滨海沙地簕竹属10个竹种根际土壤酶活性研究

对滨海沙地簕竹属10个竹种根际土壤酶活性和土壤养分进行测定分析,结果表明:(1)不同竹种根际土壤酶活性表现为河边竹、破蔑竹具有较高的蔗糖酶活性;观音竹、青皮竹具有较高的蛋白酶活性;佛肚竹、黄金间碧竹具有较高的脲酶活性;纤维素酶活性较高的为青竿竹、凤尾竹;过氧化氢酶活性较高为青皮竹、青竿竹。(2)青竿竹、佛肚竹、黄金间碧竹、凤尾竹、观音竹、鼓节竹等竹种根际土壤有机质、氮、磷、钾元素含量高于其他竹种,且显著高于裸地。(3)相关性分析表明,酶活性与pH呈现负相关,有机质与酶活性达到极显著与显著水平相关,而脲酶、纤维素酶与土壤养分元素达到极显著与显著相关水平,表明了土壤酶活性能够作为表征土壤肥力情况的一个指标。     

基于宏基因组学16S rDNA测序对烟草根际土壤细菌群落组成分析

为了研究烟草根际土壤细菌多样性,了解其细菌群落的组成和结构,从而为健康植烟土壤生态系统的构建和保持提供理论依据和指导。以2014年四川凉山州健康烟株现蕾期根际土壤为研究样本,利用Illumina平台Miseq高通量测序技术对烟草根际土壤细菌16S rDNA进行高通量测序分析。结果表明:烟草根际土壤微生物多样性水平较高,不同样品间主要菌落分布结构相对稳定。在门分类水平上,共检测分类25个菌门,其中变形菌门占有明显优势(39.04%~53.71%),其次为拟杆菌门、酸杆菌门、疣微菌门;在属分类水平上,共检测分类576类菌属,鞘脂单胞菌属、Flavisolibacter、Ohtaekwangia为烟草根际土壤细菌明显优势菌属。大部分主要菌群之间存在明显正相关关系,对烟草根际土壤细菌影响较大的环境因子为土壤速效氮、含水量和pH。运用宏基因组学16S rDNA测序技术获取的烟草根际土壤细菌信息较为丰富,为健康植烟土壤机制研究提供新的理论参考。     

广玉兰对柴油污染土壤中多环芳烃的修复作用研究

利用盆栽试验方法,在3个多环芳烃污染水平（重度L3）、（中度L2）、（轻度L1）下,研究了广玉兰（Magnoliagrandiflora）对柴油污染土壤中多环芳烃的修复作用。结果表明：（1）植物存在能有效提高PAHs的降解率,特别是促进高环组分的降解;（2）植物存在能显著提高土壤微生物的数量,且植物种植对放线菌的影响最大,真菌次之,细菌最小;（3）植物-微生物间的交互作用、微生物降解是植物-土壤系统修复PAHs污染的主要途径。     

低磷胁迫下箭筈豌豆和毛叶苕子根际过程的差异比较

采用我国北方两个豆科绿肥品种: 箭筈豌豆（Vicia sativa L.）与毛叶苕子（Vicia villosa Roth）,在控制条件下通过不同供磷处理的营养液培养,研究了不同绿肥作物适应低磷胁迫根际过程的差异,并揭示其高效利用磷的机理。试验通过分次取样的方法,测定了两种豆科作物在缺磷与供磷条件下的生物量、根系质子释放速率、根系有机酸分泌速率以及根表酸性磷酸酶活性的动态。结果表明,箭筈豌豆与毛叶苕子在生长前期对低磷胁迫的响应存在明显差异。箭筈豌豆主要靠增大质子释放量和提高酸性磷酸酶活性来适应低磷胁迫; 而毛叶苕子主要通过提高根冠比、扩大根系生物量来对外界环境中的缺磷状况做出响应,在缺磷时其根表酸性磷酸酶的活性显著提高。箭筈豌豆与毛叶苕子可通过协调根系形态和生理的适应性变化提高对磷的吸收。     

混种牧草对紫茎泽兰根际土壤微生物的影响

外来入侵植物与入侵地土壤微生物群落之间的互作关系,影响外来植物的入侵力和生态系统的抵御功能。在紫茎泽兰入侵区利用非洲狗尾草进行替代控制,测量紫茎泽兰根际土壤微生物的变化结果显示,混种区根际土壤微生物之间及其与紫茎泽兰生物量之间的相关性较入侵对照区显著增强(P0.05),表明混种非洲狗尾草可加强紫茎泽兰入侵区根际土壤微生物的互利共生关系,有利于土壤微生物多样性的改善,可明显降低紫茎泽兰的生长势。     

Effect of Different Fertilizer Treatments on Quantity of Soil Microbes and Structure of Ammonium Oxidizing Bacterial Community in a Calcareous Purple Paddy Soil

The quantity of soil microbes and the structure of ammonium oxidizing bacterial （AOB） community were analyzed using the dilution plate counting and most probable number method （MPN）, and denaturing gradient gel electrophoresis （DGGE）, respectively. Fertilizer application tended to increase the number of soil microbes and alter the AOB community compared to the control with no fertilizer application （CK）. Among the eight fertilizer treatments, soil samples from the treatments of mineral fertilizers （e.g., N, P, K） in combination with farmyard manure （M） had greater number.s of soil microbes and more complex structure of AOB community than those receiving mineral fertilizers alone. The principal component analyses （PCA） for ammonium oxidizing bacterial community structure showed that the eight fertilizer treatments could be divided into two PCA groups （PCA1 and PCA2）. For the soil sampled after rice harvest, PCA1 included NP, NM, NPM and NPKM fertilizer treatments, while PCA2 was consisted of CK, N, M and NPK fertilizer treatments. For soil samples collected after wheat harvest, PCA1 was consisted of M, NM, NPM and NPKM fertilizer treatments, while PCA2 was composed of CK, N, NP and NPK fertilizer treatments. For a given rotation, the richness of AOB community in PCA1 was greater than that in PCA2. In addition, AOB community structure was more complex in the soil after rice harvest than that after wheat harvest. The results indicated that different fertilizer treatments resulted in substantial changes of soil microbe number and AOB community. Furthermore, mineral fertilizers （N, NP, NPK） combined with farmyard manure were effective for increasing the quantity of soil microbes, enriching AOB community, and improving the soil biofertility.     

野生太白贝母生境调查与根际土壤分析

为了解野生太白贝母的生境及根际土壤状况,对太白县等4个县域的野生太白贝母进行了实地调查.结果显示:太白贝母生于海拔2000～3300 m的山地草丛或林下,海拔是影响太白贝母生境适宜性最重要的生态因子,生境内植物分布具有明显的高海拔特征,乔木层多为落叶阔叶林,郁闭度较高,林下灌木层大多呈现稀疏状.不同产地太白贝母根际土壤...     

施用芝麻饼肥对植烟根际土壤酶活性和微生物碳、氮的影响

采用盆栽试验研究了施用芝麻饼肥对烟草根际土壤酶活性和微生物C、N的影响。结果表明,施用芝麻饼肥可明显提高根际土壤酶活性和土壤微生物C和N含量,芝麻饼肥和化肥配施(CF)与单施化肥(F)相比,根际土壤脂肪酶、转化酶和脲酶活性分别提高了24.85%～60.00%、23.08%～39.46%和4.17%～56.21%;根际土壤微生物C、N含量分别提高79.88%～97.14%和29.73%～74.96%。表明施用芝麻饼肥土壤生物过程活跃,有利于土壤有机物质的转化和烤烟正常生长所需的营养供应。在烟草不同生育期,根际土壤微生物C和微生物N含量动态变化不同,土壤微生物C含量在现蕾期达到最高值,而土壤微生物N含量高峰出现在团棵期。随着烟草的生长发育土壤微生物N逐渐降低,表明一部分微生物N又被释放出来,以供烟草生长发育需要;到成熟期明显降低,反映出土壤微生物N在协调土壤N素供应方面的重要作用。适量饼肥与化肥配合施用,有利于平衡烟草N素营养,改善烟叶品质。     

Effects of nitrate addition to a diet on fermentation and microbial populations in the rumen of goats,with special reference to Selenomonas ruminantium having the ability to reduce nitrate and nitrite

This study investigated the effects of dietary nitrate addition on ruminal fermentation characteristics and microbial populations in goats. The involvement of Selenomonas ruminantium in nitrate and nitrite reduction in the rumen was also examined. As the result of nitrate feeding, the total concentration of ruminal volatile fatty acids decreased, whereas the acetate : propionate ratio and the concentrations of ammonia and lactate increased. Populations of methanogens, protozoa and fungi, as estimated by real‐time PCR, were greatly decreased as a result of nitrate inclusion in the diet. There was modest or little impact of nitrate on the populations of prevailing species or genus of bacteria in the rumen, whereas Streptococcus bovis and S. ruminantium significantly increased. Both the activities of nitrate reductase (NaR) and nitrite reductase (NiR) per total mass of ruminal bacteria were increased by nitrate feeding. Quantification of the genes encoding NaR and NiR by real‐time PCR with primers specific for S. ruminantium showed that these genes were increased by feeding nitrate, suggesting that the growth of nitrate‐ and nitrite‐reducing S. ruminantium is stimulated by nitrate addition. Thus, S. ruminantium is likely to play a major role in nitrate and nitrite reduction in the rumen.     

异噁唑草酮对玉米根际土壤微生物量碳、氮和酶活性的影响

为明确异噁唑草酮对玉米根际土壤微生物碳、氮及酶活性的影响, 采用田间试验的方法, 以1倍、5倍和10倍田间推荐剂量为供试除草剂剂量, 测定了异噁唑草酮土壤封闭处理对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶、蔗糖酶、脱氢酶和中性磷酸酶活性的影响。结果表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量无显著影响, 5倍和10倍推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量具有抑制作用。推荐剂量的异噁唑草酮对玉米根际土壤脲酶、过氧化氢酶和蔗糖酶影响较小, 5倍和10倍推荐剂量的异噁唑草酮对其具有明显的抑制作用。异噁唑草酮对土壤脱氢酶活性具有抑制作用, 且施用剂量越高, 抑制作用越强。异噁唑草酮对土壤中性磷酸酶活性的影响表现为前期促进, 后期抑制, 且施用剂量越大, 促进或抑制作用越强。研究表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶和蔗糖酶活性的影响较小, 但对土壤脱氢酶、中性磷酸酶活性有影响。