引用本文
陈丹梅, 袁玲, 黄建国, 冀建华, 侯红乾, 刘益仁. 长期施肥对南方典型水稻土养分含量及真菌群落的影响. 作物学报, 2017, 43(2): 286-295
CHEN Dan-Mei, YUAN Ling, HUANG Jian-Guo, JI Jian-Hua, HOU Hong-Qian, LIU Yi-Ren. Influence of Long-term Fertilizations on Nutrients and Fungal Communities in Typical Paddy Soil of South China. ACTA AGRONOMICA SINICA, 2017, 43(2): 286-295  
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作物学报编辑部
长期施肥对南方典型水稻土养分含量及真菌群落的影响
陈丹梅1, 袁玲1,*, 黄建国1, 冀建华2, 侯红乾2, 刘益仁2,*
1西南大学资源环境学院, 重庆 400716
2江西省农业科学院土壤肥料与资源环境研究所, 江西南昌 330200
* 通讯作者(Corresponding authors): 袁玲, E-mail: lingyuanh@aliyun.com; 刘益仁, E-mail: jxnclyr@163.com

第一作者联系方式: E-mail: 544328279@qq.com, Tel: 18608149225

收稿日期:2015-12-08 接受日期:2016-09-18 网络出版日期:2016-09-27
基金:本研究由国家自然科学基金项目(31460544), 江西省农业科学院博士启动基金(2012CBS011), 国家科技支撑计划项目(2012BAD05B05)和国家公益性行业科研专项(201203030)资助
摘要

利用江西省农业科学院31年的长期肥料定位试验, 选取不施肥(对照)、单施化肥、70%化肥配施30%有机肥、50%化肥配施50%有机肥和30%化肥配施70%有机肥等5个处理, 通过常规分析和454-高通量测序技术, 研究了长期不同施肥条件下, 我国南方典型水稻土养分含量和真菌群落结构的变化。结果表明, 在酸性水稻土上, 长期单施化肥显著降低土壤pH值, 但随着有机肥配施比例的提高pH明显上升; 有机和无机肥配施显著提高土壤有机质、有效氮磷含量以及微生物碳氮量。单施化肥土壤真菌18S rDNA序列数比配施有机肥的多1倍, 但真菌种(属)数减少了11~40种; 前20种优势真菌的丰富度占真菌总量的78.82%~91.51%, 以子囊菌最多(7’13种), 所占比例最大(23.13%’75.09%); 与对照相比, 配施有机肥的土壤中有14’15种优势真菌与之相同, 而单施化肥的土壤中仅有10种一致; 主成分分析结果表明单施化肥处理的真菌群落组成与其他各处理存在显著差异。因此, 单施化肥造成土壤酸化加剧, 真菌数量成倍增加, 但种类显著减少, 其丰富度和多样性明显降低, 并改变优势真菌种群, 相应提高了土壤病原真菌过度繁殖的风险。而有机和无机肥配施有利于维持水稻土壤健康生态环境和真菌种群多样性。

关键词: 长期施肥; 水稻; 土壤养分; 真菌
Influence of Long-term Fertilizations on Nutrients and Fungal Communities in Typical Paddy Soil of South China
CHEN Dan-Mei1, YUAN Ling1,*, HUANG Jian-Guo1, JI Jian-Hua2, HOU Hong-Qian2, LIU Yi-Ren2,*
1 College of Resources and Environment, Southwest University, Chongqing 400716, China
2 Soil and Fertilizer and Resources and Environment Institute, Jiangxi Academy of Agricultural Sciences, Nanchang 330200, China
Fund:This study was supported by the National Natural Science Foundation of China (31460544), the Doctoral Scientific Research Foundation of Jiangxi Academy of Agricultural Sciences (2012CBS011), the National Support Program of China (2012BAD05B05), and the China Special Fund for Agro-scientific Research in the Public Interest (201203030)
Abstract

A long-term field experiment was carried out for 31 years in Jiangxi Academy of Agricultural Sciences with a typical paddy soil in South China to study the influence of fertilizer application on changes of soil nutrients and fungal communities by rational analysis and 454 high-throughput sequencing technology. The fertilization treatments included control (without fertilizer), sole chemical fertilizer, 70% chemical fertilizer in combination with 30% organic fertilizer, 50% chemical fertilizer in combination with 50% organic fertilizer and 30% chemical fertilizer in combination with 70% organic fertilizer. The soil pH decreased in the treatment of sole chemical fertilizer, but increased obviously with the proportion of organic fertilizer increased. Organic-inorganic fertilizations significantly increased organic matter, available nitrogen and phosphorus, and microbial biomass carbon and nitrogen in the soil. The number of soil fungal 18S rDNA sequences was doubled while the species number of fungi decreased by 11-40 when received chemical fertilizer only, compared with the treatment of organic-inorganic fertilization. The top 20 predominant fungi ranged from 78.82% to 91.51% of the total in soil, and among them 7-13 species attributed to Ascomycetes which was the largest soil fungal group and accounted for 23.13%-75.09% of the top 20 predominant fungi. Compared with the control, 14-15 of the same species of dominant fungi were found in the treatment of organic-inorganic fertilizers but only nine in the treatment of sole chemical fertilizer. Principal component analysis showed the significant difference in soil fungal community compositions between treatment of sole chemical fertilizer and others. In general, sole application of chemical fertilizer results in soil acidification, and exponential increment of soil fungi, but significant reduction in their species, richness and diversity indexes, suggesting the great changes in fungal community composition and the risk of over production of pathogen fungi in the soil. On the contrary, organic-inorganic fertilization treatment is beneficial to maintain the healthy ecological environment of paddy soil and the diversity of soil fungal communities.

Keyword: Long-term fertilization; Rice; Soil nutrients; Fungus

在水稻种植过程中, 施肥对产量和品质的贡献仅次于品种[1]。肥料不仅供给植物营养, 而且直接影响土壤理化及生物学性质, 如pH、有机质、有效养分和微生物种群结构等。

土壤有机质、养分和微生物与作物产量和病害密切相关[2]。目前, 国内外已进行了大量的中短期肥料试验, 发现施肥对土壤的影响十分复杂, 因土壤类型、生态条件和施肥技术等不同而异[3, 4, 5, 6]。在单施化肥的土壤中, 有机质含量通常降低, 养分失调, 作物病害加重[7]; 相反, 有机无机配施则提高土壤有机质和有效养分含量, 增加作物产量, 改善作物品质[8]。但长期施肥对土壤的影响不同于中短期肥料试验, 需要多年和多点的系统研究。真菌是土壤微生物的重要组成, 直接影响土壤有机质循环、养分转化、毒物降解和作物病害发生等[9, 10, 11], 是土壤肥力和健康的重要指标之一[12]。研究表明, 长期施用有机肥提高潮土中微生物生物量, 改变细菌、真菌和放线菌之间的比例关系[13]; 秸秆还田和施用EM菌(Effective Microorganisms)堆肥提高土壤真菌的Shannon-Winner多样性指数, 大量施用化肥则相反[14]。在种植烤烟的土壤中, 真菌种类包括子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、接合菌门(Zygomycota)、壶菌门(Chytridiomycota)和未知类型的真菌; 单施化肥提高担子菌门、接合菌门和壶菌门等真菌的丰富度; 在有机无机配施的土壤中, 子囊菌的增幅显著高于单施化肥[7]。在土壤真菌的研究中, 常规培养法仅能获得0.7%左右的可培养真菌[15], 磷脂脂肪酸法通常只能检测出18:1ω 9c和18:3ω 6c (6, 9, 12)[16], PCR-DGGE法也难于甄别单个真菌的基因序列[17]。然而, 在自然环境中栖息着350~510万种真菌[18, 19], 目前人类仅认识其中的5%~10%[20], 更缺乏对土壤真菌的深入了解。高通量测序技术针对真菌18S rDNA的保守性, 先提取、扩增、纯化、定量和均一化真菌DNA序列, 再经测序、过滤、优化、聚类, 对比基因库中的已知序列, 从而鉴别真菌种(属)类, 是传统培养方法所获得微生物数量的数十倍甚至数百倍, 能准确灵敏地检测土壤真菌[21]。

国内外关于在长期施肥条件下水稻土真菌群落结构的研究甚少[22, 23]。本文利用常规分析和454-高通量测序技术, 研究长期施肥对我国南方典型水稻土养分和真菌种群结构的影响, 旨在了解其演变规律, 为水稻高产优质及构建良好的土壤生态环境提供理论依据。

1 材料与方法
1.1 试验地概况

江西省南昌县江西省农业科学院的试验农场, 地处东经115° 94′ , 北纬28° 57′ , 海拔25 m。年均气温17.5℃, ≥ 10℃积温5400℃, 年降雨量1600 mm, 年蒸发量1800 mm, 无霜期280 d。供试土壤为第四纪亚红黏土母质发育的典型、具有代表性的中潴黄泥田, 肥力中等, 0~20 cm耕层土壤的初始pH 6.50, 含有机质25.61 g kg-1、碱解氮81.6 mg kg-1、有效磷20.8 mg kg-1、速效钾35.0 mg kg-1。

1.2 试验设计

采用早稻-晚稻-休闲种植制度, 1984年春设不施肥(CK); 单施氮磷钾化肥(NPK); 70%化肥配合30%有机肥(70F+30M); 50%化肥配合50%有机肥(50F+50M); 30%化肥配合70%有机肥(30F+70M)等5种施肥模式。小区面积33.3 m2, 用水泥田埂(深0.7 m, 宽0.5 m)分隔, 独立排灌。早、晚稻栽培的窝距× 行距分别为13.3 cm × 23.3 cm和16.7 cm × 26.7 cm, 选用当地主推品种, 一般3’ 5年更换一次。早稻施纯N 150 kg hm-2、P2O560 kg hm-2、K2O 150 kg hm-2; 晚稻施纯N 180 kg hm-2、P2O560 kg hm-2、K2O 150 kg hm-2。分别由尿素(含N 46%)、过磷酸钙(含P2O5 12%)、氯化钾(含K2O 60%)和有机肥提供。早稻和晚稻的有机肥分别为紫云英(鲜草养分含量按照N 0.30%、P2O50.08%、K2O 0.23%计)和猪粪(养分含量按照N 0.45%、P2O50.19%、K2O 0.60%计)。全部磷肥、有机肥和50%的氮肥做基肥, 剩余的氮肥分2次均施于分蘖期和幼穗分化期, 并同时各施50%的钾肥。设3次重复, 随机区组排列, 田间管理同当地大田生产。

1.3 样品采集与测定

在2014年10月初, 采集晚稻灌浆期0~20 cm的耕层土壤, 滤掉多余水分, 拣去杂物, 立即用液氮冷冻部分土壤。用氯仿熏蒸, 0.5 mol L-1 K2SO4提取微生物量碳氮, K2Cr2O7氧化法测碳和腚酚蓝比色法测氮[24]。另取部分鲜土样, 用OMEGA公司的E.Z.N.A Soil DNA试剂盒提取真菌18S rDNA, 以817F (5° -TTAGCATGGAATAATRRAATAGGA-3° )和1196R (5° -TCTGGACCTGGTGAGTTTCC-3° )为引物, 用ABI GeneAmp 9700型PCR仪扩增V5~V7区, 再参照454-高通量测序方法, 纯化、定量和均一化真菌18S rDNA。然后, 送上海美吉生物科技有限公司利用Roche Genome Sequencer FLX测序平台进行454-高通量测序[25]。测序结束后, 对有效序列进行去杂、修剪、去除嵌合体序列等过滤处理, 得到优化序列, 经聚类分析形成操作分类单元(operational taxonomic units, OTUs), 用BLAST程序对比GenBank (http://ncbi.nlm.nih.gov/)中的已知序列, 根据97%的相似度确定18S rDNA基因序列对应的真菌属(种)。将另一部分土壤晾干、制样后按常规测土壤pH、有机质、碱解氮、有效磷和速效钾含量[26]。

1.4 数据处理

用Microsoft Excel对试验数据进行基本计算及统计分析, 采用SPSS16.0软件分析PCA, 差异显著性水平为P < 0.05。

2 结果与分析
2.1 水稻产量

由表1可见, 施肥对早稻、晚稻和早稻+晚稻产量的影响趋势相同。31年来, 水稻(早稻+晚稻)产量总体表现为30F+70M ≥ 70F+30M ≥ 50F+50M > CF > CK, 平均值依次为12 505、12 258、12 080、11 469和6941 kg hm-2。

表1 长期不同施肥条件下水稻的产量变化(早稻+晚稻) Table 1 Rice yield (early rice +late rice) affected by different fertilizer treatments (kg hm-2)
2.2 土壤有机质和有效养分

由表2可见, 经31年的水稻种植后, 土壤pH值变化于5.32’ 5.98, 相比原始土壤都有所降低, 表现为30F+70M > 50F+50M > CK、70F+30M > NPK。在有机无机配施的土壤中, 有机质和碱解氮含量最高, NPK和原始土壤次之, CK最低; 有效磷含量30F+70M > 50F+50M > 70F+30M > NPK > 原始土壤 > CK; 土壤速效钾含量NPK > 50F+50M、70F+30M > 30F+70M > CK > 原始土壤。

表2 不同施肥模式下土壤pH、有机质及有效养分的变化 Table 2 Soil pH, organic matter and available nutrients under different fertilization treatments
2.3 土壤微生物碳氮量

由图1可见, 土壤微生物碳含量30F+70M (496.2 mg kg-1) > 70F+30M (464.6 mg kg-1)、50F+ 50M (459.2 mg kg-1) > NPK (338.8 mg kg-1) > CK (292.5 mg kg-1); 微生物氮含量的变化与微生物碳含量类似; 微生物碳氮比变化于20.14~43.40。

图1 施肥对微生物碳氮含量的影响
不同小写字母表示差异显著, P < 0.05。Fig. 1 Microbial biomass C and N in soil as affected by different fertilization treatments
Bars superscripted by different small letters are significantly different at P < 0.05.

2.4 土壤真菌

2.4.1 土壤真菌稀释曲线 随机抽取测序样品中的18S rDNA序列数(reads), 以真菌分类单元数(OTUs)为纵坐标, 18S rDNA读数为横坐标, 获得稀释曲线(图2)[27]。结果表明, 抽样reads大约在5000以下时, OTUs数随reads提高而迅速增加; reads在5000’ 10 000之间, OTUs数随reads提高而缓慢增加; reads超过10 000之后, OTUs数的增长逐渐趋于平缓, 说明测序量达到饱和, 测序结果可以准确反映土壤生态系统中的真菌组成。此外, 真菌种(属)数以CK最多, NPK最少, 有机无机配施处理的居中。

图2 土壤真菌的稀释性曲线
CK: 不施肥; NPK: 单施氮磷钾化肥; 70F+30M: 70%化肥配合30%有机肥; 50F+50M: 50%化肥配合50%有机肥; 30F+70M: 30%化肥配合70%有机肥。Fig. 2 Fungal rarefaction curves in soil under different fertilization treatments
CK: without fertilizer; NPK: sole chemical fertilizer; 70F+30M: 70% chemical fertilizer in combination with 30% organic fertilizer; 50F+50M: 50% chemical fertilizer in combination with 50% organic fertilizer; 30F+70M: 30% chemical fertilizer in combination with 70% organic fertilizer.

2.4.2 土壤真菌门类组成及OTUs数量 在CK、NPK、70F+30M、50F+50M和30F+70M处理的土壤中, 真菌18S rDNA序列数依次为14 205、21 241、17 630、10 595和11 725, 分别代表133、93、126、125和104种真菌(OTUs), 归属于子囊菌门(Ascomycota)、壶菌门(Chytridiomycota)、担子菌门(Basidiomycota)、接合菌门(Zygomycota)、芽枝霉门(Blastocladiomycota)、球囊菌门(Glomeromycota)、其他类型(Others)和未知类型(Unclassified)(图3)。六门主要真菌的OTUs数量依次占OTUs总量的16.54%~23.08%、8.00%~11.83%、8.80%~14.42%、3.20%~4.51%、1.08%’ 2.40%和0~3.00%。在CK和NPK处理中, 球囊菌门真菌分别有4种和1种, 但在70F+30M、50F+50M和30F+70M处理土壤中均没有出现球囊菌门真菌; 在各处理的土壤中, 芽枝霉门真菌均少于3种; 在不施肥的土壤中, 子囊菌门真菌OTUs数量占总OTUs数量的16.54%, 低于施肥土壤(17.46%~23.08%)。

图3 不同施肥处理的土壤中真菌门类组成及OTUs数量
CK: 不施肥; NPK: 单施氮磷钾化肥; 70F+30M: 70%化肥配合30%有机肥; 50F+50M: 50%化肥配合50%有机肥; 30F+70M: 30%化肥配合70%有机肥。Fig. 3 Soil fungal community composition and OTUs in soil under different fertilizer treatments
CK: without fertilizer; NPK: sole chemical fertilizer; 70F+30M: 70% chemical fertilizer in combination with 30% organic fertilizer; 50F+50M: 50% chemical fertilizer in combination with 50% organic fertilizer; 30F+70M: 30% chemical fertilizer in combination with 70% organic fertilizer.

2.4.3 土壤真菌的优势菌株 由表3可知, 在供试土壤中, 前20种优势真菌的丰富度合计占真菌总量的78.82%~91.51%, 包括子囊菌、接合菌、壶菌、担子菌和球囊菌等, 均以子囊菌最多(7’ 13种), 所占比例最大(23.13%’ 75.09%)。此外, 优势真菌的丰富度因真菌种类和施肥处理不同而异。

表3 不同施肥处理中前20种优势真菌类型及丰富度 Table 3 Top 20 predominant fungi in soil under different treatments

在前20种优势真菌中, 子囊菌-1 (Ascomycota-1)、子囊菌-2 (Ascomycota-2)、子囊菌-3 (Ascomycota-3)、子囊菌-4 (Ascomycota-4)、子囊菌-6 (Ascomycota-6)和担子菌-1 (Basidiomycota-1)等6种普遍存在于各种处理的土壤中。除此之外, 在CK和NPK处理的土壤中, 还有子囊菌-10 (Ascomycota-10)、接合菌-1 (Zygomycota-1)、壶菌-1 (Chytridiomycota-1)和担子菌-2 (Basidiomycota-2) 4种(属)真菌相同; 在CK和70F+30M处理的土壤中, 相同的真菌还有子囊菌-5 (Ascomycota-5)、子囊菌-7 (Ascomycota-7)、子囊菌-8 (Ascomycota-8)、接合菌-2 (Zygomycota-2)、接合菌-3 (Zygomycota-3)、壶菌-1 (Chytridiomycota-1)、担子菌-2 (Basidiomycota-2)、未知真菌-1 (Unclassified-1)和未知真菌-2 (Unclassified-2) 9种(属); 在CK和50F+50M处理的土壤中, 相同的真菌还包括子囊菌-5 (Ascomycota-5)、子囊菌-7 (Ascomycota-7)、子囊菌-8 (Ascomycota-8)、子囊菌-9 (Ascomycota-9)、接合菌-1 (Zygomycota-1)、接合菌-3 (Zygomycota-3)、壶菌-1 (Chytridiomycota-1)、未知真菌-1 (Unclassified-1)和未知真菌-2 (Unclassified-2) 9种(属); 在CK和30F+70M处理的土壤中, 也还有8种(属)真菌相同, 即子囊菌-5 (Ascomycota-5)、子囊菌-7 (Ascomycota-7)、子囊菌-8 (Ascomycota-8)、子囊菌-9 (Ascomycota-9)、接合菌-2 (Zygomycota-2)、接合菌-3 (Zygomycota-3)、担子菌-2 (Basidiomycota-2)和未知真菌-1 (Unclassified-1)等。

在前20种优势真菌中, 球囊菌-1 (Glomeromycota-1)和壶菌-2 (Chytridiomycota-2)是CK处理土壤独有的。在NPK处理的土壤中, 独有真菌包括壶菌-3 (Chytridiomycota-3)、壶菌-4 (Chytridiomycota-4)、壶菌-5 (Chytridiomycota-5)、壶菌-6 (Chytridiomycota-6)、担子菌-4 (Basidiomycota-4)、担子菌-5 (Basidiomycota-5)、未知真菌-3 (Unclassified-3)和未知真菌-4 (Unclassified-4)等8种。在70F+30M处理的土壤中, 独有真菌是未知真菌-5 (Unclassified-5)和子囊菌-14 (Ascomycota-14)。在50F+50M和30F+70M处理的土壤中, 独有真菌分别是接合菌-4 (Zygomycota-4)和担子菌-6 (Basidiomycota-6)。

2.4.4 土壤真菌群落PCA分析 图4中, PC1和PC2分别表示不同群落间68.36%和21.42%的变异度, 真菌群落的主成分得分系数差异显著, 位于图4中的不同位置, 且相互之间的距离较远。其中, CK和30F+70M位于II象限, 50F+50M和70F+30M位于IV象限, 4个处理都靠近X轴或者Y轴; 而NPK则单独位于III象限且远离坐标轴。表明单施化肥处理与其他处理存在显著差异。

图4 不同施肥处理土壤真菌群落PCA分析
CK: 不施肥; NPK: 单施氮磷钾化肥; 70F+30M: 70%化肥配合30%有机肥; 50F+50M: 50%化肥配合50%有机肥; 30F+70M: 30%化肥配合70%有机肥。Fig. 4 PCA analysis of soil fungi under different fertilization treatments
CK: without fertilizer; NPK: sole chemical fertilizer; 70F+30M: 70% chemical fertilizer in combination with 30% organic fertilizer; 50F+50M: 50% chemical fertilizer in combination with 50% organic fertilizer; 30F+70M: 30% chemical fertilizer in combination with 70% organic fertilizer.

3 讨论

31年以来, 尽管经历过多次低温、高温、干旱、水涝、病虫害和品种更换等, 但水稻产量(早稻+晚稻)均以30F+70M处理最高, 说明有机无机适量配施可持续稳定高产, 进一步探讨施肥对土壤的影响很有必要。

经过长期的水稻种植, 供试土壤pH变化于5.32’ 5.98, 相比初始pH 6.50显著降低, 尤以NPK处理最为显著, 说明单施化肥加重了土壤酸化, 与前人研究结果一致[28]。与对照相比, 各施肥处理土壤有机质含量大幅增加, 以有机无机配施最明显, 与林治安、张国荣和徐祖祥等的研究结果类似[29, 30, 31], 不同于单施化肥降低土壤有机质的报道[32, 33]。其原因可能是施肥促进了水稻生长, 生物量增大[34, 35], 进入土壤的植株残体(桩)和根系分泌物增加, 同时施用有机肥也直接补充了土壤有机质。此外, 在各施肥处理的土壤中, 有效养分相比原始土壤显著增加, 有机无机配施处理的碱解氮和有效磷增幅最大, 说明在水稻种植过程中, 有机无机配施不仅保持水稻高产, 而且还增强土壤供肥能力。因此, 从土壤pH和养分肥力的角度看, 提倡有机无机配施很有必要。

土壤有机质是土壤微生物的碳源和氮源, 促进微生物生长繁殖[36]。施用有机肥向土壤提供种类丰富的有机质, 可满足不同微生物的生长繁殖需要。因此, 在有机无机配施处理中, 土壤微生物碳氮含量最高, 数量最多, 类似前人研究结果[37, 38, 39]。值得注意的是, 在不同处理的土壤中, 微生物碳氮比可相差2倍以上, 意味着施肥改变了土壤微生物的组成和种群结构。454-高通量测序表明, 在供试土壤中, 真菌18S rDNA的序列数为10 595’ 21 241, 分别代表93’ 133种真菌。而在旱地土壤中, 真菌种类一般超过250种[7, 40]。此外, 前20种优势真菌合计占土壤真菌总量的78.82%~91.51%, 说明在淹水条件下, 不仅真菌种群数大幅度减少, 且优势种群突出。在NPK处理的土壤中, 真菌18S rDNA序列数最多, 比50F+50M处理高1倍, 但真菌种类最少, 与Kamaa等[41]和Alguacil等[12]的报道基本相同。众所周知, 多种土壤微生物共存可互相抑制, 防止某些微生物尤其是病原微生物过度繁殖[42]。因此, 单施化肥使土壤中真菌数量增加但种类减少, 可能提高病原真菌大量繁殖的几率, 加大水稻感染真菌病害的风险, 由此可以解释单施化肥加重水稻真菌病害的现象[43]。而在有机无机配施的处理中, 真菌组成的多样性则有益于维持土壤多种多样的生理、生化和生态功能。从真菌的门类看, 子囊菌种类最多, 占OTUs总量的16.54%~23.08%; 在前20种优势菌株中, 子囊菌占7~13种, 所占比例为23.13%’ 75.09%, 说明水稻土比较适合子囊菌的生长繁殖。需要指出的是, 子囊菌是自然界中最为丰富的真菌之一, 它们比担子菌具有更快的进化速率和更高的物种多样性[44], 但大多数子囊菌的生物学功能尚不明确[7, 44], 故很有必要进一步研究它们在土壤肥力、生产力和作物病害发生中的重要作用。

不同处理土壤中优势真菌的组成各不相同。与对照相比, 配施有机肥处理的土壤中有14~15种优势真菌与之相同, 而单施化肥的土壤中仅有10种一致。各处理真菌群落的主成分得分系数差异显著, 位于图4中不同位置, NPK单独位于象限Ⅲ 且远离坐标轴, 说明单施化肥显著改变了土壤真菌群落结构。

4 结论

化肥配施有机肥不同程度地提高了酸性水稻土壤pH值、有机质、有效养分和微生物碳氮量。淹水嫌气条件适合子囊菌的生长繁殖, 但真菌种群大幅度减少, 优势种群突出, 尤以单施化肥(NPK)最为显著。此外, 单施化肥处理还显著改变土壤真菌群落结构, 提高病原真菌过度繁殖的风险, 而有机无机配施有利于维持水稻土壤健康生态环境和真菌种群的多样性。

The authors have declared that no competing interests exist.

作者已声明无竞争性利益关系。The authors have declared that no competing interests exist.

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