王雪峰,毛之夏,徐濟(jì)責(zé),常 亮,吳東輝,*

1 中國科學(xué)院東北地理與農(nóng)業(yè)生態(tài)研究所濕地生態(tài)與環(huán)境重點(diǎn)實(shí)驗(yàn)室,長春　130102 2 吉林農(nóng)業(yè)科技學(xué)院,吉林　132101

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根際效應(yīng)對(duì)大豆田土壤線蟲群落組成及多樣性的影響

王雪峰1,毛之夏1,徐濟(jì)責(zé)2,常 亮1,吳東輝1,*

1 中國科學(xué)院東北地理與農(nóng)業(yè)生態(tài)研究所濕地生態(tài)與環(huán)境重點(diǎn)實(shí)驗(yàn)室,長春130102 2 吉林農(nóng)業(yè)科技學(xué)院,吉林132101

根際作為重要的環(huán)境界面是植物與環(huán)境之間物質(zhì)能量交換的場所,關(guān)于根際效應(yīng)的研究已成為土壤生態(tài)學(xué)的新興熱點(diǎn)領(lǐng)域,然而有關(guān)大豆根際效應(yīng)對(duì)土壤動(dòng)物多樣性影響的研究報(bào)道并不多見。在三江平原選擇連續(xù)耕作15a的大豆田,對(duì)大豆根際區(qū)與非根際區(qū)土壤線蟲群落結(jié)構(gòu)組成進(jìn)行了對(duì)比分析。結(jié)果表明：大豆根際區(qū)土壤線蟲總數(shù)、辛普森多樣性指數(shù)(Dom)顯著高于非根際區(qū),根際區(qū)的物種數(shù)(S)、物種豐富度指數(shù)(SR)顯著低于非根際區(qū)。說明大豆根際效應(yīng)增加土壤線蟲的豐度,但降低了線蟲群落結(jié)構(gòu)的復(fù)雜性。大豆根際區(qū)植物寄生線蟲(PP)、食真菌線蟲(FF)和食細(xì)菌線蟲(BF)數(shù)量顯著高于非根際區(qū),而PP類群的比例在根際區(qū)卻顯著低于非根際區(qū)。這一研究結(jié)果表明食微線蟲(FF和BF)類群在大豆根際區(qū)的比例增加更顯著。食真菌與食細(xì)菌線蟲數(shù)量比值(F/B)指示大豆根際區(qū)細(xì)菌生物量相對(duì)高于真菌生物量。研究結(jié)果豐富了農(nóng)田土壤線蟲多樣性的研究內(nèi)容,并為我國東北大豆田線蟲病害的防治及定制相應(yīng)的農(nóng)業(yè)管理措施提供參考。

根際效應(yīng); 土壤線蟲; 群落組成; 大豆田

根際是一個(gè)重要的環(huán)境界面,是植物與環(huán)境之間物質(zhì)能量交換的場所,長期以來,根際環(huán)境一直是植物營養(yǎng)學(xué)、生態(tài)學(xué)、土壤學(xué)、微生物學(xué)學(xué)者研究和關(guān)注的熱點(diǎn)[1- 2]。根際一般指距細(xì)根表面2 mm以內(nèi)的土壤環(huán)境,是受根系活動(dòng)影響最直接,植物、土壤和微生物關(guān)系最復(fù)雜的區(qū)域[3]。在植物、土壤、水、大氣、微生物的綜合作用下,根際區(qū)形成獨(dú)特的物理、化學(xué)根際環(huán)境和生物區(qū)系[4- 6]。大豆是典型的固氮作物,其根際區(qū)植物有益根際細(xì)菌(plant growth-promoting rhizobacteria, PGPR)菌種資源豐富,促生菌的群落結(jié)構(gòu)復(fù)雜多樣[7],同時(shí)大豆也是農(nóng)業(yè)致病線蟲侵染研究和關(guān)注的典型作物[8],因此,大豆根際區(qū)可能形成特殊的土壤微生物及線蟲群落結(jié)構(gòu)。

土壤線蟲是土壤動(dòng)物區(qū)系的重要組成部分,土壤線蟲因其占據(jù)土壤碎屑食物網(wǎng)的關(guān)鍵位置及多個(gè)營養(yǎng)級(jí),在土壤有機(jī)質(zhì)的分解及植物營養(yǎng)物質(zhì)的礦化過程中起重要作用[9-12]。農(nóng)田土壤線蟲根據(jù)其取食習(xí)性及生活史策略被劃分為不同的營養(yǎng)類群和功能團(tuán)類群[13-14]。植物寄生線蟲以取食植物根系為主,食微線蟲(食細(xì)菌線蟲和食真菌線蟲)則通過取食微生物調(diào)控土壤微生物量進(jìn)而影響植物營養(yǎng)物質(zhì)的礦化及土壤的養(yǎng)分循環(huán)過程[15]。因此土壤線蟲群落組成、營養(yǎng)類群和功能類群多樣性,以及生態(tài)指數(shù)能夠有效指示土壤微食物網(wǎng)、生態(tài)過程的變化情況[16-18]。長期以來關(guān)于大豆田土壤線蟲的研究主要集中于植物寄生線蟲大豆胞囊線蟲的防治策略,以及不同農(nóng)作管理措施下對(duì)土壤線蟲群落組成結(jié)構(gòu)的影響[8,19-21],而關(guān)于大豆根際效應(yīng)對(duì)土壤線蟲群落組成多樣性影響的研究報(bào)道還不多見,特別是關(guān)于大豆根際區(qū)與非根際區(qū)土壤線蟲的分布特征研究還未見報(bào)道。

三江平原是我國的最大淡水沼澤分布區(qū),也是我國重要的商品糧基地,區(qū)內(nèi)農(nóng)田主要源自于1950s起大面積的濕地墾殖,大豆作為重要的經(jīng)濟(jì)作物在該區(qū)域種植普遍。本研究在三江平原腹地中國生態(tài)系統(tǒng)網(wǎng)絡(luò)監(jiān)測站(三江平原沼澤生態(tài)系統(tǒng)網(wǎng)絡(luò)監(jiān)測站)內(nèi)選擇由濕地開墾連續(xù)耕作15a的大豆田,通過比較大豆根際區(qū)與非根際區(qū)土壤線蟲群落結(jié)構(gòu)組成及多樣性的變化情況,揭示土壤線蟲群落對(duì)大豆根際效應(yīng)的響應(yīng),進(jìn)而為我國東北大豆田線蟲病害的可持續(xù)防治及制定東北大豆田農(nóng)業(yè)管理措施提供科學(xué)參考。本研究結(jié)果對(duì)農(nóng)田生態(tài)系統(tǒng)土壤線蟲生態(tài)學(xué),以及農(nóng)業(yè)土壤線蟲病蟲害的防治具有理論實(shí)踐意義。

1　研究區(qū)概況與研究方法

1.1樣地選擇與采樣方法

本研究于2013年8月初在中國科學(xué)院東北地理與農(nóng)業(yè)生態(tài)研究所三江實(shí)驗(yàn)站內(nèi)選擇連作15a大豆田內(nèi)采樣。土質(zhì)為沼澤草甸土。研究區(qū)為亞熱帶季風(fēng)氣候,海拔343 m,年均氣溫20℃,年降雨量1200—1500 mm。大豆田土壤基本理化性質(zhì)為：土壤有機(jī)碳(SOC)17.6 g/kg,全氮(TN)3.32 g/kg,pH值為5.3,施肥量為4×104kg/km2復(fù)合肥(N∶P2O5∶K2O),供試作物為大豆寶豐7號(hào)(GlycinemaxMerr)。

根據(jù)以往的研究結(jié)果大豆花期固氮作用最強(qiáng),根系作用活躍[22-23],因此本試驗(yàn)根據(jù)既定研究目標(biāo),將采樣期定為2013年8月份大豆開花期進(jìn)行采樣,人為設(shè)置面積100 m2取樣樣方5個(gè),每個(gè)樣方相距50 m,非根際土采用2.5 cm直徑的土鉆在距離大豆根10 cm的壟臺(tái)采集0—10 cm土壤樣品,五點(diǎn)混合法采集土樣放在自封袋中;大豆根際土樣采集采用“抖根法”[24],即將大豆連根拔起,輕輕抖動(dòng)后仍然粘在根上的土壤作為根際土,裝袋、封口并作好標(biāo)簽,立即帶回實(shí)驗(yàn)室分析處理。采集的根際土和非根際土土壤樣品迅速運(yùn)回實(shí)驗(yàn)室盡快完成線蟲分離工作。

1.2土壤線蟲的分離鑒定、計(jì)算

蔗糖離心法分離土壤線蟲：每個(gè)土樣稱取100 g,用淘洗一過篩一蔗糖梯度密度離心法分離線蟲,60℃溫和熱殺死,再加入等量的2倍三乙醇胺和福爾馬林(TAF)固定液固定,然后混勻,倒入標(biāo)本瓶中,待測。線蟲總數(shù)通過解剖鏡直接計(jì)數(shù),依據(jù)土壤濕度將線蟲個(gè)體數(shù)量折算成每100 g干土含有線蟲的條數(shù)[14];線蟲鑒定參照相關(guān)文獻(xiàn)[13,25],根據(jù)線蟲的頭部形態(tài)學(xué)特征和取食習(xí)性將土壤線蟲分成植物寄生線蟲(PP)、食細(xì)菌線蟲(BF)、食真菌線蟲 (FF)和捕食/雜食線蟲(OP)4個(gè)營養(yǎng)類群的分類方法,在光學(xué)顯微鏡下盡可能將線蟲分類鑒定到科屬水平,鑒定檢索參見《中國土壤動(dòng)物檢索圖鑒》[26]。

1.3線蟲多樣性指數(shù)計(jì)算方法

多樣性指數(shù)度量采用土壤線蟲生態(tài)學(xué)者普遍應(yīng)用的多樣性指數(shù)來度量土壤線蟲群落多樣性[13- 14,18]。

辛普森多樣性指數(shù)(Dom)：Dom=∑Pi2;

豐富度指數(shù)(SR)：SR=(S-1)/lnN;

營養(yǎng)多樣性指數(shù)(TD)：TD=1/∑Pi2;式中Pi為各營養(yǎng)類群在線蟲群落中所占的比例;

瓦斯樂斯卡指數(shù)[27](WI)：WI=(FF+BF)/PP;

食真菌與食細(xì)菌線蟲數(shù)量比值(F/B)：F/B=FF/BF;

線蟲通路指數(shù)[28](NCR)：NCR=NBa/(NBa+NFu);

式中,N為所鑒定的線蟲個(gè)體數(shù)目;S為鑒定分類單元的數(shù)目,某一給定的分類單元可以看作是第i個(gè)分類單元;Pi為第i個(gè)分類單元中個(gè)體所占的比例。FF、BF和PP分別為食真菌、食細(xì)菌和植物寄生性線蟲的數(shù)量。NBa和NFu分別為食細(xì)菌線蟲和食真菌線蟲占線蟲總數(shù)的相對(duì)多度。

1.4統(tǒng)計(jì)分析

采用SPSS(17.0)統(tǒng)計(jì)軟件對(duì)數(shù)據(jù)進(jìn)行T檢驗(yàn)、方差分析、相關(guān)分析等。

2　結(jié)果與分析

2.1土壤線蟲群落組成

本研究共鑒定出土壤線蟲16屬,根據(jù)其取食習(xí)性及生活史策略可劃分為4個(gè)營養(yǎng)類群,9個(gè)功能類群(表1)。根際區(qū)鑒定出土壤線蟲10個(gè)屬,非根際區(qū)15個(gè)屬,根際區(qū)線蟲物種數(shù)顯著低于非根際區(qū)。根際區(qū)優(yōu)勢屬線蟲Acrobeloides(Ba2),Aphelenchoides(Fu2)的相對(duì)多度顯著高于非根際區(qū)(P<0.01),植物寄生類群線蟲(PP)Coslenchus(H2)和Heterodera(H3)的相對(duì)多度在根際區(qū)顯著低于非根際區(qū)(P<0.01和P<0.05)。與非根際區(qū)相比,根際區(qū)土壤出現(xiàn)一個(gè)常見屬Rhabditis,同時(shí)分布于各營養(yǎng)類群的5個(gè)常見屬消失,說明大豆根際區(qū)從細(xì)菌群落組成,植物根系種類都區(qū)別于非根際區(qū),從而導(dǎo)致根際區(qū)與非根際區(qū)土壤線蟲群落組成結(jié)構(gòu)的明顯變化。

2.2土壤線蟲總數(shù)

大豆田根際區(qū)與非根際區(qū)土壤線蟲總數(shù)和優(yōu)勢屬線蟲數(shù)量分析結(jié)果表明：根際區(qū)土壤線蟲總數(shù)最高為568條/100 g干土,非根際區(qū)土壤線蟲總數(shù)為236條/100 g干土,根際區(qū)土壤線蟲總數(shù)顯著高于非根際區(qū)(P<0.01)。同時(shí)4個(gè)主要線蟲優(yōu)勢屬Acrobeloides(Ba2),Aphelenchoides(Fu2),Coslenchus(H2)和Heterodera(H3)的數(shù)量在根際區(qū)高于非根際區(qū),其中根際區(qū)與非根際區(qū)Acrobeloides(Ba2),Aphelenchoides(Fu2)和Heterodera(H3)屬線蟲的數(shù)量差異達(dá)顯著水平(P<0.01)。優(yōu)勢屬土壤線蟲數(shù)量與線蟲總數(shù)變化趨勢一致,優(yōu)勢屬土壤線蟲數(shù)量決定線蟲總數(shù),分別占線蟲總數(shù)的87.0%和67.8%。根際區(qū)優(yōu)勢屬線蟲數(shù)量對(duì)線蟲總數(shù)的貢獻(xiàn)大于非根際區(qū)(圖1)。

表1　大豆根際區(qū)與非根際區(qū)鑒定土壤線蟲屬的相對(duì)多度

Ba：食細(xì)菌線蟲 Bacterivores;Fu：食真菌線蟲 Fungivores;H：植食性線蟲 Herbivores;Ca：捕食性線蟲Carnivores;*線蟲被賦予的c-p值;—還沒有確定中文名稱

圖1　大豆根際區(qū)與非根際區(qū)土壤線蟲總數(shù)、優(yōu)勢屬線蟲數(shù)量　Fig.1　Numbers of total totality of nematodes and in Rhizosphere and Non-rhizosphere

2.3土壤線蟲營養(yǎng)類群組成

大豆田土壤線蟲根據(jù)Yeates[13]的營養(yǎng)類群劃分方法劃分為4個(gè)營養(yǎng)類群,除捕食/雜食線蟲(OP)類群外,根際區(qū)植物寄生線蟲(PP)、食細(xì)菌線蟲(BF)和食真菌線蟲(FF)3個(gè)營養(yǎng)類群的個(gè)體數(shù)量均顯著高于非根際區(qū)(P<0.01),與總數(shù)變化趨勢相一致。根際區(qū)食細(xì)菌線蟲(FF)數(shù)量最高為214條/100 g干土,最低為捕食/雜食(OP)類群線蟲7條/100 g干土(圖2)。各營養(yǎng)類群在線蟲總數(shù)中的比例如圖2所示,食真菌線蟲(FF)與食細(xì)菌線蟲(BF)比例在根際區(qū)的比例顯著高于非根際區(qū)(P<0.01),而植物寄生線蟲(PP)和捕食/雜食線蟲(OP)的比例在根際區(qū)的比例顯著低于非根際區(qū)(P<0.01)。

圖2　大豆根際區(qū)與非根際區(qū)土壤線蟲營養(yǎng)類群數(shù)量、比例分布Fig.2　Abundance and relative abundance of four trophic groups of soil nematodes in Rhizosphere and Non-rhizosphere

2.4土壤線蟲生態(tài)指數(shù)

根際區(qū)與非根際區(qū)各生態(tài)指數(shù)分析結(jié)果如表2所示,根際區(qū)線蟲的物種數(shù)(S)和線蟲物種豐富度指數(shù)(SR)均顯著低于非根際區(qū)(P<0.01);辛普森多樣性指數(shù)(Dom)對(duì)常見種敏感,稀有種對(duì)該指數(shù)的影響較小。根際區(qū)線蟲Dom指數(shù)0.23顯著高于非根際區(qū)0.17(P<0.05);線蟲營養(yǎng)類群多樣性指數(shù)(TD),根際區(qū)(3.05)>非根際區(qū)(2.81);線蟲瓦斯勒斯卡指數(shù)(WI)表現(xiàn)為根際區(qū)(2.17)>非根際區(qū)(0.81);而根際區(qū)食真菌與食細(xì)菌線蟲數(shù)量比值(F/B)和線蟲通路指數(shù)(NCR)低于非根際區(qū),其中根際區(qū)、非根際區(qū)F/B值差異達(dá)極顯著水平(P<0.01)。

表2　大豆根際區(qū)與非根際區(qū)土壤線蟲生態(tài)指數(shù)

S：線蟲物種數(shù) Spices;SR：豐富度指數(shù) Richness;Dom：辛普森指數(shù) Dominance;TD：營養(yǎng)多樣性指數(shù) Trophic Diversity;(F+B)/PP：瓦斯樂斯卡指數(shù) Wasilewska Index;F/B：食真菌與食細(xì)菌線蟲數(shù)量比值 Ratio of Fungivores to Bacterivores;NCR：線蟲通路指數(shù) Nematode Channel Ratio

3　討論

本研究在三江平原大豆田根際區(qū)與非根際區(qū)共鑒定出土壤線蟲16屬,隸屬于12科,大豆根際區(qū)、非根際區(qū)線蟲總數(shù)分別為568條/100 g干土和214條/100 g干土。鑒定到的線蟲可劃分為4個(gè)營養(yǎng)類群,9個(gè)功能類群。這一結(jié)果可能與其它有大豆田土壤線蟲研究中鑒定到的線蟲數(shù)目相比較少。如Liang等[14]對(duì)地中海農(nóng)業(yè)生態(tài)系統(tǒng)不同農(nóng)作管理措施大豆田土壤線蟲的研究中鑒定出9科23屬;陳立杰等[21]在連作和輪作對(duì)大豆胞囊線蟲的影響研究中鑒定到22科36屬線蟲;韓新華等[8]對(duì)我國黑土區(qū)輪作系統(tǒng)大豆田土壤線蟲的研究中發(fā)現(xiàn)19科43個(gè)屬線蟲。土壤線蟲的豐度分布與食物源和水分、溫度等環(huán)境條件關(guān)系密切[10-11,13]。根據(jù)各自研究目的不同,以往的研究多是對(duì)大豆的整個(gè)生長期進(jìn)行,而花期大豆根系生長迅速,根系生理代謝能力強(qiáng),根際區(qū)微生物數(shù)量豐富,根系具有較強(qiáng)的呼吸代謝活動(dòng)[22-23]。本研究側(cè)重于根際效應(yīng)對(duì)植物寄生線蟲及自由生活線蟲的研究,故選擇大豆根際效應(yīng)的旺盛時(shí)期(花期),有助于分析根際效應(yīng)對(duì)線蟲群落的影響。因此,生長期選擇的不同可能是鑒定到線蟲種類相對(duì)較少的直接原因。

辛普森指數(shù)(Dom)是Simpson在1949年利用概率論的原理提出來的,該指數(shù)對(duì)常見種敏感,稀有種對(duì)該指數(shù)的影響較小,而S、SR指數(shù)能夠有效指示群落的物種數(shù)及群落結(jié)構(gòu)的復(fù)雜性[29-30]。本研究發(fā)現(xiàn)雖然大豆根際區(qū)線蟲總數(shù)顯著高于非根際區(qū)土壤線蟲總數(shù),但是根際區(qū)的Dom多樣性指數(shù)顯著高于非根際區(qū),而根際區(qū)的S、SR指數(shù)顯著低于非根際區(qū)。由于Dom多樣性指數(shù)傾向于優(yōu)勢屬的數(shù)量,較高的Dom指數(shù)結(jié)合較低的S、SR指數(shù)說明根際區(qū)線蟲群落組成優(yōu)勢種群單一,大豆根際效應(yīng)增加土壤線蟲的豐度,但降低了線蟲群落結(jié)構(gòu)的復(fù)雜性。與非根際區(qū)相比,在根際區(qū)一些常見屬土壤線蟲類群消失,而根際區(qū)優(yōu)勢屬如Acrobeloides、Aphelenchoides和Heterodera屬線蟲豐富度顯著高于非根際區(qū)。土壤線蟲的分布主要受其取食的基質(zhì)種類和數(shù)量影響,這一現(xiàn)象可能與食物資源分布的差異有關(guān)[31]。食物資源的供給狀況是影響線蟲群落的主要因素之一。例如Griffiths等[32]研究發(fā)現(xiàn),由于大麥根系的分解而引起的微生物活性的增加,能使食細(xì)菌線蟲中雌蟲的比例迅速增大,最終導(dǎo)致整個(gè)線蟲種群數(shù)量的增加。Heterodera屬是典型的大豆根系寄生線蟲,其在根際區(qū)的豐度顯著高于非根際區(qū)的研究結(jié)果與根際區(qū)較多的大豆根系分布有關(guān)。而Acrobeloides和Aphelenchoides分別是典型的食細(xì)菌線蟲(Bacterivores)和食真菌線蟲(Fungivores),它們主要取食有益的、腐生的細(xì)菌和真菌以及有害的植物病原微生物[33-34],食微線蟲的豐富度與土壤中微生物的數(shù)量或活性有關(guān)。本研究中大豆根際區(qū)豐富的食微線蟲指示根際區(qū)可能分布某一較高的微生物生物量。大豆根際區(qū)微生物數(shù)量高于非根際區(qū)土壤,根際區(qū)豐富的根系生物量和微生物量為某些特殊的線蟲類群提供了專一的食物源,顯著刺激了其數(shù)量的增加。

從土壤線蟲營養(yǎng)類群和功能類群角度認(rèn)知土壤生物多樣性不僅有效規(guī)避了人們對(duì)許多常見類群分類知識(shí)的相對(duì)匱乏,而且為從營養(yǎng)通道角度有效地分析食物網(wǎng)奠定了基礎(chǔ)[35]。本研究發(fā)現(xiàn)構(gòu)成大豆田線蟲群落的3個(gè)主要類群(PP、FF和BF)在根際區(qū)的豐富度顯著高于非根際區(qū),然而植物寄生線蟲(PP)的比例在根際區(qū)卻顯著低于非根際區(qū),這說明大豆根際效應(yīng)對(duì)土壤線蟲群落中食微線蟲類群(FF和BF)比例增加更顯著。而根際區(qū)瓦斯樂斯卡指數(shù)(WI)高于非根際區(qū),說明在根際區(qū)雖然植物寄生線蟲數(shù)量顯著增加,但是土壤食物網(wǎng)卻比非根際區(qū)健康。食真菌與食細(xì)菌線蟲數(shù)量比(F/B)指示根際區(qū)具有相對(duì)較高的細(xì)菌生物量,而在非根際區(qū)真菌生物量相對(duì)較高,但是以往關(guān)于大豆根際微生物的研究報(bào)道多集中于細(xì)菌群落組成及多樣性的研究,而關(guān)于大豆根際區(qū)真菌群落多樣性的研究報(bào)道還不多見,因此本研究通過F/B指數(shù)顯示大豆根際微生物中,根際效應(yīng)對(duì)真菌群落多樣性的研究亦不能忽視。

4　結(jié)論

本研究結(jié)果表明,大豆根際區(qū)土壤線蟲豐富度高于非根際區(qū),但物種豐富度低于非根際區(qū),大豆根際效應(yīng)增加了土壤線蟲群落的辛普森指數(shù)(Dom)多樣性,但降低了線蟲群落結(jié)構(gòu)的復(fù)雜性。根際效應(yīng)顯著提高了Acrobeloides、Aphelenchoides和Heterodera屬線蟲的豐富度。大豆根際區(qū)、非根際區(qū)土壤線蟲均由PP、FF和BF 3個(gè)主要類群構(gòu)成。與非根際區(qū)相比,雖然根際區(qū)植物寄生類群線蟲數(shù)量顯著增加,但是低于根際效應(yīng)對(duì)食微線蟲豐度增加幅度;根際區(qū)食微線蟲與植食性線蟲的豐富度比值高于非根際區(qū)。土壤線蟲能夠有效指示大豆根際、非根際區(qū)域微生物群落特征,根際區(qū)豐度的線蟲優(yōu)勢屬數(shù)量、營養(yǎng)類群構(gòu)成以及生態(tài)指數(shù)說明大豆根際區(qū)分布較高的微生物量,且根際效應(yīng)可能增加了細(xì)菌生物量與真菌生物量的比。

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Responses of soil nematode community composition and diversity to rhizosphere effects in a soybean field

WANG Xuefeng1, MAO Zhixia1, XU Jize2, CHANG Liang1, WU Donghui1,*

1NortheastInstituteofGeographyandAgroecology,KeyLaboratoryofWetlandEcologyandEnvironment,ChineseAcademyofScience,Changchun130102,China2JilinAgricultureScienceandTechnologyCollege,Jilin132101,China

The rhizosphere is an important interface for the exchange of materials and energy between the plant and the environment. As a result, research on investigating the rhizosphere effect has become an area of considerable interest in the field of soil ecology. However, research reports on responses of soil fauna to the rhizosphere effect of soybean are lacking. Soil nematode communities can provide important information about soil food web structure and function because they are the most abundant metazoan and ubiquitous in soil. In the present study, the soil nematode trophic composition, colonizer-persister (c-p) scale (1—5) group structure, functional structure index, as well as the diversity between the rhizosphere and non-rhizosphere areas of a soybean field were investigated. The aim of the present study was to understand the effect of rhizosphere effects on soil nematode community composition and diversity. Five plots of 10 m × 10 m were selected in soybean field, which had been converted from marshland in the Sanjiang Plain of China, and continuously cultivated with soybean for 15 years. The soybean rhizosphere was collected by the Root-Shaking method, using a 2.5 cm diameter core, and sampling the soil range 0—10 cm in depth. The non-rhizosphere soil samples were collected at a depth of 10 cm. A total of 4021 nematodes were identified and classified into 12 families and 16 genera, and further divided into 4 trophic groups and 9 functional guilds. The abundance ofAcrobeloides(Ba2),Aphelenchoides(Fu2), andHeterodera(H3) in the soybean rhizosphere were significantly higher than those in the non-rhizosphere soil (P< 0.01). The results showed that the total number of nematodes and Simpson′s diversity (Dom) in rhizosphere soil were significantly higher than those in the non-rhizosphere soil (P< 0.01). In addition, the number of nematode species (S), and species richness index (SR) in the rhizosphere were significantly lower. These results indicate that the rhizosphere effect of soybean increased the abundance of soil nematodes, but reduced the complexity of the nematode community structure. The abundance of fungivores (FF), bacterivores (BF), and plant-parasitic nematodes (PP) were significantly higher in the rhizosphere than in the non-rhizosphere soil (P< 0.01). The proportion of plant-parasitic nematode (PP) taxa in rhizosphere was significantly lower than that in non-rhizosphere soil (P< 0.01). Furthermore, the ratios of microbivorous nematodes (FF and BF) in soybean rhizosphere soil increased significantly (P< 0.01). The ratio of fungi-feeding to bacteria-feeding nematodes (F/B) indicated that the soybean rhizosphere bacterial biomass was relatively higher than the fungal biomass.

rhizosphere effects;soil nematodes;community composition; soybean field

國家自然科學(xué)基金(41201245);中國博士后科學(xué)基金(2013M531003, 2014T70302)

2015- 01- 25; 網(wǎng)絡(luò)出版日期:2015- 11- 30

Corresponding author.E-mail: wudonghui@iga.ac.cn

10.5846/stxb201501250195

王雪峰,毛之夏,徐濟(jì)責(zé),常亮,吳東輝.根際效應(yīng)對(duì)大豆田土壤線蟲群落組成及多樣性的影響.生態(tài)學(xué)報(bào),2016,36(16):5256- 5262.

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