连续3 a生草对苹果园土壤理化性质及微生物群落的影响

以自然生草为对照,研究苹果园行间连续3 a种植黑麦草、白三叶和长柔毛野豌豆对土壤理化性质及微生物群落结构的影响,并进行相关性分析。结果表明,苹果园连续生草3 a,可显著提高果园土壤养分含量、降低土壤pH。其中长柔毛野豌豆和白三叶处理的土壤碱解氮含量分别从2018年的42.26 mg/kg和18.38 mg/kg提升至2020年的61.94mg/kg和70.16 mg/kg,固氮作用显著。长柔毛野豌豆处理可在一定程度上提高土壤鞘氨醇单胞菌、木霉菌等有益菌的相对丰度。相关性分析发现,在生草条件下,适当提高果园土壤有效磷和有机质含量,降低pH,可在一定程度上降低青枯菌、白粉菌、刺盘孢属、葡萄穗霉属等病原菌的相对丰度,提高芽孢杆菌、溶杆菌等有益菌的相对丰度,有助于改良土壤微生态环境。     

烤烟全生育期覆膜栽培对植烟土壤理化性质及细菌群落结构的影响

【目的】地膜覆盖会改变植烟土壤环境,进而影响土壤微生物群落结构和烤烟的生长发育,本研究旨在探究全生育期覆膜对植烟土壤理化性质和细菌群落结构的影响。【方法】应用 16S rDNA 测序,通过多种分析方法比较不同处理细菌群落结构的差异及多样性,并结合土壤理化性质进行冗余分析（RDA）,以求明确土壤理化性质和细菌群落之间的关系。【结果】全生育期覆膜显著提高了烤烟产值量,双色（SY）、黑色（HY）、白色地膜覆盖（BY）处理产量分别较对照（CK）提高 13.33%、18.24%、21.36%;产值较对照提高 20.26%、15.87%、13.28%。同时,覆膜还会提高植烟土壤温度、总钾、总磷、总铁和有效铜含量,降低土壤 pH 值、碱解氮、有效铁、总铜和总锌含量。其中,全磷和有效铜含量增幅最为明显,分别为 3.11%~27.33% 和 4.76%~19.05%,碱解氮、有效铁和全锌含量降幅最为显著,分别为 10.45%~14.50%、3.36%~13.43% 和 7.69%~10.01%。全生育期覆膜对细菌群落丰度有一定抑制作用,对照的丰度指数 Chao 1 显著高于 3 个覆膜处理,且分别较白色、双色、黑色地膜覆盖处理高 14.09%、24.20%、24.81%。冗余分析表明,影响细菌门水平群落结构的主要土壤理化因素是土壤温度、碱解氮、有效铁、总铁、有效铜和总铜含量。白色、双色地膜覆盖处理中存在 3 个共有与对照丰度明显不同的菌属,分别属于变形菌门（Proteobacteria）中的鞘脂单胞菌科（Sphingomonadaceae）、伯克霍尔德菌科（Burkholderaceae）和黄单胞菌科（Xanthomonadaceae）3 个科。【结论】烤烟全生育期覆膜栽培会显著影响植烟土壤理化性质和细菌群落结构,提高烤烟产值量,适宜搭配的地膜颜色为黑白双色膜。     

基于SNP和表型性状的籼稻种质资源遗传多样性研究

为探究籼稻表型性状遗传多样性信息,以198份籼稻种质资源为试材,进行SNP分子标记和表型性状分析,结果表明:通过2种简化基因组测序技术从198份样本中共识别91 421个SNPs,杂合位点占5.85%。基于Nei’s的遗传距离在0.014~0.596,平均遗传距离为0.284。Bayes算法把198个样本聚为3个亚类。91 421个SNPs构成的总变异中,前3个主成分可分别解释群体变异的10.98%、10.47%、4.81%。15个表型性状的平均变异系数和平均多样性指数分别为30.33%和1.95。15个表型之间的相关性系数在-0.55~0.92。15个表型性状的前3个主成分可分别解释群体变异的29.44%、16.63%、10.59%,对第一主成分贡献大的性状包括穗长、株高、穗总粒数、播始历期、穗实粒数、叶长、垩白粒率和垩白度,8个性状对第一主成分的贡献值绝对值都在0.6以上,是籼稻表型性状变异的主要因素。基于表型的前5个主成分反映总信息量的73.003%,前2个主成分将198份资源分为2个亚组。Mantel检验表明,SNPs和表型性状的遗传距离矩阵之间的r为0.041。综上,SNPs和15个表型性状的多样性分析之间相关性很低,SNPs聚类比表型性状聚类更接近系谱分析。秦巴地区198份籼稻种质资源SNPs构成的群体遗传结构相对简单。表型性状变异较丰富,多样性程度高,群体间性状差异显著。综上,穗长、株高、穗总粒数、播始历期、穗实粒数、叶长、垩白粒率和垩白度这8个性状可作为秦巴地区籼稻种质资源表型性状的综合评定指标。     

持续污染下洛克沙胂在土柱中的迁移转化及其风险评估

由于禽畜粪便未做防渗的露天堆积,导致饲料添加剂洛克沙胂（ROX）进入环境从而诱发无机砷污染。本研究通过157 d的一维土柱模拟探究了ROX长期持续污染的前提下,垂向包气带上砷化合物形态和含量的时空变化,并通过高通量测序技术揭示了不同深度的微生物群落结构响应。结果显示,在157 d的ROX持续污染模拟过程中,ROX降解速率很高,显著高于迁移速率,ROX的降解与吸附均发生在土壤浅层（0~10 cm）。ROX降解产物主要为As（Ⅴ）和As（Ⅲ）,其中As（Ⅴ）含量明显高于As（Ⅲ）含量,砷化合物均主要聚集在0~40 cm深度,土壤中砷化合物含量显著高于土壤溶液中的含量,土壤对砷化合物的固定能力很强,砷化合物的迁移速度十分缓慢,157 d最大迁移深度为40 cm。由此可见,土壤一旦被砷污染,其长期危害难以消除。表层土壤中微生物群落结构与其他深度显著不同,结合RDA与PERMANOVA分析证明深度和ROX含量是控制不同深度土壤中微生物群落多样性的主要影响因素。通过健康风险评估得知,表层土壤中ROX持续污染会诱发较大的砷致癌风险。因此,建议全面执行我国禁止使用ROX的规定,在仍然允许使用ROX的国家和地区,要加强对禽畜废弃物的规范处理,避免长期在未防渗的地面上露天堆积。     

农户田块尺度冬小麦不同产量水平土壤细菌群落差异

为了明确土壤细菌群落对小麦产量的影响,以河南省济源市冬小麦种植户田块为研究对象,通过采集扬花期麦田土壤样品,利用Illumina高通量测序技术测定细菌16S rRNA V3+V4区序列,分析冬小麦不同产量水平土壤的细菌群落差异。结果表明,高产组土壤铵态氮含量显著高于低产组(P<0.05),土壤有机质含量、速效钾含量、有效磷含量、硝态氮含量、pH值在组间均无显著差异,土壤酸性磷酸酶、碱性磷酸酶、脲酶和过氧化氢酶活性在组间也均无显著差异。酸杆菌门(Acidobacteria)和变形菌门(Proteobacteria)是土壤细菌群落的主导菌门。门水平上,小麦产量与芽单胞菌门(Gemmatimonadetes)、装甲菌门(Armatimonadetes)、纤维杆菌门(Fibrobacteres)、Latescibacteria、Dadabacteria相对丰度显著相关。属水平上,Bryobacter、黄杆菌属(Flavisolibacter)、芽单胞菌属(Gemmatimonas)、丰佑菌属(Opitutus)、黏液杆菌属(Mucilaginibacter)、Dongia、Chryseo...     

Molecular polymorphisms between populations of Pseudoperonospora cubensis from Greece and the Czech Republic and the phytopathological and phylogenetic implications

Molecular genetic polymorphisms within Pseudoperonospora cubensis isolates of different geographic origins were investigated to establish their phylogenetic relationships and to assess genetic variability between two distant pathogen populations. Thirty isolates originating from Greece (Crete; 15), the Czech Republic (13), the Netherlands (one) and France (one) were analysed by AFLP fingerprinting and ITS 5·8S rDNA sequence analysis. All isolates were obtained from cucumber ( Cucumis sativus ) plants showing typical downy mildew symptoms. Four AFLP primer combinations produced a total of 288 high-quality bands of which 45% were polymorphic, allowing isolates to be grouped into two separate clusters: one including the Central European (Czech Republic) and Western European (the Netherlands and France) and the other the Cretan isolates. Within each AFLP cluster there was some variation, which could be accounted for by geographic origin or pathogenicity. The two populations (Cretan vs. Central and Western European) exhibited a high degree of genetic isolation. There was no clear AFLP grouping of isolates on the basis of pathotypes. No variability was detected in the ITS1 region; however, ITS2 sequences grouped P. cubensis isolates in two subclusters: one with all investigated European and the other with Asian isolates. The two subclusters formed a larger P. cubensis cluster which was differentiated from the cluster of the neighbouring species Pseudoperonospora humuli . Within P. cubensis , AFLP fingerprints could resolve genetically isolated populations, even on small or medium geographic scales, while ITS2 sequence showed differences on a global scale, being only suitable for phylogenetic analyses.     

Mixtures of organic amendments and biochar promote beneficial soil microbiota and affect Fusarium oxysporum f. sp. lactucae,Rhizoctonia solani and Sclerotinia minor disease suppression

The use of soil fumigants and fungicides to control soilborne pathogens is reduced due to awareness of their negative drawbacks. Long-term application of such agrochemicals negatively affects soil microbiota and reduces natural soil suppressiveness. We investigated long-term impacts of biochar and not-pyrogenic organic amendment (OAs: manure, alfalfa straw and glucose), on disease suppression compared with conventional management in three pathosystems: Fusarium oxysporum f. sp. lactucae (FOL)–lettuce, Rhizoctonia solani–tomato and Sclerotinia sclerotiorum–lettuce, by conditioning soil for 2 years. Soil analyses included pH, electrical conductivity, organic carbon, total nitrogen, C:N ratio, N-NO₃⁻, N-NH₄⁺, cation exchange capacity, available phosphorus, Ca²⁺, Mg²⁺, K⁺, Na⁺, fluorescein diacetate (FDA), and total and active limestone. Soil microbiota was characterized by combining BIOLOG EcoPlates with next-generation sequencing of 16S and 18S rRNA genes. Soil amended with OAs generally suppressed disease by S. sclerotiorum and FOL compared to fumigants and synthetic fertilizers. However, the incidence of R. solani infection was lower in soil treated with synthetic fertilizers than soil amended with OAs. EC, pH, C:N, N-NO₃⁻, N-NH₄⁺, FDA and BIOLOG were significantly correlated with disease, depending on pathosystem. Bacterial richness and diversity, presence of some genera like Acidobacteria, Chloracidobacteria, Solibacteres, Anaerolineae, Nitrospira and Deltaproteobacteria were negatively related to disease incidence of FOL and S. sclerotiorum, whereas damping-off caused by R. solani was negatively affected by the presence of Flavobacterium and Chitinofagha. Therefore, we concluded that long-term application of OAs can effectively improve soil suppressiveness and reduce disease incidence against root pathogens, although the effects vary considerably depending upon pathosystem.     

菌肥对铜污染土壤玉米苗期光合特性的影响

采用盆栽试验,研究了在铜(100 mg·kg-1)污染土壤中,施用菌肥(0,50,100,200 g)对不同品种玉米(晋单56号、长玉16号、大正2号)苗期光合特性(净光合速率、胞间CO2浓度、蒸腾速率和气孔导度)的影响。结果表明:(1)施入菌肥100 g,大正2号、长玉16号和晋单56号玉米的苗期净光合速率、蒸腾速率和气孔导度的值有明显的增加,且含量均高于其他处理,胞间CO2浓度均低于其他处理。(2)大正2号玉米在施用菌肥100 g处理下,苗期叶片净光合速率、蒸腾速率和气孔导度的含量均高于其他品种玉米,而叶片的胞间CO2浓度含量低于其他品种玉米。4种光合特性的值分别为:8.34,3.08,69.3,23.3μmol·m-2·s-1。由此可见,在铜污染土壤中施入菌肥,对不同品种玉米苗期净光合速率、蒸腾速率和气孔导度均有明显的促进作用,对胞间的CO2浓度有明显的抑制作用,即大正2号玉米在施用菌肥100g时,苗期光合作用最强。     

金沙江峡谷退耕经济林地昆虫多样性分析

调查滇西北金沙江峡谷不同退耕经济林地和对照样地的昆虫组成,以喜地表活动的蚁科、植食性的蝗总科和捕食性瓢虫种类为对象,分析Margalef丰富度指数(R)、Shannon-W ie-ner多样性指数(H)和Pielou均匀度指数(J).结果显示:样地A昆虫共10目33科,样地B有6目26科,样地C为6目23科,样地D是7目26科.步甲科、瓢甲科、叶甲科、蝽科、长蝽科、土蝽科和斑腿蝗科等种类在较晚退耕的林地里常见.昆虫物种Margalef丰富度指数以2001年退耕木亡果林地最高,R=3.413 4;Shannon-W iener多样性指数则以2000年退耕还林的青梅林地为最大,H=2.090 1;Pielou均匀度指数值最高的是2001年退耕的撂荒坡地,J=0.999 6.从昆虫多样性来看,退耕还林有利于促进金沙江峡谷的生态恢复.