施肥模式对连作草莓枯萎病控制效果及土壤微生物群落特征的影响

通过营养调控防治连作病害是近年来的发展方向之一。本研究通过不同施肥处理的田间小区试验,采用微生物培养方法和Biolog微生物自动分析系统分析了不同施肥模式下草莓抗病能力、连作土壤微生物群落特征。研究结果表明:与当地习惯施肥相比,优化施肥模式I和II可以促进草莓生长,并有效地控制草莓枯萎病;优化施肥模式I提高了草莓连作土壤细菌/真菌和放线菌/真菌比例;Biolog结果显示在短期内不同施肥模式对土壤微生物群落碳源利用能力和Shannon指数、Simpson指数、Mcintosh指数的影响有限;PCA分析表明,优化施肥模式I的土壤微生物群落碳源利用特征与当地习惯施肥模式明显不同。综合考虑控病效果及施肥量,优化施肥模式I是更为经济有效的施肥模式。     

Do water regimes affect iron‐plaque formation and microbial communities in the rhizosphere of paddy rice?

Pot experiments were conducted to investigate the effect of soil water regimes on the formation of iron (Fe) plaque on the root surface of rice seedlings (Oryza sativa L.) and on the microbial functional diversity in a paddy soil. The rice seedlings were subjected to three moisture regimes (submergence, 100%, and 60% water‐holding capacity [WHC]), and were grown for 5 and 11 weeks. Aerobic lithotrophic Fe(II)‐oxidizing (FeOB) and acetate‐utilizing Fe(III)‐reducing bacteria (FeRB) in the rhizosphere and non‐rhizosphere soil were determined at 5 weeks using the most probable number (MPN) method. The carbon substrate use patterns of the microbial communities in the rhizosphere and non‐rhizosphere soil samples were determined at 11 weeks using Biolog‐GN2 plates. The amount of Fe plaque (per unit dry root weight) was much higher under submerged conditions than at lower soil moisture contents and decreased with plant age. There was a positive correlation between the amount of Fe plaque and phosphorus accumulated in the Fe plaque at both sampling times (r = 0.98 and 0.92, respectively, n = 12). Numbers of FeOB and FeRB in the submerged soil were lower than in aerobic soil, but by two orders of magnitude higher in the rhizosphere than in the bulk soil. On the other hand, the functional diversity of the rhizosphere microbial communities was much higher than that of the non‐rhizosphere soil, irrespective of soil water regimes. We conclude that soil flooding results in a decreased number and diversity of Fe‐oxidizing/reducing bacteria, while increasing the Fe‐plaque formation.     

外源磺胺二甲嘧啶对施用粪肥的菜地土壤中微生物群落多样性的影响

【目的】明确磺胺二甲嘧啶(SM2)随粪便施入土壤对土壤微生物群落造成的影响,为合理进行养殖场周围土壤环境质量评估和施肥管理提供参考依据。【方法】收集养殖场附近未经抗生素污染的粪便和土壤,构建粪便–土壤模型,设置不同SM2添加剂量的处理,分别为对照组(0)、低剂量组(5μg·kg~(-1))、中剂量组(500μg·kg~(-1))和高剂量组(5 000μg·kg~(-1)),并分别于粪便和SM2施入1、7、14和50 d后采集土壤样品,采用Biolog技术以及磷脂脂肪酸(Phospholipid fatty acid,PLFA)标记法对比分析不同处理组土壤微生物群落的碳源利用能力、菌群结构和功能多样性变化。【结果】SM2的施入提高了土壤微生物群落的总体碳源利用能力,中、高剂量组在施入50 d时对除酯类以外的其他碳源利用能力均强于对照组。低剂量组在施入7 d内对各类碳源利用能力增强,中、高剂量SM2的施入可能会影响土壤群落某些优势物种的繁殖和数量分配。随施入时间的延长,土壤微生物群落对不同剂量SM2反应不同,革兰阳性菌、革兰阴性菌以及真菌数量变化显著,放线菌变化不明显。【结论】SM2的施入将长期影响土壤微生物群落的结构与功能多样性。养殖场应及时处理动物排泄物以消除抗生素残留,减少粪肥对土壤环境造成的生态破坏。     

种植方式对玉米不同生长期土壤微生物群落功能多样性的影响

为探讨玉米不同种植方式下土壤微生物群落功能多样性的差异,进行田间定点试验,采用Biolog方法分别研究了4行轮作、4行连作、8行轮作和8行连作的种植方式对玉米种植前、拔节期、抽穗期和收获期土壤微生物功能多样性的影响。结果表明:4种种植方式的土壤微生物均在种植前代谢活性最弱、功能多样性最低,在玉米抽穗期土壤微生物代谢活性最强,功能多样性最高。在种植玉米前,轮作的土壤微生物代谢活性和功能多样性高于连作,8行轮作和4行轮作土壤微生物的物种多样性指数分别比相应的连作高22.93%和11.42%;4行轮作的土壤微生物物种多样性指数比8行轮作低3.17%,而4行连作比8行连作高6.83%。在玉米拔节期、抽穗期及收获期连作土壤微生物功能多样性略高于轮作,且有4行连作大于8行连作的趋势,但差异均未达显著水平。种植前,4种种植模式的土壤微生物对6大类碳源的利用程度整体上都较低,降解碳水化合物类、羧酸类和聚合物类碳源的微生物是种植方式影响的主要土壤微生物类群;随着玉米的生长,土壤微生物对6大类碳源的利用都逐渐增强,玉米拔节期、抽穗期和收获期之间土壤微生物特征碳源没有较大差异,4种种植方式的土壤微生物对聚合物类碳源利用程度差异都不显著。PLS-EDA分析结果表明种植方式对土壤微生物产生较大影响,种植前8行轮作和4行连作的土壤微生物碳源利用模式具有相似性;种植玉米后4种种植方式的土壤微生物对碳源的利用模式存在较大差异,其中4行连作的土壤微生物在玉米拔节期和收获期对碳源的利用模式与其他3种种植方式差异最大。试验说明作物长期连作栽培会影响土壤微生物群落功能,降低土壤微生物物种多样性,引起土壤微生物群落结构与功能的失调。     

Relationship between soil chemical properties and microbial metabolic patterns in intensive greenhouse tomato production systems

ABSTRACT

Intensive greenhouse production involving excessive fertilizer and organic manure application rates may affect soil chemical and biological quality. Soil samples from 50 commercial greenhouses for tomato production in northern China were collected for the evaluation of the status of soil fertility and identification of the soil chemical factor that exerts the strongest influence on microbial functional diversity. The soil total nitrogen content showed high soil fertility and was 68% higher than 1000 mg kg^?1 and 14% higher than 1500 mg kg^?1. Differential soil pH values caused statistically significant shifts in microbial metabolic activity (average well color development, AWCD) and Shannon’s diversity index using Biolog^TM ECO plates assay. The highest soil microbial functional diversity was observed at near neutral pH values. When individual data points were plotted against soil organic matter (SOM), significant positive associations with soil microbial biomass nitrogen and AWCD were observed. The canonical correspondence analysis confirmed that shifts in the soil microbial functional diversity were associated with changes in pH, total nitrogen, and SOM. This study indicated that excessive fertilization changed the community-level physiological profile of the soil microorganisms, and this effect can be a consequence of changes in soil pH under intensive greenhouse management.     

植物病原细菌的BIOLOG系统鉴定及其多元统计初析

利用Biolog细菌鉴定系统对我国水稻上几种条斑病菌及其相关菌株进行了快速鉴定研究。结果表明16株供试菌株中12株准确鉴定到种或致病变种,有4株鉴定到属。聚类分析显示李氏禾条斑病菌和“稻短条斑病菌”的Biolog代谢指纹相似性高,与小麦黑颖病菌（TAS）亲缘关系较近,而与水稻条斑病菌、稻白叶枯病菌具有明显差异。使用多元统计分析方法对供试菌株的Biolog代谢指纹进行比较研究,通过聚类分析和主成份分析不仅能够区分菌株间的显著差异,而且依据因子权重值可筛选出具有鉴别价值的碳源。     

北京地区一株葡萄酸腐病相关酵母菌的分离鉴定

近年来葡萄酸腐病在中国葡萄主要产区发生普遍而严重,已成为葡萄生产上的重要病害之一,但目前该病害的病原不明确且存在争议。采用组织分离法从北京地区采集的葡萄酸腐病病果上分离纯化出一株酵母菌sf-19,采用形态学特征观察、Biolog微生物自动分析系统和26SrDNA D1/D2区序列分析,将菌株sf-19鉴定为葡萄汁有孢汉逊酵母(Hanseniaspora uvarum)。致病性测定发现,酵母菌sf-19菌株可引起葡萄果实腐烂,且从接种腐烂的果实中又分离出葡萄汁有孢汉逊酵母。结果表明:葡萄汁有孢汉逊酵母是引起中国葡萄酸腐病的相关酵母菌之一。     

The fungicides thiram and captan affect the phenotypic characteristics of Rhizobium leguminosarum strain C1 as determined by FAME and Biolog analyses

 We assessed the effects of the fungicides captan and thiram on the survival and phenotypic characteristics of Rhizobium leguminosarum bv. viceae, strain C1. Fungicide was applied to pea seed at rates of 0.25–2 g a.i. kg^–1 seed, and treated seed was inoculated with strain C1. After 24 h, rhizobia were extracted from treated seed and viable numbers determined by plating onto yeast extract mannitol agar. Phenotypic characteristics were assessed using FAME (fatty acid methyl ester) profiles and Biolog substrate utilization patterns. Captan and thiram significantly reduced the numbers of rhizobia recovered from seed and altered the FAME and Biolog profiles of recovered rhizobia. However, only the highest concentrations of captan affected nodulation and plant growth. Contact with some seed-applied fungicides can significantly alter phenotypic characteristics of rhizobia, but these changes might be offset by the presence of host plants. Received: 20 February 1999     

Changes in microbial community metabolism and labile organic matter fractions as early indicators of the impact of management on soil biological quality

 Changes to the metabolic profiles of soil microbial communities could have potential for use as early indicators of the impact of management or other perturbations on soil functioning and soil quality. We compared the relative susceptibility to management of microbial community metabolism with a number of soil organic matter (OM) and microbial parameters currently used as indicators of changes in soil biological quality. Following long-term cereal cropping, plots were subjected to a 16-month treatment period consisting of either a mixed cropping sequence of vetch, spring barley and clover or a continuous grass-clover ley which was periodically mown and mulched. The treatments had no effect on soil biomass N or respiration of microbial populations inoculated into Biolog Gram negative (GN) plates. After 16 months there were no management-induced changes to total OM, light-fraction OM C and N, labile organic N or water-soluble carbohydrates. However, patterns of substrate utilization by the soil microbial population following inoculation into Biolog GN plates were found to be highly sensitive to management practice. In the mixed cropping sequence, substrate utilization changed markedly following plough-in of the vetch crop, with a smaller change occurring after harvesting of the barley. In the ley treatment, substrate utilization was not affected until the onset of mowing, when the pattern changed to become similar to that in the mixed cropping sequence. Metabolic diversity of the Biolog-culturable microbial population was increased by the ley treatment, but was not affected by the cropping sequence. We conclude that patterns of microbial substrate utilization and metabolic diversity are more sensitive to the effects of management than are OM and biomass pools, and therefore have value as early indicators of the impacts of management on soil biological properties, and hence soil quality. Received: 7 April 1999     

生物复混肥对土壤微生物群落功能多样性和微生物量的影响

在温室盆栽条件下,采用Biolog微平板法和氯仿熏蒸浸提法,研究了玉米施用等养分量的无机肥、有机无机复混肥和生物复混肥后土壤微生物群落功能多样性及土壤微生物量的变化。结果表明:生物复混肥处理的土壤微生物平均颜色变化率(AWCD)、微生物群落Shannon指数(H)和微生物群落丰富度指数(S)均最高;施用生物复混肥可明显提高土壤微生物对碳源的利用率,尤其是多酚化合物类和糖类;不同处理土壤微生物碳源利用特征有一定差异,生物复混肥在第1主成分上的得分值为正值,其他各处理在第1主成分上的得分值基本上为负值,起分异作用的主要碳源是糖类和羧酸类。在玉米生长期间各处理土壤微生物量大致呈先升高后逐渐平稳的趋势,且土壤微生物量碳、氮、磷的含量均以生物复混肥处理最高,最高值分别为333.21mg.kg 1、53.02 mg.kg 1和22.20 mg.kg 1。研究表明,生物复混肥的施用比等养分量的有机无机复混肥处理能显著提高土壤微生物群落碳源利用率、微生物群落丰富度和功能多样性,显著增加土壤微生物量碳、氮、磷的含量,有利于维持良好的土壤微生态环境。