The findings demonstrate the potential of B. aryabhattai and P. fluorescens as plant growth-promoting bacteria capable of enhancing soybean development, with B. aryabhattai showing particular promise for improving plant performance under water-limited conditions.
Abstract
Drought is one of the major abiotic stresses limiting productivity worldwide, highlighting the need for sustainable strategies to improve crop resilience under water-limited conditions. This study evaluated the effects of the plant growth-promoting bacteria Bacillus aryabhattai and Pseudomonas fluorescens, applied individually or in combination, on soybean growth under well-watered and water-deficit conditions. The experiment was conducted in a completely randomized design arranged in a 2 × 4 factorial scheme, consisting of two irrigation regimes (well-watered and water deficit) and four biological treatments (control, B. aryabhattai, P. fluorescens, and co-inoculation with both bacteria). Plant growth variables, including shoot and root length, root volume, fresh biomass, and dry biomass, were evaluated after the stress period. Under well-watered conditions, co-inoculation promoted the greatest fresh root biomass and consistently increased shoot biomass compared with the untreated control. Under water-deficit conditions, B. aryabhattai alone produced the highest fresh root biomass and root volume, demonstrating superior performance in promoting root development during drought stress. Although most variables did not differ significantly among treatments, inoculated plants consistently exhibited greater vegetative growth than non-inoculated plants. These findings demonstrate the potential of B. aryabhattai and P. fluorescens as plant growth-promoting bacteria capable of enhancing soybean development, with B. aryabhattai showing particular promise for improving plant performance under water-limited conditions.
Water deficit is one of the main factors limiting soybean productivity, impairing plant growth and reducing crop yield potential. In this context, the use of plant growth-promoting rhizobacteria (PGPR) has emerged as a promising strategy to enhance plant tolerance to abiotic stresses and improve crop development. This study aimed to evaluate the effects of soybean seed inoculation with Bacillus aryabhattai on seed physiological performance during germination and plant growth under water-deficit conditions. Two experiments were conducted. In the first experiment, a completely randomized design was adopted in a factorial arrangement, evaluating seed inoculation (with or without aryabhattai) and water availability (with or without water deficit). Shoot and root length, as well as shoot and root fresh and dry biomass, were determined. In the second experiment, the seed physiological performance during germination of inoculated and non-inoculated seeds was evaluated by assessing seedling biomass accumulation. Seed inoculation significantly promoted shoot and root growth under both well-watered and water-deficit conditions. Inoculated plants subjected to water restriction exhibited greater length and biomass accumulation than non-inoculated plants, demonstrating enhanced tolerance to drought stress. In addition, inoculation increased shoot biomass accumulation during the seedling stage, indicating greater early vigor. Overall, the results demonstrate that Bacillus aryabhattai has considerable potential as a soybean seed inoculant, promoting plant growth and contributing to improved crop resilience under water-deficit conditions.
Jean Roberto Ruaro, Sérgio Miguel Mazaro, Maira Cristina Schuster Russiano et al.· REMUNOM· 0 citations
Water deficit is one of the main factors limiting watermelon productivity by affecting physiological processes and plant growth. Plant growth-promoting bacteria (PGPB) have emerged as a sustainable alternative to mitigate the effects of water stress. This study evaluated the growth of watermelon plants inoculated with PGPB under different soil moisture levels (SML). The experiment was conducted in a randomized complete block design with five replications using a split-split-plot arrangement over time in a 4 × 4 × 5 factorial design. The treatments consisted of four soil moisture levels (40%, 60%, 80%, and 100% of the soil water-holding capacity), four inoculation treatments (non-inoculated control, Bacillus velezensis NB69, Bacillus subtilis NB P6.2, and co-inoculation), and five evaluation times (19, 31, 45, 59, and 72 days after sowing). Water deficit from the flowering stage onward significantly reduced watermelon plant growth. Inoculation with B. subtilis NB P6.2 mitigated the negative effects of water stress by increasing stem length and diameter, leaf number, and leaf area, regardless of soil moisture level. Co-inoculation improved root development by increasing root length and root volume under soil moisture levels between 66% and 69%, although it did not increase fresh or dry root biomass. These results indicate that specific Bacillus strains are a promising and sustainable strategy to reduce the effects of water deficit on watermelon cultivation, particularly in arid and semi-arid regions.
Mycaella Gonçalves de Araújo, Alessandro Carlos Mesquita, Welson Lima Simões et al.· Scientia Plena· 0 citations
Water deficit represents a major environmental constraint that severely limits the growth and yield of common bean (Phaseolus vulgaris L.). Although inoculation with plant growth-promoting rhizobacteria (PGPR) has emerged as a promising strategy to mitigate drought-induced stress, the efficacy of specific strains, such as Priestia aryabhattai CMAA 1363, remains to be fully elucidated. This study evaluated the morpho-agronomic and biochemical responses of common bean to seed inoculation with P. aryabhattai CMAA 1363 under two contrasting irrigation regimes: 100% (well-watered) and 40% (water-restricted) of available water capacity (AWC) under greenhouse conditions. Water restriction significantly compromised plant performance, reducing plant and pod length, root dry biomass, and yield components (pod and grain counts, and total grain mass). Conversely, bacterial inoculation enhanced vegetative traits, increasing plant length by approximately 15% and root dry biomass by approximately 25% compared to non-inoculated controls. Notably, under severe water deficit (40% AWC), inoculated plants achieved a 20% increase in total grain mass per plant relative to their non-inoculated counterparts. Biochemical profiling indicated that inoculation effectively attenuated oxidative stress, as evidenced by lower malondialdehyde (MDA) accumulation and modulated superoxide dismutase (SOD) activity, while water-stressed plants adapted by accumulating total soluble sugars and increasing peroxidase (POD) activity. Overall, P. aryabhattai CMAA 1363 promotes vegetative development, preserves grain production under drought, and orchestrates antioxidant defense mechanisms, highlighting its potential as a sustainable bioinput to improve common bean resilience in water-limited agricultural systems.
Breno Miranda Bagagi, Ronaldo de Oliveira-Elias, Jéssica Pigatto de Queiroz Barcelos et al.· Stresses· 0 citations
Drought stress is among the most critical limitations to maize productivity, particularly under rainfed conditions. In this study, we explored the Brazilian Caatinga biome as a source of drought adapted plant growth-promoting bacteria and evaluated their potential to mitigate drought effects in maize (Zea mays L.). A total of 414 thermo-tolerant bacterial strains were isolated from soil, of which 28 Bacillus strains were able to grow under low water activity. These strains exhibited multiple plant growth-promoting traits in vitro, including exopolysaccharide production, biofilm formation, siderophore production, indole-3-acetic acid synthesis, putative nitrogen fixation, and phosphate solubilization. Twelve selected strains significantly improved root morphology, relative chlorophyll content (SPAD units), and biomass accumulation in maize seedlings under osmotic stress induced by polyethylene glycol. Notably, strain 1A11 showed the most consistent effects, promoting root growth and biomass accumulation under both stressed and non-stressed conditions, indicating constitutive growth promotion across environments, whereas other strains showed stronger responses under stress. This stability across environments strengthens its agronomic value, particularly in regions characterized by high rainfall variability. Genome sequencing of five elite strains (1A11, 5D5, 6E9, 1H10, and 2E7) identified conserved gene clusters associated with exopolysaccharide production, indole-3-acetic acid synthesis, phosphate metabolism, iron acquisition (siderophore synthesis), synthesis of volatile compounds, motility, chemotaxis, and general responses to osmotic and oxidative stress. Multi-location field trials conducted across five locations in Brazil, under rainfed conditions, indicate that strains 1A11 (Bacillus subtilis), 5D5, and 6E9 (Bacillus velezensis) consistently increased grain yield compared to the non-inoculated control and performed similarly to or better than a commercial inoculant. Mean productivity gains with the strain 1A11 reached up to 39% relative to the non-inoculated treatment across environments. These results indicate that Bacillus strains isolated from semi-arid soils were able to convert multifunctional potential into measurable agronomic gains under field conditions, demonstrating their potential as bioinoculants to enhance maize resilience under water-limited agricultural systems.
U. G. de Paula Lana, S. D. de Sousa, B. T. V. Godinho et al.· Frontiers in Plant Science· 0 citations
Pre-sprouted sugarcane seedlings are increasingly used to ensure uniform crop establishment; however, their performance is highly constrained by water deficit under climate change scenarios. This research evaluated whether a consortium of
Bacillus licheniformis
(FMCH001) and
Bacillus subtilis
(FMCH002) could mitigate drought stress by improving root development, soil microbial activity, and plant nutritional and physiological responses under different water regimes.
The experiment was conducted in a randomized block design using a 4 × 2 factorial scheme, with four water regimes (20, 40, 60, and 80% of field capacity) and two inoculation treatments (with and without bacteria), with four replicates.
Bacillus
inoculation alleviated the adverse effects of water deficit, particularly under severe water restriction (20, 40, and 60% of field capacity), by increasing root length, surface area, volume, and diameter. Inoculated treatments showed higher arylsulfatase, β-glucosidase, acid phosphatase, and urease activities, indicating enhanced soil microbial functioning. These responses were associated with increased leaf concentrations of N, P, K, Ca, Fe, and Zn. Furthermore, inoculated plants exhibited improved photosynthetic performance, including higher PSII efficiency, electron transport rate, net CO
2
assimilation, water use efficiency, and carboxylation efficiency, contributing to better establishment and development throughout the sugarcane growth cycle.
Inoculation with
Bacillus subtilis
and
Bacillus licheniformis
mitigated the effects of water deficit in pre-sprouted sugarcane seedlings by promoting root development, enhancing soil microbial activity, and increasing nutrient acquisition, thereby improving plant mineral nutrition and photosynthetic performance.
Carlos Henrique de Castro Nogueira, Hariane Luiz Santos, L. de Sousa Ferreira et al.· Plant and Soil· 0 citations
ABSTRACT The use of plant growth-promoting microorganisms (PGPM) is a promising strategy to enhance crop productivity while improving soil functionality. This study evaluated the efficacy of fungal-bacterial consortium of Trichoderma asperellum, Pseudomonas fluorescens, and Bacillus subtilis, for promoting the growth of soybean and maize cultivated under distinct edaphoclimatic conditions across Brazil. Field trials were conducted in five locations within Rio Grande do Sul, Santa Catarina, São Paulo, and Minas Gerais. Treatments consisted of a fungal-bacterial consortium (200 g ha-¹, in-furrow at planting) combined with 50% or 100% of the recommended nitrogen rate. Shoot dry biomass, foliar nitrogen (N) and phosphorus (P) concentrations, grain yield, and soil microbial activity determined by fluorescein diacetate hydrolysis were assessed. The fungal-bacterial consortium significantly improved all variables in both crops. In soybean, shoot biomass increased by 10.7-13.4% and grain yield by 9.2-9.9%, while foliar N and P rose by 10.2-12.4%, and soil enzymatic activity increased up to 11.0%. In maize, biomass increased by 10.4-11.8% and grain yield by 13.1-13.9%, with foliar N and P increasing by 9.5-14.1% and soil enzymatic activity by up to 12.5%. Notably, positive responses were maintained under 50% nitrogen fertilization. These findings demonstrate that fungal-bacterial consortium enhances nutrient acquisition and soil microbial activity, improving crop performance under variable environmental conditions and reduced N input, supporting its potential as a biological tool for sustainable nutrient management in soybean and maize systems.
A.C.C. Bortolassi, Anna Flávia Neri de Almeida, E. Meyer et al.· Ciência e Agrotecnologia· 0 citations
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