中国姜瘟病的研究进展

姜瘟病是中国生姜生产上发生较为普遍的病害,是由青枯劳尔氏菌(Ralstoniasolanacearum)引起的。此病原菌寄主范围广,可侵染44个科300多种植物。菌体短杆状,在TZC选择性培养基上培养出现白边较宽和白边较窄的两种菌落。菌系划分为5个生理小种和5个生化型,中国的姜瘟菌主要属生理小种1号,生物型属II、III、IV。此病害是一种较难防治的土传病害,在高温、高湿、雨水多、氮肥过量的情况下发生较为严重。中国植病工作者对此病害作了大量的研究工作,对中国姜瘟病的病原菌、发病规律、及防治等研究进展作一综述。     

工厂化生产杏鲍菇细菌性病害的防治

工厂化生产杏鲍菇细菌性病害,是由假单孢杆菌引发的重要病害,在特定的控温、控湿、控光、控CO2条件下,每年重复利用出菇房18次以上的出菇房很容易发生、并迅速传播,给杏鲍菇工厂化生产企业带来不同程度的损失;研究、制定的10条预防措施,可以有效控制病害的发生、蔓延。     

海南甜瓜细菌性果斑病田间药效试验

进行了5种药剂防治甜瓜细菌性果斑病田间药效试验。试验结果表明,第二次施药后7 d,5种药剂处理中以20%二氯异氰尿酸钠可湿性粉剂750倍液的防效最好,为65.47%,其次为53.8%可杀得(氢氧化铜)2000干悬浮剂800倍液,防效为56.45%;25%叶枯唑可湿性粉剂750倍液、72%农用链霉素可溶性粉剂3 000倍液和12%松脂酸铜乳油800倍液3个处理的防效分别为51.60%,50.86%和50.20%。上述药剂在生产上可轮换使用,5 d 1次,连续2~3次。     

草坪草立枯丝核菌病细菌防治的研究

采用平板稀释法从健康的草地早熟禾根际土壤及根表分离、纯化获得280株细菌,利用平板筛选及盆栽试验,得到3株对立枯丝核菌具有较强拮抗活性的细菌,暂定名为G10、C26和T41。     

响应面法优化解淀粉芽孢杆菌产细菌纤维素发酵条件

[目的]实现高效生产细菌纤维素(Bacterial cellulose,BC).[方法]以解淀粉芽孢杆菌ZF-7(Bacillus amyloliquefaciens ZF-7)为菌源,通过单因素试验和中心组合试验原理设计响应面法(CCRD)对其发酵生产BC的发酵条件进行优化.[结果]利用单因素试验确定了最适碳源与氮源分别为D-葡萄糖和酵母膏,并确定了D-葡萄糖、酵母膏及无水乙醇添加量对BC产量(干重)的影响.响应面法优化得到的最佳发酵条件为:葡萄糖56.1 g/L、酵母提取物9.9 g/L、乙醇17.2 ml/L.在此条件下,测得BC产量7.88 g/L,比初始产量提高了35.4％.[结论]研究可为解淀粉芽孢杆菌工业化应用提供参考.     

多种接种途径对翘嘴鳜细菌性烂鳃和败血症的免疫预防效果

多种接种途径对翘嘴鳜细菌性烂鳃和败血症的免疫预防效果陈昌福，周文豪（华中农业大学水产学院，武汉４３００７０）陈昌福等（１９９５）先后用从患细菌性烂鳃病的翘嘴鳜（ＳｉｎｉｐｅｒｃａｃｈｕａｔｓｉＢ．）上分离的柱状嗜纤维菌（Ｃｙｔｏｐｈａｇａｃｏｌｕｍｎ...     

抗青枯病花生种质资源的鉴定与筛选

为筛选适宜河南省信阳市种植的抗青枯病花生品种,对27份花生品种青枯病田间病圃进行鉴定,计算其发病率和病情指数,从而进行抗病性鉴定和筛选.结果表明,27个供试品种中,中高抗品种共10个占总数的37％,3个品种类型各筛选出2个抗病品种.6个抗病品种发病规律表明,7天和14天病情指数增长较快,21天后基本无变化.高油型花生'...     

Sewage sludge processing determines its impact on soil microbial community structure and function

Composting and thermal drying are amongst the most commonly used post-digestion processes for allowing sanitation and biological stabilization of sewage sludge from municipal treatment plants, and making it suitable as soil conditioner for use in agriculture. To assess the impact of sludge-derived materials on soil microbial properties, fresh (LAF), composted (LAC) and thermally dried (LAT) sludge fractions, each resulting from a different post-treatment process of a same aerobically digested sewage sludge, were added at 1% (w/w) application rate on two contrasting (a loam and a loamy sand) soils and incubated under laboratory conditions for 28 days. Soil respiration, microbial ATP content, hydrolytic activities and arginine ammonification rate were monitored throughout the incubation period. Results showed that soil biochemical variables, including the metabolic quotient (qCO₂), were markedly stimulated after sludge application, and the magnitude of this stimulatory effect was dependent on sludge type (precisely LAT > LAF > LAC), but not on soil type. This effect was related to the content of stable organic matter, which was lower in LAT. Genetic fingerprinting by PCR–DGGE revealed that compositional shifts of soil bacterial and, at greater extent, actinobacterial communities were responsive to the amendment with a differing sludge fraction. The observed time-dependent changes in the DGGE profiles of amended soils reflected the microbial turnover dependent on the sludge nutrient input, whereas no indications of adverse effects of sludge-borne contaminants were noted. Our findings indicate that composting rather thermal drying can represent a more appropriate post-digestion process to make sewage sludge suitable for use as soil conditioner in agriculture.     

Soil conditions and land use intensification effects on soil microbial communities across a range of European field sites

Intensive land use practices necessary for providing food and raw materials are known to have a deleterious effect on soil. However, the effects that such practices have on soil microbes are less well understood. To investigate the effects of land use intensification on soil microbial communities we used a combined T-RFLP and pyrosequencing approach to study bacteria, archaea and fungi in spring and autumn at five long term observatories (LTOs) in Europe; each with a particular land use type and contrasting levels of intensification (low and high). Generally, due to large gradients in soil variables, both molecular methods revealed that soil microbial communities were structured according to differences in soil conditions between the LTOs, more so than land use intensity. Moreover, variance partitioning analysis also showed that soil properties better explained the differences in microbial communities than land use intensity effects. Predictable responses in dominant bacterial, archaeal and fungal taxa to edaphic conditions (e.g. soil pH and resource availability) were apparent between the LTOs. Some effects of land use intensification at individual field sites were observed. However, these effects were manifest when land use change affected soil conditions. Uniquely, this study details the responses of different microbial groups to soil type and land use intensification, and their relative importance across a range of European field sites. These findings reinforce our understanding of drivers impacting soil microbial community structure at both field and larger geographic scales.     

Azospirillum brasilense mitigates water stress imposed by a vascular disease by increasing xylem vessel area and stem hydraulic conductivity in tomato

Water stress, with its negative consequences on plant growth and survival, can be mitigated by Azospirillum brasilense inoculation. In tomato, A. brasilense delays wilting caused by a vascular pathogen, Clavibacter michiganensis subsp. michiganensis, by yet unknown mechanisms. We studied morphological, anatomical and physiological changes induced by A. brasilense in tomato that relate to water stress tolerance, which could explain the deferral in symptom expression. For this purpose, tomato seeds were treated or not with A. brasilense BNM65, and 5 weeks later plants were challenged with C. michiganensis subsp. michiganensis or mock inoculated with water. There was a large growth promotion associated to Azospirillum: treated plants had higher total biomass and leaf area. In relation to water stress tolerance, Azospirillum treated plants had larger xylem vessel area, higher stem specific hydraulic conductivity, thicker stems, and lower shoot/root dry matter and specific leaf area. These changes were opposite to those induced by C. michiganensis subsp. michiganensis. We conclude that A. brasilense favoured a better adjustment of plant-water relations by several mechanisms, and thus, transitorily alleviated symptoms expression of a vascular disease.