番茄青枯病抗性相关根际微生物的研究进展

由茄科雷尔氏菌（Ralstonia solanacearum）侵染引起的植物细菌性青枯病（Bacterial wilt）素有“植物癌症”之称,是一种毁灭性土传细菌病害。目前,青枯病已成为制约我国番茄生产的主要病害之一。抗青枯病番茄品种表现出与劣质农艺性状连锁遗传的问题一直没有得到解决,而且番茄青枯病抗性主要为数量遗传,不利于优良抗病品种的选育。根际微生物参与调控植物免疫系统,提高寄主植物青枯病抗性,反之,寄主植物的健康状况也能够影响根际微生物群落组成,根际微生物在番茄青枯病防治中具有重要作用。对抗青枯病番茄根际微生物群落特征及微生物群落形成的影响因素进行总结,讨论了根际微生物参与调控番茄青枯病抗性遗传的作用机制,并对利用有益根际微生物调控番茄青枯病研究方向的热点进行展望,为番茄青枯病诱导抗性机制的解析、遗传育种以及番茄青枯病的防治与品种的合理布局提供有效参考。     

凡纳滨对虾低盐度养殖池浮游藻类群落研究

在44口凡纳滨对虾低盐度养殖池中共鉴定藻类7门62属113种,蓝藻26种,绿藻54种,硅藻14种,裸藻11种,隐藻3种,甲藻4种,金藻1种。绿藻门种类最多,占藻类种类数的47·8%,其次为蓝藻门占23·0%,硅藻占12·4%,裸藻占9·7%。优势种主要为蓝藻,典型优势种有螺旋藻(Spirulinasp.),假鱼腥藻(Pseudoanabaenasp.),弯形尖头藻(Raphidiopsis curvata),针状蓝纤维藻(Dactylococcopsis acicularis)等,其中螺旋藻的优势度平均达到50%,为主要优势种。常见的绿藻有栅藻(Scenedesmusp.),衣藻(Chlamydomonassp.),小球藻(Chlorella vulgaris)等;常见的硅藻为梅尼小环藻(Cyclotella meneghinian),卵形隐藻(Cryptomonas ovata)、啮蚀隐藻(C.erosa)和绿裸藻(Euglenavirdis)在虾池中比较常见。养殖池中浮游藻类的种类数平均为43±9种,多样性指数平均为2·19±0·56,个体数量平均为1·45±0·87×108个/L;藻类的种类、数量及生物量表现为养殖前期低后期高的特征,而多样性表现相反,藻类的组成直接影响对虾的生长。     

日粮精粗比对瘤胃内环境及微生物区系影响的研究

瘤胃作为反刍动物体内的饲料加工厂,其内环境稳定和微生物区系的平衡影响着动物对饲料的利用,日粮精粗比的改变影响瘤胃内环境稳态以及微生物区系组成,从而影响反刍动物的生产效率。本文综述了日粮精粗比影响瘤胃pH、NH3-N浓度、VFA浓度和瘤胃微生物区系组成的研究进展,为在生产实践中提高反刍动物生产效率提供理论依据。     

Antioxidant and Antimicrobial Potential of the Bifurcaria bifurcata Epiphytic Bacteria

Surface-associated marine bacteria are an interesting source of new secondary metabolites. The aim of this study was the isolation and identification of epiphytic bacteria from the marine brown alga, Bifurcaria bifurcata, and the evaluation of the antioxidant and antimicrobial activity of bacteria extracts. The identification of epiphytic bacteria was determined by 16S rRNA gene sequencing. Bacteria extracts were obtained with methanol and dichloromethane (1:1) extraction. The antioxidant activity of extracts was performed by quantification of total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae and Candida albicans. A total of 39 Bifurcaria bifurcata-associated bacteria were isolated and 33 were identified as Vibrio sp. (48.72%), Alteromonas sp. (12.82%), Shewanella sp. (12.26%), Serratia sp. (2.56%), Citricoccus sp. (2.56%), Cellulophaga sp. (2.56%), Ruegeria sp. (2.56%) and Staphylococcus sp. (2.56%). Six (15.38%) of the 39 bacteria Bifurcaria bifurcata-associated bacteria presented less than a 90% Basic Local Alignment Search Tool (BLAST) match, and some of those could be new. The highest antioxidant activity and antimicrobial activity (against B. subtilis) was exhibited by strain 16 (Shewanella sp.). Several strains also presented high antimicrobial activity against S. aureus, mainly belonging to Alteromonas sp. and Vibrio sp. There were no positive results against fungi and Gram-negative bacteria. Bifurcaria bifurcata epiphytic bacteria were revealed to be excellent sources of natural antioxidant and antimicrobial compounds.     

EM制剂在农业清洁生产上的应用

总结有关EM（有效微生物群）制剂在畜禽养殖、作物种植、水产养殖和改善环境等方面的应用试验和生产实践,阐述其在农业清洁生产、环保治污、提高农产品产量和品质、促进畜禽生长发育、农业废弃物资源化无害化处理、农业生态环境保护和修复等方面的作用.     

Microbial dynamics and natural remediation patterns of Fusarium‐infested watermelon soil under 3‐yr of continuous fallow condition

Long‐term monoculture of watermelon results in inhibited growth and decreased crop yields, possibly because of imbalance in microbial ecology caused by accumulation of the pathogen in soil. This results in serious problems in the economics of watermelon production. We investigated the build‐up of Fusarium in soil under watermelon cultivation and changes over 3 yr of fallow in a microcosm. We focused on changes in the microbial community of Fusarium‐infected soil, including the diversity of the microfloral species composition, and species abundance. Long‐term monoculture of watermelon leads to changes in microbial diversity and community structure. The microbes most readily cultured from infested soil were suppressed by watermelon wilt pathogen Fusarium oxysporum f. sp. niveum (FON). Of 52 isolated and identified culturable microbes, 83.3% of bacteria, 85.7% of actinomycetes, 31.6% of fungi and 20.0% of Fusarium sp. were inhibited by FON on bioassay plates. Prior to fallowing, infested soil was a transformed ‘fungus‐type’ soil. After 3 yr of fallow, the infested soil had remediated naturally, and soil microbial diversity recovered considerably. Abundance of dominant bacterial populations was increased by 118–177%, actinomycetes, fungi and FON were decreased by 23–32, 33–37 and 50%, respectively. The ratio of bacteria: actnomycetes: fungus: Fusarium sp. in infested soil changed from 24 000:100:4:1 prior to fallow to 57 000:100:3.5:1 after fallowing, nearer to the 560 000:400:8:1 ratio of healthy soil not used for watermelon cultivation. This suggests the ‘fungus‐type’ soil was converting to ‘bacteria‐type’ soil and that disrupted microbial communities in infested soil were restored during fallow.     

Interactive Effect of Sulphur and Nitrogen on the Oil and Protein Contents and on the Fatty Acid Profiles of Oil in the Seeds of Rapeseed (Brassica campestris L.) and Mustard (Brassica juncea L. Czern. and Coss.)

In long-term field experiments on loamy sand and sandy loam, legumes (pea and lupine) stimulated microbial activity in the rhizosphere more than cereals (winter rye, winter wheat and spring barley), maize and oil flax. In the rhizosphere of winter wheat and maize, microbial activity and the bacteria species Pseudomonas , Agrobacterium and Xanthomonas were more stimulated by organic manuring than by mineral fertilization. A positive correlation between the stimulated bacteria species and the growth of young plants was found. Various mineral nitrogen applications had no influence on the rhizosphere microflora. The leghemoglobin content of pea nodules – an indicator of nitrogen fixation activity – was reduced by high nitrogen application in crop rotation.     

Studies of Multi-Allelic Polymorphism of Dominant Dwarfing Genes in Wheat

Dwarfing breeding of wheat in the world is confined to the exploitation of recessive dwarfing sources. None of the dominant dwarfing sources discovered in common wheat (Triticum aestivum L. ) has found wide exploitation in wheat breeding due to the extreme dwarfness of their plants (20 -55 cm). We found in our work that some stable mutant lines with their plant height enhanced to different extents could be obtained in large populations derived from the stock seeds of the dominant dwarfing sources Aibian1 carrying Rht10 on 4DS and being 20 - 55 cm tall and Aisu2 carrying Rht3 on 4BS and being 55 cm tall, or from their descendants of induced mutation treatments, or from the segregating descendants of their crosses with mid- or tall-statured genotypes. Subsequently, we studied these mutation-derived lines differing in plant height with near isogenic lines and observed that the character of their enhanced plant height bred true, each carrying a semidominant dwarfing gene for a definite height and that as the plant height of the mutation-derived lines increased, the yield-contributing characters of their near isogenic lines were significantly improved. When test crosses with marker genes and physiological and biochemical genetic marker tests were performed to re-localize the semi-dominant dwarfing genes carried by the mutation-derived lines, it was confirmed that they shared common loci with Rht10 and Rht3 and that they were all mutation-derived multiple alleles. It is thus speculated that dominant dwarfing genes are of "multi-allelic polymorphism". In other words, dominant dwarfing genes, which are ultra-dwarfing, are liable to develop by mutation into a group of multiple alleles with plant height enhanced to different extents and some may have a height close to the ideal plant height for wheat breeding. Therefore, these results offer a fundamentally new approach for the exploitation of dominant dwarfing sources in wheat breeding.     

青海省家畜生态类群分析

利用家畜生态适应指数 ,对全省各县的家畜进行了家畜生态类群优势序列的排列。结果表明 ,青海省各县饲养的家畜种类可概分为 10大优势生态序列 ,基本上反映了该地区饲养家畜的特点。其方法适宜 ,结果可信。按不同生态适宜家畜序列进行专业化生产 ,会对畜牧生产具有促进作用     

Microbial and Enzyme Activities of Saline and Sodic Soils

Salinization and sodication are abiotic soil factors, important hazards to soil fertility and consequently affect the crop production. Soil salinization is of great concern for irrigated agriculture in arid and semi‐arid regions of the world; sodicity is characterized by an excessively high concentration of sodium (Na) in their cation exchange system. In recent times, attention has been turned to study the impacts of these factors (salinity and sodicity) on soil microbial activities. Microbial activities play central role in degradation and decomposition of soil organic matter, mineralization of nutrients and stabilization of soil aggregates. To understand the ecology of soil system, therefore, it is important to be conversant with the soil microbial activities, which show quick response to little change in the soil environment. Microbial activities (generally measured as C–N dynamics, soil respiration–basal respiration, or CO₂ emission), microbial abundance, microbial biomass, quotients (microbial and metabolic) and microbial community structure, and soil enzymes have been considered as potential indicators to assess the severity of the land degradation and the effectiveness of land use management. Therefore, it is important to synthesize the available information regarding microbial activities in use and management of salt‐affected soils. The reclamation and management of such soils and their physico‐chemical properties have been reviewed well in the literature. In this review, an attempt has been made to compile the current knowledge about the effects of soil salinization and sodication on microbial and enzyme activities and identify research gaps for future research. Copyright © 2015 John Wiley & Sons, Ltd.