枯草芽孢杆菌ZH-8对黄瓜霜霉病防治效果的研究

枯草芽孢杆菌ZH-8分离于黄瓜根际,将该菌株发酵后,添加助剂制成液体菌剂。该液体菌剂在温室试验和田间试验中表现出较好的防治效果,对黄瓜霜霉病的防效分别达75．61％和69．12％。该菌剂可以有效抑制黄瓜霜霉病菌孢子囊的萌发,并且能够在黄瓜叶片上形成一层保护膜,阻止病原菌孢子的侵入。同时对其抗利福平标记菌株进行了在黄瓜叶片上定殖的研究,研究表明,该生防菌株在黄瓜叶片上具有较强的定殖能力,定殖时间达21d。     

利用缓病芽孢杆菌76—1菌株防治蛴螬的研究

1976年从山东荣成县崂山乡花生田罹病的蒙古丽金龟(Anomala mongolia Fald)蛴螬体内分离到一株缓病芽孢杆菌(Bacillus lentimorbus),编号为76—1菌株。此菌株对蒙古丽金龟、铜绿丽金龟等为害花生的虫种有较强的致病力(注射试验致病率分别为91％、81％;室内菌土与饲喂试验的致病率分别是28.9％、36.3％与35.6％、8.3％),田间小区试验累计达75％,大田防治效率平均为38.4％,且有长效性,施菌剂防区连续七年虫口持续下降。证明此菌株对防治花生田中丽金龟科一些蛴螬虫种有显著效果。     

适应玉米生产的溶磷真菌筛选及其应用

【目的】从土壤中筛选溶磷菌株,提供适应玉米生产的溶磷微生物。【方法】利用难溶磷无机盐培养基从作物根际土壤样品中筛选溶磷菌株,通过菌株在土豆液体培养基培养过程中培养液pH的变化确定溶磷菌株的溶磷能力。利用菌株在平板和土壤中对玉米根系的适应性,选择对玉米适应性好的菌株应用到盆栽实验和大田实验。【结果】从土壤中筛选到具有较高溶磷效果的真菌15株,经鉴定其中9株为草酸青霉,2株为变幻青霉,1株为刺孢青霉、1株为绿色木霉、1株为黑曲霉、1株为构巢曲霉。15株真菌能够显著降低PDB溶液的pH值,其中5株能够将溶液的pH从7.0降到2.0以下。实验室平板和土培试验发现菌株Z15+、ZQ3、ZI1、Zh和Z30能够在以玉米根系分泌物为C源的平板和土壤中很好地生长、定殖,表明这5株菌能够有效利用玉米的根系分泌物。将这5株菌进行盆栽种植玉米,菌株ZI1和Zh处理后,能显著的提高土壤中的有效磷含量,在第49天时,有效磷含量分别高于土壤初始含量的28.05%和37.04%,收获的玉米干重比对照分别高26.04%和20.21%。将菌株ZI1和Zh制成菌剂进行大田试验,试验结果表明菌剂Zh使大田玉米产量提高13.22%,达到10873.05 kg/hm2。而使用ZI1菌剂的大田玉米产量与CK相比没有显著差异。【结论】本实验获得的适应玉米的溶磷菌株Zh为构巢曲霉。     

棉铃虫致病菌BT—931菌株的应用研究

１９９２－１９９３年,作者从菏泽、聊城棉田采集的自然罹病死亡棉铃虫幼虫体内,分离到２个较高毒效的Ｂｔ菌株,编号为ＢＴ—９３１和ＢＴ—０２１,经室内毒力测定和田间药效试验表明,防效及保蕾效果接近或超过化学农药,菌药混剂３—５天平均防治效果达８７．０－９１．６％,增效作用显著。经１９９４年大田防治示范表明,利用ＢＴ—９３１菌剂。配合化学农药防治棉铃虫,具有成本低、保护天敌、持效期长、增产效益高等优点。本研究对菌剂的田间应用技术进行了试验示范。     

复合微生物菌剂对水稻稻瘟病的生防效应

【背景】单一生防菌剂存在生防效果不够稳定、持效性差等不足,研究不同功能微生物的协同增效作用,开发复合微生物菌剂是控制植物病害的有效途径之一。【目的】探究不同功能微生物组合后对水稻稻瘟病的生防效应,开发高效生防水稻稻瘟病的复合微生物菌剂。【方法】将多株高效拮抗稻瘟病菌的链霉菌和细菌进行两两组合后与助剂复配,通过盆栽和大田试验,研究了复合微生物菌剂对水稻稻瘟病的生防效应。【结果】链霉菌Ahn75和解淀粉芽孢杆菌CWJ2菌株组合效果最好,与助剂复配后对水稻叶瘟和穗颈瘟的盆栽防效分别达到65.07%和63.00%,显著高于单一菌株Ahn75、CWJ2和其他菌剂组合的生物防效。同时,该复合菌剂能有效促进水稻植株生长,盆栽分蘖数和株高与对照相比分别提高93.33%和9.83%。而且,田间小区试验的结果也表明,该复合微生物菌剂的使用可以有效降低稻瘟病的发病,防效最高可达52.16%,与农药三环唑的防效(52.97%)相当。此外,菌株Ahn75和CWJ2分别对14种和16种稻瘟病病原菌生理小种的抑菌率超过50%,表明(Ahn75+CWJ2)复合菌剂对水稻稻瘟病具有广谱抗性。【结论】复合微生物菌剂(Ah...     

多杀菌素生产菌种复壮方法及其效应的研究

用分离纯化复壮、淘汰法复壮及虫体复壮三种复壮方法对一株多杀菌素生产能力已经衰退的刺糖多孢菌进行复壮研究。结果显示：淘汰法复壮可显著提高菌株的杀虫毒力及多杀菌素的产量。通过红霉素抗性复壮筛选得到菌株杀虫死亡率达到100％,多杀菌素相对效价达1058．83％;通过NaCl抗性复壮筛选得到一菌株杀虫死亡率达到95％,多杀菌素相对效价达825．80％,因此淘汰法可作为有效的复壮方法。     

江苏省稻瘟病菌有性态的研究*

用标准菌株对１９９７～１９９９年在江苏省吴江市,宜兴市、通州市、高邮市和赣榆县采集的３２５个猪瘟病菌单孢分离菌株的可育性和交配型进行了测定,结果表明江苏省稻瘟病菌菌株的育性较低,可交配率为２２．７７％,可育率仅为７．０８％。不同年份、不同地区采集的猪瘟病菌茵株的性亲和力和交配型有较大的差异,三年的交配率分别为２６．６１％、８．２６％和３３．６４％;温州地区和赣榆地区菌株的交配率相对较高,分别为２６．１５％和２５．４２％,宜兴地区菌株的交配率较低,只有１５．３８％。江苏省稻瘟病菌菌株的交配型在不同年份亦出现很大差别,１９９７年２９个可交配菌株中有２１个菌株表现为ＭＡＴ１－２ 交配型,而１９９９年３６个可交配茵株均为ＭＡＴ１－１交配型。用江苏省稻瘟病菌的可育菌株进行互交,２５个组合中只有６个组合能产生子囊壳和子囊,但均不产生子囊孢子,提示江苏省稻瘟病菌在田间产生健康有性后代的几率不大。对杂交后代的遗传学分析表明,菌株的交配型是受单基因控制的。     

江苏省稻瘟病菌有性态的研究

用标准菌株对1997－1999年在江苏吴江市、宜兴市、通州市、高邮市和赣榆县采集的325个稻瘟病菌单孢分离菌株的可育性和交配型进行了测定,结果表明江苏省稻瘟病菌菌株的育性较低,可交配率为22．77％,可育率仅为7．08％。不同年份、不同地区采集的稻瘟病菌菌株的性亲和力和交配型有较大的差异,三年的交配率分别为26．61％、8．26％和33．64％;通州地区和赣榆地区菌株的交本相对较高,分别为26．15％和25．42％,宜兴地区菌株的交配率较低,只有15．38％。江苏省稻瘟病菌菌株的交配型在不同年份亦出现很大差别,1997年29个可交配菌株中有21个菌株表现为MAT1－2交配型,而1999年36个可交配菌株均为MAT1－1交配型。用江苏省稻瘟病菌的可育菌株进行互交,25个组合中只有6个组合能产生子囊壳和子囊,但均不产生子囊孢子,提示江苏省稻瘟病菌在田间产生健康有性后代的几率不大。对杂交后代的遗传学分析表明,菌株的交配型是受单基因控制的。     

光合微生态菌剂对种子萌芽及幼苗生长的影响

种子萌芽及幼苗生长试验结果表明,光合微生态菌剂可提高种子萌芽率,促进幼苗根系发育和生长,对苗期病害具有较好的防治效果,稀释50倍的菌剂可有效控制蔬菜苗期立枯病和恶苗病的发病率,防治效果达到70%以上。     

菌株DLL-1降解土壤和韭菜中甲基对硫磷的研究

施甲基对硫磷7．5、15和22．5kg·hm^-2(a．i．)时,韭菜中最终平均农药残留量为0．633、1．270和1．901mg·kg^-1,自然降解率分别为98．94％、96．44％和96．04％．施用高效农药残留降解菌剂能显著地降低农药残留的含量,施用75kg·hm^-2降解菌剂时,韭菜与土壤中平均农药残留量分别为0．269、0．099mg·kg^-1,与不施菌对照相比,能使农药进一步降低78．82％和98．68％．降解率随着菌剂用量增加而升高,当用量超过75kg·hm^-2时降解率不再提高．菌剂施用时间以施药后3d为最好．     

Danish Rhizobium leguminosarum strains nodulating 'Afghanistan' pea (Pisum sativum)

A wild pea ( Pisum sativum L.) native to Afghanistan normally known to be resistant to nodulation with European strains of Rhizobium leguminosarum was nodulated early and effectively in field soil in Denmark. Isolates from nodules formed effective nodules abundantly on 'Afghanistan' on reinfection under aseptic conditions. Five types differing in isoenzyme composition pattern were found among 15 isolates from 'Afghanistan' nodules. None were identical with the 'Tom' strain from Turkey, which also forms effective nodules with 'Afghanistan'. The five types were also different with respect to isoenzyme pattern from Rhizobium leguminosarum strains isolated from a modern pea variety cultivated in the same field.     

Analysis of genetic diversity among garden- and field-pea genotypes of higher Indian Himalayas

Genetic diversity among 31 genotypes of field and garden pea including primitive cultivated forms and widely cultivated varieties of India was studied using 40 random decamer and 9 ISSR primers. A total of 274 amplicons were detected using both types of markers, which amplified 192 RAPD and 82 ISSR amplicons. Average number of bands amplified per primer was higher in case of ISSR (9.1) as compared to RAPDs (4.8). ISSR primers also exhibited higher average polymorphism (89.0%) and resolving power (4.50) than RAPDs (72.4%, 1.87, respectively). Genetic similarity estimates based on the pooled data of both types of markers using Jaccard??s coefficient ranged from 0.58 to 0.85 delineating considerable diversity among the pea genotypes studied. The 31 genotypes clustered in two major groups based on pooled data. Popular cultivars of garden and field pea of the region exhibited high similarities among themselves. However, primitive cultivated forms collected from the higher Indian Himalayas were diverse from the current varieties and hold potential in pea breeding programmes.     

THE PRODUCTION OF ANTIBIOTICS IN SOIL

Conditions affecting the production of gliotoxin by a strain of Trichoderma viride , known to produce this antibiotic in synthetic culture media, were studied in two types of soil, a highly acid, sandy podsol from Wareham Heath and a less acid garden soil. High yields of an antibiotic substance, which results from bioassays showed to be similar to gliotoxin, were obtained from both inoculated soils when autoclaved and supplemented with organic material. The autoclaved soils behaved differently when unsupplemented; Wareham soil supported production of the antibiotic but little or none was produced in the garden soil. No antibiotic activity could be demonstrated in soil which had not been inoculated with T. viride.
Acidification of unsupplemented garden soil by addition of sulphuric acid had a favourable effect on production of the antibiotic, but raising the pH of Wareham soil by addition of calcium hydroxide also increased the yield. These effects, therefore, cannot be due simply to the change in pH of the soil.
The beneficial effect of autoclaving the soil on production of the antibiotic assumed to be gliotoxin was analysed and separated into three distinct effects, elimination of the microflora, increase in availability of nitrogen compounds and increase in available carbon compounds. The last effect was considered to be of greatest significance.
The antibiotic was produced in normal Wareham soil if supplemented with additional carbon compounds, but not in garden soil unless this had also been acidified before inoculation. A chromatographic method of bioassay used in the later work gave more substantial evidence that the antibiotic produced in the soil was, in fact, gliotoxin.     

Unaltered Nodulation Competitiveness of a Strain of Bradyrhizobium sp. (Lotus) after a Decade in Soil

A Bradyrhizobium sp. (Lotus) strain that formed a soil population that was highly competitive for nodulation of Lotus pedunculatus 11 years after its introduction into a field soil and a culture of the same strain stored lyophilized were compared with an antibiotic-resistant mutant in respect of their nodulation competitiveness. The mutant was less competitive than the wild-type strain it was isolated from and had to be present at a cell ratio of 5.76:1 in mixed inoculum in sand culture to form 50% of the nodules on L. pedunculatus (50% nodulation value, 5.76). The 50% nodulation values for a soil population of the mutant mixed with soil populations of the lyophilized and field soil strain were, respectively, 6.83 and 5.77, indicating that the field soil strain was not significantly different from the lyophilized strain in nodulation competitiveness. A 50% nodulation value of 11.18 obtained when soil containing a recently established mutant population was mixed with the field soil containing the population established 11 years before, indicating that the plant infection technique underestimated cell numbers of the field soil population by 100%. Nodulation competitiveness was unaffected by the size of the strain populations in the range of 100 to 1,000 cells per g of soil; at 10 cells per g a significant correlation between strain ratios in nodules and in soil was still evident. The results indicated that apparently superior nodulation competitiveness of a well-established soil population relative to that of a subsequently introduced strain may not necessarily reflect the intrinsic competitive abilites of the strain(s) involved. The soil strain did not differ from laboratory-maintained cultures in antigenic properties, effectiveness, or whole cell protein electrophoresis profiles.     

Inoculation of pea by application of Rhizobium in the planting furrow

Summary Selected streptomycin resistant strains ofRhizobium leguminosarum suspended in nutrient broth were added to the planting furrow immediately before the sowing of pea. The nodule occupancy by a strain isolated from Risø soil (Risø la) was increased from 74 to 90%, when the inoculum rate was increased from 3.7×10⁶ to 3.7×10⁸ cells per cm row. The experimental soil contained 10³ to 10⁴ cells ofR. leguminosarum per gram. An almost inefficient strain isolated from Risø soil (SV10) was less competitive with respect to nodulation on two pea cultivars than an efficient Risø strain (SV15) and an efficient non-Risø strain (R1045). The nodule occupancy by the introduced strains varied between pea cultivars.Irrespective of the generally high nodulation by the efficient strains introduced to the soil, the pea seed yield, compared to pea nodulated by the indigenous population, was not significantly increased. Neither were two commercial inoculants, applied in rates corresponding to 3 times the recommended rate, able to increase the yield. This suggests that the indigenous populations ofR. leguminosarum were sufficient in number and nitrogen fixing capacity to ensure an optimal pea crop. However, some inoculation treatments slightly increased the seed N concentration and total N accumulation, indicating that it may be possible to select or develop bacterial strains that may increase the yield.     

ACC deaminase producing Pseudomonas putida strain PSE3 and Rhizobium leguminosarum strain RP2 in synergism improves growth, nodulation and yield of pea grown in alluvial soils

Plant growth promoting rhizobacteria affects the overall performance of plants by one or combination of mechanisms. However, little information is available on how ACC deaminase secreting bacteria enhance crop production. The present study aimed at identifying ACC deaminase producing and phosphate solubilizing bacterial strains and to assess their plant growth promoting activities. Additionally, the effect of two ACC deaminase positive bacterial strains Pseudomonas putida and Rhizobium leguminosarum on pea plants was determined to find a novel and compatible bacterial pairing for developing efficient inoculants for enhancing legume production and reducing dependence on chemical fertilizers. The isolated bacterial cultures were characterized biochemically and by 16S rRNA sequence analysis. The plant growth promoting activities was determined using standard microbiological methods. The impact of P. putida and R. leguminosarum, on pea plants was determined both in pots and in field environments. Of the total 40 bacterial strains, strain PSE3 isolated from Mentha arvenss rhizosphere and RP2 strain from pea nodules produced ACC deaminase, solubilized insoluble phosphate, synthesized indole acetic acid, ammonia, cyanogenic compounds, exopolysaccharides and had antifungal activity. The dual inoculation of P. putida strain PSE3 and R. leguminosarum strain RP2 had largest positive effect and markedly increased the growth, symbiotic characteristics, nutrient pool and quantity and quality of pea seeds. The measured parameters were further augmented when inoculated pea plants were grown in soils treated with urea or DAP. A significant variation in the measured parameters of pea plants was observed under both pot and field trials following microbial inoculation but the bacterial cultures did not differ significantly in growth promoting activities. The results suggest that ACC deaminase positive bacterial cultures endowed with multiple potential can be targeted to develop mixed inoculants for enhancing pea production and hence, to reduce dependence on synthetic fertilizers.     

Survival and dispersion of genetically modified rhizobia in the field and genetic interactions with native strains

Abstract A genetically modified strain of the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum biovar viciae was used to inoculate a typical host, pea, and a control non-host cereal crop in the field. The inoculant was monitored for survival and spread from the site of application, and for genetic interactions with the native population. It could be identified by chromosomally located antibiotic resistance markers and additional markers conferred by the transposon Tn 5 inserted on its conjugative symbiotic plasmid. These markers facilitated enumeration of the strain on selective agar, enabling survival and spread to be monitored over a six year period. Although culturable cell numbers dropped two to three orders of magnitude after the first year, subsequently they remained around 10² viable cells per g soil, even in subplots where only the non-host cereals had been grown. However, peas did give the inoculant a small survival advantage compared with non-hosts. Soil cultivation appeared to play a major role in inoculant dissemination from the site of application. Transfer of the Tn 5 marker to other rhizobia could be monitored by screening for isolates with Tn 5 -encoded antibiotic resistance in the absence of the inoculant chromosomal markers. Over three years, more than 4000 pea root nodules were screened for indigenous rhizobia that had acquired the Tn 5 -marked symbiotic plasmid from the inoculant. None were detected, although overall about 2% of nodules contained the inoculant strain, and transfer of the Tn 5 -marked symbiotic plasmid to three out of four R. leguminosarum biovar viciae isolates from the field site could be demonstrated under laboratory conditions.     

The influence of lipopolysaccharides and glucans from two Rhizobium leguminosarum bv. viciae strains on the formation and efficiency of their symbioses with pea plants

The influence of lipopolysaccharides (LPS), glucans, and their unseparated complexes on nodulation activity of rhizobia and efficiency of their symbioses with pea plants was studied in vegetation experiments. Two Rhizobium leguminosarum bv. viciae strains which differed in their symbiotic properties were used: strain 31 (fix+, efficient, moderately virulent, moderately competitive), and strain 248b (fix-, inefficient, highly virulent, highly competitive). Preparations of LPS-glucan complex and the respective LPS from the highly virulent strain 248b increased the nodulation activity of both strains by 10-26%. Analogous preparations from a less virulent strain 31 did not have this ability. Unseparated LPS-glucan complexes from these strains increased the productivity of plants infected with the efficient strain by 18-23% but did not change it in plants inoculated with the other, inefficient strain. No significant influence of LPS preparations on the symbiosis productivity was observed. Glucans from both strains enhanced the nodulation ability of the highly virulent strain by 36-56%. In addition, treatment of pea plants with glucan from strain 248b increased nitrogen fixation by root nodules by 27% in plants inoculated with strain 31. In general, the formation and efficiency of the symbiosis of R. leguminosarum bv. viciae with pea plants was more influenced by preparations from strain 248b, highly virulent but deficient in nitrogen fixation, than by preparations from the nitrogen fixation-proficient but less virulent strain 31.     

沙冬青根瘤菌的抗逆性

沙冬青(Ammopiptanthus mongolicus)是西北荒漠地区珍稀常绿阔叶灌木,综合沙冬青分布区内气候、土壤和水分等因子,选取宁夏中卫县沙坡头、内蒙古磴口县、内蒙古阿拉善左旗、内蒙古乌拉特后旗作为样区,于2004年4月中下旬沙冬青的花期调查和收集根瘤,并结合地理环境对分离得到的根瘤菌进行抗逆性初步分析。调查发现根瘤的生成及其在宿主植物上的着生部位、大小、形状、颜色等因生境条件的不同而有所差异,水分是其主要的影响因子;分离得到根瘤菌17株,对其耐盐性、耐酸碱性、生长温度范围和抗生素抗性进行了研究。结果表明,64.7%的菌株可以在含3%NaCl的YMA培养基上生长;94.1%的菌株可以在pH 5~11的范围内生长;全部菌株在60 ℃处理10 min后仍能生长;不同菌株对不同抗生素表现出不同的抗性,ZW₄和WH₄¹对各抗生素表现出较强的抗性。分离自磴口县的根瘤菌普遍表现出较强的抗酸碱和抗高温的能力,这是对其环境的适应。本研究证明沙冬青根瘤菌具有较强的抗逆性,但菌株间存在差异,这可能是对沙冬青分布区多种景观生态类型的适应。同时测定了几种伴生植物中间锦鸡儿(Caragana intermedia)、猫头刺(Oxytropis aciphylla)和柠条(Caragana corshinskii)根瘤菌的抗逆性,与沙冬青根瘤菌表现出一定的相似性,具较强的抗逆性,说明生态环境对豆科植物-根瘤菌共生体有重要的影响。沙冬青的高抗性可能与沙冬青根瘤菌的高抗性有关。沙冬青与其根瘤菌的共生关系有利于其植物群落的发育和多样性的维系。     

Competition in Kenyan soils between Rhizobium leguminosarum biovar phaseoli strain Kim5 and R. tropici strain CIAT899 using the gusA marker gene

The contribution of appropriate inoculum strains to more efficient nitrogen fixation by legumes has been difficult to assess due to the laborious nature of the assays involved in assessing establishment of inoculum strains in the field. The use of marker genes, in particular the GUS system, changes this, making it possible to assess occupancy by the inoculum strain in large numbers of nodules on whole root systems. Here we used the GUS system to evaluate the competitive ability of two rhizobial strains, Rhizobium leguminosarum bv. phaseoli strain Kim5 and R. tropici strain CIAT899 in two soil types from Kenya. The results confirm that Kim5 is a highly competitive strain, forming 86% of the nodules in a near-neutral pH soil. Although the competitiveness of CIAT899 is enhanced in an acid (pH 4.5) soil it still only formed 35% of the nodules. There were no differences between inoculum strains in their efficiency of nitrogen fixation in either soil type, and virtually no N2-fixation occurred in the acid soil due to the lack of tolerance of the Phaseolus genotype to soil acidity.