沼液淹沒土壤抑制根結(jié)線蟲及對(duì)土壤線蟲群落的影響*

李鈺飛, 劉本生, 許俊香, 李吉進(jìn), 郎乾乾, 喬玉輝, 孫欽平**

沼液淹沒土壤抑制根結(jié)線蟲及對(duì)土壤線蟲群落的影響*

李鈺飛1, 劉本生1, 許俊香1, 李吉進(jìn)1, 郎乾乾1, 喬玉輝2, 孫欽平1**

(1. 北京市農(nóng)林科學(xué)院植物營(yíng)養(yǎng)與資源研究所 北京 100097; 2. 北京市生物多樣性與有機(jī)農(nóng)業(yè)重點(diǎn)實(shí)驗(yàn)室/中國(guó)農(nóng)業(yè)大學(xué)資源與環(huán)境學(xué)院 北京 100193)

為探索沼液抑制根結(jié)線蟲的效果, 本研究通過盆栽試驗(yàn), 以番茄為試供作物, 對(duì)比了種植前沼液淹沒土壤(BSS)、種植期間澆灌沼液(BS)和加熱(HE)3種方法對(duì)根結(jié)線蟲的防控效果。結(jié)果表明, 與不采取任何措施的對(duì)照(CK)處理相比, BSS處理抑制根結(jié)線蟲效果最為明顯, 防效高達(dá)97.1%, 根結(jié)指數(shù)分別比HE和BS處理降低96.9%和92.9%。HE處理盡管在處理土壤后顯著降低了根結(jié)線蟲數(shù)量, 但在最后破壞性取樣時(shí)(結(jié)束試驗(yàn))出現(xiàn)反彈, 根結(jié)線蟲數(shù)量甚至高于CK處理。對(duì)于土壤線蟲群落, CK處理中以植食性線蟲為主(81.8%); 兩個(gè)沼液處理中食細(xì)菌線蟲占優(yōu)勢(shì)(平均78.3%), 且其中的雜食捕食性線蟲在土壤前處理后消失, 在試驗(yàn)結(jié)束時(shí)又重新出現(xiàn), 但所占比例依然非常低。沼液淹水方式的高效防控效果揭示了利用沼液防控根結(jié)線蟲的關(guān)鍵期在于線蟲入侵到植物根部之前的幼蟲期。然而, 在盆栽系統(tǒng)中, 沼液淹水的方式也對(duì)作物生長(zhǎng)表現(xiàn)出了一定的抑制趨勢(shì)。高量沼液施用防控病害的同時(shí)引發(fā)的植物毒害作用以及環(huán)境污染風(fēng)險(xiǎn), 需要進(jìn)一步開展田間研究。

根結(jié)線蟲; 沼液; 淹水; 土壤線蟲群落; 土壤食物網(wǎng)

根結(jié)線蟲(spp.)是一種專性寄生在植物根系的病原物, 在世界范圍內(nèi)分布廣泛、危害嚴(yán)重[1-2]。根結(jié)線蟲通過危害植物根部, 形成根結(jié), 使得根系發(fā)育受阻和腐爛, 植物地上部分衰弱和枯死, 還能與病原菌形成復(fù)合侵染。設(shè)施蔬菜生產(chǎn)中, 蔬菜連作時(shí)間延長(zhǎng), 化肥、農(nóng)藥過度施用等不利擾動(dòng)因素造成土壤環(huán)境惡化, 土傳病害日益嚴(yán)重[3]; 設(shè)施生產(chǎn)環(huán)境溫度適宜, 為根結(jié)線蟲繁衍提供了良好的條件, 加劇了病害發(fā)生[4]。據(jù)報(bào)道, 受根結(jié)線蟲危害的番茄()一般減產(chǎn)20%~30%, 嚴(yán)重時(shí)可達(dá)80%以上, 甚至絕產(chǎn)[5-6]。全世界每年因根結(jié)線蟲病導(dǎo)致的農(nóng)業(yè)損失達(dá)1 570億美元[7], 我國(guó)每年因根結(jié)線蟲為害蔬菜造成的損失達(dá)200億元人民幣以上[6]。

設(shè)施蔬菜種植中防治根結(jié)線蟲的方法有多種, 包括物理措施、化學(xué)措施、生物防治、調(diào)整種植制度、篩選抗性品種等[6]。施用有機(jī)材料也是一種可以有效防控土傳病害的傳統(tǒng)農(nóng)業(yè)措施[8-9]。有機(jī)廢棄物的利用還可改善土壤理化性狀, 提高土壤肥力, 減少不利于環(huán)境的化學(xué)品投入, 符合循環(huán)農(nóng)業(yè)和綠色可持續(xù)發(fā)展的生態(tài)理念。對(duì)于防控根結(jié)線蟲而言, 最為常見的有機(jī)廢棄物屬農(nóng)業(yè)廢棄物或下腳料, 如植物殘?bào)w、動(dòng)物排泄物和堆肥[8]。這些材料作用于植物線蟲的機(jī)理可分為直接作用和間接作用。直接效應(yīng)為某些有機(jī)物本身含有殺線蟲物質(zhì)[10], 或在降解過程中釋放對(duì)線蟲有毒害作用的物質(zhì), 如氨[11]、脂肪酸[12]等。間接作用主要表現(xiàn)為充分調(diào)動(dòng)土壤生態(tài)系統(tǒng)的內(nèi)生資源, 通過食物網(wǎng)調(diào)控作用豐富線蟲的捕食者, 幫助相近生態(tài)位有益線蟲的競(jìng)爭(zhēng), 從而抑制有害線蟲[9,13-14]。

沼液作為沼氣工程的副產(chǎn)物, 也是一種優(yōu)質(zhì)的有機(jī)肥資源[15]。然而, 一直以來, 沼渣、沼液由于固液分離困難、運(yùn)輸不便、缺乏合理施用技術(shù)指導(dǎo)等原因, 利用率普遍較為低下。近年來, 隨著沼液特性研究的不斷深入, 固液分離瓶頸問題的解決, 人們對(duì)環(huán)保的日益重視以及國(guó)家對(duì)循環(huán)農(nóng)業(yè)理念的認(rèn)可和政策傾斜, 沼液如何合理施用受到越來越多的關(guān)注, 多種沼液應(yīng)用技術(shù)相繼得到認(rèn)可和推廣。大量研究表明, 合理施用沼液有利于提高作物產(chǎn)量和品質(zhì)[16], 改善土壤理化性質(zhì)[17], 同時(shí)沼液也是防控病害的理想材料[15,18-19]。

針對(duì)根結(jié)線蟲, 國(guó)際上一些學(xué)者已經(jīng)通過盆栽和田間試驗(yàn)進(jìn)行了嘗試, 均證實(shí)了沼液可以有效抑制根結(jié)線蟲病害發(fā)生[19-22]。然而, 這些研究采取的方法都是在作物種植期間施用稀釋的沼液。事實(shí)上, 在沼液抑制土傳病害方面, 種植前沼液淹水消毒土壤也是常見的方式, 這種方式聯(lián)合沼液自身抑病成分和土壤厭氧環(huán)境的雙重作用抑制病害發(fā)生, 例如對(duì)真菌病原物的防治[15,23], 但尚少見有關(guān)線蟲病害的報(bào)道。因此, 本研究對(duì)比沼液淹水和常規(guī)方式根結(jié)線蟲的防治效果, 同時(shí)監(jiān)測(cè)該方式對(duì)土壤食物網(wǎng)的影響, 以期為沼液的循環(huán)利用和土傳病害防控提供科學(xué)依據(jù)和新的思路。

1 材料與方法

1.1 土壤及沼液采集

土壤采集地點(diǎn)為北京順義區(qū)綠奧種植專業(yè)合作社(40°10′N, 116°89′E)。該區(qū)域?qū)贉貛Т箨懶园霛駶?rùn)季風(fēng)氣候, 年平均氣溫11.5 ℃, 無霜期195 d, 年均降雨量610 mm。區(qū)域內(nèi)土壤類型為潮褐土。試供土樣采集自合作社溫室的根結(jié)線蟲病土, 土壤基礎(chǔ)理化性狀為全氮2.82 g?kg–1、有機(jī)質(zhì)43.5 g?kg–1、速效磷410.5 mg?kg–1、速效鉀763.5 mg?kg–1、pH 7.01、EC 0.42 dS?m–1。取樣時(shí)正值黃瓜()收獲期, 根結(jié)線蟲發(fā)病嚴(yán)重, 干土二齡幼蟲平均數(shù)量達(dá)4 604.5條線蟲?(100g)–1。樣品采集時(shí)間為2017年5月17日。用鐵鏟隨機(jī)挖取作物根際0~20 cm土壤約80 kg, 帶回實(shí)驗(yàn)室常溫保存, 并于一周內(nèi)完成試驗(yàn)布置。

沼液取自北京市大興區(qū)留民營(yíng)沼氣站, 該沼氣站發(fā)酵方式為中溫發(fā)酵, 所用原料為雞糞, 水力停留期為15 d[24]。沼液的基礎(chǔ)理化性狀為全氮6.26 g?L–1、全磷3.4 g?L–1、全鉀3.6 g?L–1、有機(jī)質(zhì)27.5 g?L–1、EC 26.8 dS?m–1、pH 8.02、銨態(tài)氮5.32 g?L–1。沼液取回后一部分用于測(cè)定基礎(chǔ)理化性狀, 剩余部分置于4 ℃冰箱冷藏備用。

1.2 試驗(yàn)設(shè)計(jì)

試驗(yàn)設(shè)3種方法抑制根結(jié)線蟲。沼液常規(guī)施用(BS): 稀釋后的沼液于種植期分3次施入土壤; 沼液淹水(BSS): 種植前用70%沼液淹沒土壤; 加熱處理(HE): 模擬常規(guī)悶棚過程, 將土壤置于45 ℃環(huán)境中并覆膜; 對(duì)照(CK): 不采取任何防控措施。

1.3 土壤理化測(cè)定

土壤有機(jī)質(zhì)含量采用重鉻酸鉀氧化法測(cè)定, 全氮含量采用凱式蒸餾法測(cè)定, 有效磷含量采用鉬銻抗比色法測(cè)定(NaHCO3提取), 速效鉀含量采用乙酸銨浸提-火焰光度法測(cè)定, pH為pH計(jì)測(cè)定(水土比為2.5∶1), 電導(dǎo)率采用1∶5土壤懸液電導(dǎo)法測(cè)定。

1.4 植株分析

取樣時(shí)番茄植株地上部分齊根剪斷, 用于測(cè)定植株株高和莖粗。株高用卷尺測(cè)量, 為根部到生長(zhǎng)點(diǎn)距離; 莖粗用游標(biāo)卡尺測(cè)量, 以第1片真葉下部節(jié)間為準(zhǔn)。植株地下部分用于病情分析。參考陳志杰等[6]的方法, 根系洗凈后記錄根系受害程度, 并進(jìn)行根結(jié)分級(jí)(9級(jí)), 通過根級(jí)計(jì)算根結(jié)指數(shù)以及相對(duì)防效。

根結(jié)指數(shù)=?(各級(jí)植株數(shù)′級(jí)數(shù))/(調(diào)查總株數(shù)′9)′100 (1)

相對(duì)防效=(對(duì)照根結(jié)指數(shù)-處理根結(jié)指數(shù))/對(duì)照根結(jié)指數(shù) (2)

1.5 線蟲分析

土壤線蟲分離采取淺盤法。將60 g新鮮土壤平鋪于35目網(wǎng)篩上(直徑10 cm), 網(wǎng)篩和土壤之間隔一層面巾紙。將網(wǎng)篩置于不銹鋼托盤上, 在托盤中加入水。靜置48 h后將托盤中液體通過500目網(wǎng)篩收集線蟲。靜置2 h后保存于4%甲醛中。

所獲線蟲于40倍顯微鏡下計(jì)數(shù), 并隨機(jī)挑選100條鑒定至屬水平, 不足100條的全部鑒定。根據(jù)食性, 線蟲被劃分為4個(gè)營(yíng)養(yǎng)類群: 食細(xì)菌線蟲(Ba)、食真菌線蟲(Fu)、植食性線蟲(PP)和雜食捕食性線蟲(OP)[25]。計(jì)算線蟲的多樣性指標(biāo), 包括香農(nóng)指數(shù)(′, Shannon index)、優(yōu)勢(shì)度指數(shù)(, dominance)和營(yíng)養(yǎng)類群多樣性指數(shù)(, trophic diversity)。

′=–∑p(lnp) (3)

=∑p2(4)

式中:p是第個(gè)線蟲屬個(gè)體數(shù)在線蟲總數(shù)中的比例。

=1/∑p2(5)

式中:p是第個(gè)營(yíng)養(yǎng)類群在線蟲群落中的比例[26]。

1.6 統(tǒng)計(jì)分析

數(shù)據(jù)采用單因素方差分析, 在SPSS 16.0中完成。多重比較方法為L(zhǎng)SD, 設(shè)置顯著性水平為<0.05。分析前進(jìn)行齊次性檢測(cè), 不滿足齊次性假設(shè)的采用對(duì)數(shù)、開平方或反余弦進(jìn)行數(shù)據(jù)轉(zhuǎn)換; 仍不滿足的則采取非參數(shù)檢驗(yàn)方法。線蟲群落的排序分析采用PCA模型, 以反映不同處理的差異, 在Cannoco 5.0中完成。

2 結(jié)果與分析

2.1 不同沼液利用方式對(duì)土壤理化性狀的影響

經(jīng)過65 d的種植, 各處理在土壤有機(jī)質(zhì)和全氮含量上無顯著差異(表1), 但沼液淹水方式(BSS處理)比常規(guī)沼液施用方式(BS處理)和對(duì)照(CK)顯著增加了電導(dǎo)率、有效磷和速效鉀含量(<0.05), 而BS處理的電導(dǎo)率和速效鉀與CK無顯著差異。此外, BSS和BS處理均顯著降低了土壤pH(<0.05), 尤其是BSS處理。加熱(HE處理)顯著提升了EC值和速效鉀含量?？傮w上沼液淹水方式對(duì)土壤理化性狀的影響更為明顯。

表1 不同沼液利用方式對(duì)土壤理化性狀的影響

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。同列不同小寫字母表示不同處理間差異顯著(<0.05)。CK: control; HE: soil was heated to 45 ℃; BSS: soil was flooded with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period. Different lowercase letters in the same column represent significant differences among different treatments at<0.05 level.

2.2 不同沼液利用方式對(duì)植株生長(zhǎng)的影響

沼液淹水(BSS處理)和加熱(HE處理)有降低株高的趨勢(shì), 而沼液常規(guī)施用(BS處理)有增加株高的趨勢(shì)(圖1), 但均未達(dá)到顯著水平, 但是BSS比BS有顯著降低株高的效應(yīng)(<0.05)。各處理在莖粗上并未表現(xiàn)出顯著差異。

圖1 不同沼液利用方式對(duì)植株生長(zhǎng)的影響

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。不同小寫字母表示不同處理間差異顯著(<0.05)。CK: control; HE: soil was heated to 45 ℃; BSS: soil was flooded with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period. Different lowercase letters represent significant differences among different treatments at<0.05 level.

2.3 不同沼液利用方式防控根結(jié)線蟲效應(yīng)

沼液淹水的方式(BSS處理)抑制根結(jié)線蟲效果最為明顯, 防效高達(dá)97.1%, 比加熱(HE處理)和常規(guī)沼液施用方式(BS處理)分別降低96.9%和92.9%的根結(jié)指數(shù)(圖2)。

圖2 不同沼液利用方式下根結(jié)線蟲防效比較

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。CK: control; HE: soil was heated to 45℃; BSS: soil was flooded with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period.

分別于種植前土壤處理和破壞性取樣后監(jiān)測(cè)土壤線蟲群落。土壤前處理后的即時(shí)線蟲數(shù)量結(jié)果顯示加熱(HE處理)和沼液淹水方法(BSS處理)均能顯著降低線蟲總數(shù)和根結(jié)線蟲數(shù)量(圖3), 其中加熱方法(HE)的線蟲總數(shù)還顯著低于BSS處理(<0.05)。根結(jié)線蟲的比例也呈現(xiàn)BSS

2.4 不同沼液利用方式對(duì)線蟲多樣性的影響

種植前的土壤處理后, 加熱(HE處理)和沼液淹水(BSS處理)并未降低線蟲的多樣性, 反而顯著提升了香農(nóng)指數(shù)和營(yíng)養(yǎng)類群多樣性(圖4), 并顯著降低了優(yōu)勢(shì)度(<0.05)。試驗(yàn)結(jié)束后, 依然存在這種趨勢(shì), BSS處理的香農(nóng)指數(shù)顯著高于CK, 而BS處理的香農(nóng)指數(shù)最高; 但營(yíng)養(yǎng)類群多樣性指數(shù)各處理均無顯著差異。

2.5 不同沼液利用方式對(duì)線蟲群落結(jié)構(gòu)的影響

如表4所示, 試驗(yàn)總計(jì)發(fā)現(xiàn)16個(gè)線蟲屬, 以食細(xì)菌線蟲的種類最為豐富(10個(gè)), 食真菌線蟲僅發(fā)現(xiàn)了1個(gè)種。在種植前土壤處理后, 食細(xì)菌線蟲以cp1的為優(yōu)勢(shì)類群, 試驗(yàn)結(jié)束后轉(zhuǎn)變?yōu)閏p1的, 以及cp2線蟲(主要為和)為優(yōu)勢(shì)類群。植食性線蟲主要為根結(jié)線蟲(), 在第2次取樣時(shí)發(fā)現(xiàn)了和, 但比例極低。總體上對(duì)照中植食性線蟲比例最高(平均81.8%), 而兩個(gè)施用沼液的處理中食細(xì)菌線蟲占優(yōu)勢(shì)(平均78.3%)(圖5)。雜食捕食性線蟲在沼液淹水處理后消失, 但在試驗(yàn)結(jié)束時(shí)重新出現(xiàn), 但所占比例依然非常低(表2)。

圖3 不同沼液利用方式對(duì)線蟲總數(shù)、根結(jié)線蟲數(shù)量和比例的影響

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。不同小寫字母表示不同處理間差異顯著(<0.05)。CK: control; HE: soil was heated to 45 ℃; BSS: soil was flooded with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period. Different lowercase letters represent significant differences among different treatments at<0.05 level.

圖4 不同沼液利用方式對(duì)線蟲多樣性指標(biāo)的影響

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。不同小寫字母表示不同處理間差異顯著(<0.05)。CK: control; HE: soil was heated to 45 ℃; BSS: soil was flooded with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period. Different lowercase letters represent significant differences among different treatments at<0.05 level.

表2 不同沼液利用方式對(duì)土壤線蟲群落組成的影響

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。CK: control; HE: soil was heated to 45 ℃; BSS: soil was pretreated by flooding with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period.

圖5 不同沼液利用方式土壤線蟲各營(yíng)養(yǎng)類群相對(duì)豐度

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。CK: control; HE: soil was heated to 45 ℃; BSS: soil was flooded with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period.

圖6顯示了不同處理線蟲群落的差別程度。土壤處理后PCA分析1軸解釋度為34.34%, 2軸的為23.16%; 破壞性取樣后PCA分析1軸解釋度為47.30%, 2軸的為23.37%。土壤前處理后不同處理線蟲群落差別非常明顯(圖6A), 但在試驗(yàn)結(jié)束時(shí)加熱(HE)處理和CK的線蟲群落較為相似, 而沼液淹水(BSS)和常規(guī)施用(BS)處理依然表現(xiàn)出明顯區(qū)別于CK的差異(圖6B)。反映出HE處理對(duì)線蟲的影響持續(xù)時(shí)間較短, 施用沼液對(duì)土壤線蟲的影響更為持久。

圖6 土壤前處理后(A)和試驗(yàn)結(jié)束時(shí)(B)線蟲群落PCA分析

CK: 對(duì)照; HE: 加熱; BSS: 沼液淹水; BS: 沼液常規(guī)施用。CK: control; HE: soil was heated to 45 ℃; BSS: soil was flooded with biogas slurry before planting; BS: biogas slurry was routinely applied to soil three times during the planting period.

3 討論

本研究對(duì)比了兩種沼液施用方式和加熱處理對(duì)根結(jié)線蟲的抑制效果。其中加熱方式是為了模擬北方溫室最為常見的高溫悶棚防控線蟲病害措施。土壤經(jīng)處理后獲得了良好的即時(shí)抑制效果, 但是在試驗(yàn)結(jié)束時(shí)根結(jié)線蟲數(shù)量出現(xiàn)了強(qiáng)烈的反彈。這個(gè)結(jié)果與很多田間試驗(yàn)高達(dá)50%以上的線蟲防效結(jié)果不一致[6,27-28]。本試驗(yàn)設(shè)定的45 ℃加熱溫度源自于田間實(shí)踐中不同土層溫度的平均值[6], 而田間防治線蟲過程中實(shí)際溫度可達(dá)50 ℃以上, 甚至到60 ℃[6], 這點(diǎn)可能是本盆栽試驗(yàn)效果不及田間試驗(yàn)的原因之一。另一方面, 室內(nèi)模擬試驗(yàn)和田間試驗(yàn)由于外部環(huán)境的巨大差異, 研究結(jié)果也可能存在較大的差別。與本研究方法相似的另一個(gè)室內(nèi)培養(yǎng)試驗(yàn)[29]結(jié)果表明,短期的加熱處理(40 ℃, 18 h)后, 保護(hù)地土壤的線蟲總數(shù)也呈現(xiàn)先下降又上升的趨勢(shì), 盡管這種變化不及本試驗(yàn)中的波動(dòng)明顯。這兩個(gè)可類比的結(jié)果反映出在模擬環(huán)境中, 土壤加熱這種方式更類似于瞬時(shí)擾動(dòng)[29], 擾動(dòng)結(jié)束后線蟲數(shù)量容易恢復(fù)。

相比加熱方式, 沼液處理中對(duì)線蟲起作用的物質(zhì)一直存在于土壤中, 形成一種“延時(shí)”擾動(dòng), 因此對(duì)根結(jié)線蟲具有更為持久抑制效果。沼液中含有大量的銨態(tài)氮, 銨鹽基本身對(duì)線蟲沒有影響[30], 但是銨態(tài)氮在土壤中轉(zhuǎn)化成氨, 尤其在堿性土壤環(huán)境下[15]。氨可以穿過細(xì)胞膜, 改變細(xì)胞質(zhì)pH[31], 從而達(dá)到毒殺線蟲的作用。除此以外, 沼液中還含有各種有機(jī)小分子, 也起到抑制線蟲的作用[20-21,32]。

沼液淹水提前處理土壤的方式比常規(guī)的沼液在種植期間施用降低了92.9%的根結(jié)指數(shù)和97.6%的根結(jié)線蟲數(shù)量(試驗(yàn)結(jié)束時(shí)), 如此顯著的防效提升與淹水方式高量的沼液投入不無關(guān)系。經(jīng)換算淹水方式施入的銨態(tài)氮是常規(guī)方式的11.3倍, 盡管兩個(gè)處理的施用時(shí)機(jī)和方法都不一樣。本試驗(yàn)并沒有設(shè)定等量的沼液投入, 主要考慮到淹水方式需要高濃度、高量的沼液才能起到效果; 而常規(guī)方式如果在種植期間加入等量的沼液, 根據(jù)以往的實(shí)踐經(jīng)驗(yàn), 可能引發(fā)燒苗現(xiàn)象。因此在本試驗(yàn)更多考慮的是兩種方式的比較。另一方面, 沼液淹水處理土壤可形成厭氧的環(huán)境, 有利于維持較高的銨態(tài)氮含量, 以及釋放有機(jī)小分子物質(zhì)[15,33], 起到間接抑制根結(jié)線蟲的作用[34]。盡管對(duì)照也采用了等量的自來水處理土壤, 但高濃度沼液較為黏稠[35-36], 更容易維持土壤飽和水的狀態(tài)。最后, 沼液淹沒處理時(shí), 土壤中根結(jié)線蟲以二齡幼蟲為主, 處理結(jié)束后根結(jié)線蟲減少了82.7%(圖3), 并且沼液中的有效物質(zhì)在進(jìn)入種植期后還會(huì)持續(xù)發(fā)揮作用; 相比而言, 常規(guī)的方式加入沼液前, 大量的根結(jié)線蟲幼蟲已經(jīng)開始尋找寄主寄生[37], 防治效果勢(shì)必減弱。由此可見, 利用沼液防控根結(jié)線蟲的關(guān)鍵在于種植前的土壤處理。

在本試驗(yàn)體系中, 沼液淹沒土壤方式取得良好的根結(jié)線蟲防控效果的同時(shí), 也產(chǎn)生了些許負(fù)面效應(yīng), 作物的株高和莖粗均有所降低, 但均未達(dá)到顯著水平, 而這種趨勢(shì)在種植的前期更為明顯(觀察所得, 未做數(shù)據(jù)記錄)。沼液淹水方式可提供更多的養(yǎng)分, 然而Wentzel等[38]發(fā)現(xiàn)沼液帶入的銨態(tài)氮與作物地上部產(chǎn)量并不會(huì)呈線性關(guān)系; 相反, 過量的銨態(tài)氮以及有機(jī)酸會(huì)抑制植物根的生長(zhǎng)[30,39]。土壤在沼液淹水處理后, 又經(jīng)歷了充分晾曬, 但還是有大量養(yǎng)分殘留, 未能消除這種植物毒害影響。此外, 盆栽條件有別于田間環(huán)境, 水分缺乏徑流和淋溶的轉(zhuǎn)移作用, 使得沼液中的成分不能分散。盡管有學(xué)者報(bào)導(dǎo)這種負(fù)面效應(yīng)在田間將得到較大的緩解[21], 但是高量沼液防控病害同時(shí)引發(fā)的植物毒害作用, 甚至于潛在的地下水污染風(fēng)險(xiǎn)[15], 仍然需要進(jìn)一步開展田間研究。

沼液淹水處理并沒有削弱所有線蟲的數(shù)量而形成“生物真空”狀態(tài), 相反食細(xì)菌線蟲在收獲期占絕對(duì)優(yōu)勢(shì), 這是由于有機(jī)物的投入刺激了土壤食物網(wǎng)的上行效應(yīng), 增加了細(xì)菌的生物量[40-41]。然而, 在該處理中, 對(duì)有機(jī)物投入能做出快速響應(yīng)的ba1線蟲[42]比例并不高(試驗(yàn)結(jié)束期), 占優(yōu)勢(shì)的是抵抗環(huán)境污染和擾動(dòng)能力較強(qiáng)的ba2線蟲, 說明高量的沼液投入使得土壤食物網(wǎng)處于強(qiáng)烈的脅迫狀態(tài)[42]。有意思的是, 沼液淹水處理線蟲的多樣性指數(shù)相比對(duì)照不僅沒有降低, 反而顯著升高, 可能是因?yàn)楦Y(jié)線蟲的大幅減少?gòu)亩档土苏w的優(yōu)勢(shì)度, 而優(yōu)勢(shì)度與香農(nóng)指數(shù)常呈現(xiàn)相反的變化趨勢(shì)[13,43]。雜食捕食性線蟲是土壤食物網(wǎng)中的高級(jí)類群, 也是土壤健康的重要指示生物[44]。在本研究中, 沼液淹水處理后該類線蟲消失, 盡管在最后重新出現(xiàn), 但所占比例依然非常低, 反映出養(yǎng)分資源尚未通過食物網(wǎng)傳遞到頂級(jí)營(yíng)養(yǎng)位, 而土壤環(huán)境更多地呈現(xiàn)出脅迫的狀態(tài)。這個(gè)現(xiàn)象與Valocká等[22]報(bào)道的沼液施用可增多雜食捕食性線蟲的結(jié)果并不相符?？紤]到所有處理中雜食捕食性線蟲的比例都很低, 甚至常規(guī)施用沼液的土壤中都沒有發(fā)現(xiàn)該類線蟲。因此主要的原因應(yīng)該是盆栽環(huán)境的限制, 而并非沼液的用量。

4 結(jié)論

1)在盆栽系統(tǒng)中, 種植前用高濃度沼液淹水可大幅提升根結(jié)線蟲防控效果, 防效高達(dá)97.1%, 比加熱和常規(guī)沼液施用方式分別降低96.9%和92.9%的根結(jié)指數(shù)。相比而言, 加熱的方式在即時(shí)的土壤處理后有明顯的抑制根結(jié)線蟲效果, 但在后期出現(xiàn)反彈現(xiàn)象; 主成分分析反映出加熱處理對(duì)線蟲的影響持續(xù)時(shí)間較短, 施用沼液對(duì)土壤線蟲的影響更為持久。

2)不同處理的線蟲群落結(jié)構(gòu)差異明顯, 以食細(xì)菌線蟲的種類最為豐富, 食真菌線蟲種類最少。施用沼液的兩個(gè)處理是食細(xì)菌線蟲占優(yōu)勢(shì), 平均比例達(dá)78.3%; 而在對(duì)照中植食性線蟲的比例最高, 達(dá)81.8%。

3)盆栽系統(tǒng)中, 沼液淹沒土壤方式取得良好的防控根結(jié)線蟲效果的同時(shí), 也產(chǎn)生了些許抑制作物生長(zhǎng)的效應(yīng), 但均未達(dá)到顯著水平。未來需進(jìn)一步開展田間研究, 通過真實(shí)的生產(chǎn)過程明確高量沼液處理土壤是否會(huì)引發(fā)植物毒害作用, 以及潛在的土壤環(huán)境風(fēng)險(xiǎn)。

[1] KARSSEN G, MOENS M. Root-knot Nematodes[M]//PERRY R N, MOENS M. Plant Nematology. London, UK: CAB International, 2006: 60–90

[2] ZHOU D M, FENG H, SCHUELKE T, et al. Rhizosphere microbiomes from root knot nematode non-infested plants suppress nematode infection[J]. Microbial Ecology, 2019, 78(2): 470–481

[3] 喻景權(quán), 杜堯舜. 蔬菜設(shè)施栽培可持續(xù)發(fā)展中的連作障礙問題[J]. 沈陽農(nóng)業(yè)大學(xué)學(xué)報(bào), 2000, 31(1): 124–126 YU J Q, DU Y S. Soil-sickness problem in the sustainable development for the protected production of vegetables[J]. Journal of Shenyang Agricultural University, 2000, 31(1): 124–126

[4] 王曉云, 王秀峰, 魏珉, 等. 土元糞及浸提液對(duì)番茄根結(jié)線蟲的防治作用[J]. 應(yīng)用生態(tài)學(xué)報(bào), 2015, 26(8): 2511–2517 WANG X Y, WANG X F, WEI M, et al. Eupolyphaga frass and its extracts protected tomato frominfestation[J]. Chinese Journal of Applied Ecology, 2015, 26(8): 2511–2517

[5] YüCEL S, ?ZARSLANDAN A, ?OLAK A, et al. Effect of solarization and fumigant applications on soilborne pathogens and root-knot nematodes in greenhouse-grown tomato in turkey[J]. Phytoparasitica, 2007, 35(5): 450–456

[6] 陳志杰, 張淑蓮, 張鋒, 等. 設(shè)施蔬菜根結(jié)線蟲防治基礎(chǔ)與技術(shù)[M]. 北京: 科學(xué)出版社, 2013: 106–190 CHEN Z J, ZHANG S L, ZHANG F, et al. Control Basis and Techniques of Root-knot Nematode in Protected Vegetables[M]. Beijing: Science Press, 2013: 106–190

[7] ABAD P, GOUZY J, AURY J M, et al. Genome sequence of the metazoan plant-parasitic nematode[J]. Nature Biotechnology, 2008, 26(8): 909–915

[8] OKA Y. Mechanisms of nematode suppression by organic soil amendments — A review[J]. Applied Soil Ecology, 2010, 44(2): 101–115

[9] REN?O M. Organic amendments of soil as useful tools of plant parasitic nematodes control[J]. Helminthologia, 2013, 50(1): 3–14

[10] CHITWOOD D J. Phytochemical based strategies for nematode control[J]. Annual Review of Phytopathology, 2002, 40(1): 221–249

[11] DOCHERTY P A, SNIDER M D. Effects of hypertonic and sodium-free medium on transport of a membrane glycoprotein along the secretory pathway in cultured mammalian cells[J]. Journal of Cellular Physiology, 1991, 146(1): 34–42

[12] SAYRE R M, PATRICK Z A, THORPE H J. Identification of a selective nematicidal component in extracts of plant residues decomposing in soil[J]. Nematologica, 1965, 11(2): 263–268

[13] LI Y F, LI J, ZHENG C Y, et al. Effects of organic, low input, conventional management practices on soil nematode community under greenhouse conditions[J]. Acta Agriculturae Scandinavica, Section B-Soil & Plant Science, 2015, 64(4): 360–371

[14] SáNCHEZ-MORENO S, FERRIS H. Suppressive service of the soil food web: Effects of environmental management[J]. Agriculture, Ecosystems & Environment, 2007, 119(1/2): 75–87

[15] CAO Y, WANG J D, WU H S, et al. Soil chemical and microbial responses to biogas slurry amendment and its effect on Fusarium wilt suppression[J]. Applied Soil Ecology, 2016, 107: 116–123

[16] XU M, XIAN Y, WU J, et al. Effect of biogas slurry addition on soil properties, yields, and bacterial composition in the rice-rape rotation ecosystem over 3 years[J]. Journal of Soils and Sediments, 2019, 19(5): 2534–2542

[17] M?LLER K. Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review[J]. Agronomy for Sustainable Development, 2015, 35(3): 1021–1041

[18] CONN K L, LAZAROVITS G. Impact of animal manures on verticillium wilt, potato scab, and soil microbial populations[J]. Canadian Journal of Plant Pathology, 1999, 21(1): 81–92

[19] JOTHI G, PUGALENDHI S, POORNIMA K, et al. Management of root-knot nematode in tomato, mill., with biogas slurry[J]. Bioresource Technology, 2003, 89(2): 169–170

[20] MIN Y Y, SATO E, SHIRAKASHI T, et al. Suppressive effect of anaerobically digested slurry on the root lesion nematodeand its potential mechanisms[J]. Japanese Journal of Nematology, 2007, 37(2): 93–100

[21] MIN Y Y, TOYOTA K, SATO E, et al. Effects of anaerobically digested slurry onandin tomato and radish production[J]. Applied and Environmental Soil Science, 2011, 2011: 528712

[22] VALOCKá B, DUBINSKY P, PAPAJOVá I, et al. Effect of anaerobically digested pig slurry from lagoon on soil and plant nematode communities in experimental conditions[J]. Helminthologia, 2000, 37(1): 53–57

[23] 曹云, 馬艷, 吳華山, 等. 沼液處理對(duì)土壤微生物性狀及西瓜枯萎病發(fā)生的影響[J]. 中國(guó)土壤與肥料, 2016, (1): 34–41 CAO Y, MA Y, WU H S, et al. Suppression of fusarium wilt of watermelon by biogas slurry application and its effect on soil microbiological characteristics[J]. Soil and Fertilizer Sciences in China, 2016, (1): 34–41

[24] 薛文濤, 孫欽平, 林聰, 等. 風(fēng)速對(duì)雞糞沼液氨揮發(fā)特性的影響[J]. 農(nóng)業(yè)工程學(xué)報(bào), 2018, 34(S1): 7–12 XUE W T, SUN Q P, LIN C, et al. Effect of wind speed on ammonia volatilization characteristics of chicken manure biogas slurry[J]. Transactions of the Chinese Society of Agricultural Engineering, 2018, 34(S1): 7–12

[25] YEATES G W, BONGERS T, DE GOEDE R G M, et al. Feeding habits in soil nematode families and genera — An outline for soil ecologists[J]. Journal of Nematology, 1993, 25(3): 315–331

[26] LI Y F, CAO Z P, HU C, et al. Response of nematodes to agricultural input levels in various reclaimed and unreclaimed habitats[J]. European Journal of Soil Biology, 2014, 60: 120–129

[27] ESFAHANI M N. Integration of solar-heating and soil-amendment, an effective control measure against root-knot nematodes in cucumber fields[J]. Pakistan Journal of Nematology, 2008, 26(1): 97–106

[28] 侯茂林. 添加石灰氮和有機(jī)物進(jìn)行太陽能加熱對(duì)溫室土壤根結(jié)線蟲和黃瓜的影響[J]. 中國(guó)生態(tài)農(nóng)業(yè)學(xué)報(bào), 2008, 16(1): 75–79 HOU M L. Effect of soil solarization with calcium cyanamid and organic manure amendments on greenhouse root-knot nematodes and cucumber plants[J]. Chinese Journal of Eco-agriculture, 2008, 16(1): 75–79

[29] LIU M Q, CHEN X Y, GRIFFITHS B S, et al. Dynamics of nematode assemblages and soil function in adjacent restored and degraded soils following disturbance[J]. European Journal of Soil Biology, 2012, 49: 37–46

[30] OKA Y, PIVONIA S. Use of ammonia-releasing compounds for control of the root-knot nematode[J]. Nematology, 2002, 4(1): 65–71

[31] WARREN K S. Ammonia toxicity and pH[J]. Nature, 1962, 195(4836): 47–49

[32] CHANTIGNY M H, ROCHETTE P, ANGERS D A, et al. Ammonia volatilization and selected soil characteristics following application of anaerobically digested pig slurry[J]. Soil Science Society of America Journal, 2004, 68(1): 306–312

[33] RUNIA W T, MOLENDIJK L P G. Physical methods for soil disinfestation in intensive agriculture: Old methods and new approaches[J]. Acta Horticulturae, 2010, (883): 249–258

[34] 石磊, 趙洪海, 李明亮, 等. 土壤強(qiáng)還原處理對(duì)根結(jié)線蟲數(shù)量、番茄生長(zhǎng)及土壤性質(zhì)的影響[J]. 生態(tài)學(xué)雜志, 2018, 37(6): 1865–1870 SHI L, ZHAO H H, LI M L, et al. Effects of strong reductive approach on root-knot nematodes, the growth of tomato and soil physicochemical properties[J]. Chinese Journal of Ecology, 2018, 37(6): 1865–1870

[35] MARCATO C E, PINELLI E, POUECH P, et al. Particle size and metal distributions in anaerobically digested pig slurry[J]. Bioresource Technology, 2008, 99(7): 2340–2348

[36] 張麗萍, 劉紅江, 盛婧, 等. 發(fā)酵周期、貯存時(shí)間和過濾對(duì)沼液養(yǎng)分和理化性狀變化的影響[J]. 農(nóng)業(yè)資源與環(huán)境學(xué)報(bào), 2018, 35(1): 32–39 ZHANG L P, LIU H J, SHENG J, et al. Influence of anaerobic fermentation periods, storage time and filtration on the changes of nutrients and physical and chemical properties of biogas slurry[J]. Journal of Agricultural Resources and Environment, 2018, 35(1): 32–39

[37] 康俊. 爪哇根結(jié)線蟲致病機(jī)理及食道腺寄生基因的功能研究[D]. 廈門: 廈門大學(xué), 2009: 29–37 KANG J. Pathogenesis and function study of parasitism gene in the esophageal gland of[D]. Xiamen: Xiamen University, 2009: 29–37

[38] WENTZEL S, JOERGENSEN R G. Effects of biogas and raw slurries on grass growth and soil microbial indices[J]. Journal of Plant Nutrition and Soil Science, 2016, 179(2): 215–222

[39] SALMINEN E, RINTALA J, H?RK?NEN J, et al. Anaerobically digested poultry slaughterhouse wastes as fertiliser in agriculture[J]. Bioresource Technology, 2001, 78(1): 81–88

[40] FERRIS H, BONGERS T. Nematode indicators of organic enrichment[J]. Journal of Nematology, 2006, 38(1): 3–12

[41] MAHRAN A, TENUTA M, LUMACTUD R A, et al. Response of a soil nematode community to liquid hog manure and its acidification[J]. Applied Soil Ecology, 2009, 43(1): 75–82

[42] FERRIS H, BONGERS T, DE GOEDE R G M. A framework for soil food web diagnostics: Extension of the nematode faunal analysis concept[J]. Applied Soil Ecology, 2001, 18(1): 13–29

[43] 李鈺飛, 許俊香, 孫欽平, 等. 沼渣施用對(duì)土壤線蟲群落結(jié)構(gòu)的影響[J]. 中國(guó)農(nóng)業(yè)大學(xué)學(xué)報(bào), 2017, 22(8): 64–73 LI Y F, XU J X, SUN Q P, et al. Effects of biogas residue application on soil nematode community structure[J]. Journal of China Agricultural University, 2017, 22(8): 64–73

[44] BONGERS T, BONGERS M. Functional diversity of nematodes[J]. Applied Soil Ecology, 1998, 10(3): 239–251

Effects of soil flooding of biogas slurry on root-knot nematode (spp.) and soil nematode community*

LI Yufei1, LIU Bensheng1, XU Junxiang1, LI Jijin1, LANG Qianqian1, QIAO Yuhui2, SUN Qinping1**

(1. Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China; 2. Beijing Key Laboratory for Biodiversity and Organic Farming / College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China)

Root-knot nematodes (RKN,spp.) cause soil-borne diseases in food crops, and can lead to a huge crop damage worldwide. It has been demonstrated that application of biogas slurry during planting is an effective method to control diseases caused by RKN. We explored the inhibition effect of biogas slurry on RKN by a soil flooding method to provide scientific basis for a new idea to prevent and control soil-borne diseases. A pot experiment was conducted using soil infected with RKN from a vegetable greenhouse. Four treatments were set: 1) biogas slurry was routinely applied to soil three times during the planting period (BS), with an application rate of NH4+50 mg?kg-1; 2) soil was pretreated by flooding with 70% biogas slurry twice before planting (BSS); 3) soil was covered with mulching films and heated to 45 ℃ (HE) to simulate a conventional smothering process and, 4) soil was untreated (CK). The most obvious inhibition of RKN was BSS treatment, with a control effect of 97.1%. The root-knot index in BSS treatment decreased by 96.9% and 92.9%, respectively, compared with that of HE and BS. However, this method showed a small trend of inhibiting crop growth. Although HE significantly reduced the number of RKN compared with CK, the RKN number rebounded at the later stage (60 d after treatment), and even was higher than that of CK. Taken together, the proportion of herbivores nematode was the highest in CK (mean 81.8%), while bacterivores dominated in the two biogas slurry treatments, BS and BSS (mean 78.3%). Omnivores and carnivores nematode disappeared in soil flooded with biogas slurry, although they reappeared at the destructive sampling period, the relative abundance was still very low. In the pot system, soil flooding with biogas slurry before planting significantly improved the inhibition effect on RKN compared with the application of biogas slurry during planting. This result revealed that the critical period of using biogas slurry to prevent and control RKN is at the larval stage: that is, before nematodes invade plant roots. Further studies are needed under field conditions to study the toxic effects of biogas slurry flooding in plants, and the potential risk of environmental pollution.

Root-knot nematode; Biogas slurry; Soil flooding; Soil nematode community; Soil food web

S436.412

10.13930/j.cnki.cjea.200099

李鈺飛, 劉本生, 許俊香, 李吉進(jìn), 郎乾乾, 喬玉輝, 孫欽平. 沼液淹沒土壤抑制根結(jié)線蟲及對(duì)土壤線蟲群落的影響[J]. 中國(guó)生態(tài)農(nóng)業(yè)學(xué)報(bào)(中英文), 2020, 28(8): 1249-1257

LI Y F, LIU B S, XU J X, LI J J, LANG Q Q, QIAO Y H, SUN Q P. Effects of soil flooding of biogas slurry on root-knot nematode (spp.) and soil nematode community[J]. Chinese Journal of Eco-Agriculture, 2020, 28(8): 1249-1257

* 北京市農(nóng)林科學(xué)院科技創(chuàng)新能力建設(shè)專項(xiàng)(KJCX20180708)、北京市農(nóng)林科學(xué)院青年科研基金項(xiàng)目(QNJJ202004)、北京市優(yōu)秀人才-青年骨干個(gè)人項(xiàng)目(2016000020060G128)、奶牛產(chǎn)業(yè)技術(shù)體系北京市創(chuàng)新團(tuán)隊(duì)項(xiàng)目(BAIC06-2020)、北京市生物多樣性與有機(jī)農(nóng)業(yè)重點(diǎn)實(shí)驗(yàn)室開放課題(BOF201906)和國(guó)家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2016YFD0800602, 2018YFD0800106-04)資助

孫欽平, 主要研究方向?yàn)橛袡C(jī)廢棄物循環(huán)利用與植物營(yíng)養(yǎng)。E-mail: sunqp@126.com

李鈺飛, 主要研究方向?yàn)橥寥郎鷳B(tài)學(xué)。E-mail: liyf15@163.com

2020-02-18

2020-03-27

* This study was supported by the Special Project for Building Scientific and Technological Innovation Capacity of Beijing Academy of Agri- culture and Forestry Sciences (KJCX20180708), the Youth Foundation of Beijing Academy of Agriculture and Forestry Sciences (QNJJ202004), Beijing Excellent Talents Project (2016000020060G128), Beijing Innovation Team of Technology System in Dairy Industry (BAIC06-2020), Beijing Key Laboratory of Biodiversity and Organic Farming (BOF201906), and the National Key Research and Development Project of China (2016YFD0800602, 2018YFD0800106-04).

, E-mail: sunqp@126.com

Feb. 18, 2020;

Mar. 27, 2020