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Nitrogen fixation

About: Nitrogen fixation is a research topic. Over the lifetime, 7940 publications have been published within this topic receiving 232921 citations. The topic is also known as: GO:0009399.


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Journal ArticleDOI
TL;DR: In this paper, a quantitative estimate of the amount of nitrogen symbiotically fixed by a legume crop growing under normal field conditions was made by simultaneous determinations of the AN values by the legume and a non-nodulating crop.
Abstract: A quantitative estimate is made of the amount of nitrogen symbiotically fixed by a legume crop growing under normal field conditions. The method involves simultaneous determinations of the “AN” values by the legume and a non-nodulating crop, using15N-labelled nitrogen fertilizer. The fertilizer is applied at a low rate to the legume crop to avoid interference with the symbiotic N fixation process, but at a normal rate to the non-nodulating crop. The amount of symbiotically fixed nitrogen expressed in kg N/ha is calculated by multiplying the difference in A value between the legume and the non-nodulating crop with the % utilization of fertilizer N by the legume crop.

171 citations

Journal ArticleDOI
TL;DR: It is clear that the dual inoculation with Rhizobium and AMF biofertilizer is more effective for promoting growth of faba bean grown in alkaline soils than the individual treatment, reflecting the existence of synergistic relationships among the inoculants.

169 citations

Journal ArticleDOI
TL;DR: Beans co-inoculated with Rhizobiumtropici (CIAT899) and Paenibacilluspolymyxa (DSM 36) had higher leghemoglobin concentrations, nitrogenase activity and N2 fixation efficiency and thereby formed associations of greater symbiotic efficiency.
Abstract: A greenhouse experiment was performed to evaluate the effects of plant growth-promoting rhizobac- teria (PGPR) on nodulation, biological nitrogen fixation (BNF) and growth of the common bean (Phaseolus vul- garis L. cv. Tenderlake). Single and dual inoculation treatments of bean with Rhizobium and/or PGPR were administered to detect possible changes in the levels of and interactions between the phytohormones IAA and cytoki- nin. Bean plants cv. Tenderlake were grown in pots containing Fluvic Neosol eutrophic (pH 6.5). Fourteen kilogram aliquots of soil contained in 15-l pots were autoclaved. Bean seeds were surface sterilized and inocu- lated with Rhizobium tropici (CIAT 899-standard strain) alone and in combination with one of the PGPR strains: Bacillus endophyticus (DSM 13796), B. pumilus (DSM 27), B. subtilis (DSM 704), Paenibacillus lautus (DSM 13411), P. macerans (DSM 24), P. polymyxa (DSM 36), P. polymyxa (Loutit L.) or Bacillus sp.(65E180). The experimental design was randomized block design with three replications. Beans co-inoculated with Rhizobium tropici (CIAT899) and Paenibacillus polymyxa (DSM 36) had higher leghemoglobin concentrations, nitrogenase activity and N2 fixation efficiency and thereby formed associations of greater symbiotic efficiency. Inoculation with Rhizobium and P. polymyxa strain Loutit (L) stimu- lated nodulation as well as nitrogen fixation. PGPR also stimulated specific-nodulation (number of nodules per gram of root dry weight) increases that translated into higher levels of accumulated nitrogen. The activities of phytohormones depended on their content and interactions with Rhizobium tropici and Paenibacillus and/or Bacillus (PGPR) strains which affect the cytokinin in content in the common bean.

168 citations

Journal ArticleDOI
TL;DR: Genes for nitrogen acquisition were expressed at particularly high levels during alternative nitrogenase-dependent growth and raises the possibility that fixed nitrogen availability may be the primary signal that controls the synthesis of the V and Fe nitrogenases.
Abstract: The photosynthetic bacterium Rhodopseudomonas palustris is one of just a few prokaryotes described so far that has vnf and anf genes for alternative vanadium cofactor (V) and iron cofactor (Fe) nitrogenases in addition to nif genes for a molybdenum cofactor (Mo) nitrogenase. Transcriptome data indicated that the 32 genes in the nif gene cluster, but not the anf or vnf genes, were induced in wild-type and Mo nitrogenase-expressing strains grown under nitrogen-fixing conditions in Mo-containing medium. Strains that were unable to express a functional Mo nitrogenase due to mutations in Mo nitrogenase structural genes synthesized functional V and Fe nitrogenases and expressed vnf and anf genes in nitrogen-fixing growth media that contained Mo and V at concentrations far in excess of those that repress alternative nitrogenase gene expression in other bacteria. Thus, not only does R. palustris have multiple enzymatic options for nitrogen fixation, but in contrast to reports on other nitrogen-fixing bacteria, the expression of its alternative nitrogenases is not repressed by transition metals. Between 95 and 295 genes that are not directly associated with nitrogenase synthesis and assembly were induced under nitrogen-fixing conditions, depending on which nitrogenase was being used by R. palustris. Genes for nitrogen acquisition were expressed at particularly high levels during alternative nitrogenase-dependent growth. This suggests that alternative nitrogenase-expressing cells are relatively starved for nitrogen and raises the possibility that fixed nitrogen availability may be the primary signal that controls the synthesis of the V and Fe nitrogenases.

168 citations

Book ChapterDOI
TL;DR: A range of management options can be applied to legumes growing in farming systems to manipulate N2 fixation and improve the N benefits to agriculture and agroforestry.
Abstract: Atmospheric N2 fixed symbiotically by associations between Rhizobium spp. and legumes represents a renewable source of N for agriculture. Contribution of legume N2 fixation to the N-economy of any ecosystem is mediated by: (i) legume reliance upon N2 fixation for growth, and (ii) the total amount of legume-N accumulated. Strategies that change the numbers of effective rhizobia present in soil, reduce the inhibitory effects of soil nitrate, or influence legume biomass all have potential to alter net inputs of fixed N. A range of management options can be applied to legumes growing in farming systems to manipulate N2 fixation and improve the N benefits to agriculture and agroforestry.

168 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023390
2022831
2021263
2020240
2019250
2018261