Vertical movement of A. brasilense Sp7 and strain Cd in soil under different inoculation regimes

2021 ◽  
Author(s):  
Fengxian Chen ◽  
Zeev Ronen ◽  
Gilboa Arye
Keyword(s):  
Zeta Potential ◽  
Plant Growth ◽  
Cell Size ◽  
Soil Profile ◽  
Azospirillum Brasilense ◽  
Root Zone ◽  
Vertical Movement ◽  
Growth Stages ◽  
Plant Growth Promoting Bacteria ◽  
Soil Inoculation

<p><em>Azospirillum brasilense</em> Sp7 and <em>Azospirillum brasilense </em>Cd are two plant growth-promoting bacteria (PGPB). Traditional inoculation methods with PGPB are seed inoculation, seedling root inoculation and soil inoculation. Although these methods are simple to use, they are limited to apply at a specific plant growth stage. Therefore, PGPB inoculation by drip irrigation has been suggested as a means to deliver PGPB directly to the root zone during the plant growth stages. To quantify the intrinsic transport characteristics of two <em>A. brasilense</em> strains following point source inoculation, the properties of <em>A. brasilense</em> Sp7 and <em>A. brasilense</em> Cd (e.g., cell size, hydrophobicity, and zeta potential) and the adsorption characteristics on fine sand were measured. The transport and fate of the two strains were examined under transient water flow conditions with three soil inoculation regimes: (i) surface irrigation (ii) subsurface irrigation and (iii) soil premixing. The water content, bromide, and bacteria distribution in the soil profile were measured after 2 and 48 hours. The measured data were described using the attachment/detachment model using the Hydrus 2/3D code. The result showed that even though <em>A. brasilense</em> Sp7 and Cd exhibit similar hydrophilicity and zeta potential their adsorption and/or straining in the soil profile were differed. <em>A. brasilense</em> Cd has a smaller cell size, less adsorption and less straining than <em>A. brasilense</em> Sp7, thus its vertical movement is deeper. However, both strains accumulated at the vicinity of the water source. The results of this study will be presented and the pros and cons of three inoculation regimes<strong> </strong>will be discussed.</p>

scholarly journals Compatibility of Azospirillum brasilense with Pesticides Used for Treatment of Maize Seeds

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Mariana S. Santos ◽  
Artur B. L. Rondina ◽  
Marco A. Nogueira ◽  
Mariangela Hungria
Keyword(s):  
Plant Growth ◽  
Root Hair ◽  
Azospirillum Brasilense ◽  
Plant Protection ◽  
Plant Growth Promoting Bacteria ◽  
Root Volume ◽  
Maize Seeds ◽  
Plant Growth Promoting ◽  
Growth Promoting

Seed treatment with chemical pesticides is commonly used as an initial plant protection procedure against pests and diseases. However, the use of such chemicals may impair the survival and performance of beneficial microorganisms introduced via inoculants, such as the plant growth-promoting bacterium Azospirillum brasilense. We assessed the compatibility between the most common pesticide used in Brazil for the treatment of maize seeds, composed of two fungicides, and one insecticide, with the commercial strains Ab-V5 and Ab-V6 of A. brasilense, and evaluated the impacts on initial plant development. The toxicity of the pesticide to A. brasilense was confirmed, with an increase in cell mortality after only 24 hours of exposure in vitro. Seed germination and seedling growth were not affected neither by the A. brasilense nor by the pesticide. However, under greenhouse conditions, the pesticide affected root volume and dry weight and root-hair incidence, but the toxicity was alleviated by the inoculation with A. brasilense for the root volume and root-hair incidence parameters. In maize seeds inoculated with A. brasilense, the pesticide negatively affected the number of branches, root-hair incidence, and root-hair length. Therefore, new inoculant formulations with cell protectors and the development of compatible pesticides should be searched to guarantee the benefits of inoculation with plant growth-promoting bacteria.

scholarly journals Root-associated microbiomes of wheat under the combined effect of plant development and nitrogen fertilization

Microbiome ◽  
2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Shuaimin Chen ◽  
Tatoba R. Waghmode ◽  
Ruibo Sun ◽  
Eiko E. Kuramae ◽  
Chunsheng Hu ◽  
...  
Keyword(s):  
Community Structure ◽  
Plant Growth ◽  
Microbial Communities ◽  
Root Zone ◽  
N Fertilization ◽  
Plant Roots ◽  
Growth Stages ◽  
Ripening Stages ◽  
N Input

Abstract Background Plant roots assemble microbial communities both inside the roots and in the rhizosphere, and these root-associated microbiomes play pivotal roles in plant nutrition and productivity. Although it is known that increased synthetic fertilizer input in Chinese farmlands over the past 50 years has resulted in not only increased yields but also environmental problems, we lack a comprehensive understanding of how crops under elevated nutrient input shape root-associated microbial communities, especially through adjusting the quantities and compositions of root metabolites and exudates. Methods The compositions of bacterial and fungal communities from the roots and rhizosphere of wheat (Triticum aestivum L.) under four levels of long-term inorganic nitrogen (N) fertilization were characterized at the tillering, jointing and ripening stages. The root-released organic carbon (ROC), organic acids in the root exudates and soil organic carbon (SOC) and soil active carbon (SAC) in the rhizosphere were quantified. Results ROC levels varied dramatically across wheat growth stages and correlated more with the bacterial community than with the fungal community. Rhizosphere SOC and SAC levels were elevated by long-term N fertilization but varied only slightly across growth stages. Variation in the microbial community structure across plant growth stages showed a decreasing trend with N fertilization level in the rhizosphere. In addition, more bacterial and fungal genera were significantly correlated in the jointing and ripening stages than in the tillering stage in the root samples. A number of bacterial genera that shifted in response to N fertilization, including Arthrobacter, Bacillus and Devosia, correlated significantly with acetic acid, oxalic acid, succinic acid and tartaric acid levels. Conclusions Our results indicate that both plant growth status and N input drive changes in the microbial community structure in the root zone of wheat. Plant growth stage demostrated a stronger influence on bacterial than on fungal community composition. A number of bacterial genera that have been described as plant growth-promoting rhizobacteria (PGPR) responded positively to N fertilization, and their abundance correlated significantly with the organic acid level, suggesting that the secretion of organic acids may be a strategy developed by plants to recruit beneficial microbes in the root zone to cope with high N input. These results provide novel insight into the associations among increased N input, altered carbon availability, and shifts in microbial communities in the plant roots and rhizosphere of intensive agricultural ecosystems.

scholarly journals Quantification of Azospirillum brasilense FP2 Bacteria in Wheat Roots by Strain-Specific Quantitative PCR

2015 ◽  
Vol 81 (19) ◽  
pp. 6700-6709 ◽  
Author(s):  
Maria Isabel Stets ◽  
Sylvia Maria Campbell Alqueres ◽  
Emanuel Maltempi Souza ◽  
Fábio de Oliveira Pedrosa ◽  
Michael Schmid ◽  
...  
Keyword(s):  
Plant Growth ◽  
Quantitative Pcr ◽  
Dna Sequences ◽  
Azospirillum Brasilense ◽  
Plant Growth Promoting Bacteria ◽  
Genome Sequences ◽  
Wheat Roots ◽  
Content Type ◽  
Plant Growth Promoting ◽  
Growth Promoting

ABSTRACTAzospirillumis a rhizobacterial genus containing plant growth-promoting species associated with different crops worldwide.Azospirillum brasilensestrains exhibit a growth-promoting effect by means of phytohormone production and possibly by N2fixation. However, one of the most important factors for achieving an increase in crop yield by plant growth-promoting rhizobacteria is the survival of the inoculant in the rhizosphere, which is not always achieved. The objective of this study was to develop quantitative PCR protocols for the strain-specific quantification ofA. brasilenseFP2. A novel approach was applied to identify strain-specific DNA sequences based on a comparison of the genomic sequences within the same species. The draft genome sequences ofA. brasilenseFP2 and Sp245 were aligned, and FP2-specific regions were filtered and checked for other possible matches in public databases. Strain-specific regions were then selected to design and evaluate strain-specific primer pairs. The primer pairs AzoR2.1, AzoR2.2, AzoR5.1, AzoR5.2, and AzoR5.3 were specific for theA. brasilenseFP2 strain. These primer pairs were used to monitor quantitatively the population ofA. brasilensein wheat roots under sterile and nonsterile growth conditions. In addition, coinoculations with other plant growth-promoting bacteria in wheat were performed under nonsterile conditions. The results showed thatA. brasilenseFP2 inoculated into wheat roots is highly competitive and achieves high cell numbers (∼107CFU/g [fresh weight] of root) in the rhizosphere even under nonsterile conditions and when coinoculated with other rhizobacteria, maintaining the population at rather stable levels for at least up to 13 days after inoculation. The strategy used here can be applied to other organisms whose genome sequences are available.

Improved establishment and development of three cactus species inoculated withAzospirillum brasilensetransplanted into disturbed urban desert soil

1999 ◽  
Vol 45 (6) ◽  
pp. 441-451 ◽  
Author(s):  
Yoav Bashan ◽  
Adriana Rojas ◽  
M Esther Puente
Keyword(s):  
Soil Erosion ◽  
Plant Growth ◽  
Azospirillum Brasilense ◽  
Soil Reclamation ◽  
High Survival ◽  
Plant Growth Promoting Bacteria ◽  
Disturbed Areas ◽  
Small Roots ◽  
Plant Growth Promoting ◽  
Growth Promoting

Survival and development of cactus transplants in urban, disturbed areas of the desert near La Paz, Baja California Sur, Mexico, was monitored. Young plants of three species of pachycereid cacti (Pachycereus pringlei, Stenocereus thurberi, and Lophocereus schottii) inoculated with the plant growth promoting bacterium Azospirillum brasilense in an eroded area (a dirt road) had a high survival rate and developed more rapidly compared with uninoculated control plants during a 3.5-year period after transplantation. Soil erosion in the inoculated experimental area diminished. Small, but significant soil accumulated in association with the growth of cactus roots into the wind-deposited dust. One demonstrated mechanism for stabilizing dust was by the upward growth of small roots during the rainy season into the deposited dust. Azospirillum brasilense survived well in the rhizospheres of these cacti for 2 years, but not in root-free soil. This study demonstrated the feasibility of using bacterial inoculation of cacti to enhance their establishment in disturbed areas, with the potential to stabilize soil.Key words: Azospirillum, beneficial bacteria, cactus, plant inoculation, plant growth promoting bacteria, PGPR, soil erosion, soil reclamation.

scholarly journals RATES OF APPLICATION OF Azospirillum brasilense IN TOMATO CROP

2018 ◽  
Vol 5 (4) ◽  
pp. 81-87 ◽  
Author(s):  
Neberson De Souza Antunes De Lima ◽  
Gabriel Felipe Vogel ◽  
Rubens Fey
Keyword(s):  
Plant Growth ◽  
Azospirillum Brasilense ◽  
Dry Matter ◽  
Tomato Fruit ◽  
Fruit Production ◽  
Plant Growth Promoting Bacteria ◽  
Tomato Crop ◽  
Matter Production ◽  
Plant Growth Promoting ◽  
Tomato Cultivars

The use of plant growth-promoting bacteria (PGPB) may be a promising agronomic practice to improve the growth and productivity of vegetables. The objective of this work was to evaluate the effect of inoculation of Azospirillum brasilense on plant growth and tomato fruit production. Two experiments were carried out: the first one evaluating the growth of the plants in a greenhouse and the second one evaluating the production of fruits under field conditions. The experimental design used in two experiments was the completely randomized 2 x 5 factorial scheme, with four replications. The treatments resulted from the combination of two tomato cultivars (Gaúcho Melhorado and San Marzano) and four inoculant doses (0; 2; 4; 6 e 8 mL kg-1 of seed) containing the Ab-V5 and Ab-V6 strains of A. Brasilense. The application of inoculant containing A. brasilense improved the growth and dry matter production of tomato cultivars Gaúcho Melhorado and San Marzano. The highest values of plant height, stem diameter, root length, root volume, relative chlorophyll content and dry matter of shoots and roots are obtained with the dose of 4 to 6 mL kg-1 of inoculant, allowing to infer that the maximization of plant growth and the production of tomato fruits with the application of inoculant containing Azospirillum brasilense can be obtained with the use of approximately 5.0 mL kg-1 of seeds for tomato cultivars.

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