Seed inoculation with Azospirillum brasilense in the U.S. soybean systems

Andre Froes de Borja Reis, Luiz H.Moro Rosso, Eric Adee, Davidson Dan Davidson, Péter Kovács, Larry C. Purcell, Frederick E. Below, Shaun N. Casteel, Carrie Knott, Hans Kandel, Seth L. Naeve, Maninder P. Singh, Sotirios Archontoulis, Ignacio A. Ciampitti

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1 Scopus citations

Abstract

Symbiotic nitrogen (N) fixation (SNF) is critical to satisfying the nutritional need of soybean (Glycine max (L.) Merr.) and maintaining productivity and high seed protein concentration. Due to its low environmental impact, a key factor for increasing the sustainability of soybean systems is to enhance SNF. Seed inoculation with the free-living Azospirillum brasilense alone or with Bradyrhizobium japonicum (herein called co-inoculation) are plausible strategies that have been explored in tropical environments but lack information in temperate regions. Following this rationale, this study aimed to evaluate the impact of seed inoculation with Azospirillum brasilense (herein called Azospirillum) alone or combined with Bradyrhizobium japonicum (herein called Bradyrhizobium) in a range of environments in the United States (US) for: (i) seed yield, (ii) relative abundance of ureides (RAU) as a proxy of SNF, and (iii) seed protein concentration. Twenty-five field studies across the US states with the same experimental design were performed during the 2019 and 2020 growing seasons. The primary outcomes of this research were: (i) yield responses to co-inoculation were considered significant in only 2 out of 25 site-years, (ii) RAU was not increased by Azospirillum inoculation or co-inoculation, and lastly, (iii) seed protein concentration was marginally associated with the inoculation strategies. Although Azospirillum did not impose remarkable gain in any observed plant traits, future studies should focus on mechanistically understanding whether Azospirillum can naturalize in temperate region soils. Still, strategies for enhancing SNF are required for sustainably improving productivity and quality for US soybean systems.

Original languageEnglish (US)
Article number108537
JournalField Crops Research
Volume283
DOIs
StatePublished - Jul 1 2022

Bibliographical note

Funding Information:
United Soybean Board funded this research, project no. 2020–152-0104 . This is contribution no. 22-278-j from Kansas Agricultural Extension Station. We appreciate the support of TerraMax Inc. for providing the inoculants. Michigan State trials received support from Michigan Soybean Committee. The North Dakota trials were funded by the North Dakota Agricultural Experiment Station . This work could not have been possible without the effort of Conner Raymond, Hunter Adams, Curtis Bradley, Sloan Boren, Gracie Harper, Andy King, Marilynn Davies, Emily Wright. We appreciate the carefully editorial review of Juliann Seebauer. Lastly, we extend our appreciation to all the staff and scholars from Ciampitti Lab on their support to field research studies and coordination of this national effort.

Funding Information:
United Soybean Board funded this research, project no. 2020?152-0104. This is contribution no. 22-278-j from Kansas Agricultural Extension Station. We appreciate the support of TerraMax Inc. for providing the inoculants. Michigan State trials received support from Michigan Soybean Committee. The North Dakota trials were funded by the North Dakota Agricultural Experiment Station. This work could not have been possible without the effort of Conner Raymond, Hunter Adams, Curtis Bradley, Sloan Boren, Gracie Harper, Andy King, Marilynn Davies, Emily Wright. We appreciate the carefully editorial review of Juliann Seebauer. Lastly, we extend our appreciation to all the staff and scholars from Ciampitti Lab on their support to field research studies and coordination of this national effort.

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Bradyrhizobium japonicum
  • Co-inoculation
  • N fixation
  • Plant beneficial microorganisms
  • Sustainability

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