Effect of Indigenous Plant Growth-Promoting Rhizobacteria on Wheat (Triticum Aestivum L.) Productivity and Soil Nutrients

The present study aimed at selection of efficient bacterial isolates with multiple plant growth-promoting (PGP) traits at variable doses of chemical fertilizers for enhanced wheat productivity and sustenance of soil health. Ten bacterial isolates from wheat (rhizosphere soil and root endosphere) were screened for PGP traits (indole acetic acid, phosphate solubilization, siderophore production, and ammonia production). Only three isolates (B2, SIR1, and BIS2) possessed all PGP traits. Net house evaluation of these isolates at graded doses of chemical fertilizers revealed that the potential of B2 isolate is significantly superior for enhancing wheat yield and soil properties. On the basis of 16S rDNA analysis, the potential isolate (B2) was identified as Serratia marcescens. Conjoint use of the B2 isolate at 80% recommended doses of fertilizers (RDF) significantly increased wheat growth and saved 18 kg nitrogen and 10 kg phosphorous on per hectare basis. The developed module not only increases profitability but also protects the environment and sustains soil health.     

Plant Growth Promoting Rhizobacteria

Plant growth promoting rhizobacteria (PGPR) are soil bacteria with some beneficial effects on soil properties, plant growth and the environment. In this article, some of the most important advancements in the field of PGPR and their related properties are presented. Such knowledge can be important for understanding regarding the use of PGPR for different uses such as biological fertilization and alleviation of different stresses on plant growth and the environment.     

Harnessing Plant Growth Promoting Rhizobacteria Beyond Nature: A Review

Root-associated plant growth promoting rhizobacteria (PGPR) interact with the plant roots and influence plant health and soil fertility. Plant growth promoting rhizobacteria play an important role in plant growth by exerting various mechanisms such as biological nitrogen fixation, growth hormone production, phosphate solubilization, siderophore production, hydrolytic enzyme production, antagonistic activity against fungal pathogens etc. Hence, these are employed as inoculants for biofertilizer and biocontrol activities. This review summarizes various mechanisms of PGPR and their potential for use as inoculants. It shows that their use is a worthwhile approach for exploring disease management in conjunction with other strategies.     

根际促生菌应用于基质对水稻幼苗生长的影响

为了研究根际促生菌对水稻幼苗的促生效果,培育高效优质水稻育苗基质,本研究选用5株根际促生菌(LY5:枯草芽孢杆菌(Bacillus subtilis),LY11:解淀粉芽孢杆菌(Bacillus amyloliquefaciens),X2:摩拉维亚假单胞菌(Pseudomonas moraviensis),X3:沙芬西芽孢杆菌(Bacillus safensis),X8:绿针假单胞菌(Pseudomonas chlororaphis)分别与本实验室已筛选出的最适配比基质进行混合制作高效水稻育苗基质,以不添加促生菌为对照,在盆栽条件下,研究根际促生菌对水稻幼苗生长和代谢的影响。结果表明:①解淀粉芽孢杆菌(LY11)应用于育苗基质对水稻幼苗的促生效果及代谢活性最好。②在育苗基质中添加根际促生菌后,地上部生物量和壮苗指数均比对照显著增加,增幅分别为17.24%～31.19%和11.37%～23.28%。③添加根际促生菌的育苗基质能够促进水稻幼苗根系的生长,根体积、总根长等均比对照显著增加,且改善了根系形态结构,显著提高了根系活力。④根际促生菌处理显著促进了水稻幼苗对氮磷钾养分的吸收,且氮、钾...     

植物根际促生菌促进小麦生长及提高其抗旱性的研究进展

干旱胁迫是影响小麦生长发育与产量形成最主要的非生物胁迫因子,近年来化肥的过量使用及全球气候变化产生的不利影响,导致小麦在生长过程中受到的干旱胁迫危害日趋严重。植物根际促生菌(PGPR)不仅可以协助小麦提高养分利用率,促进其生长发育,还能够通过自身作用或产生多种代谢产物协助小麦抵御干旱胁迫。本文归纳总结了PGPR促进小麦生长及提高其抗旱性的研究进展,为利用PGPR提高小麦促生抗旱的研究奠定了理论基础。     

Effects of Root Plant Growth Promoting Rhizobacteria Inoculations on the Growth and Nutrient Content of Grapevine

The objective of this study was to evaluate the effects of seven nitrogen (N₂)-fixing and/or phosphorus (P)-solubilizing and siderophore-producing microorganism based bio-fertilizers in single and triple strain combinations isolated from the acidic rhizospheric soil of native tea, grapevine, and wild red raspberries. As a result of this study, bacterial efficiency was found to be variable and depended on the bacterial strains and evaluated growth parameters. Plant growth-promoting rhizobacteria (PGPR) has improved macro- and micro-nutrient concentrations in grapevine leaves, and stimulated plant growth. Triple inoculation and single inoculation based bio fertilizers were found to stimulate overall plant growth, including shoot and leaf weight, main shoot length, leaf ground index, chlorophyll, nitrogen, zinc and iron content of grapevine cv ‘Italy’. Bio-fertilizers increased the nutrients such as nitrogen, zinc and iron concentrations and consequently increased the chlorophyll content of the leaves.     

Plant Growth-Promoting Rhizobacteria (Pgpr) Increase Yield,Growth And Nutrition Of Strawberry Under High-Calcareous Soil Conditions

Plant growth promoting effects of Alcaligenes 637Ca, Staphylococcus MFDCa-1, MFDCa-2, Agrobacterium A18, Pantoea FF1 and Bacillus M3 were tested on strawberry cv. ‘Aromas’ based on yield, number, and weight of fruit, leaf area, vitamin C, total soluble solids (TSS), acidity and ionic composition of leaves under calcareous soil conditions. The results demonstrated that all of bacterial treatments significantly affected all parameters tested. The best result was obtained from 637Ca treatment, which significantly increased fruit yield, number and weight about 47.5, 34.7, and 9.4%, respectively, compared to control. Except for magnesium (Mg) and zinc (Zn) in the leaf, the concentrations of all plant tissue nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), iron (Fe), copper (Cu), manganese (Mn), boron (B)] were significantly increased by bacterial treatments tested. The data in the present study showed that all bacterial treatments including Alcaligenes 637Ca, Staphylococcus MFDCa-1, MFDCa-2, Agrobacterium A18, Pantoea FF1, and Bacillus M3 to strawberry plants can ameliorative the deleterious effect of high lime on fruit yield, growth and nutrition. These results suggested that plant growth-promoting Rhizobacteria (PGPR) treatments could be offer an economic and simple means to increased plant resistance for high calcareous soil conditions.     

Effect of Plant Growth Promoting Rhizobacteria on Fe Acquisition in Peach (Prunus Persica L) Under Calcareous Soil Conditions

Abstract

The effects of Alcaligenes 637Ca, Agrobacterium A18, Staphylococcus MFDCa1, MFDCa2, Bacillus M3 and Pantoea FF1 were tested on peach cv. ‘Elegant Lady’ on GF677 and Nemaguard rootstocks. Average increases in citric, malic, oxalic, butyric and fumaric acid in the leaf were obtained from rhizobacterial root inoculations of 33.1, 17.5, 21.7, 26.5, and 44.7% in Elegant Lady/Nemaguard, respectively. FF1 showed the highest FC-R activity in the roots of Nemaguard (112.4?nmol?FW?gr^?1?hr^?2) and GF677 (162?nmol?FW?gr^?1?hr^?2). The highest FC-R activity in the leaf was with MFDCa2 in Elegant Lady/Nemaguard (57.1?nmol?FW?gr^?1?hr^?2) and 637Ca in Elegant Lady/GF677 (87.9?nmol?FW?gr^?1?hr^?2). PGPR strains used in this study expressed increased leaf organic acid content, FC-R activity in the roots and leaf, increased active Fe content in the leaf, and possessed a great potential for the improvement of iron availability to plants.     

盐胁迫环境下接种根际促生细菌对白蜡树根际生物学特征及其生长的影响

[目的]探讨不同盐胁迫生境中接种根际促生细菌(PGPR)对白蜡树根际的作用效果,为明确PGPR对白蜡树耐盐性的改善效果以及盐胁迫环境下PGPR的推广应用提供理论依据。[方法]通过盆栽试验,研究不同盐胁迫(轻度、中度、重度)及其接种阴沟肠杆菌(PGPR)对白蜡树根际生物学特征与生长的影响。[结果]盐胁迫显著降低了白蜡树根际微生物数量、微生物量碳、氮含量和脲酶、多酚氧化酶、过氧化氢酶、蔗糖酶活性,且其降幅随盐胁迫梯度的增加而增大;当接种PGPR后,白蜡树根际微生物数量、微生物量碳、氮含量和脲酶、多酚氧化酶、过氧化氢酶、蔗糖酶活性均呈上升趋势,其中轻度盐胁迫接种PGPR处理的细菌数、放线菌数和微生物总量达最高,分别较对照显著提高14.64%,24.01%和17.04%,而脲酶、多酚氧化酶、蔗糖酶活性与对照差异不显著,但显著高于其他处理。同时,白蜡树的根体积、根系总吸收面积与活跃吸收面积随着盐胁迫程度的加剧呈递减趋势,但接种PGPR后,对应的根系指标均有增加,其中轻度盐胁迫接种PGPR处理的活跃吸收面积显著高于对照15.97%。此外,同对照相比,不同程度盐胁迫均显著降低了白蜡树的地径、株高,而接种PGPR却显著提高了地径、株高,其中轻度盐胁迫接种PGPR处理的地径、株高与对照差异不显著,但显著高于其他处理。[结论]轻度盐胁迫下(盐分含量0.2%)接种阴沟肠杆菌能显著改善白蜡树根际生物学特征,并促进白蜡树生长,其作用效果显著优于中度、重度盐胁迫下接种阴沟肠杆菌。     

不同雨强下各生育期玉米坡耕地的侵蚀产沙研究

[目的] 研究玉米作物对坡耕地的防蚀效果,为黄土高原坡面水土流失防治提供科学依据。[方法] 采用室外人工模拟降雨试验,分析玉米在幼苗期、拔节初期、拔节中期、拔节后期、抽雄期5个不同生育期对坡耕地侵蚀产沙量和过程的影响。[结果] ①随着玉米作物生长,它对坡面产流产沙的抵御作用增强,幼苗期效果微弱,抽雄期最盛,抽雄期相比裸地可减少48.5%径流量和73.7%产沙量。不同生长阶段玉米作物的减沙效果优于减流效果。②降雨的产流产沙过程呈现不断波动趋势,玉米作物使初始产流产沙时间延迟,稳定产流产沙阶段平均产流产沙量下降。雨强从40 mm/h增加到80 mm/h使产流产沙量增长率大于100%,径流系数和含沙量均增加,侵蚀过程更加剧烈。③叶面积指数与不同生育期玉米地坡面的土壤流失比率有较好的指数相关关系,可使用叶面积指数来估算不同生育期玉米地坡面的土壤流失比率,为估算年植被覆盖与管理因子C值奠定基础。[结论] 随着玉米生长,其防蚀效果增强,但幼苗期和拔节初期侵蚀严重,需采取辅助措施防治水土流失。雨强增加使玉米和裸地条件下侵蚀产沙更为严重。     

Influence of Plant Growth Promoting Rhizobacteria,Compost, and Biochar of Azolla on Rosemary (Rosmarinus Officinalis L.) Growth and Some Soil Quality Indicators in a Calcareous Soil

In order to study the effect of plant growth promoting rhizobacteria (PGPR), Azolla compost and Azolla biochar on some soil quality indicators and rosemary growth, a greenhouse experiment was conducted in a completely randomized design with six replications. Treatments consisted of T₁ (control), T₂ (1% Azolla compost), T₃ (1% Azolla biochar), T₄ (PGPR (P. fluorescens), T₅ (1% compost + PGPR) and T₆ (1% biochar + PGPR). Rosemary growth parameters and nutrients concentration increased in all treatments compared to control. Treatments increased soil nutrient concentrations, soil microbial respiration (SMR) and microbial biomass C (MBC) but decreased soil metabolic quotient (qCO₂) compared to control treatment. A significant enhancement in rosemary growth occurred due to the improved soil quality as a result of organic fertilizers application, particularly by co-application of P. fluorescens and compost or biochar of Azolla.     

Effects of Plant Growth-Promoting Rhizobacteria and N Source on Plant Growth and N and P Uptake by Tomato Grown on Calcareous Soils

Introducing specific microorganisms into the soil ecological system is an important strategy for improving nutrient use efficiency. Two pot experiments were conducted in the greenhouse from December 3, 2012 to January 25, 2013 (Experiment 1) and March 11 to April 23, 2013 (Experiment 2) to evaluate the effect of nitrogen (N) source and inoculation with plant growth-promoting rhizobacteria (PGPR) on plant growth and N and phosphorus (P) uptake in tomato (Lycopersicon esculentum Mill.) grown on calcareous soils from South Florida, USA. Treatments included urea, controlled release urea (a controlled release fertilizer, CRF) each at low and high N rates and with or without inoculation of PGPR. A mixture of PGPR strains Bacillus amyloliquefaciens IN937a and Bacillus pumilus T4 was applied to the soil during growing periods of tomato. Treatments with PGPR inoculation increased plant height compared to treatments without PGPR in both experiments. Inoculation with PGPR increased shoot dry weight and shoot N uptake for the same N rate and N source. In both experiments, only at high N rate, CRF and urea treatments with PGPR had significantly (P < 0.05) greater shoot biomass than those without PGPR. Only at high N rate, CRF treatment with PGPR significantly increased shoot N uptake by 39.0% and 10.3% compared to that without PGPR in Experiments 1 and 2, respectively. Meanwhile, presence of PGPR in the soil increased shoot P uptake for all treatments in Experiment 1 and for most treatments in Experiment 2. In Experiment 1, only at low N rate, CRF treatment with PGPR significantly increased shoot P uptake compared with that without PGPR. In Experiment 2, a significant increase in shoot P uptake by inoculation of PGPR was only observed in CRF treatment at high N rate. Results from this study indicate that inoculation with PGPR may increase plant growth and N and P uptake by tomato grown on calcareous soils. However, the effect of PGPR varied and was influenced by many factors such as N source, N rate, and soil fertility. Further investigations are warranted to confirm the effect of PGPR under different soil conditions.     

Remediation of Cadmium-Polluted Soil Using Plant Growth-Promoting Rhizobacteria and Natural Zeolite

Eurasian Soil Science - The impact of two strains of Pseudomonas bacteria and natural zeolite on the growth and elemental composition of barley plants was studied in an agrogray soil (Luvisol)...     

Compost Effect on Plant Growth-Promoting Rhizobacteria and Mycorrhizal Fungi Population in Maize Cultivations

The composting process allows the conversion of organic waste into organic matter that can be used in counteracting organic matter soil depletion. Moreover, agricultural use of compost increases plants defense abilities against pathogens, leading to a higher crop yield. Key plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhial fungi (AMF) populations were evaluated after incorporating high quality composts in both conventional and organic maize production in order to determine if compost application affects the presence of important PGPR and AMF. Results obtained indicate that while the use of the compost as an amendment may exert a limited influence on AMF population, it can significantly modulate the composition of PGPR in the rhizosphere of maize plants.     

西瓜根际促生菌筛选及生物育苗基质研制

通过从西瓜根际分离筛选具根际定殖能力的植物根际促生菌,将其保活添加至普通育苗基质研制生物育苗基质,以确保功能菌株能够在苗期定殖根际,进而在移栽后发挥促生功能。结果表明,分离获得一株同时具有产吲哚乙酸(IAA)和NH_3,且对尖孢镰刀菌和茄科劳尔氏菌均有拮抗作用的植物根际促生菌(PGPR)菌株N23;在三季育苗试验中,与普通基质处理(CK)相比,添加菌株N23的生物育苗基质所育种苗,在多项苗期生长指标上均表现出稳定的促生作用;盆栽试验表明,除叶绿素相对含量测量值(SPAD)外,生物基质所育西瓜种苗的其他检测指标均显著高于对照(普通育苗基质所育种苗,下同);田间试验表明,生物基质所育种苗西瓜、黄瓜、辣椒和番茄种苗移苗后,在苗期植株株高和茎粗均显著优于对照,在产量上均增产10%以上。结合形态、生理生化特征和16S rDNA基因序列分析,初步鉴定菌株N23为芽孢杆菌属细菌(Bacillus sp.)。综上,利用芽孢杆菌N23研制的生物育苗基质能够有效促进所育不同作物种苗质量,增强移栽后作物的生长和田间产量。因此,本研究能够为根际有益微生物的应用提供新的思路,为生物育苗基质的研制提供理论支撑。     

Growth Promotion of Maize (Zea mays L.) by Plant-Growth-Promoting Rhizobacteria under Field Conditions

Plant-growth promoting rhizobacteria (PGPR) play an important role in plant health and soil fertility. The experiment was conducted as factorial experiment with two factors of Azospirillum and Azotobacter. The bacterial strains were Azospirillum lipoferum s-21, A. brasilense DSM 1690, A. lipoferum DSM 1691, Azotobacter chroococcum s-5, and A. chroococcum DSM 2286. The results indicated that growth promotion by PGPR appears from early stages of growth, 45 days after inoculation (DAI). Beneficial effects of bacterial inoculation on ear growth were observed after 75 DAI. Inoculation with PGPR increased dry weights of leaf, stem, and grain and hence total biomass sampled at 90, 105, and 120 (harvest time) DAI. The greatest grain weight was produced by Azospirillum s-21 inoculation. Dual inoculation with Azotobacter s-5 + Azospirillum s-21 significantly increased total dry weight up to 115%. Results of this study showed that leaf area index and crop growth index were significantly affected by bacterial treatments.     

Antifungal and Plant Growth Promoting Activities of Indigenous Rhizobacteria Isolated from Maize (Zea mays L.) Rhizosphere

Plant growth promoting rhizobacteria (PGPR) enhance the plant growth directly by assisting in nutrient acquisition and modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogens. The aim of this study was to select effective PGPR from a series of indigenous bacterial isolates by plant growth promotion and antifungal activity assays. This study confirmed that most of the isolates from maize rhizosphere were positive for PGPR properties by in vitro tests. Azotobacter and Bacillus isolates were better phosphate solubilizers and producers of lytic enzymes, hydrocyanic acid (HCN), and siderophores than Pseudomonas. Production of indole-3-acetic acid (IAA) and antifungal activity were the highest in Azotobacter, followed by Bacillus and Pseudomonas. The most effective Azotobacter isolates (Azt₃, Azt₆, Azt₁₂) and Bacillus isolates (Bac_10, Bac₁₆) could be used as PGPR agents for improving maize productivity. Further selection of isolates will be necessary to determine their efficiency in different soils.     

不同轮作模式对青贮玉米产量、品质及土壤肥力的影响

为了探明苜蓿-青贮玉米(A-C)、大麦-青贮玉米(B-C)、小麦-青贮玉米(W-C)、燕麦-青贮玉米(O-C)、黑麦草-青贮玉米(L-C)5种不同轮作模式对青贮玉米产量、品质和土壤肥力的影响,以玉米-玉米(C-C)连作为对照,在2014年和2015年进行了田间随机区组试验。结果表明,不同轮作模式下青贮玉米产量、粗蛋白、淀粉、粗脂肪、p H值、有机质、速效养分和土壤酶活性指标均显著优于连作模式(P0.05)。A-C处理中青贮玉米产量、裹包青贮玉米的粗蛋白、淀粉、粗脂肪含量均高于其他处理,并分别高出对照(C-C)39.29%、27.90%、39.46%和28.30%。随着种植年限的延长土壤酶活性呈下降趋势,其中A-C和O-C处理中,蔗糖酶随着种植年限的延长明显下降;W-C处理中,碱性磷酸酶活性随着种植年限的延长明显下降。因子分析结果表明,不同轮作处理土壤肥力得分依次为A-CO-CB-CW-CL-C,说明苜蓿与青贮玉米轮作不仅有利于提高玉米产量和改善青贮饲料品质,还有助于改良土壤。本研究结果为长三角地区优质饲草轮作制度的建立提供了理论依据。     

两种根际促生菌在不同氮磷条件下对油菜生长 和养分吸收的影响

油菜是我国和世界主要油料作物,对氮磷肥需求量大,但是氮磷肥利用率低,会造成资源浪费和环境污染等问题。由于根际促生菌能够改善植物生长并提高养分吸收,近些年来不少生物肥料中添加有根际促生菌。采用土培试验,探究了两种根际促生菌(巨大芽孢杆菌和短小芽孢杆菌)在不同氮磷条件下对油菜生长和养分吸收的影响,以期为油菜肥料研制和施肥技术提供帮助。结果表明:油菜在缺氮或缺磷条件下的地上部干重仅为正常氮磷供应的20%;巨大芽孢杆菌在正常氮磷供应条件下改善了油菜生长,促进了油菜对P、K、Zn和B 4种营养元素的吸收,而在缺氮和缺磷条件下没有效果;短小芽孢杆菌在缺氮、缺磷和正常氮磷条件下均没有效果。因此,氮磷肥对油菜生长至关重要,巨大芽孢杆菌能够在适当氮磷供应的条件下发挥促生作用。     

产ACC脱氨酶植物根际促生菌的筛选及其对修复植物高羊茅生长的影响

以1-氨基环丙烷-1-羧酸(ACC)为唯一氮源,从石油污染的土壤中分离得到一株具有ACC脱氨酶活性的菌株D5A.该菌在以ACC为唯一氮源条件下,其ACC脱氨酶比活力为0.084 U/mg.另外,D5A还具有产生吲哚乙酸(IAA)、耐盐以及溶磷的特性.在液体培养条件下该菌株产IAA高达112 mg/L,在90 g/kg盐含量的培养基中仍能够正常生长且具有较强的溶解矿物磷能力.同时该菌对酸碱具有良好的适应性,在初始pH4～10的LB培养基中生长良好.种子发芽试验表明在3 g/kg和6 g/kg浓度NaC1的逆境条件下,该菌株能显著提高高羊茅种子的发芽率和芽长.最后,通过对其进行生理生化特性和16S rDNA序列分析,该菌株初步鉴定为克雷伯氏菌(Klebsiellasp.).