The occurrence of rhizobacteria from Paspalum genotypes and their effects on plant growth

ABSTRACT This work aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from 10 Paspalum genotypes and evaluate the effect of their inoculation on P. regnellii, P. atratum, and P. malacophyllum genotypes. The bacterial population ranged from undetectable to 107 bacterial cells per gram of fresh matter in the Paspalum genotypes. Initially, we isolated 164 bacteria from rhizospheric soil and roots of the Paspalum genotypes using media N-free LG agar plate, semi-solid NFb, and LGI. The isolates were characterized genetically and physiologically. The sequencing of 16S rRNA showed the presence of many genera, and some are new in association with Paspalum. The most common was Bacillus followed by Rhizobium, Paraburkholderia, Enterobacter, Cupriavidus, Pseudomonas, Dyadobacter and Acinetobacter. Thirty-eight per cent of isolates produced siderophores, 25 % produced solubilized phosphate, and only 9 % produced indolic compounds. Three greenhouse experiments were performed in randomized blocks with six replicates using representative bacterial strains isolated from P. regnellii, P. malacophyllum and P. atratum cv. Pojuca. We also included strain Sp245 (Azospirillum baldaniorum), uninoculated control, and nitrogen control (150 kg N ha1). There was an increase of up to 53 % in shoot dry matter in P. regnellii inoculated with strain Sp245 and the shoots accumulated more N. In contrast, only small effects were observed for the other Paspalum genotypes inoculated with PGPR from the host genotypes. This study shows a high diversity of diazotrophic rhizosphere bacteria and suggests no strain specificity between the bacterial isolates and the Paspalum genotypes.

Isolation and characterization of Klebsiella oxytoca from the rhizosphere of Lotus corniculatus and its biostimulating features / Isolamento e caracterização de Klebsiella oxytoca da rizosfera de Lotus corniculatus e suas características bioestimulantes

Significant food resource shortages are occurring worldwide. Plant growth-promoting rhizobacteria (PGPR) represent an ecofriendly and efficient approach for increasing soil fertility and plant productivity. The current study explored biostimulating traits of PGPR from the rhizosphere of Lotus corniculatus growing in the Al-Ahsa region. A bacterial isolate (LCK121) was obtained, characterized for phenotypic, and identified by 16S rRNA gene sequencing. In addition, its growth-stimulating effects on barley were investigated. The strain identity was confirmed via comparative analysis of the 16S rDNA sequences with Klebsiella oxytoca (99.3% similarity level). LCK121 exhibited multiple plant growth-promoting features, including indole-3-acetic acid (IAA) production (16.34 µg mL-1), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity (1.35±0.02 µmol α-ketobutyrate mg−1 h−1), phosphate solubilization, and nitrogen fixation. Furthermore, in vitro inoculation of barley with LCK121 significantly increased the root and shoot dry weights. The results highlight the potential of LCK121 for developing green fertilizers for sustainable agriculture.

A escassez significativa de recursos alimentares está ocorrendo em todo o mundo. As rizobactérias promotoras de crescimento de plantas (PGPR) representam uma abordagem ecologicamente correta e eficiente para aumentar a fertilidade do solo e a produtividade das plantas. O presente estudo explorou características bioestimulantes de PGPR da rizosfera de Lotus corniculatus crescendo na região de Al-Ahsa. Um isolado bacteriano (LCK121) foi obtido, caracterizado quanto ao fenotípico, e identificado por sequenciamento do gene 16S rRNA. Além disso, seus efeitos estimulantes do crescimento na cevada foram investigados. A identidade da cepa foi confirmada por meio de análise comparativa das sequências de 16S rDNA com Klebsiella oxytoca (nível de similaridade de 99,3%). LCK121 exibiu várias características de promoção do crescimento de plantas, incluindo produção de ácido indol-3-acético (IAA) (16,34 µg mL-1), atividade de desaminase de ácido 1-aminociclopropano-1-carboxílico (ACC) (1,35±0,02 µmol α-cetobutirato mg −1 h−1), solubilização de fosfato e fixação de nitrogênio. Além disso, a inoculação in vitro da cevada com LCK121 aumentou significativamente os pesos secos da raiz e da parte aérea. Os resultados destacam o potencial do LCK121 para o desenvolvimento de fertilizantes verdes para a agricultura sustentável.

Response of Rhizobacterial strains and organic amendments on chickpea growth / Resposta de cepas de rizobactérias e alterações orgânicas no crescimento do grão-de-bico

Plant Growth Promoting Rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and promote plant growth through a variety of mechanisms such as phosphate solubilization, phytohormones production, antifungal activity and also improve plant growth and yield. Field experiment was carried out to investigate the residual effect of organic amendments plus soil microbes along with integrated nutrient management. (PGPR) are important soil organism that promotes plant growth and yield root colonization is an example of a direct and indirect mechanism. The treatments included control, (inorganic fertilizer and no organic fertilization).Five bacterial strains were identified morphologically and biochemically screened from the rhizospheres of chickpea, lentil, barseem, mungbean, and sesame. The experiment was conducted at the Arid Zone Research Center in D.I.Khan (Pakistan). The majority of isolates resulted in significant increase in shoot length, root length, and dry matter production of Cicer arietinum seedlings' shoot and root. The experiment represented that isolates treated plots with rhizobium strain inoculation resulted in greater plant height (35.000 cm) and nodule count (38.00) No of pods per plant-1 (44.66) when compared to the control treatment, While (Mesorhizobium cicero) along with organic amendments showed significant response the greater root length (50 cm) was observed in T4 treatment. The Performance of rhizobial strains on chickpea germination in an arid environment was found to significantly increase crop germination percentage. This combination thus increases nitrogen and phosphorus uptake in inoculation treated plots. The study found that plots with inoculation treatments yielded significantly higher than non-treated plots Treatment with Mesorhizobium Cicero and compost resulted in a higher grain yield (8%) as compared to the control. The greater grain yield was observed in Treatment T4 (183.67).The result showed that use of PGPR have the potential to increase nutrient absorption from soil while improved growth of chickpea.(AU)

As rizobactérias promotoras de crescimento de plantas (PGPR) são bactérias benéficas que colonizam as raízes das plantas e promovem o crescimento das plantas através de uma variedade de mecanismos, como solubilização de fosfato, produção de fito-hormônios, atividade antifúngica e também melhoram o crescimento e o rendimento das plantas. O experimento de campo foi realizado para investigar o efeito residual de corretivos orgânicos mais micróbios do solo, juntamente com o manejo integrado de nutrientes. PGPR são importantes organismos do solo que promovem o crescimento das plantas e produzem a colonização de raízes, que é um exemplo de mecanismo direto e indireto. Os tratamentos incluíram controle (fertilizante inorgânico e sem adubação orgânica). Cinco cepas bacterianas foram identificadas morfologicamente e bioquimicamente selecionadas das rizosferas de grão-de-bico, lentilha, barseem, feijão-mungo e gergelim. O experimento foi conduzido no Arid Zone Research Center em D.I.Khan (Paquistão). A maioria dos isolados resultou em aumento significativo no comprimento da parte aérea, comprimento da raiz e produção de matéria seca da parte aérea e raiz das plântulas de Cicer arietinum. O experimento demonstrou que isolados de parcelas tratadas com inoculação de cepa de rizóbio resultaram em maior altura de planta (35.000 cm) e contagem de nódulos (38,00) n.º de vagens por planta-1 (44,66), quando comparado ao tratamento controle, enquanto (Mesorhizobium cicero), juntamente com as alterações orgânicas, apresentaram resposta significativa quanto maior o comprimento da raiz (50 cm) observado no Tratamento T4. O desempenho de linhagens de rizóbios na germinação do grão-de-bico em ambiente árido aumentou significativamente a porcentagem de germinação da cultura. Esta combinação aumenta assim a absorção de nitrogênio e fósforo nas parcelas tratadas com inoculação. O estudo constatou que as parcelas com tratamentos de inoculação produziram significativamente mais do que as parcelas não tratadas. O tratamento com Mesorhizobium cicero e composto resultou em maior produtividade de grãos (8%) em comparação com o controle. A maior produtividade de grãos foi observada no Tratamento T4 (183,67). O resultado mostrou que o uso de PGPR tem potencial para aumentar a absorção de nutrientes do solo enquanto melhora o crescimento do grão-de-bico.(AU)

The occurrence of rhizobacteria from Paspalum genotypes and their effects on plant growth

This work aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from 10 Paspalum genotypes and evaluate the effect of their inoculation on P. regnellii, P. atratum, and P. malacophyllum genotypes. The bacterial population ranged from undetectable to 107 bacterial cells per gram of fresh matter in the Paspalum genotypes. Initially, we isolated 164 bacteria from rhizospheric soil and roots of the Paspalum genotypes using media N-free LG agar plate, semi-solid NFb, and LGI. The isolates were characterized genetically and physiologically. The sequencing of 16S rRNA showed the presence of many genera, and some are new in association with Paspalum. The most common was Bacillus followed by Rhizobium, Paraburkholderia, Enterobacter, Cupriavidus, Pseudomonas, Dyadobacter and Acinetobacter. Thirty-eight per cent of isolates produced siderophores, 25 % produced solubilized phosphate, and only 9 % produced indolic compounds. Three greenhouse experiments were performed in randomized blocks with six replicates using representative bacterial strains isolated from P. regnellii, P. malacophyllum and P. atratum cv. Pojuca. We also included strain Sp245 (Azospirillum baldaniorum), uninoculated control, and nitrogen control (150 kg N ha−1). There was an increase of up to 53 % in shoot dry matter in P. regnellii inoculated with strain Sp245 and the shoots accumulated more N. In contrast, only small effects were observed for the other Paspalum genotypes inoculated with PGPR from the host genotypes. This study shows a high diversity of diazotrophic rhizosphere bacteria and suggests no strain specificity between the bacterial isolates and the Paspalum genotypes.

The occurrence of rhizobacteria from Paspalum genotypes and their effects on plant growth

This work aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from 10 Paspalum genotypes and evaluate the effect of their inoculation on P. regnellii, P. atratum, and P. malacophyllum genotypes. The bacterial population ranged from undetectable to 107 bacterial cells per gram of fresh matter in the Paspalum genotypes. Initially, we isolated 164 bacteria from rhizospheric soil and roots of the Paspalum genotypes using media N-free LG agar plate, semi-solid NFb, and LGI. The isolates were characterized genetically and physiologically. The sequencing of 16S rRNA showed the presence of many genera, and some are new in association with Paspalum. The most common was Bacillus followed by Rhizobium, Paraburkholderia, Enterobacter, Cupriavidus, Pseudomonas, Dyadobacter and Acinetobacter. Thirty-eight per cent of isolates produced siderophores, 25 % produced solubilized phosphate, and only 9 % produced indolic compounds. Three greenhouse experiments were performed in randomized blocks with six replicates using representative bacterial strains isolated from P. regnellii, P. malacophyllum and P. atratum cv. Pojuca. We also included strain Sp245 (Azospirillum baldaniorum), uninoculated control, and nitrogen control (150 kg N ha–1). There was an increase of up to 53 % in shoot dry matter in P. regnellii inoculated with strain Sp245 and the shoots accumulated more N. In contrast, only small effects were observed for the other Paspalum genotypes inoculated with PGPR from the host genotypes. This study shows a high diversity of diazotrophic rhizosphere bacteria and suggests no strain specificity between the bacterial isolates and the Paspalum genotypes.

Effect of Fat Sources and Emulsifier Levels in Broiler Diets on Performance, Nutrient Digestibility, and Carcass Parameters

The objective of the current study was to check the effect of fat types and polyglycerol polyricinoleate (PGPR) levels in broiler diets on broilers performance. For this purpose, three sources of fat {soy oil (SO), poultry oil (PO), and oxidized oil (OO) (oxidized soy oil)} and four levels of PGPR were used in a 3×4 factorial arrangement. The trial had 12 different dietary treatments: (T1) basal ration (BR) containing SO without PGPR supplementation, (T2) BR containing PO without PGPR supplementation, (T3) BR containing OO without PGPR supplementation, (T4) BR containing SO with PGPR supplementation (0.025%), (T5) BR containing PO with PGPR supplementation (0.025%), (T6) BR containing OO with PGPR supplementation (0.025%), (T7) BR containing SO with PGPR supplementation (0.035%), (T8) BR containing PO with PGPR supplementation (0.035%), (T9) BR containing OO with PGPR supplementation (0.035%), (T10) BR containing SO with PGPR supplementation (0.045%), (T11) BR containing PO with PGPR supplementation (0.045%), (T12) BR containing OO with PGPR supplementation (0.045%). Results revealed that interaction was present for fat sources and PGPR levels in the current experiment (p 0.05) for feed conversion ratio, body weight, dry matter (DM) and crude fat (CF) digestiblities (p 0.05). In overall trial, interaction results of PGPR and fat sources showed that performance of birds and nutrient digestiblities of DM and CF was increased in birds received diet contained SO and PGPR @ 0.35%. It is concluded that PGPR @ 0.035% could be successfully used in broiler ration contained soy oil to improve the performance.(AU)

Effect of Fat Sources and Emulsifier Levels in Broiler Diets on Performance, Nutrient Digestibility, and Carcass Parameters

The objective of the current study was to check the effect of fat types and polyglycerol polyricinoleate (PGPR) levels in broiler diets on broilers performance. For this purpose, three sources of fat {soy oil (SO), poultry oil (PO), and oxidized oil (OO) (oxidized soy oil)} and four levels of PGPR were used in a 3×4 factorial arrangement. The trial had 12 different dietary treatments: (T1) basal ration (BR) containing SO without PGPR supplementation, (T2) BR containing PO without PGPR supplementation, (T3) BR containing OO without PGPR supplementation, (T4) BR containing SO with PGPR supplementation (0.025%), (T5) BR containing PO with PGPR supplementation (0.025%), (T6) BR containing OO with PGPR supplementation (0.025%), (T7) BR containing SO with PGPR supplementation (0.035%), (T8) BR containing PO with PGPR supplementation (0.035%), (T9) BR containing OO with PGPR supplementation (0.035%), (T10) BR containing SO with PGPR supplementation (0.045%), (T11) BR containing PO with PGPR supplementation (0.045%), (T12) BR containing OO with PGPR supplementation (0.045%). Results revealed that interaction was present for fat sources and PGPR levels in the current experiment (p 0.05) for feed conversion ratio, body weight, dry matter (DM) and crude fat (CF) digestiblities (p 0.05). In overall trial, interaction results of PGPR and fat sources showed that performance of birds and nutrient digestiblities of DM and CF was increased in birds received diet contained SO and PGPR @ 0.35%. It is concluded that PGPR @ 0.035% could be successfully used in broiler ration contained soy oil to improve the performance.

Impact of phosphate solubilizing bacteria on wheat (Triticum aestivum ) in the presence of pesticides / Impacto das bactérias solubilizantes de fosfato no trigo (Triticum aestivum ) na presença de pesticidas

Three phosphate solubilizing bacteria were isolated and identified by 16S rRNA sequencing as Pseudomonas putida, Pseudomonas sp and Pseudomonas fulva . The strains were subjected to plant biochemical testing and all the PGPR attributes were checked in the presence of pesticides (chlorpyrifos and pyriproxyfen). The phosphate solubilizing index of strain Ros2 was highest in NBRIP medium i.e 2.23 mm. All the strains showed acidic pH (ranges from 2.5-5) on both medium i.e PVK and NBRIP. Strain Ros2 was highly positive for ammonia production as well as siderophore production while strain Rad2 was positive for HCN production. The results obtained by the strains Rad1, Rad2 and Ros2 for auxin production were 33.1, 30.67 and 15.38 µg ml-1, respectively. Strain Rad1 showed 16% increase in percentage germination in comparison to control in the presence of pesticide stress. Most promising results for chlorophyll content estimation were obtained in the presence of carotenoids upto 6 mgg-1 without stress by both strains Rad1 and Rad2. Study suggests that especially strain Ros2 can enhance plant growth parameters in the pesticide stress.(AU)

Três bactérias solubilizantes de fosfato foram isoladas e identificadas por seqüenciamento de rRNA 16S como Pseudomonas putida, Pseudomonas sp e Pseudomonas fulva. As estirpes foram submetidas a testes bioquímicos de plantas e todos os atributos PGPR foram verificados na presença de pesticidas (clorpirifos e piriproxifeno). O índice de solubilização de fosfato da estirpe Ros2 foi mais elevado no meio NBRIP, isto é, 2,23 mm. Todas as estirpes apresentaram um pH ácido (varia de 2,5-5) em ambos os meios, isto é PVK e NBRIP. A estirpe Ros2 foi altamente positiva para a produção de amoníaco, bem como a produção de sideróforos enquanto a estirpe Rad2 foi positiva para a produção de HCN. Os resultados obtidos pelas estirpes Rad1, Rad2 e Ros2 para a produção de auxina foram 33,1, 30,67 e 15,38 g ml-1 , respectivamente. A deformação Rad1 mostrou aumento de 16% na germinação percentual em comparação com o controlo na presença de stress de pesticida. Os resultados mais promissores para a estimativa do teor de clorofila foram obtidos na presença de carotenóides até 6 mgg-1 sem estresse por ambas as cepas Rad1 e Rad2. Estudo sugere que especialmente a estirpe Ros2 pode melhorar parâmetros de crescimento de plantas no estresse de pesticidas.(AU)

Bactérias promotoras do crescimento radicular em plântulas de dois cultivares de arroz irrigado por inundação / Growth promoting bacteria on root lenght of seedlings of two flooded lowland rice cultivars

Para o crescimento e desenvolvimento na natureza, as plantas contam com os benefícios de microrganismos residentes em sua rizosfera. Rizobactérias promotoras de crescimento vegetal (RPCV) são exemplos desses microrganismos que interagem de forma benéfica com espécies vegetais. Portanto, a inoculação de sementes com RPCV pode representar uma alternativa importante e sustentável para melhorar o desenvolvimento inicial e a produção de plantas cultivadas. Objetivou-se com esse estudo determinar o efeito da microbiolização de sementes com RPCV no comprimento radicular de plântulas de arroz irrigado por inundação. Em condições controladas, conduziram-se dois experimentos com cultivares de arroz irrigado (BRS Catiana e BRS A702 CL), em delineamento inteiramente casualizado, com sete tratamentos e 10 repetições. Os tratamentos constituíram-se de seis microrganismos: BRM32109 (Bacillus sp.), BRM32110 (Bacillus sp.), BRM32111 (Pseudomonas fluorescens), BRM32112 (Pseudomonas sp.), BRM32113 (Burkholderia pyrrocinia), BRM32114 (Serratia sp.) e um controle (sem microrganismo). Os maiores comprimentos radiculares foram apresentados pelas sementes tratadas com os isolados BRM32110, BRM32112, BRM32109 e BRM32114. Para ambas cultivares houve significância quando comparado microrganismos e controle. Destaque para as sementes da cultivar BRS Catiana, que quando tratadas com os isolados BRM32110 e BRM32112 apresentaram aumento médio de 25, 7% no comprimento radicular, em comparação com o tratamento controle. Para a cultivar BRS A702CL, todos os microrganismos proporcionaram incrementos com um valor médio de 31% no comprimento radicular das plântulas de arroz. Com base nos resultados pode-se inferir que as RPCV proporcionam incrementos significativos no comprimento radicular de plântulas de cultivares de arroz irrigado por inundação.

For growing and development in nature, plants count with the benefits of microorganisms residing in their rhizosphere. Plant growth promoting rhizobacteria (PGPR) are some of these microorganisms that interact in a beneficial way with plant species. Therefore, seed inoculation with PGPR can be an important and sustainable alternative to improve initial development and crop production. The aim was to determine effect of seeds microbiolization with PGPR on root length of flooded lowland rice seedlings. Under controlled conditions, two experiments were conducted with lowland rice cultivars (BRS Catiana and BRS A702 CL) in completely randomized design, with seven treatments and 10 replications. The treatments consisted of six microorganisms: BRM32109 (Bacillus sp.), BRM32110 (Bacillus sp.), BRM32111 (Pseudomonas fluorescens), BRM32112 (Pseudomonas sp.), BRM32113 (Burkholderia pyrrocinia), BRM32114 (Serratia sp.) and a control (no microorganism). Only the cultivar BRS Catiana showed difference among the treatments. The highest root length was presented by the seeds treated with the isolates BRM32110, BRM32112, BRM32109, and BRM32114. Both of cultivars had significance when compared microorganisms to the control. Highlight for seeds of cultivar BRS Catiana, that when treated with the isolates BRM32110 and BRM32112 presented an average increase of 25. 7% on the root length, compared to control treatment. For the cultivar BRS A702 CL, all the microorganisms provided increments with average value of 31% in the root length of rice seedlings. Based on the results it can be inferred that PGPR provide significant increases in seedling root length of flooded lowland rice cultivars.

Bactérias promotoras do crescimento radicular em plântulas de dois cultivares de arroz irrigado por inundação / Growth promoting bacteria on root lenght of seedlings of two flooded lowland rice cultivars

Para o crescimento e desenvolvimento na natureza, as plantas contam com os benefícios de microrganismos residentes em sua rizosfera. Rizobactérias promotoras de crescimento vegetal (RPCV) são exemplos desses microrganismos que interagem de forma benéfica com espécies vegetais. Portanto, a inoculação de sementes com RPCV pode representar uma alternativa importante e sustentável para melhorar o desenvolvimento inicial e a produção de plantas cultivadas. Objetivou-se com esse estudo determinar o efeito da microbiolização de sementes com RPCV no comprimento radicular de plântulas de arroz irrigado por inundação. Em condições controladas, conduziram-se dois experimentos com cultivares de arroz irrigado (BRS Catiana e BRS A702 CL), em delineamento inteiramente casualizado, com sete tratamentos e 10 repetições. Os tratamentos constituíram-se de seis microrganismos: BRM32109 (Bacillus sp.), BRM32110 (Bacillus sp.), BRM32111 (Pseudomonas fluorescens), BRM32112 (Pseudomonas sp.), BRM32113 (Burkholderia pyrrocinia), BRM32114 (Serratia sp.) e um controle (sem microrganismo). Os maiores comprimentos radiculares foram apresentados pelas sementes tratadas com os isolados BRM32110, BRM32112, BRM32109 e BRM32114. Para ambas cultivares houve significância quando comparado microrganismos e controle. Destaque para as sementes da cultivar BRS Catiana, que quando tratadas com os isolados BRM32110 e BRM32112 apresentaram aumento médio de 25, 7% no comprimento radicular, em comparação com o tratamento controle. Para a cultivar BRS A702CL, todos os microrganismos proporcionaram incrementos com um valor médio de 31% no comprimento radicular das plântulas de arroz. Com base nos resultados pode-se inferir que as RPCV proporcionam incrementos significativos no comprimento radicular de plântulas de cultivares de arroz irrigado por inundação.(AU)

For growing and development in nature, plants count with the benefits of microorganisms residing in their rhizosphere. Plant growth promoting rhizobacteria (PGPR) are some of these microorganisms that interact in a beneficial way with plant species. Therefore, seed inoculation with PGPR can be an important and sustainable alternative to improve initial development and crop production. The aim was to determine effect of seeds microbiolization with PGPR on root length of flooded lowland rice seedlings. Under controlled conditions, two experiments were conducted with lowland rice cultivars (BRS Catiana and BRS A702 CL) in completely randomized design, with seven treatments and 10 replications. The treatments consisted of six microorganisms: BRM32109 (Bacillus sp.), BRM32110 (Bacillus sp.), BRM32111 (Pseudomonas fluorescens), BRM32112 (Pseudomonas sp.), BRM32113 (Burkholderia pyrrocinia), BRM32114 (Serratia sp.) and a control (no microorganism). Only the cultivar BRS Catiana showed difference among the treatments. The highest root length was presented by the seeds treated with the isolates BRM32110, BRM32112, BRM32109, and BRM32114. Both of cultivars had significance when compared microorganisms to the control. Highlight for seeds of cultivar BRS Catiana, that when treated with the isolates BRM32110 and BRM32112 presented an average increase of 25. 7% on the root length, compared to control treatment. For the cultivar BRS A702 CL, all the microorganisms provided increments with average value of 31% in the root length of rice seedlings. Based on the results it can be inferred that PGPR provide significant increases in seedling root length of flooded lowland rice cultivars.(AU)

Can co-inoculation of Rhizobium tropici and Azospirillum brasilense increase common bean nodulation and grain yield? / A coinoculação de Rhizobium tropici e Azospirillum brasilense pode aumentar a nodulação e o rendimento de grãos do feijoeiro?

O uso de rizobactérias promotoras de crescimento de planta (RPCP) associado a inoculação de rizóbio pode otimizar a fixação biológica de nitrogênio (FBN), diminuindo o uso de fertilizantes nitrogenados e aumentando o crescimento da planta e o rendimento da cultura do feijão. Um estudo foi conduzido para investigar a eficácia da coinoculação de Rhizobium tropici e Azospirillum brasilense e da adubação nitrogenada em cobertura na nodulação, no crescimento e no rendimento de grãos do feijoeiro (Phaseolus vulgaris L.) cultivado em solo arenoso da região do Cerrado brasileiro, durante duas safras de produção ("safra das águas" e "safra da seca"). O delineamento experimental foi o de blocos casualizados em esquema de parcelas subdivididas, com quatro repetições. As parcelas constituíram de quatro tratamento de inoculação das sementes: controle (não inoculado); inoculação com Rhizobium tropici; inoculação com Azospirillum brasilense; e, coinoculação com R. tropici e A. brasilense; e as subparcelas por cinco doses de N em cobertura (0, 30, 60, 90 e 120 kg ha

The use of plant growth-promoting rhizobacteria (PGPR) associated with rhizobia may optimize the biological nitrogen fixation (BNF), decrease chemical fertilizer-N use and increase plant growth and yield of the bean crop. A study was conducted to investigate the effectiveness of co-inoculation of Rhizobium tropici and Azospirillum brasilense, and nitrogen fertilizer topdressing on nodulation, growth, and yield of common bean (Phaseolus vulgaris L.) in a sandy soil from the Brazilian tropical savanna (Cerrado) region, during the two growing seasons (“spring-summer” and “summer-fall”). The experimental design was a split plot in randomized blocks with four replicates. Plots consisted of four inoculation treatment on seeds: control (non-inoculated); inoculation with Rhizobium tropici; inoculation with Azospirillum brasilense; and co-inoculation with R. tropici and A. brasilense; and subplots of five N rates in topdressing (0, 30, 60, 90 and 120 kg ha <->1). The inoculation with R. tropici alone or combined with A. brasilense enhanced root nodulation and grain yield of the common beans when the crop was grown during the dry season in the Brazilian savanna region. Therefore, the positive response of inoculation with rhizobia and azospirilla on the grain yield is dependent of the environmental conditions during the growing season, especially the low rainfall rate by stimulating root nodulation. The inoculation with A. brasilense alone was not an efficient agronomic practice to be used in common beans cropping under Brazilian conditions, because resulting grain yield equivalent to the non-inoculated plants in the two growing seasons. The increase of N application rates inhibits the formation and growth of root nodules of the common beans. The optimal N application rate in topdressing for common beans grown in sandy soils from the Brazilian savanna region may range between 80 and 90 kg N ha <->1.(AU)

Growth promotion of common bean and genetic diversity of bacteria from Amazon pastureland

ABSTRACT: A significant number of bacterial species, particularly in the rhizosphere, may benefit plant growth and development. This group of bacteria is known as plant growth-promoting rhizobacteria (PGPR). This study identified genetically isolates of common bean nodules used to trap bacteria from Amazon pastureland and investigated their capacity of nodulating and promoting growth of common bean when inoculated or co-inoculated with CIAT899 strain (Rhizobium tropici). Two experiments were carried out in a greenhouse, in axenic conditions, using the common bean cultivar Talismã. In the first experiment, 56 PGPR strains were evaluated individually regarding growth promotion and nodulation. In the second experiment, inoculation of seven PGPR strains previously selected in the first experiment was evaluated in three forms of N supply: Co-inoculation with CIAT 899 in the presence of low N-mineral concentration; individual inoculation in the presence of high N-mineral concentration; and individual inoculation in the presence of low N-mineral concentration. The 16S rRNA gene sequencing showed predominance of Pseudomonas genus, identified in 35 % of the sequenced strains. Other genera were identified: Rhizobium, Burkholderia, Xanthomonas and Bacillus. Inoculation of the seven strains with CIAT 899 promoted distinct plant growth in different forms of N supply. In addition, N-mineral supply can be replaced by co-inoculation with strains of Pseudomonas sp. (UFLA 02-281 and UFLA 02-293) and Bacillus sp. (UFLA 02-298) identified in this study.

Growth promotion of common bean and genetic diversity of bacteria from Amazon pastureland

ABSTRACT: A significant number of bacterial species, particularly in the rhizosphere, may benefit plant growth and development. This group of bacteria is known as plant growth-promoting rhizobacteria (PGPR). This study identified genetically isolates of common bean nodules used to trap bacteria from Amazon pastureland and investigated their capacity of nodulating and promoting growth of common bean when inoculated or co-inoculated with CIAT899 strain (Rhizobium tropici). Two experiments were carried out in a greenhouse, in axenic conditions, using the common bean cultivar Talismã. In the first experiment, 56 PGPR strains were evaluated individually regarding growth promotion and nodulation. In the second experiment, inoculation of seven PGPR strains previously selected in the first experiment was evaluated in three forms of N supply: Co-inoculation with CIAT 899 in the presence of low N-mineral concentration; individual inoculation in the presence of high N-mineral concentration; and individual inoculation in the presence of low N-mineral concentration. The 16S rRNA gene sequencing showed predominance of Pseudomonas genus, identified in 35 % of the sequenced strains. Other genera were identified: Rhizobium, Burkholderia, Xanthomonas and Bacillus. Inoculation of the seven strains with CIAT 899 promoted distinct plant growth in different forms of N supply. In addition, N-mineral supply can be replaced by co-inoculation with strains of Pseudomonas sp. (UFLA 02-281 and UFLA 02-293) and Bacillus sp. (UFLA 02-298) identified in this study.

Plant growth promoting rhizobacteria reduce aphid population and enhance the productivity of bread wheat

Abstract Plant growth promoting rhizobacteria increase plant growth and give protection against insect pests and pathogens. Due to the negative impact of chemical pesticides on environment, alternatives to these chemicals are needed. In this scenario, the biological methods of pest control offer an eco-friendly and an attractive option. In this study, the effect of two plant growth promoting rhizobacterial strains (Bacillus sp. strain 6 and Pseudomonas sp. strain 6K) on aphid population and wheat productivity was evaluated in an aphid susceptible (Pasban-90) and resistant (Inqlab-91) wheat cultivar. The seeds were inoculated with each PGPR strain, separately or the combination of both. The lowest aphid population (2.1 tiller1), and highest plant height (85.8 cm), number of spikelets per spike (18), grains per spike (44), productive tillers (320 m2), straw yield (8.6 Mg ha1), and grain yield (4.8 Mg ha1) were achieved when seeds were inoculated with Bacillus sp. strain 6 + Pseudomonas sp. strain 6K. The grain yield of both varieties was enhanced by 35.538.9% with seed inoculation with both bacterial strains. Thus, the combine use of both PGPR strains viz. Bacillus sp. strain 6 + Pseudomonas sp. strain 6K offers an attractive option to reduce aphid population tied with better wheat productivity.

Plant growth promoting rhizobacteria reduce aphid population and enhance the productivity of bread wheat

Plant growth promoting rhizobacteria increase plant growth and give protection against insect pests and pathogens. Due to the negative impact of chemical pesticides on environment, alternatives to these chemicals are needed. In this scenario, the biological methods of pest control offer an eco-friendly and an attractive option. In this study, the effect of two plant growth promoting rhizobacterial strains (Bacillus sp. strain 6 and Pseudomonas sp. strain 6K) on aphid population and wheat productivity was evaluated in an aphid susceptible (Pasban-90) and resistant (Inqlab-91) wheat cultivar. The seeds were inoculated with each PGPR strain, separately or the combination of both. The lowest aphid population (2.1 tiller−1), and highest plant height (85.8 cm), number of spikelets per spike (18), grains per spike (44), productive tillers (320 m−2), straw yield (8.6 Mg ha−1), and grain yield (4.8 Mg ha−1) were achieved when seeds were inoculated with Bacillus sp. strain 6 + Pseudomonas sp. strain 6K. The grain yield of both varieties was enhanced by 35.5–38.9% with seed inoculation with both bacterial strains. Thus, the combine use of both PGPR strains viz. Bacillus sp. strain 6 + Pseudomonas sp. strain 6K offers an attractive option to reduce aphid population tied with better wheat productivity.(AU)

Growth-promoting bacteria change the development of aerial part and root system of canola / Bactérias promotoras de crescimento alteram o desenvolvimento da parte aérea e sistema radicular da canola

Plant growth promoting rhizobacteria (PGPR) are soil bacteria that have the ability to colonize the rhizosphere and favor the growth of plants through several mechanisms, such as phytohormone production, biological fixation in nitrogen (BNF), increased efficiency in uptake of nutrients in the soil, and greater tolerance to water stress or disease attack. The objective of this work was to evaluate the effects of inoculation of different growth promoting bacteria on the development of canola plants. The experiment was conducted in a greenhouse with a completely randomized design. Four treatments were evaluated: control - without inoculation, Azospirillum brasilense of strain Ab-V5, Rhizobium sp. strain 8121, and Bacillus sp. strain CM. The height parameter of plants was evaluated weekly, starting at 25 days after sowing (DAS). At the end of the evaluations, at 53 DAS, the length of the main root, the dry mass of the aerial part and the root system were measured. The canola showed a linear increase in height from 25 to 53 DAS. Bacillus sp. negatively influenced the growth of the plants, reducing their height in periods 25, 32 and 39 DAS in relation to the control group. A. brazilense. yielded 2.64 times more dry root mass (0.7 g plant-1) than the control plants (0.3 g plant-1). Even though Rhizobium sp. produced an increase in the length of the main root, this was not reflected in an increment of dry mass in the root system. The greatest development of the root system was provided by A. brazilense.(AU)

As rizobactérias promotoras de crescimento de plantas (PGPR) são bactérias do solo que possuem a capacidade de colonizar a rizosfera e favorecem o crescimento das plantas através de diversos mecanismos, tais como produção de fitohormônios, a fixação biológica no nitrogênio (FBN), aumento da eficiência na captação de nutrientes do solo, maior tolerância ao stress hídrico ou ao ataque de doenças. Objetivou-se nesse trabalho avaliar os efeitos da inoculação de diferentes bactérias promotoras de crescimento sobre o desenvolvimento da parte aérea e sistema radículas de plantas canola. O experimento foi realizado em condições de casa de vegetação com delineamento inteiramente casualizado. Foram avaliados quatro tratamentos: controle - sem inoculação, Azospirillum brasilense da estirpe Ab-V5, Rhizobium sp. estirpe 8121, Bacillus sp. estirpe CM. O parâmetro altura de plantas foi avaliado semanalmente, iniciando-se aos 25 dias após a semeadura (DAS). No término das avaliações, aos 53 DAS, foram mensurados o comprimento da raiz principal, a massa seca da parte aérea e do sistema radicular. A canola apresentou aumento em altura dos 25 aos 53 DAS. Bacillus sp. influenciou negativamente o crescimento das plantas, reduzindo a altura das mesmas nos períodos 25, 32 e 39 DAS em relação ao controle. A. brazilense proporcionou 2.64 vezes mais massa seca de raízes (0,7 g planta-1) em comparação ao controle (0,3 g planta-1). O Rhizobium sp. apesar de proporcionar aumento no comprimento da raiz principal, este não refletiu em incremento de massa seca no sistema radicular. O maior desenvolvimento do sistema radicular foi proporcionado por A. brazilense.(AU)

Growth promotion of common bean and genetic diversity of bacteria from Amazon pastureland

A significant number of bacterial species, particularly in the rhizosphere, may benefit plant growth and development. This group of bacteria is known as plant growth-promoting rhizobacteria (PGPR). This study identified genetically isolates of common bean nodules used to trap bacteria from Amazon pastureland and investigated their capacity of nodulating and promoting growth of common bean when inoculated or co-inoculated with CIAT899 strain (Rhizobium tropici). Two experiments were carried out in a greenhouse, in axenic conditions, using the common bean cultivar Talismã. In the first experiment, 56 PGPR strains were evaluated individually regarding growth promotion and nodulation. In the second experiment, inoculation of seven PGPR strains previously selected in the first experiment was evaluated in three forms of N supply: Co-inoculation with CIAT 899 in the presence of low N-mineral concentration; individual inoculation in the presence of high N-mineral concentration; and individual inoculation in the presence of low N-mineral concentration. The 16S rRNA gene sequencing showed predominance of Pseudomonas genus, identified in 35 % of the sequenced strains. Other genera were identified: Rhizobium, Burkholderia, Xanthomonas and Bacillus. Inoculation of the seven strains with CIAT 899 promoted distinct plant growth in different forms of N supply. In addition, N-mineral supply can be replaced by co-inoculation with strains of Pseudomonas sp. (UFLA 02-281 and UFLA 02-293) and Bacillus sp. (UFLA 02-298) identified in this study.(AU)

Polyphasic characterization of bacteria obtained from upland rice cultivated in Cerrado soil

This work aimed to characterize 20 isolates obtained from upland rice plants, based on phenotypic (morphology, enzymatic activity, inorganic phosphate solubilization, carbon source use, antagonism), genotypic assays (16S rRNA sequencing) and plant growth promotion. Results showed a great morphological, metabolic and genetic variability among bacterial isolates. All isolates showed positive activity for catalase and protease enzymes and, 90% of the isolates showed positive activity for amylase, catalase and, nitrogenase. All isolates were able to metabolize sucrose and malic acid in contrast with mannitol, which was metabolized only by one isolate. For the other carbon sources, we observed a great variability in its use by the isolates. Most isolates showed antibiosis against Rhizoctonia solani (75%) and Sclerotinia sclerotiorum (55%) and, 50% of them showed antibiosis against both pathogens. Six isolates showed simultaneous ability of antibiosis, inorganic phosphate solubilization and protease activity. Based on phylogenetic analysis of the 16S rRNA gene all the isolates belong to Bacillus genus. Under greenhouse conditions, two isolates (S4 and S22) improved to about 24%, 25%, 30% and 31% the Total N, leaf area, shoot dry weight and root dry weight, respectively, of rice plants, indicating that they should be tested for this ability under field conditions.(AU)

Control potential of Meloidogyne javanica and Ditylenchus spp. using fluorescent Pseudomonas and Bacillus spp.

Plant Growth Promoting Rhizobacteria (PGPR) have different mechanisms of action in the development of plants, such as growth promotion, production of phytohormones and antibiotic substances and changes in root exudates. These help to control plant diseases. In order to evaluate the potential of microorganisms in the control of Meloidogyne javanica and Ditylenchus spp., five rhizobacteria isolated from rhizosphere of garlic cultivated in the Curitibanos (SC) region were tested. Hatching chambers were set on Petri dishes, in which were added 10 mL of bacterial suspension and 1 mL of M. javanica eggs suspension, at the rate of 4500, on the filter paper of each chamber. The same procedure was performed with 300 juvenile Ditylenchus spp. The experimental design was completely randomized, with four replications. The evaluations were performed every 72 h for nine days. The antagonized population of nematodes was determined in Peters counting chamber, determining the percentage hatching (for M. javanica) and motility (for Ditylenchus spp). Isolates CBSAL02 and CBSAL05 significantly reduced the hatching of M. javanica eggs (74% and 54.77%, respectively) and the motility of Ditylenchus spp. (55.19% and 53.53%, respectively) in vitro. Isolates were identified as belonging to the genera Pseudomonas (CBSAL05) and Bacillus (CBSAL02).(AU)

Tricalcium phosphate solubilization and nitrogen fixation by newly isolated Aneurinibacillus aneurinilyticus CKMV1 from rhizosphere of Valeriana jatamansi and its growth promotional effect

Aneurinibacillus aneurinilyticus strain CKMV1 was isolated from rhizosphere of Valeriana jatamansi and possessed multiple plant growth promoting traits like production of phosphate solubilization (260 mg/L), nitrogen fixation (202.91 nmol ethylene mL-1 h-1), indole-3-acetic acid (IAA) (8.1 µg/mL), siderophores (61.60%), HCN (hydrogen cyanide) production and antifungal activity. We investigated the ability of isolate CKMV1 to solubilize insoluble P via mechanism of organic acid production. High-performance liquid chromatography (HPLC) study showed that isolate CKMV1 produced mainly gluconic (1.34%) and oxalic acids. However, genetic evidences for nitrogen fixation and phosphate solubilization by organic acid production have been reported first time for A. aneurinilyticus strain CKMV1. A unique combination of glucose dehydrogenase (gdh) gene and pyrroloquinoline quinone synthase (pqq) gene, a cofactor of gdh involved in phosphate solubilization has been elucidated. Nitrogenase (nif H) gene for nitrogen fixation was reported from A. aneurinilyticus. It was notable that isolate CKMV1 exhibited highest antifungal against Sclerotium rolfsii (93.58%) followed by Fusarium oxysporum (64.3%), Dematophora necatrix (52.71%), Rhizoctonia solani (91.58%), Alternaria sp. (71.08%) and Phytophthora sp. (71.37%). Remarkable increase was observed in seed germination (27.07%), shoot length (42.33%), root length (52.6%), shoot dry weight (62.01%) and root dry weight (45.7%) along with NPK (0.74, 0.36, 1.82%) content of tomato under net house condition. Isolate CKMV1 possessed traits related to plant growth promotion, therefore, could be a potential candidate for the development of biofertiliser or biocontrol agent and this is the first study to include the Aneurinibacillus as PGPR.(AU)