Biological Nitrogen Fixation

Bruijn, Frans J. de

doi:10.1002/9781119053095

Cited by 60 publications

(15 citation statements)

References 12 publications

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“…Some works report that Azospirillum is a PGPB because of its hormonal effect (Rodriguez et al 2004;Turan et al 2012;Spaepen and Vanderleyden 2015;Fukami et al 2017;Singh et al 2017), but our results showed that A1626 also solubilized phosphate, increasing maize growth. Rosa et al (2020) also observed that the inoculation of sugarcane with B. subtilis and A. brasilense along with the application of 45 kg P 2 O 5 ha − 1 improved available P soil content more than four times and the P total accumulation in the entire plant in comparison to non-inoculated treatments.…”

Section: Synergy Amongcontrasting

confidence: 70%

“…Azospirillum species are widely used as plant inoculants due to their positive effects on plant growth (Okon et al 2015). Their main mechanisms include nitrogen xation (Hungria et al 2006;Helman et al 2011;Fukami et al 2018), phosphate solubilization and phytohormone synthesis, especially IAA, which is suggested to be a major actor in promoting plant growth (Spaepen and Vanderleyden 2015;Calzavara et al 2018;Cassán et al 2020). Azospirillum alters root architecture, increasing root branching and volume, which leads to greater soil exploration, nutrient absorption, and abiotic stress resilience (Yang et al 2009;Vacheron et al 2013; Dar et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Co-inoculation With Tropical Strains of Azospirillum and Bacillus Is More Efficient Than Single Inoculation for Improving Plant Growth and Nutrient Uptake in Maize.

Ribeiro

Gomes

Sousa

et al. 2021

Preprint

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Usage of Bacillus and Azospirillum as new eco-friendly microbial consortium inoculants is a strategy to increase plant growth and crop yield by improving nutrient availability in agricultural systems. In this study, we designed a multispecies inoculum containing B. thuringiensis (strain B116), B. subtillis (strain B2084) and Azospirillum brasilense (strains A1626 and A2142) to investigate their individual or co-inoculated ability to solubilize and mineralize phosphate, produce indole acetic acid (IAA) and their effect on maize growth promotion in hydroponics and in a non-sterile soil. All strains showed significant IAA production, P mineralization (sodium phytate) and Ca-P, Fe-P (tricalcium phosphate and iron phosphate, respectively) solubilization. In hydroponics, co-inoculation with A1626 x A2142, B2084 x A2142, B2084 x A1626 resulted in higher root total length, total surface area, and surface area of roots with diameter between 0 and 1 mm than other treatments with single inoculant, except B2084. In a greenhouse experiment, maize inoculated with the two Azospirillum strains exhibited enhanced shoot dry weight, shoot P and K content, root dry weight, root N and K content and acid and alkaline phosphatase activities than the other treatments. There was a significant correlation between soil P and P shoot, alkaline phosphatase and P shoot and between acid phosphatase and root dry weight. It may be concluded that co-inoculations are most effective than single inoculants strains, mainly between two selected Azospirillum strains. Thus, they could have synergistic interactions during maize growth, and be useful in the formulation of inoculants to improve the cropping systems sustainable.

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Section: Synergy Amongcontrasting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Co-inoculation With Tropical Strains of Azospirillum and Bacillus Is More Efficient Than Single Inoculation for Improving Plant Growth and Nutrient Uptake in Maize.

Ribeiro

Gomes

Sousa

et al. 2021

Preprint

View full text Add to dashboard Cite

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“…The changes in plant growth observed by Azospirillum inoculation and the bacterial capacity to improve the negative effects of abiotic stress on crops has attracted the attention of researchers interested in developing field applied studies (Okon and Labandera-Gonzalez 1994). Okon et al (2015) suggested that because the diverse modes of action of Azospirillum mostly stimulate plant root growth, inoculation with this microbe could contribute to the increase and stabilization of crop production. However, evaluations of the efficacy of Azospirillum under current crop management practices and at regular environmental conditions are scarce and have been conducted on different crops and in different regions.…”

Section: The Impact Of Azospirillum Inoculation On Agriculturementioning

confidence: 99%

Everything you must know about Azospirillum and its impact on agriculture and beyond

et al. 2020

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Azospirillum is one of the most studied plant growth-promoting bacteria (PGPB); it represents a common model for plantbacterial interactions. While Azospirillum brasilense is the species that is most widely known, at least 22 species, including 17 firmly validated species, have been identified, isolated from agricultural soils as well as habitats as diverse as contaminated soils, fermented products, sulfide springs, and microbial fuel cells. Over the last 40 years, studies on Azospirillum-plant interactions have introduced a wide array of mechanisms to demonstrate the beneficial impacts of this bacterium on plant growth. Multiple phytohormones, plant regulators, nitrogen fixation, phosphate solubilization, a variety of small-sized molecules and enzymes, enhanced membrane activity, proliferation of the root system, enhanced water and mineral uptake, mitigation of environmental stressors, and competition against pathogens have been studied, leading to the concept of the Multiple Mechanisms Hypothesis. This hypothesis is based on the assumption that no single mechanism is involved in the promotion of plant growth; it posits that each case of inoculation entails a combination of a few or many mechanisms. Looking specifically at the vast amount of information about the stimulatory effect of phytohormones on root development and biological nitrogen fixation, the Efficient Nutrients Acquisition Hypothesis model is proposed. Due to the existence of extensive agriculture that covers an area of more than 60 million hectares of crops, such as soybeans, corn, and wheat, for which the bacterium has proven to have some agronomic efficiency, the commercial use of Azospirillum is widespread in South America, with over 100 products already in the market in Argentina, Brazil, and Uruguay. Studies on Azospirillum inoculation in several crops have shown positive and variable results, due in part to crop management practices and environmental conditions. The combined inoculation of legumes with rhizobia and Azospirillum (co-inoculation) has become an emerging agriculture practice in the last several years, mainly for soybeans, showing high reproducibility and efficiency under field conditions. This review also addresses the use of Azospirillum for purposes other than agriculture, such as the recovery of eroded soils or the bioremediation of contaminated soils. Furthermore, the synthetic mutualistic interaction of Azospirillum with green microalgae has been developed as a new and promising biotechnological application, extending its use beyond agriculture.

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“…The HGT between Mesorhizobium strains is very common as reviewed by Andrews et al [21]. The symbiotic (accessary) genes determine biogeographic patterns, host niche and are prone to HGT, while the housekeeping (core) genes determine evolutionary relationships among rhizobia as they transfer vertically between strains [52,66].…”

Section: Discussionmentioning

confidence: 99%

Phylogeography and Symbiotic Effectiveness of Rhizobia Nodulating Chickpea (Cicer arietinum L.) in Ethiopia

et al. 2020

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Chickpea (Cicer arietinum L.) used to be considered a restrictive host that nodulated and fixed nitrogen only with Mesorhizobium ciceri and M. mediterraneum. Recent analysis revealed that chickpea can also establish effective symbioses with strains of several other Mesorhizobium species such as M. loti, M. haukuii, M. amorphae, M. muleiense, etc. These strains vary in their nitrogen fixation potential inviting further exploration. We characterized newly collected mesorhizobial strains isolated from various locations in Ethiopia to evaluate genetic diversity, biogeographic structure and symbiotic effectiveness. Symbiotic effectiveness was evaluated in Leonard Jars using a locally released chickpea cultivar “Nattoli”. Most of the new isolates belonged to a clade related to M. plurifarium, with very few sequence differences, while the total collection of strains contained three additional mesorhizobial genospecies associated with M. ciceri, M. abyssinicae and an unidentified Mesorhizobium species isolated from a wild host in Eritrea. The four genospecies identified represented a subset of the eight major Mesorhizobium clades recently reported for Ethiopia based on metagenomic data. All Ethiopian strains had nearly identical symbiotic genes that grouped them in a single cluster with M. ciceri, M. mediterraneum and M. muleiense, but not with M. plurifarium. Some phylogeographic structure was observed, with elevation and geography explaining some of the genetic differences among strains, but the relation between genetic identity and symbiotic effectiveness was observed to be weak.

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Biological Nitrogen Fixation

Cited by 60 publications

References 12 publications

Co-inoculation With Tropical Strains of Azospirillum and Bacillus Is More Efficient Than Single Inoculation for Improving Plant Growth and Nutrient Uptake in Maize.

Co-inoculation With Tropical Strains of Azospirillum and Bacillus Is More Efficient Than Single Inoculation for Improving Plant Growth and Nutrient Uptake in Maize.

Everything you must know about Azospirillum and its impact on agriculture and beyond

Phylogeography and Symbiotic Effectiveness of Rhizobia Nodulating Chickpea (Cicer arietinum L.) in Ethiopia

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