It is confirmed that bio-stimulants can serve as efficient and reliable regulators to advance green and sustainable crop production and promote nutrient absorption and vegetative growth of tomato plants.
Abstract
Bio-stimulants are promising environment friendly alternatives to support sustainable agricultural development, capable of boosting crop growth and yield while cutting down excessive dependence on chemical synthetic fertilizers. Nevertheless, the explicit regulatory mechanisms by which bio-stimulants exert the role of growth-promoting functions still remain largely unclear and require further systematic clarification. In this study, we explored the influences of bio-stimulants (rich in humic acid) on tomato growth performance and rhizosphere microbial community assembly via greenhouse trials, and comparatively analyzed the functional differences between foliar spraying and root irrigation application modes. The results demonstrated that bio-stimulants treatment markedly improved tomato aboveground biomass, plant nitrogen and phosphorus accumulation by 17.1%, 27.4% and 22.7%, respectively. Meanwhile, bio-stimulants application effectively raised soil available nitrogen and soil organic matter levels, and further facilitated phosphorus assimilation in tomato plants. Metagenomic sequencing confirmed that bio-stimulants substantially reshaped the overall structure and composition of tomato rhizosphere microbiome. Specifically, they dramatically enriched the relative abundance of core microbial taxa responsible for soil nitrogen fixation and phosphorus solubilization. Collectively, these results clearly elaborate the underlying action mechanism: bio-stimulants optimize rhizosphere micro-ecological environment, enrich functional nutrient-solubilizing microorganisms, improve soil nutrient availability, and ultimately promote nutrient absorption and vegetative growth of tomato plants. This study confirms that bio-stimulants can serve as efficient and reliable regulators to advance green and sustainable crop production.
The integration of nanomaterials (NMs) with plant-beneficial microorganisms has emerged as a promising strategy to improve crop resilience to abiotic stresses. Evidence from multiple studies indicates that NM-microbe co-application often enhances plant growth, nutrient uptake, biomass accumulation, and stress tolerance more effectively than either approach alone. Under drought and salinity stress, these combinations help maintain ionic balance, particularly higher K+/Na+ ratios, sustain photosynthesis, and reduce oxidative damage by increasing the activities of antioxidant enzymes such as superoxide dismutase, catalase, and peroxidase. Nanoparticles, including ZnO, Fe3O4, and SiO2, when combined with plant growth-promoting rhizobacteria (PGPR) or arbuscular mycorrhizal fungi (AMF), stimulate root development, increasing water and nutrient acquisition. Additionally, NMs can reshape rhizosphere microbial communities by enriching beneficial taxa such as Pseudomonas, Bacillus, and Trichoderma while suppressing certain phytopathogens. Nanoformulated fertilizers and micronutrients further enhance nutrient use efficiency and may reduce dependence on conventional agrochemicals, supporting sustainable agricultural practices. However, the benefits of NM-microbe integration are not universal. Several studies report that some nanomaterials can inhibit beneficial microorganisms, including nitrogen-fixing bacteria and AMF, at concentrations only slightly above stimulatory levels, highlighting a narrow safety margin. Concerns also remain regarding NM persistence, soil-dependent mobility, trophic transfer through food webs, and potential disruption of soil microbial communities. This review evaluates both the advantages and risks of NM-microbe interactions, emphasizing the importance of dose, soil characteristics, and microbial strain selection. Current evidence, largely derived from short-term laboratory studies, remains insufficient to support widespread field application without long-term ecological monitoring, standardized assessment protocols, and evaluation of economic feasibility for smallholder farming systems.
O. Oyewole, S. A. Oyegbade, Abdullah S Albaqami· Integrated Environmental Ass...· 0 citations
The role of PGPF in climate-resilient cropping systems and circular bioeconomy frameworks, including waste valorization and biofertilizer development is highlighted and key limitations such as host specificity, environmental variability, and scalability challenges are identified.
Kallol Das, A. Sarker, D. Deepo et al.· Phyton· 0 citations
The increasing demand for sustainable and environmentally responsible agricultural practices has accelerated the search for alternatives to chemical fertilizers. Microbial biofertilizers, particularly plant growth-promoting rhizobacteria (PGPR), offer a promising strategy to enhance crop productivity while maintaining soil health. Among these, Bacillus species have gained significant attention due to their ecological versatility and functional diversity. This review provides a comprehensive evaluation of the biofertilization potential of Bacillus spp. in sustainable agriculture. Prominent species such as Bacillus subtilis, B. megaterium, and B. amyloliquefaciens contribute to improved nutrient acquisition through nitrogen fixation, phosphate solubilization, and potassium mobilization. In addition, Bacillus spp. produce phytohormones, siderophores, and volatile organic compounds that stimulate plant growth and enhance tolerance to biotic and abiotic stresses. Their endospore-forming ability ensures high survival, prolonged shelf life, and reliable performance under diverse field conditions, supporting their commercial application as biofertilizers. This review also discusses interactions between Bacillus spp. and native soil microbiota, their influence on rhizosphere dynamics, and their role in improving soil fertility and crop productivity. However, inconsistent field performance, formulation challenges, and regulatory constraints remain key barriers to large-scale adoption. Recent advances in genomics, strain improvement, and formulation technologies present new opportunities to enhance the efficacy of Bacillus-based biofertilizers. Integrative approaches combining microbiology, agronomy, and policy frameworks are essential to realize their full potential in sustainable agricultural systems and global food security.
Soumendranath Chatterjee, Dibyendu Saha, Souvik Bag et al.· Discover Plants· 0 citations
ABSTRACT Maize intensive cultivation with excessive fertilizer use generates environmental impacts. Plant growth-promoting bacteria offer a sustainable alternative by favoring nitrogen fixation, phosphorus solubilization, and phytohormone production. This study aimed to evaluate the effect of microorganisms previously recognized as growth promoters in rice on maize biomass and yield. The experiment was conducted under laboratory and greenhouse conditions, in a completely randomized design, with 13 treatments (12 microorganisms and one control). Lysinibacillus boronitolerans (BRM 71995) promoted the greatest increase in shoot dry mass (48.64 %, compared to the control), whereas Acinetobacter sp. (BRM 71990) stood out for root dry mass (217.12 %, compared to the control). For 100-grain weight, Herbaspirillum seropedicae (BRM 71996) increased values by 110.40 %, compared to Bacillus velezensis (BRM 71986). H. seropedicae (BRM 71997) was responsible for the greatest productive gains, increasing the number of grains (57.35 %, compared to the control) and yield per pot (85.14 %, compared to the control).
A. C. M. Façanha, Wendel Gabriel Magalhães Vieira, Nathalia Morais Ventura et al.· Pesquisa Agropecuária Tropic...· 0 citations
Background: Maize (Zea mays L.) is one of the world's most important cereal crops, and improving its productivity while reducing dependence on chemical fertilizers has become a major goal of sustainable agriculture. The potential role of plant growth promoting rhizobacteria (PGPR) as a biofertilizer evolved as appropriate substitute to neutralize adverse environmental impacts wielded by manmade agrochemical.
Objective: This study aimed to evaluate the effects of Pseudomonas fluorescens and Bacillus subtilis, individually and in combination, on the growth and yield of maize compared with conventional NPK fertilization.
Methods: A field experiment was conducted during the 2025 growing season at the Field Crops Research Station, College of Agriculture, University of Samarra, using a Randomized Complete Block Design (RCBD) with three replicates. Six treatments were evaluated: Untreated control (T1), Pseudomonas fluorescens (T2), Bacillus subtilis (T3), combined inoculation (P. fluorescens + B. subtilis) (T4), combined inoculation with NPK fertilizer (T5), and NPK fertilizer (20:20:20) only (T6). Vegetative growth and yield-related traits were recorded and statistically analyzed.
Results: Inoculation of plants with PGPR bacteria resulted in a significant improvement in both vegetative growth and yield compared to the untreated control group. Pseudomonas fluorescens (T2) exhibited the highest vegetative growth rate, recording the highest plant height (148.00 cm), leaf area (365.00 cm²), leaf area index (2.63), and number of grains per spike (688 grains) compared control group recorded (92.33 cm), (10.67 plant⁻¹), (151.73 cm²), (0.70) respectively. Bacillus subtilis (T3), achieved the highest productivity, producing the largest number of spikes per plant (2.67 spikes) and the highest spike weight (283.50 g) compared control group recorded (2.00) and (161.60 g).
Conclusion: The use of PGPR, and especially Pseudomonas fluorescens and Bacillus subtilis as potential biofertilisation agents is a promising sustainable alternative to chemical fertilisation that can enhance maize growth and production, while decreasing dependence on mineral fertilisers.
Waser saad Khalaf, Ahmed waleed Abdulrahman· International Journal of Bio...· 0 citations
Abiotic and biotic stresses significantly threaten global food security and agricultural sustainability. Achieving the United Nations Sustainable Development Goals (SDGs), particularly SDG 2 (Zero Hunger), SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 15 (Life on Land), requires sustainable agricultural approaches. Recently, plant growth-promoting bacterial (PGPB) consortia have emerged as an effective strategy for enhancing crop productivity under stress conditions. These microbial communities improve plant growth through mechanisms such as nitrogen fixation, phosphate solubilization, phytohormone production, siderophore secretion, ACC deaminase activity, induction of systemic resistance, while enhancing nutrient uptake, antioxidant activity, osmotic regulation, and stress-responsive signalling pathways, thus improving plant health and productivity. Compared with single-strain inoculants, consortia provide synergistic effects that enhance rhizosphere colonization, microbial survival, and plant-microbe interactions, thus contributing to the achievement of the SDGs. Recent advances in modern tools such as metagenomics, metatranscriptomics, metabolomics, and machine learning for predictive microbiome modelling, as well as field-level engineering approaches such as encapsulation technologies, biochar-based carriers, seed coating, and root microbiome editing, have accelerated the development of efficient microbial formulations for sustainable agriculture. This review discusses the potential of PGPB consortia as a sustainable solution for boosting crop productivity under stress. The integration of consortia into modern agricultural practices can play a crucial role in supporting resilient farming systems and advancing the global SDG agenda. This review highlights the key limitations, challenges, and research gaps associated with PGPB consortia, as well as future prospects for enhancing crop productivity.