張翰林, 白娜玲, 鄭憲清, 李雙喜, 張娟琴, 張海韻, 周 勝, 孫會(huì)峰, 呂衛(wèi)光**

秸稈還田與施肥方式對(duì)稻麥輪作土壤細(xì)菌和真菌群落結(jié)構(gòu)與多樣性的影響*

張翰林1,2, 白娜玲1,2, 鄭憲清1,2, 李雙喜1,2, 張娟琴1,2, 張海韻1,2, 周 勝1,3, 孫會(huì)峰1,3, 呂衛(wèi)光1,2**

(1. 上海市農(nóng)業(yè)科學(xué)院生態(tài)環(huán)境保護(hù)研究所/上海市設(shè)施園藝技術(shù)重點(diǎn)實(shí)驗(yàn)室/上海市農(nóng)業(yè)環(huán)境保護(hù)監(jiān)測站 上海 201403; 2. 農(nóng)業(yè)部上海農(nóng)業(yè)環(huán)境與耕地保育科學(xué)觀測實(shí)驗(yàn)站 上海 201403; 3. 上海低碳農(nóng)業(yè)工程技術(shù)研究中心 上海 201403)

為探索秸稈還田與施肥方式2種農(nóng)田措施對(duì)水稻-小麥(稻麥)輪作土壤微生物群落的影響, 闡釋其對(duì)土壤細(xì)菌和真菌群落結(jié)構(gòu)和多樣性的影響機(jī)制, 本研究通過7年稻麥輪作長期定位監(jiān)測試驗(yàn), 設(shè)置無肥空白(CK)、常規(guī)施肥(RT)、秸稈還田+常規(guī)施肥(RS)和秸稈還田+緩釋肥(SS) 4個(gè)處理, 采用Illumina Miseq高通量測序技術(shù), 分析土壤細(xì)菌和真菌群落結(jié)構(gòu)和多樣性, 探索影響微生物群落的主控環(huán)境因子。結(jié)果表明, SS作物產(chǎn)量在2016年和2017年分別比RT顯著提高11.6%和8.2% (水稻)、4.8%和3.6% (小麥), 與RS無顯著差異。相比RT, 秸稈還田處理顯著降低了土壤pH, 提升了土壤有機(jī)碳和銨態(tài)氮含量; 與RS相比, SS處理提高了銨態(tài)氮含量。秸稈還田處理提升了真菌群落多樣性, 但對(duì)細(xì)菌群落多樣性無顯著影響。SS與RS在細(xì)菌真菌群落多樣性方面均無顯著差異。相關(guān)性分析表明, 細(xì)菌群落多樣性與土壤pH呈負(fù)相關(guān), 與總氮含量呈正相關(guān); 真菌群落多樣性則與土壤有機(jī)碳含量顯著正相關(guān)。NMDS分析表明, 施肥對(duì)于細(xì)菌群落結(jié)構(gòu)影響較大(55.61%), 真菌群落結(jié)構(gòu)則對(duì)秸稈還田響應(yīng)更明顯(26.94%)。與RT相比, 秸稈還田顯著提升了細(xì)菌放線菌門、綠彎菌門、厚壁菌門的相對(duì)豐度, 同時(shí)顯著提升了真菌中子囊菌門的相對(duì)豐度, 降低了擔(dān)子菌門和接合菌門的相對(duì)豐度, 加強(qiáng)了土壤碳氮循環(huán)能力并抑制了病原菌。SS與RS相比, 僅提升了真菌中子囊菌門的相對(duì)豐度。綜上, 秸稈還田配施緩釋肥有助于維持或者提高土壤養(yǎng)分有效性、作物產(chǎn)量及細(xì)菌真菌群落多樣性, 可以促進(jìn)土壤碳氮循環(huán)。

土壤微生物; 群落結(jié)構(gòu); 土壤養(yǎng)分; 秸稈還田; 緩釋肥; 高通量測序

土壤微生物在陸地生態(tài)系統(tǒng)中具有重要作用, 負(fù)責(zé)調(diào)節(jié)土壤養(yǎng)分的生物地球化學(xué)循環(huán), 促進(jìn)植物生長, 維持生態(tài)系統(tǒng)的穩(wěn)定性[1]。細(xì)菌作為土壤中最豐富的微生物種之一, 在多種土壤生態(tài)過程中均起到重要的功能性作用, 如分解有機(jī)質(zhì)和促進(jìn)土壤養(yǎng)分礦化等[2]。真菌則是重要的分解者, 可以分解土壤中植物殘?bào)w和纖維素、半纖維素、木質(zhì)素等難降解有機(jī)物, 在降解過程中釋放養(yǎng)分, 促進(jìn)植物生長[3]。由于土壤中細(xì)菌、真菌群落對(duì)環(huán)境因素變化十分敏感, 土壤細(xì)菌和真菌群落多樣性常常被認(rèn)為是揭示土壤質(zhì)量狀況的重要指標(biāo)。一般來說, 較高的細(xì)菌和真菌多樣性表示土壤生態(tài)系統(tǒng)更加穩(wěn)定和健康[4-5]。

農(nóng)作物秸稈是數(shù)量最大的農(nóng)業(yè)可再生資源。隨著我國生態(tài)農(nóng)業(yè)的大力提倡, 農(nóng)作物秸稈還田已成為農(nóng)業(yè)資源循環(huán)利用的重要方式[6]。秸稈還田可以通過改變土壤理化性狀, 直接或間接地影響土壤微生物群落。郭梨錦等[7]發(fā)現(xiàn)短期(2年)水稻(L.)、小麥(L.)秸稈還田顯著提升了土壤細(xì)菌和真菌的生物量和多樣性指數(shù); 而Sun等[8]認(rèn)為麥秸稈還田對(duì)土壤細(xì)菌群落的影響不大, 且細(xì)菌群落受pH影響較大; Chen等[9]采用磷脂脂肪酸(PLFA)的研究發(fā)現(xiàn), 我國中東部3個(gè)水稻-小麥輪作地區(qū)中, 只有1個(gè)地點(diǎn)的秸稈還田顯著增加了細(xì)菌多樣性, 其余地點(diǎn)變化不顯著; 薩如拉等[10]在砂壤土和中壤土的玉米(L.)田開展秸稈配施秸稈腐熟劑研究, 發(fā)現(xiàn)不同秸稈腐熟劑與土壤質(zhì)地對(duì)真菌群落的影響并不相同。上述研究表明土壤細(xì)菌和真菌群落對(duì)秸稈還田的響應(yīng)受土壤質(zhì)地、理化性質(zhì)、地理位置等多種因素影響, 因此加強(qiáng)秸稈還田在不同農(nóng)業(yè)管理方式下對(duì)土壤微生物群落多樣性影響的認(rèn)識(shí)十分必要。

緩/控釋肥料施用技術(shù)作為近年來農(nóng)業(yè)部的一項(xiàng)主推技術(shù), 可以有效降低施肥次數(shù)和減輕養(yǎng)分流失, 從而提高氮素利用率[11], 在華東地區(qū)已經(jīng)逐步進(jìn)行推廣。Pan等[12]發(fā)現(xiàn)與常規(guī)化肥相比, 單獨(dú)施用緩釋肥并沒有顯著改變土壤細(xì)菌數(shù)量與多樣性。而孫會(huì)峰等[13]的研究表明, 與秸稈還田+常規(guī)化肥對(duì)比, 秸稈還田配施緩釋肥提高了水稻產(chǎn)量, 提升了氮素利用率, 具有良好的應(yīng)用前景。但目前秸稈還田配施緩釋肥對(duì)土壤微生物群落的影響還鮮有研究。本研究采用長期定位試驗(yàn)方式, 應(yīng)用Illumina高通量測序技術(shù), 考察比較水稻-小麥輪作秸稈還田配施常規(guī)施肥和緩釋肥對(duì)土壤細(xì)菌和真菌群落結(jié)構(gòu)和多樣性的影響, 識(shí)別特殊細(xì)菌和真菌種類, 闡明影響微生物群落結(jié)構(gòu)的主控環(huán)境因子, 以期為華東地區(qū)農(nóng)田秸稈還田與施肥技術(shù)優(yōu)化提供科學(xué)依據(jù)。

1 材料與方法

1.1 試驗(yàn)區(qū)概況

試驗(yàn)在上海低碳農(nóng)業(yè)工程技術(shù)研究中心定位試驗(yàn)基地進(jìn)行, 位于上海市奉賢區(qū)莊行鎮(zhèn)(30°53′N, 121°23′E), 年平均氣溫15.7 ℃, 年降水量1162.0 mm, 全年無霜期225 d。土壤類型為砂壤土, 常年采用水稻-小麥兩熟輪作制度。試驗(yàn)開始時(shí)部分土壤理化性質(zhì)如下: pH 8.41, 有機(jī)碳(SOC) 8.71 g?kg?1, 總氮(TN) 0.94 g?kg?1, 總磷(TP) 0.98 g?kg?1。

1.2 試驗(yàn)設(shè)計(jì)

試驗(yàn)自2011年水稻季開始至2017年水稻季結(jié)束。水稻試驗(yàn)品種為‘花優(yōu)14’, 每年6月中旬進(jìn)行人工插秧, 栽插行株距20 cm′25 cm, 11月上旬收獲。小麥試驗(yàn)品種為‘揚(yáng)麥12號(hào)’, 每年12月上旬播種, 行距16 cm, 5月下旬收獲。設(shè)置常規(guī)施肥(RT)、秸稈還田+常規(guī)施肥(RS)、秸稈還田+緩釋肥(SS)和不施肥對(duì)照(CK)共4個(gè)處理。每個(gè)處理設(shè)置3個(gè)重復(fù), 所有重復(fù)均采用隨機(jī)區(qū)組設(shè)計(jì)。每個(gè)長方形小區(qū)面積為60 m2, 四周用水泥壟和防滲膜隔開。試驗(yàn)所用肥料為普通尿素、樹脂和硫磺雙包膜尿素、過磷酸鈣和硫酸鉀。根據(jù)上海地區(qū)水稻和小麥的平均施肥量, 3個(gè)施肥處理均施用相同的純量氮、磷、鉀(水稻季分別為225 kg?hm?2、112.5 kg?hm?2和255 kg?hm?2, 小麥季分別為180 kg?hm?2、90 kg?hm?2和204 kg?hm?2)。RT和RS中氮肥按基肥、蘗肥、穗肥比例5∶3∶2施用, SS氮肥則作基肥一次性施入。在RS和SS中, 稻麥兩季均在作物收獲后, 將秸稈深翻還田, 翻耕深度約為10~15 cm, 還田量為秸稈產(chǎn)生量的1/2。秸稈的養(yǎng)分含量測定后計(jì)入總施肥量, 稻秸稈和麥秸稈的平均氮、磷、鉀含量分別為3.3 g?kg-1、1.9 g?kg-1、13.5 g?kg-1和3.8 g?kg-1、2.4 g?kg-1、18.4 g?kg-1。

在試驗(yàn)的最后一季水稻收獲期(2017年11月5日)采集土壤樣本。每個(gè)小區(qū)采用S型取樣法隨機(jī)采集5個(gè)土樣(0~20 cm)并混合成1個(gè)樣本。土樣儲(chǔ)存在低溫保鮮袋中, 立即帶回實(shí)驗(yàn)室。一部分樣品風(fēng)干后進(jìn)行土壤理化性質(zhì)測定, 另一部分則保存在-20 ℃下進(jìn)行DNA提取和高通量測序分析。

1.3 測定項(xiàng)目與方法

高通量測序分析: 取0.5 g土樣, 采用MoBio PowerSoil?DNA提取試劑盒(12888)提取土壤DNA。將純化后的基因組DNA作為聚合酶鏈反應(yīng)(PCR)的模板。細(xì)菌V3-V4區(qū)擴(kuò)增引物采用515F (5′-GTGCCAGCMGCCGCGG-3′)/907R(5′-CCGTCAATTCMTTTRAGTTT-3′)[15], 真菌ITS1區(qū)段擴(kuò)增引物采用ITS5(5′-GGAAGTAAAAGTCGTAACAAG G-3′)/ITS4(5′-TCCTCCGCTTATTGATATGC-3′)[16]。PCR采用25 μL反應(yīng)體系: 10倍PCR buffer 5 μL (with MgCl2), dNTP 0.5 μL, 正向反向引物各0.5 μL, Tap酶0.25 μL (250 U), DNA模板1 μL, ddH2O補(bǔ)齊至25 μL。PCR反應(yīng)策略: 98 ℃預(yù)變性3 min, 98 ℃15 s, 50 ℃30 s和72 ℃ 30 s, 分別進(jìn)行25個(gè)(細(xì)菌)和35個(gè)(真菌)循環(huán), 最后在72 ℃下延伸7 min。PCR產(chǎn)物用1.7%瓊脂糖凝膠電泳檢測后, 送至上海派森諾生物科技有限公司, 在Illumina MiSeq測序平臺(tái)上進(jìn)行高通量測序分析。獲得原始序列后進(jìn)行質(zhì)量控制, 之后在97%序列相似性水平上聚類成可操作的分類單元(Operational Taxonomic Units, OTUs)。對(duì)照RDP和UNITE數(shù)據(jù)庫進(jìn)行分類注釋, 獲取對(duì)應(yīng)的細(xì)菌和真菌分類學(xué)信息。

1.4 統(tǒng)計(jì)分析

采用Tukey’s-HSD單因素方差分析(ANOVA)對(duì)各處理間的理化指標(biāo)差異顯著性進(jìn)行分析(SPSS 19.0)。細(xì)菌和真菌的豐富度和多樣性采用Chao1和Shannon指數(shù)表征(Mothur, v 1.30.1)。采用非度量多維尺度分析(non-metric multidimensional scaling, NMDS)確定細(xì)菌和真菌的群落結(jié)構(gòu)差異(R語言, v 3.0.2)。通過Galaxy在線分析平臺(tái)(http://huttenhower.sph.harvard. edu/galaxy/), 應(yīng)用LEfSe分析揭示導(dǎo)致細(xì)菌和真菌群落顯著差異的物種。采用Pearson相關(guān)性分析法研究細(xì)菌和真菌多樣性與環(huán)境因子之間的關(guān)聯(lián)度。

2 結(jié)果與分析

2.1 秸稈還田與施肥方式對(duì)水稻-小麥輪作體系產(chǎn)量和土壤理化性質(zhì)的影響

不同試驗(yàn)處理顯著影響了水稻和小麥產(chǎn)量(圖1)。SS的水稻產(chǎn)量在2016年和2017年分別為8.0 t?hm?2、9.3 t?hm?2, 小麥產(chǎn)量分別為5.4 t?hm?2、5.8 t?hm?2, 均顯著高于RT, 分別高出11.6%和8.2% (水稻)、4.8%和3.6% (小麥); 與RS相比, 3年內(nèi)稻麥產(chǎn)量均無顯著差異。與RT相比, RS僅在2016年稻、麥產(chǎn)量顯著升高, 分別高出9.3%和4.8%, 其余均無顯著差異。

CK: 不施肥空白; RT: 常規(guī)施肥; RS: 秸稈還田+常規(guī)施肥; SS: 秸稈還田+緩釋肥。不同小寫字母表示同一年份不同處理間差異顯著(0.05)。CK: no fertilizer; RT: conventional fertilization; RS: straw returning + conventional fertilization; SS: straw returning + slow-release fertilization. Different lowercase letters indicate significant differences among treatments in the same year at0.05.

表1 秸稈還田與施肥方式對(duì)水稻-小麥輪作土壤理化性質(zhì)的影響

CK: 不施肥空白; RT: 常規(guī)施肥; RS: 秸稈還田+常規(guī)施肥; SS: 秸稈還田+緩釋肥。表中數(shù)據(jù)為3個(gè)數(shù)值的平均值±標(biāo)準(zhǔn)誤; 同列數(shù)據(jù)后不同字母表示處理間差異顯著(<0.05)。CK: no fertilizer; RT: conventional fertilization; RS: straw returning + conventional fertilization; SS: straw returning + slow-release fertilization. Date in the table are mean±SE. Values followed by different letters in a column are significantly different (<0.05).

2.2 秸稈還田與施肥方式對(duì)土壤細(xì)菌和真菌群落多樣性的影響

各施肥處理的土壤細(xì)菌群落豐富度和多樣性分別采用Chao1和Shannon指數(shù)表征, 結(jié)果顯示其受施肥影響顯著(表2)。3個(gè)施肥處理的細(xì)菌群落Chao1和Shannon范圍分別為2760~2795和9.74~9.77, 均顯著高于CK, 且彼此之間無顯著差異; 各施肥處理土壤真菌群落多樣性則是受秸稈還田影響顯著, 2個(gè)秸稈還田處理的真菌群落Chao1和Shannon范圍分別為630~631和6.48~6.51, 均顯著高于RT和CK, 但SS和RS之間無顯著差異, RT的真菌群落多樣性指數(shù)最低, 但與CK之間無顯著差異。

表2 秸稈還田與施肥方式對(duì)水稻-小麥輪作土壤細(xì)菌和真菌群落多樣性指數(shù)(Chao1和Shannon)的影響

CK: 不施肥空白; RT: 常規(guī)施肥; RS: 秸稈還田+常規(guī)施肥; SS: 秸稈還田+緩釋肥。表中數(shù)據(jù)為3個(gè)數(shù)值的平均值±標(biāo)準(zhǔn)誤; 同列數(shù)據(jù)后不同字母表示處理間差異顯著(<0.05)。CK: no fertilizer; RT: conventional fertilization; RS: straw returning + conventional fertilization; SS: straw returning + slow-release fertilization. Date in the table are mean ± SE. Values followed by different letters in a column are significantly different (<0.05).

2.3 秸稈還田與施肥方式對(duì)土壤細(xì)菌和真菌群落組成的影響

土壤細(xì)菌群落在門水平上的組成如圖2a所示。水稻-小麥輪作土壤優(yōu)勢細(xì)菌門(相對(duì)豐度>10%)有變形菌門(Proteobacteria, 29.2%~33.9%)、綠彎菌門(Chloroflexi, 21.0%~27.2%)、放線菌門(Actinobacteria, 12.2%~16.4%)和酸桿菌門(Acidobacteria, 9.7%~12.5%), 其余相對(duì)豐度高于1%的細(xì)菌門還有擬桿菌門(Bacteroidetes, 2.5%~4.3%)、芽單胞菌門(Gemmatimonadetes, 3.0%~ 3.5%)、硝化螺旋菌門(Nitrospirae, 3.1%~3.3%)和厚壁菌門(Firmicutes, 1.9%~3.3%)。與RT相比, 2個(gè)秸稈還田處理(SS和RS)均提升了放線菌門、綠彎菌門和厚壁菌門的相對(duì)豐度, 分別平均提高30.2%、13.0%和63.5%。SS和RS之間各細(xì)菌門相對(duì)豐度均無顯著差異。

土壤真菌群落在門水平上的組成(相對(duì)豐度>1%)如圖2b所示。水稻-小麥輪作土壤主要有子囊菌門(Ascomycota, 51.0%~69.8%)、擔(dān)子菌門(Basidiomycota, 11.9%~24.7%)、接合菌門(Zygomycota, 1.6%~12.7%)和球囊菌門(Glomeromycota, 5.0%~5.8%)。與RT相比, 2個(gè)秸稈還田處理(SS和RS)顯著提升了子囊菌門的相對(duì)豐度, 平均提高32.3%, 并且降低了擔(dān)子菌門和接合菌門的相對(duì)豐度, 分別平均減少46.8%和36.9%。與RS相比, SS僅在子囊菌門有提高, 其他真菌門相對(duì)豐度均無顯著差異。

CK: 不施肥空白; RT: 常規(guī)施肥; RS: 秸稈還田+常規(guī)施肥; SS: 秸稈還田+緩釋肥。CK: no fertilizer; RT: conventional fertilization; RS: straw returning + conventional fertilization; SS: straw returning + slow-release fertilization.

LEfSe分析結(jié)果顯示, 不同處理細(xì)菌群落(圖3a)有5個(gè)存在顯著差異的類群(LDA值>3)。其中與SS相關(guān)1項(xiàng), 為植物棲居菌屬(, 放線菌門); 與RT相關(guān)2項(xiàng), 草桿菌科(Oxalobacteraceae, 變形菌門)和馬賽菌屬(, 變形菌門); 與CK相關(guān)2項(xiàng), β-變形菌綱(Betaproteobacteria, 變形菌門)和亞硝化單胞菌目(Nitrosomonadales, 變形菌門)。真菌群落(圖3b)中有7個(gè)存在顯著差異的類群(LDA值>3)。其中與SS相關(guān)1項(xiàng), 多孢囊霉目(Diversisporales, 球囊菌門); 與RS相關(guān)2項(xiàng), 珊瑚菌屬(, 擔(dān)子菌門)和牛肝菌目(Boletales, 擔(dān)子菌門); 與RT相關(guān)3項(xiàng), 蛙糞霉目(Basidiobolales, 接合菌門)、蛙糞霉科(Basidiobolaceae, 接合菌門)和蛙糞霉屬(, 接合菌門); 與CK相關(guān)1項(xiàng), 彎孢霉屬(, 子囊菌門)。

CK: 不施肥空白; RT: 常規(guī)施肥; RS: 秸稈還田+常規(guī)施肥; SS: 秸稈還田+緩釋肥。CK: no fertilizer; RT: conventional fertilization; RS: straw returning + conventional fertilization; SS: straw returning + slow-release fertilization.

2.4 秸稈還田與施肥方式對(duì)土壤細(xì)菌和真菌群落結(jié)構(gòu)的影響

通過NMDS分析可以發(fā)現(xiàn), CK延X軸方向與其他3種施肥處理明確分離(圖4a), 不施肥土壤細(xì)菌群落結(jié)構(gòu)與其他3種施肥處理差異顯著, 解釋度為55.61%, 而3個(gè)施肥處理細(xì)菌群落結(jié)構(gòu)之間則分離不明顯, 說明施肥與否對(duì)細(xì)菌群落結(jié)構(gòu)變化影響顯著; 4個(gè)處理的真菌群落結(jié)構(gòu)相比細(xì)菌群落結(jié)構(gòu)分離趨勢更加明顯(圖4b), 延X軸CK、RT與RS、SS明顯分離, 解釋度為26.94%, 說明真菌群落結(jié)構(gòu)對(duì)于秸稈還田措施的相應(yīng)更加顯著, 而RS和SS之間的真菌群落結(jié)構(gòu)差異不明顯。

CK: 不施肥空白; RT: 常規(guī)施肥; RS: 秸稈還田+常規(guī)施肥; SS: 秸稈還田+緩釋肥。CK: no fertilizer; RT: conventional fertilization; RS: straw returning + conventional fertilization; SS: straw returning + slow-release fertilization.

2.5 土壤細(xì)菌和真菌群落多樣性與環(huán)境因子間的關(guān)聯(lián)性

土壤細(xì)菌和真菌豐富度及多樣性指數(shù)(Shannon和Chao1)與土壤性質(zhì)的相關(guān)分析結(jié)果如表3所示。pH影響細(xì)菌群落多樣性最顯著, 與細(xì)菌多樣性呈顯著負(fù)相關(guān)(<0.01), 本研究中pH均高于8, 說明趨近中性的pH更有利于細(xì)菌群落的多樣性; 同時(shí)細(xì)菌群落多樣性還與TN呈顯著正相關(guān)(<0.05), 氮素養(yǎng)分供應(yīng)更易改變細(xì)菌群落多樣性; 真菌群落多樣性則僅與SOC呈顯著正相關(guān)(<0.05), 與其他指標(biāo)均無顯著相關(guān), 說明有機(jī)物的輸入對(duì)于真菌群落多樣性影響顯著。

表3 水稻-小麥輪作土壤細(xì)菌和真菌多樣性指數(shù)(Shannon和Chao1)與理化性質(zhì)間的相關(guān)性分析

**和*分別表示<0.01和<0.05水平顯著相關(guān)。** and * mean significant correlation at<0.01and<0.05 levels, respectively.

3 討論與結(jié)論

本研究發(fā)現(xiàn), 秸稈還田處理并未顯著提升土壤細(xì)菌群落多樣性, 與前人研究結(jié)果相似[8,21], 但同時(shí)也有一些研究認(rèn)為秸稈還田可以顯著提升細(xì)菌群落多樣性。這可能與秸稈還田的年限因素有關(guān), 如郭梨錦等[7]和周陽等[22]的研究均為短期秸稈還田(2年和1年), 對(duì)土壤細(xì)菌群落的促生作用明顯, 而在秸稈還田年限超過3年時(shí)(本研究秸稈還田年限為7年)[8,21], 對(duì)于細(xì)菌群落多樣性的影響則趨于不顯著, 除此之外細(xì)菌群落也可能受土壤類型、氣候條件和種植作物等多因素的綜合影響。本研究中秸稈還田處理的真菌群落多樣性均有顯著提高, 一方面可能是由于纖維素、木質(zhì)素等有機(jī)物隨秸稈輸入土壤, 刺激了真菌的生長[3]; 另一方面秸稈還田促進(jìn)了土壤團(tuán)聚體的形成, 為真菌的生長創(chuàng)造了良好的條件[23]。秸稈還田條件下, 配施常規(guī)化肥和緩釋肥并沒有對(duì)細(xì)菌和真菌群落多樣性產(chǎn)生顯著影響, 說明配施緩釋肥與常規(guī)化肥一樣可以維持土壤微生物群落多樣性穩(wěn)定。

土壤細(xì)菌和真菌群落多樣性與土壤性質(zhì)息息相關(guān)。本研究發(fā)現(xiàn)細(xì)菌群落多樣性與pH呈顯著負(fù)相關(guān), 與TN呈正相關(guān), 這與前人研究結(jié)果相似[8,21]。pH被認(rèn)為是微生物群落的指示性指標(biāo), 越趨近于中性越有利于細(xì)菌群落多樣性[24]。土壤TN含量與施肥直接相關(guān), 施肥可以直接提供大量氮素養(yǎng)分供給細(xì)菌群落的生長, 促進(jìn)其多樣性的增加[5]。本研究中, 真菌群落多樣性與SOC呈正相關(guān), 與何敏紅等[25]的研究結(jié)果一致, 原因可能是真菌更易并可以更有效地利用有機(jī)質(zhì), 有機(jī)質(zhì)的輸入有利于真菌群落生長。

本研究結(jié)果顯示, 與常規(guī)施肥處理相比, 秸稈還田顯著提升了放線菌門、綠彎菌門和厚壁菌門的相對(duì)豐度。前人研究發(fā)現(xiàn), 放線菌門在秸稈降解中起重要作用, 可以產(chǎn)生有效降解有機(jī)碳的活性酶, 加速秸稈等有機(jī)物的降解, 其豐度與微生物的作物秸稈分解能力呈正比[26-27]。綠彎菌門是一種廣泛報(bào)道的異養(yǎng)寡養(yǎng)菌和兼性厭氧菌, 具有將大分子有機(jī)物降解至小分子有機(jī)物的能力, 對(duì)土壤pH十分敏感, 在中性pH下生長旺盛[28]。厚壁菌門同樣在有機(jī)物分解中有重要意義, 可以促進(jìn)纖維素的降解, 是一種碳循環(huán)促進(jìn)菌[26,29]。上述分析表明, 秸稈還田通過有機(jī)物輸入和改善土壤pH, 可以加速有機(jī)物分解和養(yǎng)分釋放, 有效加強(qiáng)稻麥輪作土壤碳循環(huán)。在秸稈還田條件下緩釋肥和常規(guī)施肥對(duì)于細(xì)菌群落影響不明顯, 這與Wu等[20]的研究結(jié)果相似, 與常規(guī)施肥相比, 芹菜施用緩釋肥并沒有顯著改變土壤微生物群落結(jié)構(gòu)。

本研究中, 秸稈還田顯著提升了真菌群落中子囊菌門的相對(duì)豐度, 降低了擔(dān)子菌門和接合菌門的相對(duì)豐度。中子囊菌門是真菌群落中最豐富和最主要的門, 是土壤有機(jī)質(zhì)(腐殖質(zhì)、秸稈、枝條等)的主要分解者, 具有分解木質(zhì)纖維素的重要能力, 在不同類型的農(nóng)業(yè)土壤中廣泛存在[30-31]。秸稈還田條件下, 配施緩釋肥比常規(guī)施肥更能提高中子囊菌門的相對(duì)豐度, 其相對(duì)豐度增長有助于土壤碳氮循環(huán)能力的提升。擔(dān)子菌門同樣具有分解有木質(zhì)纖維素的能力, 但屬于寡養(yǎng)微生物, 適應(yīng)相對(duì)貧瘠的營養(yǎng)環(huán)境[32], 其豐度與C/N呈反比[33], 擔(dān)子菌門相對(duì)豐度的降低也說明了秸稈還田增加了土壤碳含量, 提高了C/N, 同時(shí)改善了土壤的營養(yǎng)狀態(tài), 增加了土壤養(yǎng)分的有效性。接合菌門主要包括寄生蟲、小動(dòng)物病原體和一些真菌[34], 秸稈還田能夠降低接合菌門相對(duì)豐度說明其具有控制部分病原菌的能力。同時(shí)根據(jù)LEfSe分析結(jié)果, 常規(guī)施肥處理中蛙糞霉屬顯著高于其他處理, 該屬是已知的人類病原菌[35]。這說明長期常規(guī)施肥會(huì)使稻麥輪作系統(tǒng)土壤病原菌數(shù)量提升, 而秸稈還田可以有效降低病原菌數(shù)量。

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Effects of straw returning and fertilization on soil bacterial and fungal community structures and diversities in rice-wheat rotation soil*

ZHANG Hanlin1,2, BAI Naling1,2, ZHENG Xianqing1,2, LI Shuangxi1,2, ZHANG Juanqin1,2, ZHANG Haiyun1,2, ZHOU Sheng1,3, SUN Huifeng1,3, LYU Weiguang1,2**

(1. Eco-environmental Protection Institute of Shanghai Academy of Agricultural Sciences / Shanghai Key Laboratory of Horticultural Technology / Environmental Protection Monitoring Station of Shanghai City, Shanghai 201403, China; 2. Agricultural Environment and Farmland Conservation Experiment Station of Ministry Agriculture, Shanghai 201403, China; 3. Shanghai Low Carbon Agriculture Engineering Technology Research Center, Shanghai 201403, China)

Straw returning and slow-release fertilizers are widely used in agriculture to reduce non-point source pollution and improve nitrogen use efficiency. However, there are few studies on the effect of straw return combined with slow-release fertilizers on the soil microbial community. This study determined how straw returning combined with fertilization affected the bacterial and fungal communities in rice-wheat rotation soil and the underlying mechanisms. Based on a seven-year rice-wheat rotation system monitoring experiment, four treatments were selected: no fertilizer (CK), regular chemical fertilization (RT), straw returning combined with chemical fertilization (RS), and straw returning combined with slow-release fertilizer (SS). The Illumina MiSeqplatform was used to evaluate the community structure and diversity of soil bacteria and fungi and to detect the primary environmental factors affecting the microbial community. The results showed that the SS rice and wheat yields in 2016 and 2017 were significantly higher than the RT yields (by 11.6% and 8.2% in rice, and 4.8% and 3.6% in wheat, respectively); there was no difference between SS and RS yields. Compared to RT, straw returning significantly decreased soil pH and increased soil organic carbon (SOC) and ammonium nitrogen (NH4+-N) contents; SS had more NH4+-N than RS. The fungal community diversity was higher with straw returning than with RT, but there was no difference in the bacterial community diversity among fertilization treatments; the bacterial and fungal community diversities were the same between RS and SS. Correlation analysis showed that the bacterial community diversity was negatively correlated with pH and positively correlated with soil total nitrogen content, while the fungal community diversity was positively correlated with SOC. Non-metric multidimensional scaling analysis showed that fertilization had a greater effect on the bacterial community structure (55.61%), and straw returning had a greater effect on the fungal community structure (26.94%). Proteobacteria, Chloroflexi, and Acidobacteria (in successive order) were the dominant phyla across all treatments, accounting for 66.07%–71.76% of the total bacterial sequence data. Ascomycota, Basidiomycota, and Zygomycota (in successive order) were the dominant phyla across all treatments, accounting for 88.05%–89.04% of the total fungal sequence data. Compared with RT, the treatments with straw returning significantly increased the relative abundance of Actinobacteria, Chloroflexi, and Firmicutesin the bacterial community, and significantly increased the relative abundance of Ascomycota and decreased the relative abundance of Basidiomycota and Zygomycotain thefungal community. Ecological function analysis of these bacterial and fungal communities showed that straw returning may enhance soil carbon and nitrogen cycling and inhibit pathogens. Compared with RS, SS only increased the relative abundance of Ascomycota in the fungal community; there were no other differences between the relative abundances of bacteria and fungi in RS and SS at the phylum level. Straw returning with slow-release fertilizers can help maintain or improve soil nutrient availability, crop yield, and the diversity of bacterial and fungal communities and can promote soil carbon and nitrogen cycling.

Soil microorganism; Community structure; Soil nutrient; Straw returning; Slow release fertilizer; High throughput sequencing

10.13930/j.cnki.cjea.200502

張翰林, 白娜玲, 鄭憲清, 李雙喜, 張娟琴, 張海韻, 周勝, 孫會(huì)峰, 呂衛(wèi)光. 秸稈還田與施肥方式對(duì)稻麥輪作土壤細(xì)菌和真菌群落結(jié)構(gòu)與多樣性的影響[J]. 中國生態(tài)農(nóng)業(yè)學(xué)報(bào)(中英文), 2021, 29(3): 531-539

ZHANG H L, BAI N L, ZHENG X Q, LI S X, ZHANG J Q, ZHANG H Y, ZHOU S, SUN H F, LYU W G. Effects of straw returning and fertilization on soil bacterial and fungal community structures and diversities in rice-wheat rotation soil[J]. Chinese Journal of Eco-Agriculture, 2021, 29(3): 531-539

S154.3

* 國家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2016YFD0200804)、上海市科技興農(nóng)推廣項(xiàng)目[滬農(nóng)科推字(2018)第4-14號(hào)]和上海市農(nóng)業(yè)科學(xué)院卓越團(tuán)隊(duì)建設(shè)計(jì)劃項(xiàng)目[農(nóng)科創(chuàng)2017(A-03)]資助

呂衛(wèi)光, 主要研究方向?yàn)檗r(nóng)田生態(tài)。E-mail: lvweiguang@saas.sh.cn

張翰林, 主要研究方向?yàn)檗r(nóng)田微生物驅(qū)動(dòng)碳氮循環(huán)。E-mail: zhanghanlinchick@163.com

2020-06-26

2020-11-23

* This study was supported by the National Key Research and Development Program of China (2016YFD0200804), Shanghai Agriculture Applied Technology Development Program, China (T20180414) and the Outstanding Team Program of Shanghai Academy of Agricultural Sciences [Nongke Chuang 2017(A-03)].

, E-mail: lvweiguang@saas.sh.cn

Jun. 26, 2020;

Nov. 23, 2020