Abstract
The success of beneficial bacteria in improving the crop growth and yield depends on an adequate plant-bacteria interaction. In this work, the capability of Azospirillium brasilense Sp7, Pseudomonas putida KT2440, Acinetobacter sp. EMM02, and Sphingomonas sp. OF178A to interact with six maize varieties was evaluated by both single-bacterium application and consortium application. The bacterial consortium efficiently colonized the rhizosphere of the autochthonous yellow and H48 hybrid varieties. Bacterial colonization by the consortium was higher than under single-bacterium colonization. The two maize varieties assayed under greenhouse conditions showed increased plant growth compared to the control. The effect of consortium inoculation plus 50% fertilization was compared with the 100% nitrogen fertilization under field conditions using the autochthonous yellow maize. Inoculation with the consortium plus 50% urea produced a similar grain yield compared to 100% urea fertilization. However, a biomass decrease was observed in plants inoculated with the consortium plus 50% urea compared to the other treatments. Furthermore, the safety of these bacteria was evaluated in a rat model after oral administration. Animals did not present any negative effects, after bacterial administration. In conclusion, the bacterial consortium offers a safety alternative that can reduce chemical fertilization by half while producing the same crop yield obtained with 100% fertilization. Decreased chemical fertilization could avoid contamination and reduce the cost in agricultural practices.
Highlights
The study of the interaction of plant growth-promoting rhizobacteria (PGPR) with plants of agricultural interest has led to the development of biofertilizers or bio-inoculants (Kumar et al, 2007; Zahid et al, 2015)
All hybrid varieties showed a germination percentage of 100% when they were inoculated with the bacterial consortium
Individual and consortium bacterial adhesion to maize for A. brasilense Sp7, P. putida KT2440, Acinetobacter sp
Summary
The study of the interaction of plant growth-promoting rhizobacteria (PGPR) with plants of agricultural interest has led to the development of biofertilizers or bio-inoculants (Kumar et al, 2007; Zahid et al, 2015). The rhizobacteria with the capability to promote the growth of plants include several species such as Pseudomonas flourescens and P. aeruginosa for maize (Adjanohoun et al, 2011); Paenibacillus lentimorbus and Bacillus amyloliquefaciens for rice (Bisht and Chauhan, 2020); Rhizobium pisi and Pseudomonas monteilii for bean (Sánchez et al, 2014); and Bacillus subtilis and Pseudomonas fluorescens for Capsicum annumen (Sundaramoorthy et al, 2012) Some of those bacteria perform control of fungal diseases produced by Fusarium solani (Sundaramoorthy et al, 2012). Regarding to microbial consortia applied to maize plants, the inoculation of A. brasilense and Bacillus subtillis improved phosphorus uptake, plant development, and corn grain yield (Pereira et al, 2020) the consortium of Trichoderma harzianum OMG16 and B. amyloliquefaciens FZB42 increased the shoot dry matter and grain yield in maize (Mpanga et al, 2019)
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