Уточнить поиск
Результаты 1-10 из 14
Research progress and development potential analysis of bioenergy grass in the north of China | 我国北方能源草研究进展及发展潜力
2012
Fan Xifeng, Beijing Academy of Agriculture and Forestry Sciences,Beijing (China),Beijing Research and Development Center for Grass and Environment | Hou Xincun, Beijing Academy of Agriculture and Forestry Sciences,Beijing (China),Beijing Research and Development Center for Grass and Environment | Wu Juying, Beijing Academy of Agriculture and Forestry Sciences,Beijing (China),Beijing Research and Development Center for Grass and Environment
能源草是一类重要的能源植物。立足北方地区边际土地,我国已在能源草种质资源收集筛选、产量潜力评价、生物质品质分析、生态效应评估等方面开展了大量研究工作,并取得重要研究进展。在我国北方有栽培历史且生物质产量高于3.0t/(hm2.年)的草种主要有23种,其中生物质产量高于20t/(hm2.年)的有柳枝稷(Panicum virgatum)、芒草(Miscanthus spp.)、芦竹(Arundodonax)和杂交狼尾草(Pennisetum americanum×P.Purpureum)4种,它们在适应性、产量、品质方面各有优势,在我国北方地区开发利用前景广阔,但存在杂交狼尾草在我国北方地区不能越冬,芦竹和低地型柳枝稷越冬率低的问题。因此,在我国北方地区收集能源草资源,既要考虑产量、品质,还需兼具耐寒、抗旱或耐盐能力。在广泛收集资源的基础上,明确各能源草在我国北方的适应范围、种植区划和发展潜力,通过育种技术进一步提高能源草的产量、品质和抗逆能力,建立配套栽培管理技术,实现能源草多元化、区域化种植利用,对其经济社会效益和生态效应进行系统评估,构建评价技术体系,应是目前我国北方能源草开发利用的重点研究方向。 | Bioenergy grasses display many beneficial attributes as energy crops,and a lot of works have been carried out for their germplasm screening,yield and quality evaluation,ecological effects evaluation in the north of China.23 species of grass continuously cultivated in the north area with biomass yield higher than 3.0 t/(hm2・year) have been identified.Among these species,the biomass yield of switchgrass(Panicum virgatum),miscanthus(Miscanthus spp.),giant reed(Arundodonax) and hybrid pennisetum(Pennisetum americanum×P.Purpureum) are higher than 20 t/(hm2・year),they have been superior in adaptability,yield and quality etc.The four kinds of grasses are promising in the north area,but existing problems should be taken into consideration:hybrid pennisetum cannot live through the winter;giant reed and highland ecotype's switchgrass have a low overwintering rate.In conclusion,the germplasm collected in north area should be with superior yield,quality and relatively high cold,drought and salt resistance.The main researches on the development and utilization of bioenergy grass in north area include:extensive collection of germplasm,reveal of the applicable scope,regional planning and development potential of grass and taping the comprehensive potential,improvement of yield,quality and stress resistance by means of breeding,technology of cultivation and management,systematic evaluation of beneficial and ecological effects and establishment of evaluation system.
Показать больше [+] Меньше [-]Selective strategy of the new type maize hybrid ludan718 | 玉米杂交种鲁单718的选育策略
2012
Liu Zhixian, Shandong Academy of Agricultural Sciences, Jinan (China), Maize Institute | Ding Zhaohua, Shandong Academy of Agricultural Sciences, Jinan (China), Maize Institute | Liu Changhong, Shandong Academy of Agricultural Sciences, Jinan (China), Maize Institute
玉米品种的选育策略决定育种工作的成败。根据目前我国玉米生产实际情况,确定“从拓宽种质基础、丰富遗传多样性人手,改良品种的适应性;把国内种质良好的丰产性与热带、亚热带种质突出的多抗性融合在一起,提高育成品种的多抗性和稳产性能;把成熟早、灌浆快、配合力高、株型紧凑的塘四平头种质与丰产、大穗的旅大红骨种质融合在一起,挖掘育成品种的丰产潜力,改善商品品质”的创新理念,确立“高产、优质、多抗、广适和易制种”的育种目标,结合单倍体快速选系等技术,成功选育出配合力高、抗病抗倒能力强、适应性广的优良自交系齐3925和黄572,杂交育成高产、优质、多抗玉米新杂交种鲁单718。 | The breeding strategy of the maize varieties decides success or failure for breeding work. According to the actual situation of maize production in China, establish the breeding objectives with high-yield, high-quality, multi-resistance and wide adaptabihty and ease of seed. By the haploid fast selected hnes technology, the high yield of new type maize hybrid Ludan718 had been bred by crossing Qi3925 with Huang572. The results of regional trials showed that Ludan718 has high yield and stable yield, much resistance, high quality, wide adaptability, medium late-maturing, big ear and high yield potential. This paper introduces the breeding goals, selecting methods and use of heterosis modes about Ludan718.
Показать больше [+] Меньше [-]Comparison of protective enzyme activity in leaves of soybean at different yield levels | 不同产量水平大豆叶片保护酶活性的比较
2012
Chen Zhanyu, Jilin Agricultural University, Changchun (China), College of Agronomy | Li Dayong, Jilin Agricultural University, Changchun (China), College of Agronomy | Liu Guoning, Jilin Agricultural University, Changchun (China), College of Agronomy
探讨不同产量水平大豆叶片保护酶活性的变化规律,为大豆育种和高产栽培提供生理依据。选择3个不同产量水平(低产品种、高产品种、中产品种)的9个栽培大豆(Glycine max (L.)Merr.)品种,在相同的环境条件下种植,在大豆结荚期以后,测定大豆叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性及叶片丙二醛(MDA)含量和细胞膜透性。在结荚期后,不同产量水平大豆叶片的SOD、POD、CAT活性表现为高产品种>中产品种>低产品种,其活性变化趋势相同,均在鼓粒盛期达到最大,然后下降,高产品种叶片SOD、POD、CAT活性均显著高于低产品种;不同产量水平大豆叶片MDA含量和细胞膜透性则表现为低产品种>中产品种>高产品种,随生育进程均呈上升趋势,以成熟期最大,高产品种MDA含量和细胞膜透性极显著低于低产品种。在结荚期以后,高产大豆品种清除活性氧的能力较强,膜脂过氧化程度较低,叶片衰老延缓,而功能期延长,有利于后期干物质积累,进而有助于提高产量。 | The study was performed to explore changes of protective enzyme activities in leaves of soybean at different yield levels. The purpose was to provide some physiological basis for soybean breeding and high-yield cultivation. Nine soybean (Glycine max (L.) Merr.) cultivars were divided into three yield levels (low yield cultivars, high yield cultivars, middle yield cultivars) were planted under the same environmental condition. After podding stage, the superoxide dismutase (SOD) activities, catalase (CAT) activities, peoxidase (POD) activities, malondialdehyde (MDA) contents and cell membrane permeability were measured in soybean leaves. After podding stage, the activities of SOD, CAT and POD in leaves were the highest at high yield cultivars, then at middle yield cultivars and the lowest at low yield cultivars. The change tendency of those enzymes was consistent, which all reached maximum value at seedfilling-flourishing stage and then decreased. The activities of SOD, CAT and POD in leaves of high yield cultivars were significantly higher than that of low yield cultivars. The contents of MDA and cell membrane permeability in leaves were the highest at low yield cultivars, then at middle yield cultivars and the lowest at high yield cultivars after podding stage. Following the breeding proceeding, the contents of MDA and cell membrane permeability all showed rising tendency and reached maximum value at maturation stages, then the MDA contents and the cell membrane permeability of high yield cultivars were very significantly lower than those of low yield cultivars. After podding stage, the ability in leaves of high yield cultivars to eliminate active oxygen was better and the degree of lipid peroxidation was low. The leaf of high yield cultivars senescence was delayed and the function of leaves extended, which make for dry matter accumulation at later stage and conduce to increase yields.
Показать больше [+] Меньше [-]Thoughts about century drought in USA――how does agricultural production cope with climate changes | 美国世纪大旱引发的思考――农业生产如何应对气候变化
2012
Song Lili, Chinese Academy of Agricultural Sciences, Beijing (China), Institute of Agricultural Resources and Regional Planning | Wang Xiudong, Chinese Academy of Agricultural Sciences, Beijing (China), Institute of Agricultural Economics and Development
2012年入夏以来,持续发展的旱情致使美国农作物大幅减产、农产品价格持续飙升,美国的经济和社会受到了极大的影响。与此同时,美国大旱对我国这样一个自然灾害频发的农业大国也敲响了警钟。通过分析美国世纪大旱的特点、成因、影响以及气候变化背景下我国农业生产面临的自然灾害频发多发、农业投入品增加等问题,提出应从建立和完善气象监测预警系统,加强以水利为主的农业基础设施建设,加大农业减灾技术研究与推广的投入等角度提升我国农业生产应对气候变化的能力。 | Since early summer of 2012, the continuous drought has caused the yields of crops in America declining dramatically, and the price of agricultural products have been roaring sustainably. Thus, the American economy and society are affected greatly. At the same time, USA drought sounds the alarm to China, where natural disasters outbreak frequently. By analyzing the characteristics, causes and impacts of the USA century drought, and the main problems faced by Chinese agricultural production in the context of climate changes, such as frequent occurrence of natural disasters, increase of agricultural inputs, etc. the authors put forward suggestions as: to establish and perfect weather monitoring and warning system; to strengthen agricultural infrastructure construction mainly water conservancy; to increase investment in studying and promoting agricultural disasteralleviation technology etc.
Показать больше [+] Меньше [-]Phosphorus solubilizing capability, IAA secretion and characteristics of phosphorus-solubilizing bacteria in rhizosphere of alfalfa in Guizhou Province | 贵州紫花苜蓿根际溶磷菌溶磷能力、分泌IAA及菌株特性研究
2012
Liu Xiaoxia, Guizhou Institute of Prataculture, Guiyang ( China) | Wang Xiaoli, Guizhou Institute of Prataculture, Guiyang ( China) | Lu Ruixia, Guizhou Institute of Prataculture, Guiyang ( China)
[目的]分离筛选贵州紫花苜蓿根际高效溶磷菌株,探索其促生机理。[方法]采用无机磷和有机磷培养基,从贵州省种植的紫花苜蓿根际分离具有溶磷能力的菌株,通过溶磷圈法筛选解磷能力较强的菌株,并对其进行深入研究,同时,利用钼蓝比色法对菌株在液体培养条件下的溶磷能力进行测定。[结果]筛选的11株菌株分解磷酸钙的能力差异较大,溶磷量在150.40~268.20 ug/ml之间,各菌株的溶磷量与分泌有机酸量、培养介质pH之间均不存在显著相关性;各菌株均具有分泌IAA的能力,分泌量在12.09~22.16 ug/ml之间,分离的菌株均为产碱菌,大多数菌株菌落呈灰白色或乳白色、不规则、不透明、边缘不整齐、扁平、无色素;不同的菌株对碳源的利用存在着差异。[结论]该研究为缓解贵州地区贫瘠土地磷素供给、节约磷矿资源、降低环境污染以及生产苜蓿绿色产品提供肥料奠定了基础。 | [Objective] The study aimed to isolate and screen efficient phosphorus-solubilizing strains from the root soil of alfalfa in Guizhou, and investigate its growth promoting mechanism. [Method] Phosphorus solubilizing bacteria were isolated from rhizosphere of alfalfa with inorganic and organic phosphorous medium and the strains with higher capacity of dissolving phosphorus were screened through dissolving phosphate zone and further researched. Meanwhile the phosphorus solubilizing capability of strains cultured in liquid medium was investigated by molybdenum blue colorimetric method. [Result] The capacity of dissolving calcium phosphate of 11 selected strains differed significantly and tended to be volatile from 150.40 to 268.20 ug/ml; phosphate solubilization capacity, IAA secretion and the pH of culture media did not show any significant correlation; all strains could produce IAA, and the secretion was from 12.09 to 22.16 ug/ml; the selected strains all could produce alkaline matter, and most of colonies were pale or milky white, irregular, opaque, jagged, flat and non-pigmented; utilization of carbon sources by different strains varied significantly. [Conclusion] The study laid the foundation for relieving phosphorus in unproductive land, saving phosphate resources, reducing environmental pollution and providing fertilizer in alfalfa production.
Показать больше [+] Меньше [-]Combining ability and heterosis of sorghum for biomass energy | 基于能源利用的高粱配合力和杂种优势分析
2012
Han Dongqian, China Agricultural University,Beijing(China),College of Agronomy and Biotechnology | Han Lipu, Chinese Academy of Sciences,Shijiazhuang (China),Institute of Genetics and Developmental Biology | Xue Shuai, China Agricultural University,Beijing(China),College of Agronomy and Biotechnology
为选育生物量高的能源高粱(Sorghum bicolor L.Moench),本研究对不同类型的15个高粱品种和4个不育系,采用NCⅡ遗传交配设计,获得60个杂交组合,对地上部生物量等11个性状进行了配合力和杂交优势分析。结果表明:地上部生物量等10个性状的遗传是由加性和非加性基因共同控制,倒伏率主要受加性基因控制。父本NW-21、绿能3号和母本A3晋粱5A地上部生物量的一般配合力效应值极显著高于对照,是适宜组配高生物产量能源高粱杂交种的父、母本材料。A3三尺三A×绿能3号和A3三尺三A×Saccaline是地上部生物量特殊配合力效应值较高的组合。杂交高粱中在地上部生物量上存在超标优势。 | One of the breeding objectives of sorghum(Sorghum bicolor L.Moench)is to obtain high biomass yield.Fifteen different types of sorghum R lines and four male sterile lines were used to analyze the combining ability and heterosis of 11 traits with NCⅡ genetic mating design mating scheme.The results indicated that lodging percentage was controlled additive effects;other traits such as aboveground biomass were contributable to both additive and non-additive effects.Those parental lines of NW-21,Lvneng-3 and maternal parental line of A3Jinliang-5A with higher general combing ability for the aboveground biomass were identified as potential parental materials for high biomass hybrid breeding program.The two crosses of A3Sanchisan A×Lvneng-3 and A3Sanchisan A×Saccaline revealed significantly higher aboveground biomass than that of A3Sanchisan A×Rio(check).Hybrids displayed over-standard heterosis in aboveground biomass.
Показать больше [+] Меньше [-]Effect of antimicrobial actinomycetes on growth and medicine quality of Salvia miltiorrhiza Bge. | 放线菌剂对丹参生长及有效成分的影响
2012
Duan Jiali, Northwest Agriculture and Forestry University, Yangling (China), College of Resources and Environment | Shu Zhiming, Northwest Agriculture and Forestry University, Yangling (China), College of Life Sciences | Sun Qun, Northwest Agriculture and Forestry University, Yangling (China), College of Life Sciences
探讨施用生防放线菌剂对丹参生长及品质的影响。以常规移栽处理为对照,采用小区和大田试验相结合的方法,研究用放线菌剂蘸根处理后,放线菌剂对丹参生长、产量、品质及抗根结线虫侵染的影响。放线菌剂对丹参生长及产量提高有明显的促进作用。在小区试验中,与对照相比,放线菌剂稀释10倍、100倍处理丹参茎叶鲜质量分别增加了29.7%,35.5%,丹参根鲜质量分别增加了44.0%,39.6%,根干质量分别增加了26.3%,33.3%。在大田试验中,与对照相比,放线菌剂蘸根处理丹参单株根鲜质量、干质量分别提高了10.1%,8.2%,丹参产量提高了7.2%,增产2 022.0 kg/hm2。放线菌剂蘸根接种可大幅度提高丹参药材中有效成分的含量。在小区试验中,放线菌剂稀释100倍处理丹参根内丹参酮ⅡA、丹酚酸B及丹参素含量和产量分别较对照增加了175.0%,102.6%和110.0%及348.7%,230.6%和242.6%。在大田试验中,放线菌剂蘸根处理丹参根内丹酚酸B、丹参素含量和产量分别较对照增加了19.4%,20.8%及27.1%,28.5%。放线菌剂接种对丹参根结线虫侵染有一定抑制作用,可使大田根结线虫侵染率降低50%。生防放线菌剂蘸根处理后能明显促进丹参生长,提高丹参产量和品质及抗虫能力。 | This study was to investigate the effect of actinomycetes on growth and medicine quality of Salvia miltiorrhiza Bge.. Taking conventional transplantation treatment as control, we combined plot and field experiment by using root dipping with actinomycetes preparation to investigate survival rate, biomass, active constituents and root-knot nematode of S. miltiorrhiza Bge.. In the plot experiment, inoculating with actinomycetes of 10 and 100 times dilution, the stem-leaf natural weight of S. miltiorrhiza Bge. increased by 29.7% and 35.5% respectively compared with the control treatment; Inoculating with actinomycetes of 10 and 100 times dilution, the root natural weight of S. miltiorrhiza Bge. increased by 44.0% and 39.6% respectively, and the root dry weight of S. miltiorrhiza Bge. increased by 26.3% and 33.3% respectively. In the field experiment, inoculating with actinomycetes preparation, the root natural weight and dry weight per plant increased by 10.1% and 8.2% respectively compared with the control treatment, also the root natural weight per mu increased by 7.2%. In the plot experiment, under the treatment of actinomyces diluted 100 times by wood ash, the contents of tanshinoneⅡA, salvianolic acid B and danshensu in S. miltiorrhiza Bge. all achieved maximum value which increased by 175.0%, 102.6% and 110.0% respectively compared with that of control. Similarly, the contents of these three active constituents per plant increased by 348.7%, 230.6% and 242.6% compared with that of control. In the field experiment, the contents of salvianolic acid B and danshensu in S. miltiorrhiza Bge. were 19.4% and 20.8% higher than that in the control treatment, also, the contents of this two active constituents per plant improved by 27.1% and 28.5% compared with the control treatment. Inoculating with actinomycetes may control the disease of root-knot nematode. The infection rate of root-knot nematode in S. miltiorrhiza Bge. decreased by 50% by using actinomycetes preparation. This research suggested that actinomycetes can improve the growth, biomass, medicine quality and anti-insect ability of S. miltiorrhiza Bge.
Показать больше [+] Меньше [-]Research on lodging resistance of A1-type and A3-type cytoplasm sweet sorghum(Sorghum bicolor) | A1、A3型细胞质甜高粱品种抗倒性能研究
2012
Zou Jianqiu, China Agricultural University,Beijing (China),College of Agronomy and Biotechnology | Wang Yanqiu, China Agricultural University,Beijing (China),College of Agronomy and Biotechnology | Zhang Fei, China Agricultural University,Beijing (China),College of Agronomy and Biotechnology
为探讨比较A1和A3两种细胞质甜高粱品种在抗倒性上的异同点,以便有针对性地培育抗倒伏品种,解决生产中的倒伏问题。试验应用5个典型的A1细胞质品种和5个A3细胞质品种为试材,对其自然倒伏率、倒折率,各倒伏影响因子以及抗倒参数进行了比较与分析,同时进行了拉力试验。结果表明:在自然条件下,A3细胞质品种的倒折率和倒伏率均明显低于A1细胞质品种;A3细胞质品种茎秆充实度和茎秆壁厚度显著高于A1细胞质品种;A3细胞质品种较A1细胞质品种在抗弯能力上有较大的优势;用拉力秤将茎秆拉至偏离竖直方向45°、60°和75°时,A3细胞质品种所用的拉力可分别比A1细胞质品种高16.4%、15.6%和18.6%,回复后角度分别低3.70°、3.96°和4.08°。说明A3细胞质品种的抗倒潜力很大,用做生物乙醇的原材料栽培有明显优势,有必要进行进一步研究。 | The purpose of this study was to investigate the similarities and differences of lodging resistance between A1-type and A3-type cytoplasm sweet sorghum.The result may help breed lodging-resistant hybrids and solve the lodging problem in sweet sorghum.Five A3-type and 5 A1-type cytoplasm sweet sorghum hybrids were used for this study and the natural lodging rate,breaking rate,and results of tensile force test were compared and analyzed.We found that the natural lodging rate and breaking rate of A3-type cytoplasm sweet sorghum was significantly lower than that of A1-type cytoplasm sweet sorghum.The stalk enrichment degree and stalk wall thickness of A3-type cytoplasm sweet sorghum was significantly higher than that of A1-type cytoplasm sweet sorghum.A3-type cytoplasm sweet sorghum had a great superiority in anti-bending ability compared with A1-type cytoplasm sweet sorghum.When stalk was pulled to 45°,60° and 75° from vertical direction with spring scale,the used tensile force of A3 cytoplasm sweet sorghum was 16.44% 15.63% and 18.58%,respectively,which was more than that of A1-type cytoplasm sweet sorghum hybrids,and the corresponding retrieved angles were 3.70°,3.96° and 4.08° lower than A1-type cytoplasm sweet sorghum,respectively.We showed that A3-type cytoplasm sweet sorghum hybrids had a great lodging resistance potential and obvious advantages to used for bio-ethanol production.
Показать больше [+] Меньше [-]Biological control of postharvest diseases of fruits and vegetables by microbial antagonists | 果蔬采后病害生物防治的研究进展
2012
Wei Yingying, Nanjing Agricultural University, Nanjing (China),College of Food Science and Technology | Mao Shubo, Nanjing Agricultural University, Nanjing (China),College of Food Science and Technology | Tu Kang, Nanjing Agricultural University, Nanjing (China),College of Food Science and Technology
采用生防菌进行果蔬采后病害的生物防治是一种安全有效的方法。过去20年内,国内外研究者在生防菌的筛选、作用机制、提高生防效果的途径等方面做了大量的研究,而且目前国际市场上已有几种商业化生防产品。尽管如此,未来仍需要筛选效力高的生防菌,深入研究其生防机制以及生防菌、病原菌、寄主之间的互作模式,使生物防治成为能真正替代化学杀菌剂的方法。本文综述了近年来果蔬采后病害生物防治的研究成果,探讨了未来提高生防效果的研究方向。 | Biological control of postharvest diseases of fruits and vegetables by microbial antagonists is a safe and effective method. During the last two decades, huge information and advances concerning the selection of antagonists, mode of action and different ap- proaches to enhance biocontrol activity have been achieved, and some biofungicides are already in the market. Nonetheless, it is necessary to continue finding new potential microorganisms, better understanding the mode of action, and pathogen, antagonist and host interactions, to increase the potential of biocontrol, and turn into a real alternative to chemical synthetics. This article presents an overview of postharvest biological control studies and explores new research possibilities to improve biocontrol activity.
Показать больше [+] Меньше [-]Identification and Nematicidal Activity Assay on Root-knot Nematode of a Bacillus Strain | 对根结线虫高毒力芽胞杆菌的鉴定及其活性测定
2012
Yu Ziquan, Hunan Normal University, Changsha( China), College of Life Science | Luo Hui, Hunan Normal University, Changsha( China), College of Life Science | Xiong Jing, Hunan Normal University, Changsha( China), College of Life Science
为筛选高效安全的杀虫资源,从海底淤泥中分离到一株对根结线虫(Meloidogyne spp.)高毒力的芽胞杆菌YBf-10,PCR扩增16S rRAN基因,经测序、序列比对分析和系统进化树构建,发现其与坚强芽胞杆菌(Bacillus firmus)Z1-7菌株16S rDNA同源性为99%,初步确定所分离的菌株为坚强芽胞杆菌。将该菌株培养至芽胞成熟,离心取上清,10倍稀释后进行生物测定,发现其对北方根结线虫二龄幼虫有很高的毒力。处理24 h校正死亡率达到50%以上,72 h达到100%。对根结线虫虫卵进行毒力测定表明,作用48 h后能显著抑制虫卵孵化达到80%以上。在培养过程中分不同时段取样,并用所取样品上清进行生物测定,发现从稳定期开始表现出了对北方根结线虫的毒力,在整个稳定期毒力持续增强,直到衰亡期后期,毒力达到最高,表明坚强芽胞杆菌所产生的杀线虫活性物质主要是在稳定期合成的。将发酵上清80℃处理30 min毒力无明显变化,通过饱和硫酸铵沉淀上清中蛋白,该蛋白对线虫无明显毒力,但是去蛋白后的上清对线虫仍然具有与未经处理上清相似的杀线虫活性,表明坚强芽胞杆菌产生的杀线虫活性物质是一种非蛋白类的小分子化合物。研究结果提示,本研究所分离的坚强芽胞杆菌在稳定期能够大量合成对线虫具有毒杀活性的小分子化合物,对根结线虫表现出极高毒力,为利用该菌株开发植物寄生线虫生防制剂提供了杀虫资源。 | For screening of high efficiency and safe nematicidal resource, a Bacillus strain YBf-10 which exhibits extreme toxicity to root-knot nematode was isolated from marine sediment. The 16S rRAN gene of this strain was amplified by PCR, then sequenced and analysed with Blast in NCBI. The result indicated that it showed 99% identity with the 16S rDNA of Bacillus firmus strain Z1-7. It means the isolated Bacillus strain is B. firmus. The YBf-10 strain was cultured in LB medium until spores were mature, the supernatant was harvested by centrifuged. The supernatant was diluted by 10-folds, and bioassay to 2nd stage juveniles (J2) of Meloidogyne hapla was conducted. The results showed that YBf-10 exhibited extreme toxicity, and the adjusted mortality reached to 50% at 24 h, and even up to 100% at 72 h. The supernatant could obviously suppress hatching of eggs of M. hapla to 80% at 48 h. For ascertaining the synthetic phase of the nematicidal substance, samples were collected at interval of culturing times, the supernatant of the samples was prepared by centrifugalization, and assayed toxicity to J2 of M. hapla. The result indicated that, from onset of the stationary phase, it exhibited obvious toxicity. The toxicity enhanced persistently during all the stationary phase, this meant that the nematicidal substance was synthesized at stationary phase of YBf-10 strain. The nematicidal activity of supernatant treated at 80℃ for 30 min showed no obvious change. The protein in supernatant was prepared by ammonium sulfate precipitation with 30% relative saturation, and exhibited no toxicity to J2 of M. hapla. Whereas, the supernatant removed protein exhibited the same nematicidal activity with the raw supernatant. The result indicated that the nematicidal substance produced by YBf-10 was micromolecular compound, not protein. On the basis of above research, we conclude that the Bacillus strain which exhibits toxic to nematode is characterized as Bacillus firmus, and it synthesizes micromolecular nematicdidal compound at stationary stage. The compound exhibits extreme virulence to root knot nematode, and supplies nematicidal resource for exploring biological control nematicide with the YBf-10 strain.
Показать больше [+] Меньше [-]