不同青枯病抗性的番茄品种内生细菌生理群数量研究

本论文对青枯病抗性不同的番茄品种其内生细菌生理群数量变化进行了研究,结果表明,番茄内生细菌生理群数量的变化随品种抗性、生育期和季节的不同而变化.在7大类生理群细菌中,氨化细菌的数量最多,且在幼苗期以后,高抗青枯病番茄品种中数量明显高于高感品种,初步认为,氨化细菌可能是影响青枯病发生的关键性微生物.番茄抗病品种在不同生育期,其内生细菌的总体数量要比感病品种多,呈交替波动变化.氨化细菌、硝化细菌、固氮细菌和反硫化细菌平均数量均表现为在夏季高于冬季,硫化细菌的数量则冬季高于夏季,厌气性细菌数量最少.     

新疆野生樱桃李林不同生态条件下土壤细菌数量变化及其影响因子研究

采用稀释平板法,研究了新疆野生樱桃李林3种不同样地土壤细菌数量变化及其与土壤有机质和全氮含量的相关关系。结果表明细菌数量在不同样地间的差异较大,细菌数量为林下>沟边>林窗,在P<0.01水平上,细菌数量在不同样地间的差异性显著,林下的细菌数量最多(79.15×106个/g),林窗的最少(5.71×106个/g)。土壤细菌数量垂直分布均是随着垂直深度的增加,细菌数量逐渐减少(P<0.05),其中细菌数量在林下层次间差异性显著(P<0.05),在林窗不同层次间差异性不显著(P>0.05)。土壤细菌数量与土壤有机质和全氮含量的相关分析表明,土壤细菌数量与土壤有机质和全氮含量间均存在极显著正相关。     

不同肥力条件下的桑树根际微生物种群分析

通过平板梯度稀释培养,测定了不同肥力土壤桑树根际细菌、真菌、放线菌和三类促生细菌的数量,并采用BOX-PCR技术,对根际细菌进行了聚类分析.主要结果为:肥沃土壤根际细菌和放线菌的数量均高于贫瘠土壤,而真菌数量低于贫瘠土壤;相同肥力条件下,三类促生细菌中溶磷细菌的数量最多,其次是硅酸盐细菌,固氮细菌的数量最少.根际细菌的BOX-PCR聚类分析图显示,肥沃土壤细菌分离株的DNA同源性高于贫瘠土壤,两种土壤中,促生细菌分离株的遗传进化距离比较接近.在细菌BOX-PCR图谱相异百分数为0.2的水平上,肥沃和贫瘠土壤根际细菌分别分为71个和33个聚类群,根际促生细菌分别分为33个和28个聚类群.土壤肥力对根际细菌的种类和数量都有影响,肥沃土壤根际细菌和促生细菌的数量、种类均高于贫瘠土壤.     

细菌间的通讯与细菌的致病性

细菌之间可以通过分泌和感应特定的信号分子进行“通讯”,帮助细菌判断环境中同类细菌的数量,决定自身的生长和基因表达以及毒力因子的产生。细菌的这一功能称为“数量阈值感应”。数量阈值感应与细菌的致病性有密切关系。也可以成为控制细菌致病的有效途径。     

番茄附生和内生细菌分离与群落相似性分析

为了溯清番茄生境以及各组织细菌群落间的相关性,以中杂302为试材,采用传统平板培养法结合16S r RNA拷贝数分析、变性梯度凝胶电泳(DGGE)分析,对番茄根区、根际土壤以及根、茎、叶片、果实、种子等组织附生和内生细菌的数量和群落相似性进行分析。结果表明,番茄根际的细菌数量最多,根区土壤次之;番茄组织附生细菌的数量显著低于根区和根际土壤中的细菌数量;组织附生细菌中,以根部最多,茎和叶片次之;组织内生细菌的数量较附生细菌少2-4个数量级,并以根内生细菌数量最多,种子表面胶状物中数量最少。DGGE细菌群落相似度分析表明,根际与组织内生样品间的相似度显著高于根区土壤,各组织内生细菌相互间的相似度最高,尤其是根、茎和叶片,以及种子、胎座、胶状物等相邻组织内生细菌间的相似度达到0.6以上。番茄组织尤其是相邻组织间的内生细菌群落结构相似,并与根际细菌密切相关。     

对虾综合养殖生态系底泥细菌的数量动态

1997年5～9月于山东海阳市黄海集团公司养虾场,用5个实验围隔研究了对虾综合养殖生态系底泥细菌的数量动态.结果表明,底泥细菌数量波动在4.10×108～12.36×108cells·g-1之间,平均为8.09×108±2.17×108cells·g-1.随着养殖时间的推移,底泥细菌数量逐渐增加.底泥细菌数量最大值出现在表层1cm之内,2～3cm以下泥层,细菌数量明显减小     

草莓连作土壤酚酸类物质积累对土壤线虫的影响

通过大田试验和盆栽试验相结合的方式,对不同连作年限草莓土壤酚酸类物质含量、土壤线虫数量和食细菌线虫数量以及外源酚酸类物质对土壤线虫数量和食细菌线虫数量的影响进行了研究。结果表明:随连作年限的增加,草莓连作土壤中酚酸类物质含量明显增加,土壤线虫总数和食细菌线虫总数整体呈现下降趋势,且连作5年的土壤线虫总数和食细菌线虫数量最低,酚酸类物质含量与土壤线虫总数和食细菌线虫数量呈负相关;对羟基苯甲酸和对香豆酸在浓度低于200μg·g-1时使土壤线虫总数和食细菌线虫数量增加,而高于200μg·g-1时起抑制作用;肉桂酸在浓度低于100μg·g-1时增加了土壤线虫总数和食细菌线虫数量,而高于100μg·g-1时起抑制作用;随阿魏酸浓度的增加,线虫数量变化规律不明显,当其浓度高于100μg·g-1时起抑制作用;混合酚酸随浓度增加对土壤线虫总数和食细菌线虫数量的抑制作用增强。     

秸秆覆盖免耕对土壤细菌群落区系的影响

多年连续秸秆覆盖免耕对土壤细菌群落影响很大,免耕可提高０－１０ｃｍ土层土壤细菌总数、放线菌数、棒状细菌数和贫营养细菌数量,特别是免耕土壤能使芽孢杆菌数量增多几倍。     

广西番茄内生细菌的多样性和数量动态

为了探明内生细菌在番茄中的分布和数量变化规律,有目的地筛选防治番茄青枯病的内生细菌,我们对广西可培养的番茄内生细菌的类群和数量动态进行了调查。从广西部分县市采集的303个番茄样本中分离到624株内生细菌菌株,初步确定有芽孢杆菌(Bacillus)、假单胞菌(Pseudomonas)、黄单胞菌(Xanthomonas)、棒杆菌(Corynebacterium)、土壤杆菌(Agrobacterium)、微杆菌(Microbacterium)、肠杆菌(Enterobacter)和欧文氏菌(Erwinia)8个属,其中以芽孢杆菌、假单胞菌和土壤杆菌为芽孢杆菌为优势类群。番茄内生细菌在植株器官中的分布以根部数量最多,其次是茎和叶。内生细菌的总量在番茄生育期的变化趋势是从苗期到花期数量上升,而从结果期到成熟期数量逐渐下降。多数内生细菌种群的数量变化动态符合细菌总量的变化趋势,只有微杆菌在番茄植株整个生育期中始终保持下降的趋势。春季种植的番茄植株的内生细菌类群数量比秋季种植的少。     

寡聚糖生物农药对棉花体内细菌数量和作物生长的作用

通过常规分离方法,测定寡聚糖生物农药对中棉12品种的棉茎体内细菌群落数量的影响。2批实验结果表明喷寡聚糖后棉茎体内细菌群落数量均低于对照,喷寡聚糖10d后棉茎体内细菌群落数量显著下降(8.0×10     

人工森林群落中红松、落叶松种群生态位计测方法的研究

采用树高级种群分类,在一维和多维主导生态因子梯度上,提出了人工红松森林群落、人工落叶松森林群落,红松、落叶松种群生态位计算公计算结果表明,同林令最高树高级种群只出现在土壤含水率）２５％、上壤有机质含量）６％的资源位上。     

Vertical distribution of bacterial community is associated with the degree of soil organic matter decomposition in the active layer of moist acidic tundra

The increasing temperature in Arctic tundra deepens the active layer, which is the upper layer of permafrost soil that experiences repeated thawing and freezing. The increasing of soil temperature and the deepening of active layer seem to affect soil microbial communities. Therefore, information on soil microbial communities at various soil depths is essential to understand their potential responses to climate change in the active layer soil. We investigated the community structure of soil bacteria in the active layer from moist acidic tundra in Council, Alaska. We also interpreted their relationship with some relevant soil physicochemical characteristics along soil depth with a fine scale (5 cm depth interval). The bacterial community structure was found to change along soil depth. The relative abundances of Acidobacteria, Gammaproteobacteria, Planctomycetes, and candidate phylum WPS-2 rapidly decreased with soil depth, while those of Bacteroidetes, Chloroflexi, Gemmatimonadetes, and candidate AD3 rapidly increased. A structural shift was also found in the soil bacterial communities around 20 cm depth, where two organic (upper Oi and lower Oa) horizons are subdivided. The quality and the decomposition degree of organic matter might have influenced the bacterial community structure. Besides the organic matter quality, the vertical distribution of bacterial communities was also found to be related to soil pH and total phosphorus content. This study showed the vertical change of bacterial community in the active layer with a fine scale resolution and the possible influence of the quality of soil organic matter on shaping bacterial community structure.     

稀土尾矿土壤细菌群落结构对植被修复的响应

选用赣州-安远稀土弃废尾矿及其不同植被修复的堆浸田为研究对象,调查废弃尾矿及6种不同植被修复方案下土壤理化性质的变化,并利用变性凝胶梯度电泳(DGGE)技术,分析土壤微生物群落结构对植被修复的响应。结果表明:与未修复尾矿土壤相比,经不同植被修复后的土壤理化性质均得到明显改良,其中土壤含水量、有机质含量均比未修复尾矿土壤增加2—3倍。微生物群落结构分析表明,植被修复后土壤微生物群落与废弃尾矿土壤微生物群落亲缘度仅为0.21,表明植被修复后,土壤微生物群落结构发生了明显变化,且微生物多样性、均匀度、丰富度与未修复尾矿土壤相比均有了明显的提高。而在不同植被修复方案中,以湿地松和山胡椒为优势群落的两种植被修复方案对土壤改良效果最为明显,这两种修复方案不仅能显著改善土壤的固水性、有机质含量,并且对微生物群落的改善作用也最为显著。典范对应分析表明,废弃尾矿土壤微生物群落结构受土壤p H影响最为显著,而植被修复后土壤微生物群落的环境影响因子则转变为含水量、有机质、有机碳及总磷含量。进一步揭示了微生物在植被修复过程中所起到的重要作用,并为矿山生态重建过程中的土壤改良工作提供了丰富的理论依据。     

乌梁素海野生芦苇群落生物量及影响因子分析

 对内蒙古乌梁素海湿地野生芦苇(Phragmites australis)生物量的调查基础上,探讨了富营养化湖泊湿地水体的物理化学性质对芦苇生物量的影响。结果表明：1）由于环境因子的影响,芦苇群落生物量变化较大,介于1.73～3.00 kg·m-2之间;地下和地上生物量之比介于1.14～2.19之间;2）芦苇群落生物量受多种因素的影响,其中水深是最主要的限制因子,水上生物量和地上生物量随着水深的增加而增加,而地下与地上生物量的比值则随水深的增加而减少,这主要是由于水深改变了芦苇群落的结构（群落密度）和个体形态(株高和株茎);3）芦苇群落生物量随着水体N浓度增加而增加。芦苇各器官（叶、茎、根状茎和根）的N∶P为7.59～12.21,小于14,这也说明该水体中的N负荷是影响芦苇生长的主要限制因子;4）土壤有机质分解对芦苇生长没有产生毒害作用。     

东北羊草草原羊草种群生长与环境关系的研究

本文研究了东北单草草原单草种群的生长, 并利用灰色系统理论考查了环境因子对单草生长的作用规律. 结果表明:羊草种群的生长具有明显的季节进程, 7-8月份生长最快, 生长速率为0.20-0.403g/m²·d, 相对单草的生长. 土壤水解氮、速效钾、活性有机质、温度、pH值和有效磷具有较大的灰色关联度, 其中水解氮、速效钾和活性有机质是羊草生长的优势因子, pH值是限制因子. 羊草生长的最优模型为y=4.74x₁+6.15x₂+2.48x₃-73.64.     

冬虫夏草生境选择主导因子

采用样方法对冬虫夏草生境的海拔、坡度、植被和土壤等环境因子进行了探索研究。结果表明:(1)冬虫夏草主要分布在海拔4000～4500m、坡度为15°～30°的上坡位高山草甸中。(2)PCA分析表明:植被和地形是影响冬虫夏草分布的主导因子。(3)不同深度土壤养分含量统计分析表明:在不同深度层次的土壤中,水分、pH值、全氮和全磷的差异不显著,有机质、有机碳、水解氮和有效磷的差异极显著。(4)对土壤养分含量判别分析表明:5cm土壤中,吸湿水、有机碳、有机质和水解氮显著影响冬虫夏草种群分布;15cm土壤中,全氮显著影响冬虫夏草种群分布;25cm土壤中,吸湿水、有机碳和有机质显著影响冬虫夏草种群分布;而自由水、pH值、全磷和有效磷对冬虫夏草种群分布的影响不显著。(5)植物盖度、植物数量和坡度直接影响冬虫夏草种群分布,而土壤则通过影响植物和土壤温湿度来间接影响冬虫夏草种群分布。     

河西走廊盐化草甸主要植物群落分布特点及其土壤环境特征

 采用系统网格法调查河西走廊盐化草甸典型地段的植被和土壤环境因素,用DCA排序技术进行定量分析,来划分该区植物群落的分布格局,并以土壤环境指标(有机质、全盐含量、pH值、潜水位埋深)解释其所形成的5个样方组,反映出内陆干旱次生盐渍化区土壤水盐分布的差别同潜水位的关系。     

Comparison of temperature effects on soil respiration and bacterial and fungal growth rates

Temperature is an important factor regulating microbial activity and shaping the soil microbial community. Little is known, however, on how temperature affects the most important groups of the soil microorganisms, the bacteria and the fungi, in situ. We have therefore measured the instantaneous total activity (respiration rate), bacterial activity (growth rate as thymidine incorporation rate) and fungal activity (growth rate as acetate-in-ergosterol incorporation rate) in soil at different temperatures (0-45 degrees C). Two soils were compared: one was an agricultural soil low in organic matter and with high pH, and the other was a forest humus soil with high organic matter content and low pH. Fungal and bacterial growth rates had optimum temperatures around 25-30 degrees C, while at higher temperatures lower values were found. This decrease was more drastic for fungi than for bacteria, resulting in an increase in the ratio of bacterial to fungal growth rate at higher temperatures. A tendency towards the opposite effect was observed at low temperatures, indicating that fungi were more adapted to low-temperature conditions than bacteria. The temperature dependence of all three activities was well modelled by the square root (Ratkowsky) model below the optimum temperature for fungal and bacterial growth. The respiration rate increased over almost the whole temperature range, showing the highest value at around 45 degrees C. Thus, at temperatures above 30 degrees C there was an uncoupling between the instantaneous respiration rate and bacterial and fungal activity. At these high temperatures, the respiration rate closely followed the Arrhenius temperature relationship.     

Nitrification and seasonal changes in bacterial populations in the rhizosphere ofSuaeda andArthrocnemum species growing in saline soils

Summary The nitrification rate in the rhizosphere of Suaeda and Arthrocnemum plants growing in saline soils, as affected by microbial populations, temperature, pH, and organic matter, was examined in the field throughout the year. The genera Nitrosomonas and Nitrobacter were most common in the rhizosphere soil. The bacterial counts in the rhizosphere of both plants fluctuated during the study period, reaching peak values during February–March and in August. The nitrate concentration in the rhizosphere soil could be related with the observed increase in the numbers of ammonium-oxidizers and nitrite-oxidizers in the latter part of the study period. The pH of the rhizosphere soils did not have any influence on the nitrification rate at the values measured. The rhizosphere organic content varied between 1.8 and 4% (w/w), showing the continuous availability of organic matter in the soil. The seasonal changes in bacterial populations in the rhizospheres of both plants was described as the result of the combination of several factors.     

东北羊草草原土壤微生物呼吸速率的研究

本文主要报道了东北羊草草原土壤微生物呼吸速率的季节变化规律,并将测试数据进行回归分析。研究表明:土壤温度和土壤水分的季节变化对土壤微生物的呼吸速率影响较大。三者呈明显的正相关,相关系数r=1。随着土壤温度升高、水分增多,微生物呼吸速率加快,但超过一定限度则呈现出呼吸速率减慢现象。土壤微生物只有在适宜的生态环境中才能进行正常的生命活动。