Glasnik Zaštite Bilja, Vol. 48. No. 4., 2025.
Original scientific paper
https://doi.org/10.31727/gzb.48.4.9
Synergistic effect of Rhizobium hidalgonense and Bacillus sp. in nitrogen fixation and growth promotion of common bean (Phaseolus vulgaris L.)
Ivana Rajnović
orcid.org/0000-0002-0521-787X
; Agronomski fakultet, Sveučilište u Zagrebu, Zagreb, Hrvatska
*
Iva Garofulić
orcid.org/0009-0000-5028-4791
; Agronomski fakultet, Sveučilište u Zagrebu, Zagreb, Hrvatska
Anastazija Huđ
orcid.org/0000-0001-9993-8709
; Institut Ruđer Bošković, Zagreb, Hrvatska
Ines Sviličić Petrić
orcid.org/0000-0003-3875-9373
; Institut Ruđer Bošković, Zagreb, Hrvatska
* Corresponding author.
Abstract
The aim of this study was to phenotypically characterize nitrogen-fixing symbiotic strains of Rhizobium hidalgonense and to select those with the most favorable traits for bean inoculation. A further objective was to examine the potential synergistic effect of co-inoculation with selected strains and PGPR (Plant growth Promoting Rhizobacteria) of the genus Bacillus (B. thuringiensis, B. amyloliquefaciens, B. megaterium) in comparison to single inoculation.
Phenotypic analysis revealed traits important for successful root colonization and nitrogen fixation, including catalase, urease, and oxidase activity, as well as the ability produce organic acids. Strain 22BT exhibited the highest potential based on its phenotypic characteristics. In vitro assays confirmed that all analyzed strains possessed biological nitrogen fixation capacity. No antagonistic interactions were observed between Rhizobium and Bacillus spp. in compatibility testing.
Co-inoculation treatments tested under controlled conditions showed statistically significantly higher values for bean biomass and for nitrogen content in the plant compared to single rhizobium strain inoculations. The combination of R. hidalgonense 22BT with B. megaterium (R2B3) resulted in the highest nitrogen content in the plant (9.1 mg/plant), while the combination of the same strain with B. thuringiensis (R2B1) yielded the highest shoot dry weight (2,62 g). Nodule biomass did not correlate with the amount of fixed nitrogen.
These results confirm the potential of R. hidalgonense in nitrogen fixation as well as in promoting bean growth when combined with PGPR bacteria. This highlights their suitability as promising strains for the development of effective microbial plant biostimulants for sustainable agriculture.
Keywords
biological nitrogen fixation, coinoculation, PGPR, biostimulants, sustainable agriculture
Hrčak ID:
333915
URI
Publication date:
22.7.2025.
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