Changed isoflavone Levels in Red Clover (<Emphasis Type="Italic">Trifolium pratense</Emphasis> L.) Leaves with Disturbed Root Nodulation in Response to Waterlogging

The effect of disturbed root nodulation on the quantitative and qualitative composition of the main isoflavonoid glucoside–malonates, glucosides, and aglycones in the leaves of Trifolium pratense L. grown under waterlogging conditions was investigated. Isoflavonoids are involved in the regulation of root nodule activity and the establishment of the mycorrhizal association. Isoflavonoid determination was performed using reversed-phase liquid chromatography coupled to mass spectrometric and UV absorbance detection. In response to waterlogging, the concentrations of biochanin A and biochanin A–7-O-glucoside–malonate, biochanin A–7-O-glucoside, and genistein–7-O-glucoside in the leaves increased two- to threefold after a lag period of 3 wk because of disturbed root nodulation. The other isoflavones detected—formononetin, formononetin–7-O-glucoside–malonate, and formononetin–7-O-glucoside—did not show any significant changes related to waterlogging. After restoring normal soil water conditions, the concentrations of biochanin A and its glucoside and glucoside–malonate rapidly returned to the initial values, whereas the concentration of genistein–7-O-glucoside remained high.     

Role of Isoflavonoids in Resistance of Subterranean Clover Trifoliates to the Redlegged Earth Mite Halotydeus destructor

Mature leaves of variety SE014 of Trifolium subterraneum are resistant to the redlegged earth mite (Halotydeus destructor). Compounds with feeding deterrent activity present in the leaves were isolated and identified by using a membrane bioassay technique. The free isoflavones, formononetin, genistein, and biochanin A, their corresponding 7-O-glucosides, and biochanin A 7-O-glucoside-6-O-malonate and genistein 7-O-glucoside-6-O-malonate, were active. In addition, the biosynthetic precursors of formononetin and genistein, 2,5,7-trihydroxy-4-methoxyisoflavanol and 2,5,7,4-tetrahydroxyisoflavanol, also were deterrent to the redlegged mites. The relative activity of these compounds was determined and some structure-activity correlations are noted. The constitutive defense mechanism that contributes to the resistance of subclover trifoliates to the mite contrasts with the induced chemical mechanism previously found for subterranean clover cotyledons.     

The Influence of Ecological and Conventional Plant Production Systems on Soil Microbial Quality under Hops (Humulus lupulus)

The knowledge about microorganisms—activity and diversity under hop production is still limited. We assumed that, different systems of hop production (within the same soil and climatic conditions) significantly influence on the composition of soil microbial populations and its functional activity (metabolic potential). Therefore, we compared a set of soil microbial properties in the field experiment of two hop production systems (a) ecological based on the use of probiotic preparations and organic fertilization (b) conventional—with the use of chemical pesticides and mineral fertilizers. Soil analyses included following microbial properties: The total number microorganisms, a bunch of soil enzyme activities, the catabolic potential was also assessed following Biolog EcoPlates^®. Moreover, the abundance of ammonia-oxidizing archaea (AOA) was characterized by terminal restriction fragment length polymorphism analysis (T-RFLP) of PCR ammonia monooxygenase α-subunit (amoA) gene products. Conventional and ecological systems of hop production were able to affect soil microbial state in different seasonal manner. Favorable effect on soil microbial activity met under ecological, was more probably due to livestock-based manure and fermented plant extracts application. No negative influence on conventional hopyard soil was revealed. Both type of production fulfilled fertilizing demands. Under ecological production it was due to livestock-based manure fertilizers and fermented plant extracts application.     

微生物降解土壤残留农药的研究进展

综述了在环境中降解土壤农药的微生物、微生物降解农药的机理、在自然条件下影响微生物降解农药的因素以及农药微生物降解研究方面的新技术和新方法。在农药的微生物降解研究中,应重视自然状态下微生物对农药的降解过程,分离构建由天然的微生物构成的复合系,利用微生物复合系进行堆肥或把堆肥应用于被污染的环境。     

P/O-丁酰基苯酚的土壤微生物生态效应

研究了P／O-丁酰基苯酚对土壤微生物活性的影响,结果表明：P／O-丁酰基苯酚在所设计的浓度下,对土壤呼吸作用、过氧化氢酶和脲酶活性没有显著影响。对土壤放线菌数量没有影响;对真菌数量影响不大;对细菌数量的影响则为先抑制,且随浓度增大抑制作用增强,后逐渐恢复稳定。     

Soil effects due to sewage sludge application in agriculture

Field trials show that increased nutrients (mainly P) and heavy metals in soil due to agricultural use of sewage sludge have mainly to be expected when sludge is applied in too high amounts. The biological effects of heavy metals on plants are determined by their solubility which is increased by pH decrease and degradation of organic matter. Normally, it should be expected that the microbial activity in soil would increase with the application of organic matter in sewage sludge. But, also negative effects on the microflora by simultaneous enrichment of organic matter or inorganic and organic pollutants were found. The most important deleterious effects on soil microorganisms are the reduction in size of the total biomass, a reduced nitrogen fixing activity and changes in the composition of microbial populations of the soil. At what stage heavy metal toxicity to soil microorganisms or to microbial processes in soil is likely to become evident is unfortunately still uncertain. Again, the soluble fraction of heavy metals (also of organic pollutants) is a determing factor. To minimize the shown environmental risks an adequate sludge management is proposed.     

Hypolipidemic principles ofCicer Arietinum: Biochanin-A and formononetin

Two isoflavones, biochanin-A and formononetin isolated from gramCicer arietinum, have been shown to possess hypolipidemic properties for Triton WR-1339 induced hyperlipidemia in male albino rats, when administered as a crude extract or as individual compounds.     

咪唑乙烟酸对土壤微生物生态的影响

通过实验室培养研究了除草剂咪唑乙烟酸对土壤微生物生物量和群落结构的影响.结果表明:咪唑乙烟酸在土壤中的降解动态符合一级动力学方程,而且原药比制剂降解的更快,半衰期更短.除草剂咪唑乙烟酸显著增加了土壤微生物的生物量碳和总的磷脂脂肪酸(PLFA)含量,而且原药的增加作用更加显著.原药显著提高了土壤微生物的GN/GP值和压力指数(Stress level);原药和制剂显著降低了微生物的真菌/细菌值和多样性指数(Shannon指数).除草剂咪唑乙炯酸显著影响了土壤微生物的群落结构,而且原药比制剂的影响更加显著.     

土壤微生物多样性研究的新进展

土壤微生物是土壤生态系统的一个重要组成部分,在维持整个土壤生态系统能量流动和物质循环中发挥着关键作用,同时,土壤微生物多样性影响土壤生态系统的结构、功能和过程。因此,对土壤微生物多样性的研究有着重大意义。本文从土壤微生物多样性的影响因素以及目前该领域研究所采用的研究方法等方面阐述了国内外土壤微生物多样性的研究现状,同时对各种研究方法的适用范围、优缺点等作了较为详细的分析、比较,并对该领域未来研究工作的重点方面作了展望。     

Relationships Between Phenolics and Soil Microorganisms in Spruce Forests: Significance for Natural Regeneration

Plant-produced phenolic compounds inhibit soil microbial activity and are suspected to be involved in the failure of natural regeneration of French subalpine Norway spruce (Picea abies) forests. This work evaluated relationships between phenolic compounds and soil microorganisms in humus collected in spruce forest during winter and summer seasons. After having identified and quantified different phenolics from humus samples, we incubated another set of humus samples with 10 times the concentration of naturally occurring phenolics, and effects on the density of microorganisms were compared to humus with no addition of phenolic compounds. Furthermore, in order to follow the degradation of phenolic compounds by microbes, the concentration of phenolics in the incubated humus samples was determined by HPLC after three and six days of incubation. The results indicate that humus microorganisms use phenolics as a carbon source, since almost all phenolic compounds had disappeared after six days of incubation. Addition of phenolic compounds to the humus samples also affected the soil microbial populations so that bacteria were inhibited in the humus collected both in the winter and in the summer. However, there were differences between the experiments. Fungi and cellulose hydrolyzers were stimulated in the winter humus experiment, while fungi were unaffected and cellulose hydrolyzers were inhibited in the summer experiment. The addition of phenolic compounds stimulated ammonifiers in the summer experiment. We anticipate that the role of soil microorganisms in the problem of natural regeneration failure is probably more important than previously thought.     

多菌灵在土壤中的降解及其生态环境效应

多菌灵是国内外广泛使用的一种茎叶喷洒类杀菌剂,过量施用或者喷施后降雨、灌溉会使多菌灵在土壤中累积。明确多菌灵在土壤中的降解转化过程以及对土壤生态环境的影响对于合理施用杀菌剂具有重要意义。综述了多菌灵在土壤中降解的影响因素以及对土壤微生物和氮素转化过程影响的研究进展。认为未来还需进一步加强多菌灵对微生物结构和组成的影响以及对土壤肥力和生态环境影响的综合评价等方面的研究。     

增值尿素的氨挥发特征及其对土壤微生物量碳和脲酶活性的影响

通过向普通尿素中添加风化煤粉、腐植酸钾和脱盐液,利用熔融造粒工艺制备出普通尿素（U）、风化煤尿素（F U）、腐植酸尿素（H A U）、脱盐液尿素（T U）3个增值尿素试验产品,在25℃条件下,进行土壤培养试验,研究了增值尿素的氨挥发特征及其对土壤微生物量碳、脲酶活性的影响。结果表明,与普通尿素相比,各增值尿素氨挥发累积量降低29.52%～39.78%,延迟了氨挥发的峰值;各增值尿素处理,在培养的前7天内土壤的脲酶活性降低,延缓了尿素态氮在土壤的转化速率;延缓了土壤微生物量碳峰值出现时间;风化煤和腐植酸尿素处理在整个培养期内表现处理了较好的稳定性,减少氨挥发效果明显。     

矿区复垦土壤微生物群落和功能多样性分析

采用复合基质和丛枝菌根真菌对矿区土壤进行九个月的复垦。为评估复垦效果,利用Biolog方法分析不同复垦时期土壤微生物群落和功能多样性。借助SPSS17．0等软件进行分析,发现微生物群落各项指标在不同复垦阶段的变化明显;对比复垦稳定土和校园绿地土可知,土壤微生物活性及群落功能多样性得到显著改善,并恢复至正常水平。究其原因,是复垦基质中添加30％的污泥以及接种丛植菌根真菌。     

多粘类芽孢杆菌在黄瓜叶面和土壤中定殖能力及其对土壤微生物的影响

研究了康地蕾得有效成分多粘类芽孢杆菌在黄瓜叶面和土壤中的定殖情况及其对土壤微生物的影响。结果表明：在田间条件下,多粘类芽孢杆菌在黄瓜叶片上的定殖菌量为0．9×10^6～2．3×10^6cfu／g鲜叶,在土壤中的定殖菌量为0．8×10^7～1．6×10^7cfu／g土;施用该药剂30d后,仅使土壤中细菌菌数有明显增加,对真菌、放线菌无明显影响。     

Soil application of ash produced by low-temperature fluidized bed gasification: effects on soil nutrient dynamics and crop response

Recycling of residual products of bioenergy conversion processes is important for adding value to the technologies and as a potential beneficial soil fertility amendment. In this study, two different ash materials originating from low temperature circulating fluidized bed (LT-CFB) gasification of either wheat straw (SA) or residue fibers mainly from citrus peels (CP) were tested regarding their potential to be used as fertilizer on agricultural soils. A soil incubation study, a greenhouse experiment with barley and faba bean, and an accompanying outdoor experiment with maize were carried out to investigate the effects of the ashes on soil microbiological and chemical properties and on the response of the three crops. The ash treatments were compared with a control treatment that received only nitrogen, magnesium, and sulphur (CO) and a fully fertilized control (COPK). Soil microbial parameters were not significantly altered after ash application. SA was generally able to increase the levels of Olsen-P and of the ammonium acetate/acetic acid-extractable K in soil as well as to improve the yield of barley and maize, whereas faba bean did not react positively to ash amendment. CP did not show beneficial effects on soil nutrient levels or on crop biomass. We conclude from the results of this study, that??depending on the feedstock used??ashes from LT-CFB gasification of plant biomass can be used to replace mineral fertilizers if they are applied according to their nutrient content, the crop demand, and soil properties.     

土壤微生物降解磺酰脲类除草剂的研究进展

简要地综述了土壤微生物对磺酰脲类除草剂的降解、降解机理及影响微生物降解磺酰脲类除草剂的因素,并指出了利用土壤微生物修复磺酰脲类除草剂的残留药害是一个有效手段。     

Soil microbial communities in different rangeland management systems of a sandy savanna and clayey grassland ecosystem,South Africa

Soil nutrient supply in rangelands depends on the maintenance and performance of soil microbiological communities. In this study we investigated how different rangeland management systems affects the structure and function of soil microbial communities in the clayey grassland and sandy savanna ecosystems, South Africa. These ecosystems differ in climate, soil and vegetation, with the sandy savanna ecosystem being drier, and encroached by bush. Soils were sampled under continuous and rotational grazing systems along a gradient with increasing grazing pressure. Analyses comprised of enzyme activities and phospholipid fatty acids (PLFA). The results revealed that the clayey grassland ecosystem displayed elevated enzyme activities and PLFA contents compared with the drier, sandy savanna ecosystem, irrespective of the rangeland management practices, likely because soil texture played a significant role in maintaining microbial communities. However, when microbial activity was normalized to carbon, nitrogen and microbial biomass, specific enzyme activities were significantly higher in the sandy savanna ecosystem, indicating a more efficient functioning of microbes here. Furthermore, these microbial parameters were more sensitive to grazing pressure in the clayey grassland ecosystem than other chemical or physical soil properties, whereas in the sandy savanna ecosystem this was not the case. Decreasing the grazing pressure on rangeland, as, e.g., done by commercial farmers practicing rotational grazing, appeared to stimulate microbial performance and thus microbial mediated nutrient mineralization with positive consequences on plant growth.     

Relationships between culturable soil microbial populations and gross nitrogen transformation processes in a clay loam soil across ecosystems

The size and quality of the soil organic matter (SOM) pool can vary between ecosystems and can affect many soil properties. The objectives of this study were to examine the relationship between gross N transformation rates and microbial populations and to investigate the role that SOM plays in these factors. In our study, culturable microbial and actinomycete populations were positively correlated with gross mineralization and ammonium (NH₄⁺) consumption rates over time in both ecosystems. These correlations provide evidence that microbial plate counts could be a good representation of all microbes responsible for gross mineralization and gross NH₄⁺ consumption. Rates of gross mineralization, nitrification and NH₄⁺ consumption were significantly greater in forest soil than old-field soil. These greater rates in forest soil could be due to the presence of higher levels of readily transferable substrates in SOM. Gross nitrification rates were considerably lower than gross mineralization and NH₄⁺ consumption rates over the experimental period, indicating heterotrophic uptake of NH₄⁺ rather than use by autotrophic nitrifiers under soil and environmental conditions in this study. Additionally, microbial populations were significantly (p<0.01) greater in forest soil than in old-field soil, which could also be related to the higher level of SOM in the forest soil. Net mineralization and nitrification rates were similar between ecosystems. Results also showed that net rates were highly correlated to each other, but were not correlated with culturable microbes or gross N transformation rates, indicating the isolation of net rates in relation to fundamental controlling factors.     

不同侵蚀部位微生物变异性研究

土壤是一个由生物和非生物组成的复杂综合体,肥力是土壤的本质和属性。土壤养分含量和土壤微生物特征是表示土壤肥力高低的重要指标,水土流失不仅导致土壤养分含量下降,而且对土壤微生物特征产生明显的影响,进而影响到土壤养分的循环和转化。本研究对华南赤红壤丘陵坡地不同侵蚀部位微生物特性的变异性进行了对比分析。结果表明：随着土壤侵蚀程度的加剧和植被的破坏,土壤微生物总数逐渐减少,土壤基础呼吸和土壤诱导呼吸显著下降。在没有草本植物的情况下,仅有人工荷木并不能起到明显的水土保持作用,近地表覆盖的草本植物应是水土保持植被建设必不可少植物类群。以此为华南赤红壤丘陵区土壤生态环境修复和水土保持提供科学依据。     

辛硫磷对土壤微生物种群结构的影响

采用室内培养法研究了土壤中200～1000mg／kg三种不同质量分数的辛硫磷对好氧性细菌、真菌和放线菌三大主要微生物种群数量及其优势菌生长速率的影响。结果表明,土壤中各微生物种群对不同质量分数的辛硫磷具有各自不同的反应。辛硫磷对细菌种群数量及优势细菌生长速率的影响表现为明显的刺激效应,且随加药质量分数的提高刺激效应越明显,而且对种群数量的刺激效应随加药时间延长趋势越明显;对放线菌种群数量的影响表现为抑制效应,且随药剂质量分数的提高抑制效应越明显。但随着加药时间的延长,这种抑制效应又趋于减弱．逐渐恢复到正常水平。但对优势放线菌生长速率的影响却表现为刺激效应;对真菌种群数量及优势真菌生长速率的影响也表现为抑制效应,且随药剂质量分数的提高和加药时间的延长抑制效应越明显。因此,有望从土壤中筛选到能降解辛硫磷的细菌,同时真菌可以作为土壤受辛硫磷污染的敏感指示菌。