一優(yōu)勢(shì)種群,造成農(nóng)作物減產(chǎn)甚至絕產(chǎn),威脅自然生態(tài)系統(tǒng)生物多樣性,且易引發(fā)易感人群的枯草熱[20-21]。目前,基于某一類(lèi)群(科、屬)內(nèi)入侵植物與非入侵植物之間的生理生態(tài)特性比較研究很少,由于同科屬植物間有著相同的進(jìn)化背景和相近的生物學(xué)特性,開(kāi)展此類(lèi)研究更有助于揭示入侵種得以擴(kuò)展危害的特有生理生態(tài)學(xué)機(jī)制。鑒于此,本試驗(yàn)比較了不同菊科入侵植物與本地菊科共生種之間的光合特性和葉片性狀,以期為探討菊科入侵植物對(duì)環(huán)境光強(qiáng)變化的響應(yīng)機(jī)制,并對(duì)潛在入侵植物風(fēng)險(xiǎn)評(píng)估和制定有效阻控措施提供科學(xué)依據(jù)。

1 材料與方法

1.1 研究區(qū)域概況

采樣區(qū)位于遼寧省沈陽(yáng)市棋盤(pán)山(42°1′58″N,123°51′43″E,海拔192 m),為豚草和三裂葉豚草重發(fā)生區(qū)。該區(qū)屬于中溫帶大陸性季風(fēng)氣候,冬寒多雪,時(shí)間較長(zhǎng);夏熱多雨,時(shí)間較短。全年平均氣溫7.41℃,無(wú)霜期148 d,年平均降水量為750 mm,平均相對(duì)濕度為65%～70%。樣地為豚草和三裂葉豚草兩種菊科入侵植物典型共同發(fā)生區(qū),主要植被構(gòu)成為入侵植物與本地植物自然混生群落,各入侵種呈斑塊狀分布。植物紫菀(Aster tataricus)為同科伴生優(yōu)勢(shì)非入侵植物,伴生雜草還有葎草(Humulusscandens)、苦荬菜(Lactuca indica)、狗尾草(Setaria viridis)等。土壤類(lèi)型為棕壤土,土壤pH 6.4,有機(jī)質(zhì)14.62 g·kg-1,全氮 1.53 g·kg-1,全磷 0.99 g·kg-1。

于2015年8月27日開(kāi)展試驗(yàn)的測(cè)定和樣品采集,此時(shí)供試菊科入侵植物與本地植物已經(jīng)完成葉片形態(tài)建成,生育時(shí)期為營(yíng)養(yǎng)生長(zhǎng)盛期至初花期。

1.2 試驗(yàn)方法

每一種植物設(shè)置1個(gè)試驗(yàn)區(qū)組,面積為10 m×10 m,每區(qū)組內(nèi)隨機(jī)設(shè)置5個(gè)1 m×1 m的小樣方,每個(gè)小樣方內(nèi)隨機(jī)選取生長(zhǎng)相對(duì)一致的具有代表性的植株10株,并在其對(duì)應(yīng)位置分別隨機(jī)采集30片健康完整的成熟葉片,因此每種植物采集葉片數(shù)5×30=150。5個(gè)小樣方樣品采集均設(shè)5次重復(fù)。采用Li-3100A葉面積儀(Li-Cor,Lincoln,Nebraska,USA)測(cè)定葉面積,隨后將葉片放入自封袋,置于冰盒中低溫保存,用于測(cè)定葉綠素含量、葉片N、P含量等理化指標(biāo)。同時(shí)用土壤采樣器取各植物根圍0～10 cm的土壤樣品,帶回實(shí)驗(yàn)室供理化分析。

光合-光強(qiáng)(Pn-PAR)響應(yīng)測(cè)定:于9:00—11:00在各小樣方中選取菊科入侵植物和本地種處于營(yíng)養(yǎng)生長(zhǎng)期的植株。采用LI-6400便攜式光合測(cè)定儀(Li-Cor Inc.,Lincoln,NE,USA)對(duì)兩種菊科入侵植物和本地植物功能葉的凈光合速率(net photosynthetic rate,Pn)、蒸騰速率(transpiration rate,Tr)、氣孔導(dǎo)度(stomatal conductance,Gs)等指標(biāo)進(jìn)行測(cè)定[22]。葉室溫度設(shè)為25℃,CO2濃度控制在400 μmol·mol-1,設(shè)置有效光合輻射(μmol·m-2·s-1)梯度為2 000、1 500、1 000、800、500、300、100、50 和0,利用自動(dòng)測(cè)量程序進(jìn)行光合-光強(qiáng)響應(yīng)的測(cè)定[23]。測(cè)定時(shí),均選取完全展開(kāi)的成熟葉片,測(cè)定時(shí)保持葉片自然生長(zhǎng)角度不變,每個(gè)葉片測(cè)3次,每區(qū)組重復(fù)測(cè)定5次。

光合-光強(qiáng)響應(yīng)曲線采用Ye[24]、葉子飄等[25]提出的直角雙曲線修正模型進(jìn)行擬合:

式中:Pn為凈光合速率(μmol·m-2·s-1);I為光合有效輻射(μmol·m-2·s-1);α為AQY(apparent quantum yield,表觀量子效率),即植物葉片光響應(yīng)曲線在I=0時(shí)的斜率,也被稱(chēng)為光響應(yīng)曲線的初始斜率或初始量子效率;β和γ分別為獨(dú)立于I的系數(shù)(m2·s·μmol-1);Rd為暗呼吸速率(mg·h-1·g-1)。

水分利用率( water use efficiency,WUE)的計(jì)算公式[26]:

式中:Pr為光合速率(μmol·m-2·s-1);Tr為蒸騰速率(mmol·m-2·s-1)。

葉綠素含量的測(cè)定:把采集的新鮮植物葉片用去離子水清洗干凈,用打孔器切取干凈的葉片,然后切成長(zhǎng)細(xì)絲,用80%的丙酮浸提細(xì)絲至其完全變?yōu)榘咨珵橹?于663 nm和645 nm處讀取光密度(記為OD663、OD645),按照下列公式計(jì)算葉綠素含量[27]:

式中:ρ(Chla)、ρ(Chlb)分別為葉綠素a、葉綠素b的含量(mg·L-1);ρ(Chl)為葉綠素總量(mg·L-1)。

葉片元素含量的測(cè)定:植物樣品于105℃下殺青30 min,然后65℃烘干至恒質(zhì)量,葉片粉碎過(guò)篩,混勻后保存在塑封袋中備用。植物的全N采用開(kāi)氏消煮法測(cè)定;全P采用鉬銻抗比色法測(cè)定[28-30]。

葉片灰分含量的測(cè)定:植物樣品在馬弗爐中500℃灼燒6 h,稱(chēng)量剩余殘?jiān)?記錄重量。干重?zé)嶂挡捎醚鯊検綗崃坑?jì)(HWR-15E,上海上立檢測(cè)儀器廠)測(cè)定:取0.5 g左右植物樣品粉末,經(jīng)完全燃燒測(cè)定熱值,每個(gè)樣品分別測(cè)定5個(gè)重復(fù),取其平均值作為干重?zé)嶂礫31]。

式中:Hc為去灰分熱值(kJ·g-1);Ash為灰分含量(%);CV為干重?zé)嶂?kJ·g-1);CCmass為葉片單位質(zhì)量建成成本[g(glucose)·g-1];ON為有機(jī)氮含量,%;EG為生長(zhǎng)效率;k為N的氧化態(tài)形式[31-32]。不同植物的平均葉片生長(zhǎng)效率為0.87[33],對(duì)于每個(gè)樣品,先以銨態(tài)氮(-3價(jià))和硝態(tài)氮(+5價(jià))作為N的氧化態(tài)形式分別計(jì)算,再按照土壤中的比例,求加權(quán)平均值作為葉片的CCmass。

式中:SLA為葉片比葉面積(cm2·g-1);ULA為單位葉片面積(cm2);DW為葉片干質(zhì)量(g);CCarea為葉片單位面積建成成本[g(glucose)·m-2];Nmass為葉片單位質(zhì)量N含量(mg·g-1);Narea為葉片單位面積N含量(g·m-2);PEUE為光合能量利用效率[μmol(CO2)·g-1(glucose)·s-1];PNUE為光合氮利用效率[μmol(CO2)·g-1·s-1]。

1.3 數(shù)據(jù)分析

參考陳新微等[23]的方法計(jì)算光飽和點(diǎn)(light saturation point,LSP)、光補(bǔ)償點(diǎn)(light compensation point,LCP)、表觀量子效率(apparent quantum yield,AQY)和最大凈光合速率(maximum net photosynthetic rate,Pnmax)。所有數(shù)據(jù)應(yīng)用SPSS 16.0對(duì)測(cè)定數(shù)據(jù)進(jìn)行統(tǒng)計(jì)分析,應(yīng)用Excel 2007對(duì)分析結(jié)果進(jìn)行作圖。各統(tǒng)計(jì)數(shù)據(jù)以平均值及標(biāo)準(zhǔn)誤差表示,采用單因素方差分析(one-way ANOVA)和最小顯著差數(shù)法(LSD法)進(jìn)行不同物種間均值的方差分析和差異顯著性比較(P=0.05)。

2 結(jié)果與分析

2.1 兩種菊科入侵植物與本地植物對(duì)有效光合輻射的響應(yīng)

由圖1可見(jiàn),隨著有效光合輻射的增強(qiáng),入侵植物豚草、三裂葉豚草及其共生植物紫菀的Pn均呈先增加后降低的趨勢(shì),其中,兩種入侵植物的增幅均高于紫菀。當(dāng)達(dá)到一定的有效光合輻射時(shí),3種植物的Pn均達(dá)到最大值,即為光飽和點(diǎn)。豚草(R2=0.997,P<0.001)、三裂葉豚草(R2=0.999,P<0.001)、紫菀(R2=0.995,P<0.001)的Pn與有效光合輻射的相關(guān)性均達(dá)極顯著水平(P<0.01),由直角雙曲線修正模型可以計(jì)算出3種植物的光合響應(yīng)參數(shù)(表1)。由表1可見(jiàn),3種植物的LSP均高于800 μmol·m-2·s-1,其大小順序?yàn)槿讶~豚草>豚草>紫菀,且差異顯著;LCP的大小順序?yàn)樽陷?三裂葉豚草>豚草,其中,本地種紫菀的LCP為30.736 μmol·m-2·s-1,顯著高于豚草;而兩種入侵植物的AQY均顯著低于紫菀(P<0.05);3種植物的Pnmax大小順序?yàn)殡嗖?三裂葉豚草>紫菀,入侵種豚草和三裂葉豚草的Pnmax分別比紫菀高出151.28%和82.80%,差異顯著,顯示兩種菊科入侵植物對(duì)光能的利用率較高,在相同的有效光合輻射下,具備更強(qiáng)的光合同化能力。

圖1 遼寧菊科入侵植物豚草和三裂葉豚草與本地植物紫菀的光合-光響應(yīng)曲線的比較Fig.1 Comparison ofPn-PAR curves of invasive plant species,Ambrosia artemisiifoliaandAmbrosia trifida,with native plant species,Aster tataricusin Liaoning

表1 遼寧菊科入侵植物豚草和三裂葉豚草與本地植物紫菀的光合響應(yīng)特征參數(shù)Table 1 Photosynthetic parameters of invasive plant species,Ambrosia artemisiifoliaandAmbrosia trifida,and native plant species,Aster tataricusin Liaoning

隨著有效光合輻射的增加,3種植物的Gs、Tr和WUE均有一定程度的增加,但在有效光合輻射大于500 μmol·m-2·s-1時(shí),紫菀的Gs、Tr和WUE并未隨著有效光合輻射的增強(qiáng)而增加,反而是穩(wěn)定在一個(gè)恒定值附近,而其他兩種入侵植物的Gs和Tr卻一直表現(xiàn)為增加。由圖1d可知,兩種入侵植物的WUE隨著有效光合輻射增加而增加的幅度明顯高于本地種紫菀,顯示兩種入侵植物更高的水分利用效率。

2.2 兩種菊科入侵植物與本地植物葉片特性指標(biāo)的比較

由表2可見(jiàn),豚草、三裂葉豚草的葉綠素含量均顯著高于紫菀(P<0.05),從高到低依次為豚草>三裂葉豚草>紫菀。兩種入侵植物的SLA、Nmass、葉片單位質(zhì)量磷含量(leaf P content per unit mass,Pmass)、PEUE、PNUE均顯著高于其本地種紫菀(P<0.05),但3種植物的CCmass差異不顯著。

表2 遼寧菊科入侵植物豚草和三裂葉豚草與本地植物紫菀葉片特性的比較Table 2 Comparison of leaf traits of invasive plant species,Ambrosia artemisiifoliaandAmbrosia trifida,with native plant species,Aster tataricusin Liaoning

3 討論

入侵植物可以改變自然群落生態(tài)系統(tǒng)基本的生物學(xué)特征[34-35]。對(duì)入侵植物而言,成功入侵的因素是多方面的,而其自身的生理特性對(duì)于其生存、建立種群入侵和擴(kuò)展至關(guān)重要,有些外來(lái)植物具有比本地種更強(qiáng)的光能利用率、光合響應(yīng)機(jī)制以及生理生態(tài)特性,從而使它們具有很強(qiáng)的入侵潛力[36]。環(huán)境和植物本身特性的相互作用共同決定植物的入侵能力,在繁殖能力和天敵壓力相同的條件下,入侵種能夠迅速擴(kuò)散并取代當(dāng)?shù)刂参?通常認(rèn)為外來(lái)入侵植物能更有效地利用有限的環(huán)境資源,或在時(shí)間上可以利用本地種不能利用的資源[37]。

3.1 兩種菊科入侵植物與本地植物氣體交換參數(shù)之間的差異

植物對(duì)光的吸收能力和光合作用對(duì)生境的適應(yīng)特征在很大程度上體現(xiàn)了植物生長(zhǎng)與競(jìng)爭(zhēng)的能力[38]。LSP和LCP反映了植物對(duì)強(qiáng)光和弱光環(huán)境的適應(yīng)能力[39],AQY和Pn則是植物光合機(jī)構(gòu)功能效率和初級(jí)生產(chǎn)力高低的指標(biāo)[40]。本研究中,在一定光強(qiáng)范圍內(nèi)入侵植物豚草和三裂葉豚草Pn、Gs、WUE的增幅明顯高于本地種紫苑,說(shuō)明與共生本地植物相比,兩種入侵植物的氣孔伸展范圍和靈活性更大,可以根據(jù)環(huán)境條件的變化進(jìn)行調(diào)節(jié),從而保證在水分損失較少的情況下能夠同化更多的CO2。WUE是植物水分生理的一個(gè)重要指標(biāo),高WUE對(duì)處在干旱環(huán)境中的植物非常重要[26]。隨著有效光合輻射的增加,入侵植物的Gs也隨之增加,然而并沒(méi)有導(dǎo)致較低的WUE,可能因?yàn)镻nmax的增加彌補(bǔ)了由于Gs的增加而導(dǎo)致的水分散失[41],并且豚草和三裂葉豚草WUE的最大值均高于紫苑,也顯示出兩者有更高的水分利用效率。與本研究結(jié)果相同,Feng等[42]和梁作盼等[43]研究表明,入侵植物紫莖澤蘭與本地種相比有更高的WUE;王曉紅等[15]的研究也表明入侵植物小飛蓬水分的利用效率顯著高于其伴生種山苦荬和鴨跖草。

3.2 兩種菊科入侵植物與本地種葉片特性指標(biāo)之間的差異

植物吸收光能同化CO2主要是在葉綠體內(nèi)完成的,所以葉綠素含量直接影響植物光合作用[44]。本研究中,豚草和三裂葉豚草葉綠素含量均顯著高于本地種紫苑。SLA與氮素的分配緊密相關(guān)[45],王滿(mǎn)蓮等[46]研究表明,高氮促進(jìn)了入侵植物光合能力的提高,利于碳積累;磷素又可促進(jìn)植物開(kāi)花結(jié)實(shí),在細(xì)胞膜結(jié)構(gòu)、物質(zhì)代謝、酶活性調(diào)節(jié)以及信號(hào)傳導(dǎo)等方面都起著極為重要的作用,在植物的光合作用中同樣起著極其重要的作用[47],較高的葉片氮磷含量不僅可以促進(jìn)植物生長(zhǎng),而且還能增強(qiáng)植物光合能力[45]。本研究中,豚草和三裂葉豚草葉片N、P含量均顯著高于本地植物紫苑,則可能顯示其對(duì)土壤中N、P養(yǎng)分利用能力更強(qiáng)[37]。

Feng等[42]也指出,入侵植物相比原產(chǎn)地種群有著更高的Nmass和SLA,這可能是因?yàn)槿肭址N為了逃避自然天敵而出現(xiàn)的基因定向選擇,當(dāng)外來(lái)種入侵到新的地區(qū)時(shí),自然天敵相對(duì)于原始產(chǎn)地減少,于是入侵種就會(huì)將較少的氮素分配到植物細(xì)胞壁中(合成防御物質(zhì)),進(jìn)而將較多的氮素分配到光合作用中(促進(jìn)植物生長(zhǎng)),從而增強(qiáng)自身的競(jìng)爭(zhēng)力。本研究中,豚草和三裂葉豚草SLA均顯著高于本地植物紫苑;同時(shí),豚草和三裂葉豚草葉片的Nmass、Pmass均高于紫苑,且差異顯著;CCmass、PEUE和PNUE作為植物能量利用效率的重要指標(biāo),反映了植物適應(yīng)環(huán)境的能量策略[33]。其中,CCmass是衡量植物葉片建成所需能量的重要指標(biāo),反映了植物葉片的能量利用策略,較低的CCmass可能會(huì)增加植物的競(jìng)爭(zhēng)優(yōu)勢(shì)[32]。本研究中,豚草和三裂葉豚草較高的Pnmax并沒(méi)有導(dǎo)致較低的CCmass,原因可能是植物葉片較高的含氮量以及合成蛋白質(zhì)、氨基酸等大分子物質(zhì)的高消耗,會(huì)導(dǎo)致葉片CCmass的增加[42],這與Geng等[41]的研究結(jié)果也一致。PNUE是植物氮素生理利用效率的特征之一[48]。PEUE則是反映植物能量利用效率最直接的指標(biāo),入侵植物的PNUE和PEUE均顯著高于本地種,與Funk等[49]的研究結(jié)果相一致。

光合作用過(guò)程中最重要的指標(biāo)是Pn,其大小決定著物質(zhì)積累能力的高低,在一定程度上也決定著植物生長(zhǎng)的快慢和在群落中競(jìng)爭(zhēng)能力的強(qiáng)弱[50]。本研究中,豚草和三裂葉豚草較高的植物Pn并沒(méi)有導(dǎo)致較低的CCmass,這與Penning等[33]、Feng等[42]的結(jié)果一致,這可能是因?yàn)槿肭种参锏腜EUE和PNUE顯著高于本地種,而PEUE和PNUE是表征植物葉片能量利用效率的重要指標(biāo)[51],導(dǎo)致入侵植物較高的CCmass,從而前者在表征植物資源獲取能力方面更具參考價(jià)值。

本研究表明,入侵植物豚草、三裂葉豚草及當(dāng)?shù)刈陷业膬艄夂纤俾示c有效光合輻射極顯著相關(guān)。3種植物的光飽和點(diǎn)均高于800 μmol·m-2·s-1,且表現(xiàn)為三裂葉豚草>豚草>紫菀;光補(bǔ)償點(diǎn)順序?yàn)樽陷?三裂葉豚草>豚草,本地種紫菀顯著高于豚草;兩種入侵植物的表觀量子效率均顯著低于紫菀;3種植物的Pnmax順序?yàn)殡嗖?三裂葉豚草>紫菀。兩種入侵植物的水分利用效率隨有效光合輻射增加而增加幅度明顯高于本地種紫菀?？傊?相同條件下,兩種入侵植物較當(dāng)?shù)刂参镲@示出了較高光合能力、光能利用率和水分利用效率。

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Comparison of gas exchange characteristics between two invasive plants and a co-occurring native plant in Liaoning Province*

WEI Zishang1,2,CHEN Xinwei1,2,YANG Dianlin1,HUANGFU Chaohe1,2**
(1.Agro-Environmental Protection Institute,Ministry of Agriculture,Tianjin 300191,China;2.College of Plant Protection,Shenyang Agriculture University,Shenyang 110866,China)

Biological invasion is one of the century’s most serious environmental problems.A comparative study of invaders and co-occurring natives is an effective approach to gaining insights into the invasiveness of exotic plants.Ambrosia artemisiifoliaL.andA.trifidaL.are two aggressive North American annual weeds in China,whereasA.trifidaoccurs mainly in Northeast China.They usually invade cultivated fields and reduce crop productivity,causing significant ecological and socio-economic impacts in introduced areas.Besides its economic impact on crop yield,A.artemisiifoliaalso represents a major health problem since its pollen is a strong allergen and one of the main causes of hay fever.To explore the traits contributing to invasiveness ofA.artemisiifoliaandA.trifidaand to test the relationship between plasticity of these traits and invasiveness,we conducted a comparative study of two invasive species and their co-occurring native Asteraceae plant,Aster tataricus,intataricus,in terms of gas exchange and efficiencies in resource utilization.We tested the hypothesis thatA.artemisiifoliaandA.trifidahad growth-related ecophysiological advantages over the natives in its non-native range,which resulted in its rapid growth and enhanced its invasiveness.Photosynthesis,specific leaf area (SLA),and the efficiency of resource use (light,phosphorus,and nitrogen) were examined in field.Leaf construction cost (CC) is considered as a quantifiable measure of energy demand for biomass production and is related to energy use efficiency as it includes component of both morphological and physiological traits.The results showed that the light saturation point (LSP) ofA.artemisiifolia,A.trifidawere significantly higher than that of the native speciesA.tataricus.The order ofPnmaxwas thatA.artemisiifolia>A.trifida>A.tataricus,and this parameter of two invasive species were significantly higher than that ofA.tataricusby 151.28%,82.80%,respectively.The specific leaf area (SLA),leaf N content per unit mass (Nmass),leaf P content per unit mass (Pmass),photosynthetic energy use efficiency (PEUE),photosynthetic nitrogen use efficiency (PNUE) of two invasive plants were significantly higher than those of the native,but the difference of leaf construction cost per unit mass (CCmass) between the three plant species was not significant.In summary,the two Asteraceae invasive plant species has higher gas exchange characteristics and leaf traits as compared with co-family non-invasive plant species,and their photosynthetic characteristics and leaf characteristics were closely linked.The two Asteraceae invasive plant species had higher photosynthetic characteristics and energy use parameters,includingPnmax,PNUE,PEUE,water use efficiency (WUE),leading to more effectively resources capturing and utilization efficiency,which may be one of the reasons for successful invasion of these Asteraceae invasive plants in the studied area.

Asteraceae invasive plants;Gas exchange characteristics;Maximum net photosynthetic rate;Leaf traits;Resources utilization efficiency

Dec.30,2016;accepted Mar.22,2017

X171.1

:A

:1671-3990(2017)07-0975-08

10.13930/j.cnki.cjea.161190

魏子上,陳新微,楊殿林,皇甫超河.遼寧地區(qū)兩種菊科入侵植物與本地植物光合特性比較[J].中國(guó)生態(tài)農(nóng)業(yè)學(xué)報(bào),2017,25(7):975-982

Wei Z S,Chen X W,Yang D L,Huangfu C H.Comparison of gas exchange characteristics between two invasive plants and a co-occurring native plant in Liaoning Province[J].Chinese Journal of Eco-Agriculture,2017,25(7):975-982

*天津市自然科學(xué)基金項(xiàng)目(12JCQNJC09800)資助

** 通訊作者:皇甫超河,主要從事入侵生態(tài)學(xué)研究。E-mail:huangfu24@163.com

魏子上,研究方向?yàn)槿肭稚鷳B(tài)學(xué)。E-mail:602796418@qq.com

2016-12-30 接受日期:2017-03-22

*This study was supported by the Natural Science Foundation of Tianjin (12JCQNJC09800).

** Corresponding author,E-mail:huangfu24@163.com