添加毛叶苕子对红壤旱地土壤真菌群落的影响

【目的】长期高强度的连作及大量化肥施用导致红壤旱地退化和土传植物病原菌累积。真菌是农业生态系统中与土壤健康密切相关的微生物。本文通过研究土壤真菌群落的变化,探究施用毛叶苕子对红壤旱地农业生态系统的影响。【方法】采用定量聚合酶链式反应和高通量测序技术,研究红壤旱地真菌群落对单施矿质肥(mineral nitrogen,phosphorus and potassium fertilization,NPK)与矿质肥配施毛叶苕子(mineral nitrogen,phosphorus and potassium fertilization with hairy vetch,NPKG) 2种施肥措施的响应。【结果】与对照NPK相比,NPKG显著提高土壤肥力、花生产量和土壤真菌丰度,降低土壤p H和土壤真菌多样性。不同处理显著改变土壤真菌群落组成。与对照NPK相比,NPKG处理土壤腐生营养型真菌相对丰度显著提高37.42%,花生尾孢菌(Cercospora arachidicola)和可可毛色二孢菌(Lasiodiplodia theobromae) 2种花生病原菌相对丰度分别降低89.11%和8...     

Replant problems in South Tyrol: role of fungal pathogens and microbial population in conventional and organic apple orchards

The South Tyrol, the main apple-growing area in Italy, is characterised by intensive soil cultivation. Previous investigations have revealed the existence of replant disorders although the main causes of these have not been evaluated. A survey was carried out in this area with two main aims: to evaluate the role of soil-borne pathogens in apple replant disease and to compare the impact of organic and conventional management on replant diseases caused by soil-borne pathogens. The experimental sites were chosen to obtain three pairs of contiguous conventional and organic apple orchards. There was a high level of organic matter in both the organic and the conventional apple orchards with no appreciable differences in humic fractions. The soil sickness test with apple seedlings revealed a significant reduction in growth for all soil samples as compared to the peat control. The growth score on soil samples from organic orchards was significantly higher than that obtained on conventional soil. Total fungal population in soil samples was positively correlated to the apple seedlings growth score and negatively correlated to the frequency of root colonisation. Most of the root-colonising pathogens belonged to the well-known root rot complex, Rhizoctonia solani and Pythium spp. being the most pathogenic on apple seedlings.     

Comparison of crop productivity and soil microbial activity among different fertilization patterns in red upland and paddy soils

Soil enzyme activity and microorganism community can be changed through different long-term fertilization patterns. However, the effect of different fertilization practices on soil microorganisms might differ among crop systems. The objective of the study was to reveal the change of soil enzyme activity and soil microorganism community in different fertilizations both in upland and paddy soils. Therefore, based on long-term fertilization experiments in upland soil started in 1986 and adjacent paddy soil experiment commenced in 1981, with both consisting of 4 treatments: Control (no fertilization), N (only nitrogen fertilizer), NPK (nitrogen, phosphate and potassium fertilizers) and NPKM (nitrogen, phosphate and potassium fertilizers plus organic manure), grain yield, soil fertility, activities of soil urease, catalase, acid phosphatase, microorganism community (the number of bacteria, fungus and actinomycete) were analyzed. The result showed that: the highest grain yield was attained under the application of chemical fertilizers plus manure, as compared with Control, NPKM significantly increased the grain yield by 908.63% in corn and 118.80% in rice (p < 0.05). Meanwhile, NPKM treatment increased significantly soil organic matter and nutrient contents in upland and paddy soils. Interestingly, there was no significant difference in soil pH among all the treatments of paddy soil, but in upland, NPKM increased pH in comparison to Control by 23.06% (1.15 units of pH). Compared with Control, soil urease, catalase activities, bacteria and actinomycete numbers of NPKM were increased by 321.39%, 129.64%, 229.79%, 85.81% in upland soil, and 25.11%, 251.12%, 292.83%, 196.34% in paddy soil. However, in paddy soil, the soil acid phosphatase activity of Control, NPK and NPKM treatments were higher than upland soil by 34.87%, 44.81%, 52.73% and 30.11%. Then, the soil fungus and actinomycete numbers of paddy soil were lower than upland soil by 20.20% and 88.29%. Therefore, it indicated that long-term application of chemical and organic fertilizers delivered highest productivity in both experiment but the effect of fertilizer practices differed between land uses.     

不同稻作制对红壤性水稻土中锰剖面分布的影响

为了探讨红壤性水稻土锰的迁移和转化行为,通过长达16a的定位试验研究了不同稻作制、有机肥以及地下水位对土壤剖面中全锰、活性锰和交换态锰分布的影响。试验结果表明,长期淹水种稻引起0-20cm土壤层次全锰、活性锰和交换态锰含量的显著下降,而在20－40cm和40－75cm土层相对累积。不同稻作制比较,0－20cm土层中全锰、活性锰和交换态锰含量以稻稻泡显著高于稻稻绿和稻稻油处理,而20－40cm和40－75cm土层3种锰形态的含量各稻作制之间无显著差异,表明实行水旱轮作的稻稻绿与稻稻油两种稻作制耕层土壤锰的淋溶损失比持续淹水的稻稻泡制更为严重。相对而言,不同有机肥施用水平和地下水位对土壤剖面中锰分布的影响要小于稻作制,总的趋势为：土壤剖面中锰的空间分异程度以高量有机肥＞常量有机肥＞单施化肥;低水位＞高水位。从土壤中锰的空间分布规律可以看出,水旱轮作（尤其是在低水位和有机无机配合的条件下）比长期淹水更有利于土壤锰氧化还原引起的深层淋溶与淀积,加速了典型水稻土剖面的形成。     

Potential of yeasts as biocontrol agents of soil-borne fungal plant pathogens and as plant growth promoters

Among soil microorganisms, yeasts have received little attention as biocontrol agents of soil-borne fungal plant pathogens in comparison to bacterial, actinomycetes, and filamentous fungal antagonists. The mechanisms of action of potential antagonism by yeasts in relation to soil-borne fungal plant pathogens are expected to be similar to those involved with pathogens of aerial parts of the plant, including leaves and fruits. Several taxa of yeasts have been recorded as endophytes in plants, with a small proportion recorded to promote plant growth. The ability of certain taxa of yeasts to multiply rapidly, to produce antibiotics and cell wall-degrading enzymes, to induce resistance of host tissues, and to produce plant growth regulators indicates the potential to exploit them as biocontrol agents and plant growth promoters. More than ten genera of yeasts have been used to control postharvest diseases, especially of fruits. Suppression of classes of fungal pathogens of fruits and foliage that are similar to those associated with soil-borne fungal root pathogens, strongly suggests that yeasts also have potential for the biological control of diseases caused by soil-borne fungal plant pathogens, as is evident in reports of certain yeasts in suppressing some soil-borne fungal plant pathogens. This review explores the potential of soil yeasts to suppress a wider range of soil-borne fungal plant pathogens and to promote plant growth.     

双季稻田改制对土壤剖面构型及性质的影响

利用田间试验方法,研究了红壤区双季稻田改为稻-稻-紫云英、牧草、水旱轮作和旱作4种种植模式对土壤剖面构型及耕层土壤性质的影响.结果表明: 与试验前相比,旱作种植模式下,耕作层厚度增加了4 cm、犁底层厚度减少了2 cm、湿筛>2 mm粒级团粒含量提高了6.94%、湿筛法平均质量粒径增加了0.37 mm、水稳性结构商是试验前的1.78倍,腐殖酸碳和富里酸碳含量分别提高了0.15和0.49 g·kg^-1;水旱轮作种植模式下,土壤水稳性结构商较高(95.86)、养分含量变幅小;稻-稻-紫云英种植模式下,除有机质含量(增加1.3 g·kg^-1)和土壤水稳性结构商(降低8.82)变化较大外,其余指标变化不大;牧草种植模式下,耕作层厚度增加2 cm、过渡层厚度增加9 cm、土壤水稳性结构商增加1.39,而土壤有机质和全钾含量分别下降5.6和2.8 g·kg^-1,在所有处理中变化幅度最大.表明在当前红壤地区对灌溉条件较差的双季稻田进行改制是可行的,建议优先考虑改成旱作或水旱轮作,但无论在何种耕作方式下,均应注意土壤钾素的亏损问题.     

红壤丘陵区水田和旱地土壤可溶性有机碳矿化对水分的响应

以亚热带红壤丘陵区典型水田和旱地土壤为研究对象,向土壤中添加¹⁴C标记稻草,培养30 d后,提取与原位土壤中结构相似的¹⁴C可溶性有机碳(DOC);将¹⁴C DOC加入水田和旱地土壤中,并设置45%、60%、75%、90%和105%田间持水量(WHC)5个水分梯度,在标准状态下(25 ℃)培养100 d,监测¹⁴C DOC在土壤中的矿化过程.结果表明: 培养100 d后,两种土壤中28.7%～61.4%的标记DOC被矿化为CO₂,且5个水分条件下,水田土壤DOC的矿化率均显著高于旱地,这主要是由于水田土壤DOC的结构组成比旱地土壤更简单.好气条件(56%～75%WHC)有利于两种土壤DOC的分解,淹水条件(105%WHC)则有利于DOC的积累.土壤处于好气条件(45%～90%WHC)时,DOC的生物可分解率及易分解态所占比例均随着含水量的增加而增加.100 d内,水田和旱地易分解态DOC分别占其累积矿化量的80.5%～91.1%和66.3%～72.4%,说明DOC的生物可分解率主要由其易分解态组分所占比例决定.     

江苏省主要农田杂草种子库物种组成和多样性及其与环境因子的相关性分析

采用水洗镜检法对江苏省31个农田样点(包括旱田和水田)0～15 cm土层土壤杂草种子库的种类组成和物种多样性进行了调查研究;采用典范对应法分析了杂草种子库种类与环境因子(包括淹水天数、土壤有机质含量、土壤pH、年降水量、年均温、样点经度和样点纬度)的相关性并绘制了样点和种类与环境因子的二维排序散点图.调查结果表明:在31个样点的土壤杂草种子库中共检测到杂草种子15科54种,旱田和水田各有41和45种,二者共有种类占多数但优势种有差异,通泉草[ Mazus japonicus (Thunb.) Kuntze]、异型莎草(Cyperus difformis L.)、水苋菜(Ammannia baccifera L.)、千金子[Leptochloa chinensis (L.) Nees]、棒头革(Polypogon fugax Nees ex Steud.)和牛繁缕[ Malachium aquaticum (L.) Fries]等种类为二者的共有优势种;杂草种类最多的为禾本科(Gramineae)和莎草科(Cyperaceae),分别占种类总数的22.6％和20.8％.旱田不同样点杂草种子库的优势种类变化较大,而水田杂草种子库优势种较稳定;二者优势种频度差异较大,旱田中频度高于0.30的杂草有19种,水田中频度高于0.50的杂草有20种;旱田和水田中平均重要值大于0.03的杂草各有11和9种,这些频度高的种类重要值也较大.旱田和水田土壤种子库种子密度分别为21 015和37 847 m-2,平均为31 008 m-2;旱田3层土壤中种子密度差异不显著,而水田上、中层土壤的种子密度显著高于下层.旱田以夏熟和秋熟杂草为主,而水田则以水田和夏熟杂草为主.按形态类型划分,水田及旱田中杂草种类数和密度从大到小均依次排序为阔叶草类、禾草类、莎草类,且水田中这3类杂草的种类数和种子密度均高于旱田.与旱田相比,水田杂草种子库的物种丰富度指数(S)、Shannon-Wiener 指数(H')和Simpson指数(D)较高,但Pielou均匀度指数(E)较低;旱田杂草种子库的S、H'和D指数随土层深度增加而降低、E指数逐渐升高,水田各土层的物种多样性指数则无明显变化趋势.第1种类排序轴与淹水天数负相关性最高(R=-0.8143),第2种类排序轴与年降水量和经度也有较高的负相关性;相关性分析和CCA分析结果均表明淹水天数是影响杂草种子库群落构成的最大因素.通过二维排序可将31个样点分为旱田和水田2大类,旱田可划分为长期旱连作和水旱轮作2个亚类;水田可划分为淮河以北地区和淮河以南长江流域地区2个亚类.研究结果说明:杂草种子库潜群落优势种与地上部农田杂草显群落优势种具有一致性,通过土壤杂草种子库的研究可以预测地上杂草的发生和危害情况.     

铜陵矿区土壤和油菜中铜的分布特征

采集铜陵市几个矿区周围土壤和油菜作物样品,研究了铜在矿区不同土壤及油菜中的分布特征.结果表明:铜陵矿区周边耕作土壤铜含量普遍较高;矿区周围残坡积母质上发育的旱作土壤和下游水稻土的污染较严重,而距矿区较远的潮土污染水平较低;水稻土与矿区周围残坡积母质上发育的旱作土壤全铜含量相近,前者的铜主要来自受污染的灌溉水并有着较高的生物有效性.3种类型土壤的有效铜与全铜含量均显著相关.供试土壤中铜的平均活化率(有效铜占全铜含量的百分比)为15.0%,且与土壤全铜和有机质含量呈正相关,与土壤pH和锰含量呈负相关.油菜籽和油菜秸秆中铜的平均含量分别为4.0和5.8mg.kg-1.当土壤中有效铜含量较低时,油菜中的铜含量随着土壤中有效铜含量增加而上升的趋势十分明显,当土壤中有效铜含量大于30mg.kg-1时,油菜作物吸收铜的能力下降,油菜富集铜的效率逐渐降低.     

Production of volatile organic compounds by an antagonistic strain Paenibacillus polymyxa WR-2 in the presence of root exudates and organic fertilizer and their antifungal activity against Fusarium oxysporum f. sp. niveum

The volatile organic compounds (VOCs) produced by antagonistic microbes have great antifungal potential against soil-borne fungal pathogens. The VOCs produced by Paenibacillus polymyxa strain WR-2 in the presence of root exudates and organic fertilizer were identified and their effects on the growth and spore germination of Fusarium oxysporum f. sp. niveum were evaluated. The VOCs produced by WR-2 inhibited the growth of F. oxysporum by 38%, 36% and 40% in agar medium, sterilized soil and natural soil, respectively. This inhibitory effect was increased to 60%, 58% and 64% with the addition of organic fertilizer in agar medium, sterilized soil and natural soil, respectively. The addition of root exudates did not affect the production of antifungal VOCs by WR-2. The VOCs produced by WR-2 completely inhibited the germination of F. oxysporum spores. Out of 42 identified VOCs, seven VOCs; benzothiazole, benzaldehyde, undecanal, dodecanal, hexadecanal, 2-tridecanone and phenol were found to inhibit the growth of F. oxysporum. The results of these experiments suggest another significance of using organic fertilizer as a carrier material with the biocontrol agents to control soil-borne fungal pathogens.     

Microbial Communities Involved in Fe Reduction and Mobility During Soil Organic Matter (SOM) Mineralization in Two Contrasted Paddy Soils

Lowland rice fields of West Africa (Ivory Coast) and South Asia (Thailand) are affected by ferrous toxicity or salinity, respectively, and their soil waters contain large amounts of ferrous iron, depending on reducing irrigation condition and suggesting occurrence of bacterial reducing processes. To determine the involvement, dynamic and activities of bacterial communities in Fe(III) reduction and mobilization during anaerobic degradation and mineralization of soil organic matter (SOM), different experiments and analyses have been performed. Results demonstrated that the utilization of SOM as sole carbon, nutrient and energy sources favored the presence of large bacterial communities: facultative anaerobic and anaerobic bacteria, Fe(III)-reducing bacteria (FeRB) (fermentative and Fe respiring), sulfate reducing bacteria (SRB) which are involved in carbon, nitrogen, iron and sulfur cycling. The larger functional diversity is observed in the Ivory Coast paddy soils containing larger amounts of organic matter and sulfur compounds. These communities contained complementary populations (chemoorganotrophic, chemolitotrophic, aerobic, facultative anaerobic and anaerobic) that can be active at different steps of iron solubilization with simultaneous organic matter mineralization. Our results indicate that the pH controlled by bacterial activity, the nature much more than the content of organic matter, and consequently the structure and activity of bacterial communities influence significantly the availability and dynamic of iron in paddy fields which affect the soil quality.     

自然免耕下的稻田生态系统

自然免耕是一种新型的稻田耕作法,通过人为改变地表微地形,建立了一个适合水旱作物复种轮作,鱼、萍、鸭周年共生的稻田生态系统．自然免耕促进了土壤内、外环境的物质、能量和信息交换,水、热、气、肥谐调．并通过环境网络效应,强化了环境与生物区系间的缓冲－调节力．提高了土壤自调能力和土壤有序度．     

水旱轮作对滩涂绿花椰菜根际土壤真菌群落结构的影响

本研究比较轮作和连作下滨海滩涂地绿花椰菜根际土壤真菌群落结构和多样性的变化特征,以探索不同轮作方式减缓绿花椰菜连作田连作障碍的效果。采用Illumina Miseq高通量测序技术,分析单季稻-绿花椰菜水旱轮作、南瓜-绿花椰菜旱旱轮作和绿花椰菜连作3种耕作方式对绿花椰菜根际土壤真菌群落结构和多样性的影响。结果表明,在浙江省台州湾滨海滩涂地绿花椰菜种植区,水旱轮作、旱旱轮作和连作绿花椰菜根际土壤共获得11门、27纲、52目、94科、155属真菌。在门水平上相对丰度较高的为子囊菌门Ascomycota、油壶菌门Olpidiomycota、担子菌门Basidiomycota、接合菌门Zygomycota、壶菌门Chytridiomycota。与连作相比,轮作显著提高了绿花椰菜根际土壤中子囊菌门、壶菌门菌群的相对丰度,而以水旱轮作对其相对丰度的提高幅度更大。轮作显著降低了绿花椰菜根际土壤中油壶菌门、接合菌门菌群的相对丰度,而以水旱轮作对这2门菌群相对丰度的降低幅度更大。在属水平上轮作显著降低了绿花椰菜根际土壤中油壶菌属Olpidium、镰刀菌属Fusarium等的相对丰度,显著提高了绿花椰菜根际土壤中格孢腔菌属Pleospora的相对丰度,而水旱轮作更提高了格孢腔菌属的相对丰度,降低了油壶菌属、镰刀菌属的相对丰度。因此,轮作能改善台州湾滨海滩涂地上绿花椰菜根际土壤真菌群落结构,但水旱轮作更能增加绿花椰菜根际土壤真菌有益菌丰度,减少绿花椰菜根际土壤真菌有害菌群丰度,提高根际土壤真菌多样性指数,改良绿花椰菜根际土壤生态环境。     

Effect of green manure on Pythium spp. population and microbial communities in intensive cropping systems

Saprophytic soil-borne pathogens can be either actively suppressed by organic amendments or enhanced, depending on soil health conditions. This can be deleterious in the event of selection of a soil-borne population by previous soil management and short crop rotation. Trials were performed in the open field and in pots, using naturally infected soil from intensive crop systems, i.e., soil from fields with 8 years of strawberry cultivation. The aim was to study short-term response of Pythium and soil microbial populations to green manure. The use of green manure in these naturally infested soils, 3–10 weeks after fresh tissue incorporation, caused Pythium populations to increase concurrent with an increase in soil microbial populations, and did not result in the suppression of the pathogen. A more elaborate trial was performed under controlled conditions, amending soil with fresh wheat plant material, air-dried wheat plant material and an organic fertilizer with a high level of humic substances. Although compared to the original soil, all amendments caused a similar increase in organic matter content and small differences in soil respiration, incorporation of fresh, not decomposed, plant material strongly increased Pythium, while the organic fertilizer did not affect the original level of the pathogen population. The increase in total number of fungi and bacteria did not have any suppressive effect on the Pythium population in naturally infested soil used for this study.     

Direct microscopy of bacillus endospore germination in soil microcosms

Antagonistic endospore-forming Bacillus spp. offer a large potential as seed inoculants for control of soil-borne pathogens. In the soil, however, inoculated Bacillus endospores may remain dormant without germination, and plant protection can therefore be inefficient and unpredictable. A method based on direct fluorescence microscopy in soil microcosms was used to determine whether low-cost organic additives incorporated into seed coating material could stimulate endospore germination. Complex organic additives supported a high level of endospore germination of the fungal antagonist Paenibacillus polymyxa CM5-5. Skim milk is a low-cost additive that may be incorporated into seed coating material for efficient induction of Bacillus endospore germination in soil.     

Degradation of the fungal cell wall by clostridial strains isolated from soil subjected to biological soil disinfestation and biocontrol of Fusarium wilt disease of spinach

Applied Microbiology and Biotechnology - Biological soil disinfestation (BSD) involves elimination of soil-borne plant pathogens in an environmentally friendly manner. Two anaerobic bacterial...     

外源氧化铁对水稻土中有机酸含量的影响

在水稻土泥浆中添加Fe(OH) 3 可显著降低乙酸浓度 .在新鲜水稻土样品中 ,由于添加Fe(OH) 3导致对乙酸的竞争消耗 ,在培养 5d后 ,乙酸浓度降至 10～ 2 0 μmol·L-1的稳态浓度 ,而此刻对照中的乙酸浓度仍在 12 0 0 μmol·L-1以上 .在乙酸产生量较低的土壤中 ,添加Fe(OH) 3 可完全消耗体系中的乙酸 ,并导致产CH4过程的完全被抑制 .添加纤铁矿同样可使乙酸浓度显著减少 ,但作用效果不如无定形氧化铁 .添加赤铁矿可造成培养初期 (10d以内 )乙酸的大量积累 ,但并不引起产CH4量的增大 .添加Fe(OH) 3 、纤铁矿及铝取代针铁矿 ,能引起厌氧培养的水稻土中丙酸浓度的降低 ,其抑制效率为Fe(OH) 3 >纤铁矿 >铝取代针铁矿 .新鲜土样和经过 11周厌氧处理后的土样中 ,有机酸种类和含量有较大差别 .     

不同利用方式对红壤CO2排放的影响

采用静态箱法研究了我国亚热带红壤区农田利用方式 (旱地或水田 )对土壤 CO2 排放及其相关因子的影响 ,并估算了旱地和水田 CO2 的年排放通量。结果表明 ,水田在淹水植稻期 (夏季 ) ,其排放通量明显低于旱地 ,而在非淹水期 (排水落干或休闲期 ) ,其排放通量则显著高于旱地。 CO2 排放通量呈现明显的季节性变异 ,旱地以夏季最高、春秋季次之、冬季最低 ;而水田则以秋季最高、其次是春冬季、夏季最低。土壤温度和湿度分别是影响旱地和水田 CO2 排放的主导因子 ,可将二者与通量的指数关系作为模型 ,分别进行旱地和水田 CO2 排放的估算。经模型估算 ,我国中亚热带旱地和水田红壤 CO2 的年排放通量分别为 1.37和 2 .73kg CO2 / (m2 · a) )。     

不同施肥处理下水稻根际和非根际土壤中氨基糖积累特征

以水稻长期定位施肥试验土壤为研究对象,选取不施肥(CK)、化肥(NPK)、秸秆还田+化肥(NPKS)、30%有机肥+70%化肥(LOM)和60%有机肥+40%化肥(HOM)5种处理,分析水稻分蘖旺期根际土和非根际土中氨基糖积累特征.结果表明: 与CK和NPK处理相比,长期施用有机物料(NPKS、LOM、HOM)显著增加了水稻根际土和非根际土中有机碳、总氨基糖及其氨基单糖(胞壁酸、氨基葡萄糖和氨基半乳糖)含量.不同施肥处理下3种氨基单糖的积累规律不同,说明不同微生物对施肥处理的响应趋势和强度有所不同.受稻田翻耕等均匀化土壤的农事操作影响,各处理总氨基糖含量在根际土与非根际土间无显著差异.氨基糖碳对土壤有机碳积累的贡献范围为24.0～28.3 mg·g^-1,且以NPKS处理最高,HOM和CK处理最低.真菌氨基葡萄糖/胞壁酸比值范围为24.4～36.6,说明该试验点所有处理的根际土与非根际土中有机质的降解与转化过程以真菌为主导,且与NPK和CK相比,NPKS处理的真菌参与度提高,而施用HOM处理的细菌参与度提高.