一株甜瓜枯萎病病原拮抗菌的筛选与防治效果初报

从海南11个市县甜瓜地、蔬菜地中分离到570株菌株,通过室内平板对峙、继代培养、发芽率等实验,筛选出3株对甜瓜枯萎病防治效果较好和对甜瓜种子发芽率有促进作用的菌株D1、F1、H3,进行盆栽试验,结果显示,F1菌株防治效果最好,并且在先接种108 CFU/mL的F1再接种107 CFU/mL的病原菌,对甜瓜枯萎病的防治效果达到70.6％;经形态特征、生理生化和16SrDNA测序实验鉴定,确定F1菌属于Bacillus methylotrophicus.     

布氏乳杆菌PG-7去除胆固醇和抗氧化能力的研究

从糖蒜中筛选分离到的一株具有降胆固醇和抗氧化能力的产乳酸菌株PG-7,该菌对胆固醇的去除率为58.1%,对DPPH自由基和超氧自由基的清除率分别为91.7%和16.2%。克隆了PG-7的16S rD-NA序列,并以其同源性为基础构建了相关属种的系统发育树。结果表明,该菌16S rDNA序列全长1 638 bp,BLAST显示该菌株与乳杆菌属同源;PG-7菌株在进化关系上与布氏乳杆菌属(Lactobacillus buchneri)聚成一族。将其鉴定为布氏乳杆菌属,命名为:Lactobacillus buchneri PG-7。     

The Effect of a Substrate Containing Arbuscular Mycorrhizal Fungi and Rhizosphere Microorganisms (Trichoderma,Bacillus, Pseudomonas and Streptomyces) and Foliar Fertilization on Growth Response and Rhizosphere pH of Three Strawberry Cultivars

Abstract

Vegetatively propagated plants of three strawberry cultivars-‘Senga Sengana’, ‘Elsanta’ and ‘Kent’-were grown for 20 weeks in rhizoboxes filled with 1.85 kg of sterilized mineral soil. Ten plants were treated with an N-P-K foliar fertilizer (F, control), or inoculated with a substrate containing arbuscular mycorrhizal fungi, Trichoderma viride and rhizosphere bacteria (PGPR-Plant Growth Promoting Rhizobacteria) without any fertilization (M), or inoculated with the mixture of microorganisms and treated with the foliar fertilizer (MF). Total plant biomass was increased by the M treatment in all cultivars. M treatment resulted in higher total root length and number of root tips in ‘Senga Sengana’, whereas the other two cultivars showed different responses of root morphology. Shoot/root ratio was decreased by the M and MF treatments in comparison with control plants. Foliar fertilization of inoculated plants caused different growth responses in the three cultivars and a general decrease of root growth. After the MF treatment, the biomass of ‘Senga Sengana’ increased and the biomass of ‘Elsanta’ and ‘Kent’ decreased. Inoculation with the mycorrhiza-PGPR substrate increased rhizosphere pH irrespective of foliar fertilization. Plant mineral content was highly modified by the treatments in all the cultivars examined. In particular, changes were noted in N, P, K, Fe, B and Mn uptake. The results show an interaction between foliar fertilization and root inoculation with microorganisms, as well as genotype-dependent influences, on growth responses and rhizosphere pH of strawberry plants.     

根际ACC脱氨酶活性细菌的分离及其促生作用研究

从不同来源的植物根际土壤中分离出能以1-氨基环丙烷-1-羧酸(ACC)为唯一氮源生长的细菌4株,经测定均具有较高的ACC脱氨酶活性,并进一步研究了菌株对植物的促生长作用。首先进行了种子根长试验,利用菌株菌悬液处理玉米和番茄种子,结果表明,经过细菌1101、2101、4201和GXGD002处理,种子的生根长度较对照组均有明显增长,玉米种子根长相对伸长率依次为78.73%、61.72%、47.37%、47.08%;番茄种子根长相对伸长率依次为61.19%、55.84%、54.34%、51.19%。其次进行了番茄穴盘栽培试验,分别在播种后40 d和55 d收苗,测定植株的株高、茎粗、根长等生长指标,结果表明,菌株4201和GXGD002具有显著促进生长作用,其处理组植株在株高、根长、根系活力等方面较对照组均有明显增强。     

棉花根际解钾细菌的生理活性和促生效果

考察优良棉花根际解钾菌株K1111、K1114、K2115、K3105和K3205的溶磷、解钾、产铁载体和产吲哚乙酸等生理活性。将其接种到棉花根际,通过盆栽试验,研究5株菌株对棉花根系发育与生长的影响。结果表明,这5株菌的产铁载体能力均达到5+(极高量)水平;分泌吲哚乙酸的浓度在6.6～12.4μg/mL之间;同时具有很高的溶磷能力。接种5株菌株的棉花根系活力、株高和干重均显著高于不施钾肥的对照组,高于或相当于施钾对照组。     

Microbially Enhanced Phytoextraction of Heavy-Metal Fly-Ash Amended Soil

A study was carried out for the phytoextraction of metals by S. munja with the interventions of growth-promoting bacteria isolated from fly ash (FA). It was observed that when a consortium of Bacillus endophyticus NBRFT4, Paenibacillus macerans NBRFT5, and Bacillus pumilus NBRFT9 was inoculated in the rhizospheric zone of S. munja, it not only enhanced metal uptake through mobilization but also promoted the plant growth. A combined effect of both factors accelerated the phytoextraction of nickel (Ni), zinc (Zn), and iron (Fe) by two- or three-fold. Plant growth and metal bioavailability both were promoted by the synthesis of siderophore (ACC), indole acetic acid (IAA), gibberellic acid, and cytokinins by bacteria. In addition, bacteria might also change the speciation of metals to make it more water soluble for plant uptake. Hence, a microbe-based phytoextraction of metals from contaminated sites may be recommended for use as an environmentally sound technology in place of conventional methods.     

Evaluation of cultivation methods and sustainable agricultural practices for improving shallot bulb production – a review

Abstract

Shallot is an economically important nutritive bulb vegetable and medicinal plant from Alliaceae family. Distributed in limited regions worldwide, in most cases, shallots widely grow in very cold to moderate cold temperate climates at high elevations required to induce bolting and overcome their bulbs and true seeds dormant period. Shallot responses to agricultural management and environmental conditions vary among different species and genotypes and, thus, selection of the elite genotypes is a prerequisite for obtaining desired yield and quality of bulbs and true seeds. Plant material (seed or bulb), plant selection, as well as cultivation and agricultural practices (importantly fertilization, spacing, planting date, and irrigation in greenhouse or farmland) critically affect productivity, phytonutrient value, and economic profit of the shallot produces. The knowledge of using biofertilizers and mulching techniques on shallots are currently evolving, but the information on the efficiency of nanobiofertilizers and eco-friendly and biodegradable mulching materials on shallots farming are still lacking. With the emphasis on sustainable agricultural systems, the efficiency of combined organic and inorganic fertilization is discussed and the potential biofertilizer agents are recommended. This review highlights the importance of using the integrated fertilization (organic and inorganic methods combined with biofertilizers) and irrigation methods (such as two-line spray hose irrigation combined with mulching), and the practices with the highest potential to further improve shallot farming are suggested. The information on shallots breeding is still lacking and requires extensive researches in the future.     

联苯菊酯降解菌的筛选、鉴定及降解特性研究

联苯菊酯是一种广谱高效杀虫剂,大规模的应用使其广泛残留在环境中,因此筛选联苯菊酯的高效降解菌具有重要意义。从扬州农药厂附近的地表土壤取样,利用富集驯化培养分离得到一株编号为S8的降解细菌,经表形特征、生理生化特性和16S rDNA序列分析其为醋酸钙不动杆菌（Acinetobacter calcoaceticus）,该菌株在pH7.0和30 ℃的条件下,对100 mg·L-1联苯菊酯的3 d降解率达56.4%,半衰期为60.7 h。其最适生长条件为：pH6.0~8.0,温度30~35 ℃,接种量5%。研究结果可为今后治理联苯菊酯残留污染提供理论参考。     

Phosphate Solubilizing Ability and Phylogenetic Diversity of Bacteria from P-Rich Soils Around Dianchi Lake Drainage Area of China

The phylogenetic diversity of phosphate solubilizing bacteria(PSB)distributed in P-rich soils in the Dianchi Lake drainage area of China was characterized,and the tricalcium phosphate(TCP)solubilizing activities of isolated PSB were determined.Among 1 328 bacteria isolated from 100 P-rich soil samples,377 isolates(28.39%of the total)that exhibited TCP solubilization activity were taken as PSB.These PSB showed different abilities to solubilize TCP,with the concentrations of solubilized P in bacterial cultures varying from 33.48 to 69.63 mg L^-1.A total of 123 PSB isolates,with relatively high TCP solubilization activity(>54.00 mg L^-1),were submitted for restriction fragment length polymorphism(RFLP)analysis,which revealed 32 unique RFLP patterns.Based on these patterns,62 representative isolates,one to three from each RFLP pattern,were seffected for 16S rRNA sequencing.Phylogenetic analysis placed the 123 PSB into three bacterial phyla,namely Proteobacteria,Actinobacteria and Firmicutes.Members of Proteobacteria were the dominant PSB,where 107 isolates represented by 26 RFLP patterns were associated with the genera of Burkholderia,Pseudomonas,Acinetobacter,Enterobacter,Pantoea,Serratia,Klebsiella,Leclercia,Raoultella and Cedecea.Firmicutes were the subdominant group,in which 13 isolates were affiliated with the genera of Bacillus and Brevibacterium.The remaining 3 isolates were identified as three species of the genus Arthrobacter.This research extends the knowledge on PSB in P-rich soils and broadens the spectrum of PSB for the development of environmentally friendly biophosphate fertilizers.     

Yield promotion and phosphorus solubilization by plant growth–promoting rhizobacteria in extensive wheat production in Turkey

Plant growth–promoting rhizobacteria (PGPR) have been reported to stimulate the growth and yield of grain crops, particularly when nutrient supply is poor. However, the mechanisms underlying stimulation of plant growth may vary depending not only on growth conditions and crop management but also on plant and bacterial species. The present study assessed the effect of an inoculation with single or multiple PGPR strains on phosphorus (P)‐solubilization processes in the soil and on grain yield in wheat. Single inoculation with Bacillus subtilis OSU‐142, Bacillus megaterium M3, or Azospirillum brasilense Sp245 increased grain yield by 24%, 19%, and 19%, respectively, while a mixed inoculation with OSU‐142, M3, and Sp245 increased grain yield by 33% relative to noninoculated plants. Single inoculations with Paenibacillus polymyxa RC05 or Bacillus megaterium RC07 were less effective. Single or mixed treatments with OSU‐142, M3, and Sp245 increased the concentrations of the labile and moderately labile P fractions in rhizosphere soil. The growth‐stimulating effect of OSU‐142, M3, and Sp245 was also reflected by higher P concentrations in most plant organs. Among all inocula tested, the highest plant P acquisition was obtained in the presence of M3 and accompanied by the highest microbial P levels and the highest phosphatase activities in the rhizosphere soil. In conclusion, seed inoculation with mixed PGPR strains may effectively substitute for a part of P‐fertilizer application in extensive wheat production, and in particular M3 appears to improve the solubilization of inorganic soil P.