Bradyrhizobium strain and the 15N natural abundance quantification of biological N2 fixation in soybean

In commercial plantations of soybean in both the Southern and the Cerrado regions, contributions from biological nitrogen fixation (BNF) are generally proportionately high. When using the 15N natural abundance technique to quantify BNF inputs, it is essential to determine, with accuracy, the 15N abundance of the N derived from BNF (the 'B' value). This study aimed to determine the effect of four recommended strains of Bradyrhizobium spp. (two B. japonicum and two B. elkanii) on the 'B' value of soybean grown in pots in an open field using an equation based on the determination of δ15N natural abundance in a non-labelled soil, and estimate of the contribution of BNF derived from the use of 15N-isotope dilution in soils enriched with 15N. To evaluate N2 fixation by soybean, three non-N2-fixing reference crops were grown under the same conditions. Regardless of Bradyrhizobium strain, no differences were observed in dry matter, nodule weight and total N between labelled and non-labelled soil. The N2 fixation of the soybeans grown in the two soil conditions were similar. The mean 'B' values of the soybeans inoculated with the B. japonicum strains were -1.84 ‰ and -0.50 ‰, while those inoculated with B. elkanii were -3.67 ‰ and -1.0 ‰, for the shoot tissue and the whole plant, respectively. Finally, the 'B' value for the soybean crop varied considerably in function of the inoculated Bradyrhizobium strain, being most important when only the shoot tissue was utilised to estimate the proportion of N in the plant derived from N2 fixation.

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Importance of correct B value determination to quantify biological N2 fixation and N balances of faba beans (Vicia faba L.) via 15N natural abundance

Biology and Fertility of Soils ◽

10.1007/s00374-013-0874-7 ◽

2013 ◽

Vol 50 (3) ◽

pp. 517-525 ◽

Cited By ~ 23

Author(s):

Amsalu Nebiyu ◽

Dries Huygens ◽

Hari Ram Upadhayay ◽

Jan Diels ◽

Pascal Boeckx

Keyword(s):

Vicia Faba ◽

N2 Fixation ◽

B Value ◽

15N Natural Abundance ◽

Natural Abundance ◽

Biological N2 Fixation ◽

Vicia Faba L ◽

Faba Beans ◽

Value Determination

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Growth patterns of common bean cultivars affect the ‘B’ value required to quantify biological N2 fixation using the 15N natural abundance technique

Plant and Soil ◽

10.1007/s11104-017-3331-9 ◽

2017 ◽

Vol 419 (1-2) ◽

pp. 293-304 ◽

Cited By ~ 4

Author(s):

Rafael Sanches Pacheco ◽

Robert Michael Boddey ◽

Bruno José Rodrigues Alves ◽

Rosângela Straliotto ◽

Adelson Paulo Araújo

Keyword(s):

Common Bean ◽

N2 Fixation ◽

B Value ◽

15N Natural Abundance ◽

Growth Patterns ◽

Natural Abundance ◽

Biological N2 Fixation

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Nitrogen fixation in annual Trifolium species in alkaline soils as assessed by the 15N natural abundance method

Crop and Pasture Science ◽

10.1071/cp11039 ◽

2011 ◽

Vol 62 (8) ◽

pp. 712 ◽

Cited By ~ 6

Author(s):

Matthew D. Denton ◽

David R. Coventry ◽

William D. Bellotti ◽

John G. Howieson

Keyword(s):

N2 Fixation ◽

Rhizobium Leguminosarum ◽

Farming Systems ◽

15N Natural Abundance ◽

Natural Abundance ◽

Soil Conditions ◽

Nodule Occupancy ◽

Alkaline Soil ◽

Alkaline Soils ◽

Mixed Farming

Annual clover species such as Trifolium purpureum Loisel., T. resupinatum L., and T. alexandrinum L. are adapted to alkaline soil conditions and provide certain agronomic advantages over annual medics (Medicago spp.). Annual clovers have not been widely grown in alkaline soils in Australia, and quantifying their dinitrogen (N2) fixation in alkaline soils is important in understanding their potential role in mixed farming systems of southern Australia. Using the 15N natural abundance technique, it was estimated that annual clovers fixed 101–137 kg N/ha at Roseworthy and 59–62 kg N/ha at Mallala, on Calcarosols with soil pH of 8.0 and 8.5, respectively. Species differed in the percentages of fixed N2 estimated in shoot dry matter, which was highest in T. alexandrinum (77–85%), moderate in T. resupinatum (76%), and lowest in T. purpureum (65–74%). Naturally occurring soil rhizobia (Rhizobium leguminosarum bv. trifolii) provided adequate nodulation, as inoculation with different strains of rhizobia had little influence on nodulation or N2 fixation. These results indicate that clovers can provide a significant contribution of fixed N2 to mixed farming systems. Examination of nodules indicated variable nodule occupancy by the inoculant rhizobia and that 69% of shoot N was fixed when clovers were nodulated by the soil populations of rhizobia. A simple model is defined to identify the potential interactions between inoculated legumes and soil rhizobia, and the options for enhancing symbiotic effectiveness are discussed.

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Influence of growth stage and seed nitrogen on B values and potential contributions to error in estimating biological N2 fixation using the 15N natural abundance method

Plant and Soil ◽

10.1007/s11104-018-3600-2 ◽

2018 ◽

Vol 425 (1-2) ◽

pp. 389-399 ◽

Cited By ~ 5

Author(s):

Terry J. Rose ◽

Lee J. Kearney ◽

Dirk V. Erler ◽

Michael T. Rose ◽

Lukas Van Zwieten ◽

...

Keyword(s):

N2 Fixation ◽

Growth Stage ◽

15N Natural Abundance ◽

Natural Abundance ◽

B Values ◽

Biological N2 Fixation ◽

15N Natural Abundance Method

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Variations in the 15N natural abundance of plant-available N with soil depth: Their influence on estimates of contributions of biological N2 fixation to sugar cane

Applied Soil Ecology ◽

10.1016/j.apsoil.2013.08.008 ◽

2014 ◽

Vol 73 ◽

pp. 124-129 ◽

Cited By ~ 17

Author(s):

Rafael Butke Baptista ◽

Rafael Fiusa de Morais ◽

José Marcos Leite ◽

Nivaldo Schultz ◽

Bruno José Rodrigues Alves ◽

...

Keyword(s):

Sugar Cane ◽

N2 Fixation ◽

Soil Depth ◽

15N Natural Abundance ◽

Natural Abundance ◽

Available N ◽

Biological N2 Fixation

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Natural abundance of 15N of N derived from the atmosphere by different strains of Bradyrhizobium in symbiosis with soybean plants

Ciência Rural ◽

10.1590/0103-8478cr20180265 ◽

2019 ◽

Vol 49 (12) ◽

Author(s):

Karla Emanuelle Campos Araujo ◽

Carlos Vergara Torres Júnior ◽

Ana Paula Guimarães ◽

Mara Alexandre da Silva ◽

Bruno José Rodrigues Alves ◽

...

Keyword(s):

N2 Fixation ◽

Isotopic Fractionation ◽

15N Natural Abundance ◽

Natural Abundance ◽

Soybean Cultivar ◽

B Values ◽

Shoot Tissue ◽

Whole Plant ◽

Soybean Plants ◽

Different Strains

ABSTRACT: To quantify the BNF contribution to legumes using the 15N natural abundance technique, it is important to know the abundance of 15N of the plants grown entirely dependent on BNF (value ‘B’). The aim of the study was to determine the 15N natural abundance of N2 fixed by different Bradyrhizobium strains in symbiosis with one soybean cultivar. Treatments consisted of soybean plants cultivated with and without inoculation with ten Bradyrhizobium strains, in five replicates planted in Leonard jars in a sand/vermiculite mixture. Plants were harvested after 46 days. The ‘B’ values of the aerial tissue (‘Bs’) ranged from -2.6 to -3.9 ‰. There was a tendency for the ‘Bs’ values of plants inoculated with strains of B. elkanii to be more negative than plants inoculated with other strains. All ‘B’ values of the whole plant were less than 1 unit of δ15N (‰) different from zero, suggesting that the symbioses have little tendency to show significant isotopic fractionation during N2 fixation, but there is considerable depletion in 15N of the N translocated to the shoot tissue.

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