有机无机复混肥施用量对热带水稻土微生物群落和酶活性的影响

  【目的】  研究一次性施用不同量的有机无机复混肥对热带地区水稻产量及土壤微生物群落与酶活性的影响,为该区域水稻高效肥料管理提供科学依据。  【方法】  水稻田间试验连续进行了3季 (2018年早稻–晚稻,2019年早稻)。施肥设5个处理:不施肥对照 (CK),常规化肥分3次施用 (CF),采用一次性基施的等量、减10%和减20%氮磷钾养分投入量的有机无机复混肥处理 (OF、–10%OF和–20%OF)。2019年早稻收获后测产,同时取0—20 cm土壤样品,分析土壤理化性质和酶活性,采用Illumina高通量测序技术测定土壤细菌和真菌群落组成、多样性和结构。  【结果】  OF、–10%OF和 –20%OF处理的水稻产量没有显著差异,均与化肥处理 (CF) 相当。与CF相比,3个有机无机复合肥处理显著提高了土壤pH,对土壤全量氮磷钾没有显著影响;OF处理显著提高了土壤有机质含量;–20%OF处理显著提高了土壤碱解氮 (15.40%)、速效钾含量 (39.75%);OF和–10%OF处理显著提高了土壤有效磷 (49.82%、46.02%) 和速效钾含量 (91.40%和30.44%);有机无机复混肥处理对土壤酶活性没有显著影响。施用有机无机复混肥影响了真菌和细菌的多样性。其中–20%OF处理显著提高了细菌、真菌的Chao1指数和真菌的物种丰富度指数。在群落结构方面,–20%OF处理的土壤变形菌门和酸杆菌门的丰度显著高于CF处理,分别提高6.64%和8.37%,厚壁菌门丰度较CK显著降低了72.67%;–20%OF处理较CF处理显著增加土壤接合菌门丰度 (77.40%),而–10%OF土壤真菌球囊菌门较CK处理降低了117.38%。相关性分析表明,土壤细菌多样性与土壤速效磷呈正相关,真菌多样性与土壤碱解氮呈正相关。冗余分析表明,细菌群落的主要驱动因子为酸性磷酸酶、速效钾、有效磷和碱解氮,而碱解氮、全钾、有效磷和脲酶是土壤真菌群落的主要限制因子。  【结论】  施用有机无机复混肥能显著改善南方红壤水稻土速效养分含量和pH,减少10%～20%的常规养分投入量,对水稻产量没有明显影响,但是比施用化肥明显提高了土壤中有效磷、钾含量,同时提高了土壤细菌和真菌群落的数量和多样性。     

配施木霉微生物肥对连作黄瓜的影响

研究减量化肥与哈茨木霉SQR-T037微生物肥配施对盆栽黄瓜产量、品质及土壤有效养分和可培养微生物数量的影响。试验以当地农民惯用化肥施用量的100%作为对照处理(CF),75%的农民惯用化肥量配施普通有机肥(OF)或木霉SQR-T037微生物肥(BF)作处理进行连续盆栽试验。结果表明,75%的农民惯用化肥量配施木霉微生物肥BF与100%的化肥处理CF产量相等且后期有所增产,相对配施普通有机肥处理OF则产量显著提高,同时黄瓜果实中硝酸盐含量降低45%以上,维生素C含量明显增加。此外,BF处理能有效改善土壤养分供应状况,有效磷和速效钾含量明显高于对照CF和OF处理,并显著提高黄瓜根际土壤细菌、有益菌种木霉的数量,维持放线菌数量稳定,且在施用第三季后显著减少真菌数量。因此,减少25%的化肥并配施一定量的木霉微生物肥(50g株~(-1)),不仅能保证黄瓜稳产,还能显著改善黄瓜果实品质,促进土壤中养分的高效利用,节约施肥成本,促进农业可持续发展。     

Effects of tillage and fertilizer on nematode communities in a Japanese soybean field

No-tillage (NT) cropping systems develop distinct soil ecosystems characterized by a diverse soil fauna and slow fungal decomposition. However, nematode community analyses sometimes fail to detect these characteristics because the treatment before study or the sampling period is too short or the studies are not comprehensive. Different nematode taxa may occur depending on the geographic region and soil type, thereby affecting the usefulness of nematode analyses for soil biological assessment. However, studies in Asia are scarce. Thus, in this 2-year study, we compared nematode populations, community structures, and soil physicochemical properties between long-term NT and conventional tillage (CT) treatments combined with chemical (CF), organic (OF), or no (NF) fertilizer treatments in a Japanese soybean field. We then examined whether nematode diversity and community indices could detect differences among the treatments in the Japanese andosols. Although the effects of tillage on nematode densities were significant, the overall trend in NT–CT differences was not clear, except for omnivores and Meloidogyne. The effects of tillage on nematode diversity and community indices were apparent: diversity indices, maturity index (MI) and related indices, structure index, and channel index were higher, whereas enrichment index (EI) was lower in NT because of higher densities of K-strategy taxa, fungal and facultative root feeders, and lower densities of r-strategy bacterial feeders. Fertilizer treatments also affected nematode densities: most feeding groups were less abundant in NF and predatory nematodes were more abundant in OF than in other treatments. OF increased nematode diversity via an increase in microbivorous and predaceous nematodes. However, the effects of fertilizer on most community indices were not apparent. Interactions between tillage and fertilizer effects were significant for Pratylenchus and total nematode densities, MI, and EI. Among the soil properties differing among treatments, Ca and Mg content, cation exchange capacity, and percent total nitrogen affected nematode community structure. In conclusion, nematode community analyses using index calculations are useful for assessing soil biological properties under different tillage treatments in Japanese andosols, as well as in soil types in other countries. However, index calculations were less sensitive at detecting fertilizer treatment effects, probably because of simultaneous increases in r- and K-strategy nematodes and OF compost that was too decomposed. Other community analyses such as indicator species analysis or diversity evaluations should be used to detect fertilizer effects.     

Plant growth stages and fertilization regimes drive soil fungal community compositions in a wheat-rice rotation system

Fungal communities may have different response to fertilization under different conditions. Therefore, it is necessary to reveal the effects of fertilizations on fungal communities considering temporal heterogeneity at different crop stages. To address this, soil samples were collected across eight typical plant growth stages of a wheat-rice rotation system under four fertilization regimes: no nitrogen fertilizer (NNF), chemical fertilizer (CF), organic-inorganic mixed fertilizer (OIMF), and organic fertilizer (OF). Soil temperature and moisture that co-vary with plant growth stages were the strongest predictors of fungal community compositions; meanwhile, fertilization regimes also played important roles. Shannon index and the relative abundance of Ascomycota were consistently increased when compared OF treatment with CF and OIMF treatments, while CF treatment had a higher relative abundance of Zygomycota when compared with NNF and OF treatments. For the functional guilds, application of urea-nitrogen fertilizers (CF and OIMF treatments) significantly decreased the relative abundance of saprotrophs and symbiotrophs, while soil treated with OF had less relative abundance of pathotrophs when compared to inorganic fertilizers. Our study provided a detailed picture of how fungal community composition responded to fertilization regimes across different plant growth stages.     

Long-term and legacy effects of manure application on soil microbial community composition

We analyzed soil prokaryotic and fungal community composition in soils with varying histories of cattle manure application. The manure treatments were (i) annual application for 43 years (MF), (ii) annual application for 14 years followed by 29 years without application (MF14), and (iii) annual application for 30 years followed by 13 years without application (MF30). An annual application of chemical nitrogen (N) fertilizer (CNF) and a non-amended control (Con) were also included. Soil prokaryotic evenness and diversity significantly decreased in MF relative to other treatments in fall, but were similar to the other fertilizer treatments in spring and summer. Distinct prokaryotic and fungal community composition was observed in MF compared to other treatments across fall, spring, and summer seasons. The MF treatment significantly increased the relative abundance of Firmicutes, Gammaproteobacteria, and Gemmatimonadetes, but significantly decreased the relative abundance of Acidobacteria. In fall, the soil prokaryotic and fungal community composition with MF30 was significantly different than the other fertilization treatments. Overall, the study showed that annual manure application (MF) led to a different microbial community composition than the other fertilizer treatments. Soil without manure application for 13 years (MF30) had a significantly different microbial community composition from other fertilizer treatments in fall, while the soil without manure application for 29 years (MF14) resembled a microbial community that had never received manure.     

长期施肥对农田土壤真菌的影响

不合理施肥所引发的土壤环境问题逐渐成为制约我国农业可持续发展的重要因素之一,而土壤真菌作为一类重要的土壤微生物,研究施肥措施对真菌群落的影响对促进农业生产具有重要意义。本研究以有20年历史的长期定位试验田为研究对象,利用末端限制性片段长度多态性分析技术,对长期定位施肥农田生态系统中不同施肥方式对土壤真菌群落的影响以及时间变化规律进行了系统研究。长期施肥定位试验包括EM堆肥(EM)、传统堆肥(OF)、化肥(CF)和不施肥(CK)处理。主要研究结果如下:在0~20 cm土层,施肥处理对土壤真菌多样性有显著影响,Shannon-Weiner多样性指数为2.64~3.53,Simpson集中性指数为0.03~0.08;EM和OF处理的Shannon-Weiner多样性指数均显著高于CF和CK;在3月、6月和10月,EM和OF处理与CF和CK处理相比,有较高的真菌多样性;Simpson集中性指数最高的是3月的CK处理,最低的是10月的EM和OF处理。冗余分析结果表明,土壤pH、有机质、总氮、有效磷和有效钾等对真菌影响显著。因此,长期施用有机肥与化肥相比可以提高土壤真菌多样性,改变其群落结构;与化肥处理相比,施用EM堆肥,不仅可以保持土壤可持续利用性,同时改善0~20 cm土层土壤真菌的生存环境;3种施肥处理对土壤真菌群落结构影响程度由强到弱:EMOFCF。     

Effects of vermicompost amendment as a basal fertilizer on soil properties and cucumber yield and quality under continuous cropping conditions in a greenhouse

Purpose

We examined the effects of vermicompost application as a basal fertilizer on the properties of a sandy loam soil used for growing cucumbers under continuous cropping conditions when compared to inorganic or organic fertilizers.

Materials and methods

A commercial cucumber (Cucumis sativus L.) variety was grown on sandy loam soil under four soil amendment conditions: inorganic compound fertilizer (750 kg/ha,), replacement of 150 kg/ha of inorganic compound fertilizer with 3000 kg/ha of organic fertilizer or vermicompost, and untreated control. Experiments were conducted in a greenhouse for 4 years, and continuous planting resulted in seven cucumber crops. The yield and quality of cucumber fruits, basic physical and chemical properties of soil, soil nutrient characteristics, and the soil fungal community structure were measured and evaluated.

Results and discussion

Continuous cucumber cropping decreased soil pH and increased electrical conductivity. However, application of vermicompost significantly improved several soil characteristics and induced a significant change in the rhizosphere soil fungal community compared to the other treatments. Notably, the vermicompost amendments resulted in an increase in the relative abundance of Ascomycota, Chytridiomycota, Sordariomycetes, Eurotiomycetes, and Saccharomycetes, and a decrease in Glomeromycota, Zygomycota, Dothideomycetes, Agaricomycetes, and Incertae sedis. Compared to the organic fertilizer treatment, vermicompost amendment increased the relative abundance of beneficial fungi and decreased those of pathogenic fungi. Cucumber fruit yield decreased yearly under continuous cropping conditions, but both inorganic and organic fertilizer amendments increased yields. Vermicompost amendment maintained higher fruit yield and quality under continuous cropping conditions.

Conclusions

Continuous cropping decreased cucumber yield in a greenhouse, but basic fertilizer amendment reduced this decline. Moreover, basal fertilizer amendment decreased beneficial and pathogenic fungi, and the use of vermicompost amendment in the basic fertilizer had a positive effect on the health of the soil fungal community.

     

Microbial composition and diversity of an upland red soil under long-term fertilization treatments as revealed by culture-dependent and culture-independent approaches

Background, aim, and scope  Fertilization is an important agricultural practice for increasing crop yields. In order to maintain the soil sustainability, it is important to monitor the effects of fertilizer applications on the shifts of soil microorganisms, which control the cycling of many nutrients in the soil. Here, culture-dependent and culture-independent approaches were used to analyze the soil bacterial and fungal quantities and community structure under seven fertilization treatments, including Control, Manure, Return (harvested peanut straw was returned to the plot), and chemical fertilizers of NPK, NP, NK, and PK. The objective of this study was to examine the effects on soil microbial composition and diversity of long-term organic and chemical fertilizer regimes in a Chinese upland red soil. Materials and methods  Soil samples were collected from a long-term experiment station at Yingtan (28°15′N, 116°55′E), Jiangxi Province of China. The soil samples (0–20 cm) from four individual plots per treatment were collected. The total numbers of culturable bacteria and fungi were determined as colony forming units (CFUs) and selected colonies were identified on agar plates by dilution plate methods. Moreover, soil DNAs were extracted and bacterial 16S rRNA genes and fungal 18S rRNA genes were polymerase chain reaction amplified, and then analyzed by denaturing gradient gel electrophoresis (DGGE), cloning, and sequencing. Results  The organic fertilizers, especially manure, induced the least culturable bacterial CFUs, but the highest bacterial diversity ascertained by DGGE banding patterns. Chemical fertilizers, on the other hand, had less effect on the bacterial composition and diversity, with the NK treatment having the lowest CFUs. For the fungal community, the manure treatment had the largest CFUs but much fewer DGGE bands, also with the NK treatment having the lowest CFUs. The conventional identification of representative bacterial and fungal genera showed that long-term fertilization treatments resulted in differences in soil microbial composition and diversity. In particular, 42.4% of the identified bacterial isolates were classified into members of Arthrobacter. For fungi, Aspergillus, Penicillium, and Mucor were the most prevalent three genera, which accounted for 46.6% of the total identified fungi. The long-term fertilization treatments resulted in different bacterial and fungal compositions ascertained by the culture-dependent and also the culture-independent approaches. Discussion  It was evident that more representative fungal genera appeared in organic treatments than other treatments, indicating that culturable fungi were more sensitive to organic than to chemical fertilizers. A very notable finding was that fungal CFUs appeared maximal in organic manure treatments. This was quite different from the bacterial CFUs in the manure, indicating that bacteria and fungi responded differently to the fertilization. Similar to bacteria, the minimum fungal CFUs were also observed in the NK treatment. This result provided evidence that phosphorus could be a key factor for microorganisms in the soil. Thus, despite the fact that culture-dependent techniques are not ideal for studies of the composition of natural microbial communities when used alone, they provide one of the more useful means of understanding the growth habit, development, and potential function of microorganisms from soil habitats. A combination of culture-dependent and culture-independent approaches is likely to reveal more complete information regarding the composition of soil microbial communities. Conclusions  Long-term fertilization had great effects on the soil bacterial and fungal communities. Organic fertilizer applications induced the least culturable bacterial CFUs but the highest bacterial diversity, while chemical fertilizer applications had less impact on soil bacterial community. The largest fungal CFUs were obtained, but much lower diversity was detected in the manure treatment. The lowest bacterial and also fungal CFUs were observed in the NK treatment. The long-term fertilization treatments resulted in different bacterial and fungal compositions ascertained by the culture-dependent and also the culture-independent approaches. Phosphorus fertilizer could be considered as a key factor to control the microbial CFUs and diversity in this Chinese upland red soil. Recommendations and perspectives  Soil fungi seem to be a more sensitive indicator of soil fertility than soil bacteria. Since the major limitation of molecular methods in soil microbial studies is the lack of discrimination between the living and dead, or active and dormant microorganisms, both culture-dependent and culture-independent methods should be used to appropriately characterize soil microbial diversity.     

菜田种养结合模式下施肥方式对土壤编码碱性磷酸酶基因微生物群落的影响

为明确菜田种养结合模式下施肥方式对土壤编码碱性磷酸酶基因phoD的微生物群落结构和多样性的影响机制,通过Illumina MiSeq高通量测序手段,系统分析了4种不同施肥方式,即不施肥（CK）、施常规化肥（CF）、施有机肥（OF）、有机无机肥混施（MF）对花菜收获时0−20cm土层土壤理化性质、碱性磷酸酶（ALP）、微生物量磷（MBP）以及phoD微生物群落的影响。结果表明：（1）与CK相比,OF处理可显著提高土壤有机质、总氮、速效磷和Ca含量47.83%、38.46%、104.81%和69.21%（P<0.05）;OF和MF处理均显著提高ALP活性;CF和OF分别显著增加MBP含量56.12%和195.16%,OF处理中MBP含量最高（105.40mg·kg⁻¹）;（2）菜田种养结合模式不同施肥处理中假单胞菌属（Pseudomonas）为优势属,CF和MF较CK显著降低了假单胞菌属相对丰度33.39%和45.52%;施肥降低土壤phoD微生物Chao1指数,MF提高其多样性（Simpson）和均匀度（Simpsoneven）;（3）影响phoD微生物群落结构的关键环境因子为MBP、AP、ALP;phoD微生物α多样性指数与土壤性状指标无显著相关性。因此,菜田种养结合模式下,不同施肥处理改变了土壤理化和生物性质,从而驱动了土壤phoD微生物群落组成、结构和多样性变化。     

Reducing chemical fertilizer use mitigates obstacles in intensive monocropping of cucumber: a probable role of Pseudomonads in the process

A five-year continuous monocropping of cucumber in a greenhouse receiving 50% NPK and 100% NPK was conducted to explore if reducing chemical fertilizer use can mitigate obstacles in intensive monocropping, and the microbial mechanism of the process. Significant decreases in living seedling rates and total yields with time were exhibited in the 100% NPK treatments, showing an obvious obstacles event, which can be mitigated by reducing fertilizer use. It was found that both total yields and living seedling rates were negatively correlated with the proportion of Fusarium oxysporum f. sp. cucumerinum (a known cucumber wilt pathogen) in F. oxysporum, suggesting the two fungal groups out of balance in the rhizosphere, was the key factor for the decline in cucumber growth in the monocropping system. Furthermore, the abundance of pseudomonas group, not hydrogen cyanide- or phenazine-producing pseudomonas, can act as the defender against possible fungal pathogens. The opposite relationships between HCN-producing pseudomonas and two plant indicators (cucumber yield and living seedling rate) suggested that HCN-producing pseudomonas exerted positive effects only when cucumber plants’ density was above a certain threshold. The Redundancy Analysis (RDA) showed that changes in soil microbial population size, especially in pseudomonas groups, contributed to the mitigation process.     

<Emphasis Type="Italic">Trichoderma</Emphasis> improves the growth of <Emphasis Type="Italic">Leymus chinensis</Emphasis>

Bio-fertilizer application has been proposed as a strategy for enhancing soil fertility, regulating soil microflora composition, and improving crop yields, and it has been widely applied in the agricultural yields. However, the application of bio-fertilizer in grassland has been poorly studied. We conducted in situ and pot experiments to investigate the practical effects of different fertilization regimes on Leymus chinensis growth, with a focus on the potential microecological mechanisms underlying the responses of soil microbial composition. L. chinensis biomass was significantly (P?<?0.05) increased by treatment with 6000 kg ha^?1 of Trichoderma bio-fertilizer compared with other treatments. We found a positive (R² =?0.6274, P <?0.001) correlation between bacterial alpha diversity and L. chinensis biomass. Hierarchical cluster analysis and nonmetric multidimensional scaling (NMDS) revealed that soil bacterial and fungal community compositions were all separated according to the fertilization regime used. The relative abundance of the most beneficial genera in bio-fertilizer (BOF) (6000 kg ha^?1Trichoderma bio-fertilizer) was significantly higher than in organic fertilizer (OF) (6000 kg ha^?1 organic fertilizer) or in CK (non-amend fertilizer), there the potential pathogenic genera were reduced. There were significant negative (P?<?0.05) correlations between L. chinensis biomass and the relative abundance of several potential pathogenic genera. However, the relative abundance of most beneficial genera were significantly (P?<?0.05) positively correlated with L. chinensis biomass. Soil properties had different effects on these beneficial and on these pathogenic genera, further influencing L. chinensis biomass.     

生物有机肥对黄瓜幼苗生长、基质环境以及幼苗根系特征的影响

以黄瓜为材料,以不施生物有机肥为对照(CK),以添加生物有机肥2%、4%、8%、15%(质量比)为处理,研究不同生物有机肥用量对黄瓜幼苗植株形态指标、基质养分和微生物数量、及根系特征参数的影响,并对所有参数进行主成分分析。结果表明,播种25d后,8%处理促进植株生长效果最显著,15%处理促进植株生长效果次之。所有测试期内基质速效磷、速效钾、铵态氮均随生物有机肥施用量的增加而增加;15%处理在播种10、18和25d后显著增加了脲酶活性,且在播种10d和25d后显著增加了蔗糖酶活性;15%处理在播种18d和25d后增加细菌和真菌效果最显著;8%处理在播种25d后增加根系鲜质量和干质量效果最显著,且增加总根长、根体积、根表面积效果最佳,通过主成分分析表明,在播种25d后8%处理综合得分最高。因此8%生物有机肥施用量是显著促进穴盘黄瓜幼苗生长和维持基质质量的最优施用量,为基质穴盘黄瓜育苗中生物有机肥合理施用提供参考。     

The effects of combinations of biochar,lime, and organic fertilizer on nitrification and nitrifiers

Here, we report results from a field experiment investigating the application of biochars, lime, organic fertilizer, and their combinations. Soil pH was increased by ameliorants. Wheat biochar produced the largest increase, of approximately 2 pH units, and mixed treatment (one third rice husk biochar, one third lime, and one third organic fertilizer) also caused large increases, of almost 1 pH unit. There was strong evidence that the ratio of ammonia-oxidizing archaea to ammonia-oxidizing bacteria (AOB) abundance greatly increased with decreased soil pH, indicating that soil pH was an important factor affecting the abundance of AOB. High-throughput MiSeq sequencing showed that the soil ameliorants significantly increased the relative abundances of Nitrosomonas and Nitrospira. Soil pH was an important determinant of the bacterial community composition and diversity. Our study suggests that the ameliorants (biochar, lime, organic fertilizer, and their combinations) change soil nitrification by altering nitrifying bacteria abundance, diversity, and composition, caused by the changed soil pH.     

Soil microbial biomass,crop yields,and bacterial community structure as affected by long-term fertilizer treatments under wheat-rice cropping

Soil microbial biomass carbon (SMBC) and nitrogen (SMBN), soil microbial community structure, and crop yields were studied in a long-term (1982–2004) fertilization experiment carried out in Suining, Sichuan province of PR China. Eight treatments included three chemical fertilizer (CF) treatments (N, NP, NPK), three CF + farmyard manure (M) treatments (NM, NPM, NPKM), M alone and no fertilizer (CK) as control. The results showed that the soil microbial biomass was higher in soil treated with CFM than in soil treated with CF alone, and that NPKM gave the highest rice and wheat yields. The SMBC and SMBN were higher after rice than those after wheat cropping. SMBC correlated closely with soil organic matter. Average yields of wheat and rice for 22 years were higher and more stable in the fertilized plots than in control plots. Bacterial community structure was analyzed by PCR-DGGE targeting eubacterial 16S rRNA genes. A higher diversity of the soil bacterial community was found in soil amended with CFM than in other fertilizer treatments. Some specific band emerged in the soil amended with M. The highest diversity of bacterial communities was found in the NPKM treated soil. The bacterial community structures differed in rice and wheat plots. Sequencing of PCR products separated in DGGE showed that some of the common and dominant bands were closely related to Aquicella lusitana and to Acidobacteria. This study demonstrated that mixed application of N, P, and K with additional M amendment increased soil microbial biomass, diversified the bacterial communities and maintained the crop production in the Calcareous Purplish Paddy soil.     

Control of Fusarium wilt disease of cucumber plants with the application of a bioorganic fertilizer

Two field experiments were conducted to evaluate the effect of organic fertilizer application either with or without antagonistic bacteria (Bacillus subtilis SQR-5 and Paenibacillus polymyxa SQR-21) on the control of Fusarium oxysporum f. sp. Cucumerinum J. H. Owen wilt disease in cucumber. The incidence of Fusarium wilt disease was 5.3–13.5% for cucumber plants treated with bioorganic fertilizer, while it was 30.3–51% in controls (only with organic fertilizer). Higher yields and lower disease incidences were observed in the dry season when compared with the wet season for both types of organic fertilizer treatments. Biolog analysis showed a significant change in soil bacterial composition and activity after bioorganic fertilizer application. The numbers of colony-forming units of F. oxysporum f. sp. Cucumerinum J. H. Owen for bioorganic-fertilizer-treated soils were significantly decreased compared with control. Scanning electron micrographs of cucumber basal stems showed a presence of mycelia-like mini strands accompanied by an amorphous substance within the xylem vessels. This amorphous substance and mini strands were richer in calcium and phosphorus but had low carbon and oxygen than the living mycelia. Reverse-phase high-pressure liquid chromatography and mass spectroscopic analysis showed that the antagonistic bacteria produced the antifungal compounds fusaricidin A, B, C, and D with molecular weights of 883.5, 897.5, 947.5, and 961.5 Da, respectively. The application of bioorganic fertilizer has a great potential for the control of F. oxysporum wilt disease in cucumber plants.     

土壤消毒结合施用生物有机肥对西瓜病土改良效果的影响

选取西瓜枯萎病发病严重的大棚,设置5个处理:对照、棉隆熏蒸、棉隆熏蒸后种植西瓜过程中施用不同次数生物有机肥,研究棉隆消毒土壤及配合不同生物有机肥施用次数对土壤理化和生物学性质及西瓜枯萎病发病率的影响。结果表明:棉隆熏蒸土壤后,施用生物有机肥虽未减缓尖孢镰刀菌增长速率、降低西瓜枯萎病发病率,但显著增加了土壤细菌和真菌数量,改变了细菌和真菌群落结构。此外,施用生物有机肥会降低土壤pH,过量施用会导致土壤NO–3累积、盐分增加。从改良土壤微生物群落结构和避免NO–3累积及土壤盐渍化加重角度出发,种植西瓜过程中生物有机肥最佳施用方式为移栽时施用1次+种植过程中追施1～2次。     

黄瓜与西芹间作土壤细菌多样性及其对黄瓜枯萎病发生的影响

本试验以黄瓜与西芹间作种植模式为处理,黄瓜单作和西芹单作种植模式为对照,利用Illumina公司Miseq平台对上述不同处理土壤进行16S rDNA细菌群落多样性高通量测序分析和田间接种黄瓜枯萎病菌,探讨黄瓜与西芹间作模式土壤细菌的多样性及其对田间黄瓜枯萎病发生的影响。16S rDNA测序结果表明,黄瓜与西芹间作土壤的细菌物种总数最多,群落多样性水平最高,与对照相比显著提高了土壤细菌observed species指数、Shannon指数和Chao1指数(P0.05);Beta多样性聚类分析表明,黄瓜与西芹间作土壤的环境群落物种与黄瓜单作和西芹单作有一定差异性。在门分类水平上,共检测到45个菌门,其中变形菌门占明显优势,其次为酸杆菌门和放线菌门等;黄瓜与西芹间作土壤细菌种类所占比例最高,达98.63%。在属水平上,共检测到428类菌属,GP6、GP16、GP4、芽单胞菌属、节细菌属5属的丰度值较大;黄瓜与西芹间作土壤的节细菌属分布比例最高,红游动菌属、鞘氨醇单胞菌属和芽球菌属丰度值较大,为黄瓜与西芹间作土壤细菌明显优势菌属。田间接种黄瓜枯萎病菌试验结果表明,采用上述3种不同种植模式土壤种植黄瓜,在黄瓜苗期接种黄瓜枯萎病菌,黄瓜与西芹间作处理的黄瓜枯萎病的田间发病率较西芹单作和黄瓜单作分别降低57.03%~63.54%和66.95%~72.15%。因此,黄瓜与西芹间作增加了土壤细菌群落多样性,降低了黄瓜枯萎病的发病率,对后茬黄瓜土传病害防控具有一定科学指导意义。     

连续施用有机肥对连作花生根际微生物种群和 酶活性的影响

花生连作导致土传病害易发,严重制约其产量和品质。为探讨持续施用有机肥缓解连作花生病害发生的防治机理,大田条件下研究了连续6年施用化肥、普通有机肥和生物有机肥(接种内生菌拟茎点霉B3)后对连作花生根腐病、根际土壤典型微生物种群和酶活的影响。结果表明:与单施化肥相比,持续施用普通有机肥和生物有机肥可有效控制连作花生土传病害发生,荚果产量提高23.8%和47.9%。连续施用普通有机肥和生物有机肥均显著提高根际过氧化氢酶、脱氢酶和酚氧化酶活性,荧光定量PCR进一步测定出连续施用有机肥可显著增加连作花生根际细菌和真菌的数量,说明连续施用有机肥后连作花生根际微生物活性显著提升。连续施用普通有机肥和生物有机肥显著增加了连作花生根际有益微生物种群的数量,其中放线菌增加0.9倍和1.6倍,假单胞菌增加10.9倍和13.1倍,伯克氏菌增加2.6倍和1.9倍,芽孢杆菌增加1.1倍和2.1倍;然而连续施用有机肥对连作花生根际主要致病微生物种群(如镰刀菌属和青枯雷尔氏菌)无明显影响。表明通过持续施用有机肥可有效提高连作花生根际有益微生物种群的数量和土壤酶活性,进而改善连作花生根际微生态环境,增强连作土壤抑病能力,以达到控制连作花生土传病害易发的目的。     

不同施肥处理对长期不施肥区稻田土壤微生物生态特性的影响

采用室内恒温培养方法,研究了不同施肥处理对水稻长期肥料试验中不施肥区（CK）和全肥区（NPK）土壤酶活性及微生物群落结构的变化。结果表明,施肥处理（单施化肥、施猪粪和施秸杆）可以显著提高土壤的微生物量碳以及脲酶、酸性磷酸酶的活性,施用有机肥的效果明显大于单施化肥; 有机肥在无肥区（CK）的施用效果与在全肥区（NPK）的效果接近。PLFA分析表明,施肥使无肥区（CK）土壤微生物群落结构发生了显著的变化,施用有机肥显著增加了土壤微生物群落结构的多样性。与不施肥和单施化肥相比,施有机肥主要增加了细菌和真菌的特征脂肪酸如不饱和脂肪酸、环状脂肪酸cy19∶0等的相对含量,而降低了放线菌标记性脂肪酸10Me18∶0的相对含量。