Application Of Plant Growth Promoting Rhizobacteria Research Articles

Impact of Poultry Manure-Derived Biochar and Bio-Fertilizer Application to Boost Production of Black Cumin Plants (Nigella sativa L.) Grown on Sandy Loam Soil

Biochar derived from poultry manure increases nutrient availability and promotes plant growth. This study investigated the effect of biochar with mycorrhizal and/or plant growth-promoting rhizobacteria on soil fertility, chemical properties, oil, and seed yield of Black Cumin (Nigella sativa L.) plants. A split-plot design with three replicates was employed, with biochar derived from poultry litter (BC) applied at rates of 0, 5, and 10 t ha−1, with beneficial microbes such as arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) affecting the growth of Black Cumin plants, and some soil properties, such as pH, electrical conductivity (EC), soil organic matter (SOM) and fertility index (FI), showing significant differences (p ≤ 0.05) among biochar and/or bio-fertilizer treatments. All biochar treatments with or without bio-fertilizers significantly increased pH, EC, OM and FI in comparison to the control treatment. The results demonstrated that applying biochar at the highest rate (10 t ha−1) increased fresh and dry capsule weights by 94.51% and 63.34%, respectively, compared to the control treatment (C). These values were significantly increased by 53.05 and 18.37%, compared to untreated plants when combined with AMF and PGPR. Furthermore, when biochar was applied in conjunction with both AMF and PGPR, fresh and dry capsule weights saw significant increases of 208.84% and 91.18%, respectively, compared to the untreated control treatment. The interaction between biochar, AMF, and PGPR significantly improved plant growth, yield, soil properties, and the fixed and volatile oil content of Black Cumin. These findings suggest that the combined application of biochar, AMF, and PGPR enhances nutrient availability and uptake, leading to improved growth and higher yields in Black Cumin plants, resulting in increased yield production.

Synergism or Antagonism: Do Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Rhizobacteria Work Together to Benefit Plants?

In agriculture, abiotic and biotic stress reduce yield by 51–82% and 10–16%, respectively. Applications of biological agents such as plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) can improve plant growth. Applications of lone PGPR and AMF also help plants resist abiotic and biotic stressors. The reports for dual inoculation of AMF and PGPR to benefit plants and tackle stressors are largely unknown. It is speculated that PGPR colonization in plants enhances AMF infection during dual AMF and PGPR application, although increased AMF colonization does not always correlate with the increased benefits for the plant hosts. Further research is needed regarding molecular mechanisms of communication during dual inoculations, and dual-inoculation enhancement of induced systemic resistance under pathogen stress, to understand how dual inoculations can result in enhanced plant benefits. The influence of application timing of AMF and PGPR dual inoculations on mitigating abiotic and biotic stress is also not well understood. This review documents the factors that govern and modulate the dual application of AMF and PGPR for plant benefits against stress responses, specifically abiotic (drought) stress and stress from pathogen infection.

The Effect Addition of Soil Amandments and PGPR (Plant Growth Promoting Rhizobacteria) on the Growth and Yield of Cotton Plants Intercropped with Corn Plants in Dry Land of North Lombok Regency of Indonesia

This research investigates the effect of soil amendments in the form of cow, form goat manures and PGPR biofertilizer on cotton plants intercropped with corn in the dry lands of North Lombok Regency. The research aims is to determine the growth and yield response of cotton plants due to the application of soil amendments and PGPR in an intercropped system with corn in dryland areas. The research was conducted from December 2023 to June 2024 in Andalan Village, Bayan District, North Lombok Regency. The method used is an experimental method with field trials. The design used was Randomized Block Design (RBD), incorporating two factors: soil amendment treatment (P) as the main plot and PGPR (K) concentration treatments as the subplot. Soil amendments consisted of three levels: P0 (no cow manure and no goat manure), P1 (20 tons/ha cow manure), P2 (20 tons/ha goat manure). PGPR concentration consisted of four levels: K0 (without PGPR), K1 (20 ml/liter PGPR application), K2 (30 ml/liter PGPR application), and K3 (40 ml/liter PGPR application). The research results indicated that the application of 20 tons/ha of goat manure (P2) produced the highest average across all observed parameters (plant height, number of leaves, branch number, stem diameter, and plant yield). Similarly, the application of 40 ml/liter PGPR produced the highest average for these observed parameters. Based on the results of the land equivalent ratio (LER) analysis, this integration system shows highly suitable and relevant to be applied in the dry lands of North Lombok.

PGPR: Key to Enhancing Crop Productivity and Achieving Sustainable Agriculture.

Due to the burgeoning global population and the advancement of economies, coupled with human activities leading to the degradation of soil ecosystems and the depletion of non-renewable resources, concerns have arisen regarding food security and human survival. In order to address these adverse impacts, the spotlight has been cast upon plant growth-promoting rhizobacteria (PGPR), driven by a strong environmental consciousness. PGPR possesses the capability to foster plant growth and amplify crop yield through both direct and indirect mechanisms. By expediting plant growth, augmenting nutrient assimilation, heightening crop yield and caliber, and fortifying stress resilience, the application of PGPR can mitigate reliance on chemical fertilizers and pesticides while diminishing ecological perils. This exposition delves into the function of PGPR in modulating plant hormones, fostering nutrient solubilization, and fortifying plant resistance against biotic and abiotic stressors. This review offers valuable insights into the intricate interplay between PGPR and plants, elucidating uncertainties ripe for further investigation. Profound comprehension and judicious utilization of PGPR are indispensable for attaining sustainable agricultural progression, making substantial contributions to resolving the conundrums of global food security and environmental conservation.

Pseudomonas consortium improves soil health and alleviates cadmium (Cd) toxicity in Brassica juncea L. via biochemical and in silico approaches

The exponential rise in Cd in the environment has raised concerns for its adequate remediation worldwide. Its non-biodegradable nature and highly migratory feature make it more toxic. Plant growth-promoting rhizobacteria (PGPR) have shown great potential in the remediation of Cd-polluted agricultural lands. PGPR is comparatively efficient, convenient and economical. PGPR application enhances plant growth and development by conferring direct and indirect benefits. This study aimed to evaluate bacterial strains, Pseudomonas putida (Pp) and Pseudomonas fluorescens (Pf), for their PGPR traits, soil physiochemical analyses, and physiological and anatomical traits of B. juncea under Cd stress. Results showed that both microbial strains shared positive interaction and had minimum inhibitory concentration (MIC) ranging from 0.8mM and 0.6mM values for Pp and Pf respectively. P. fluorescens displayed better anti-phytopathogenic activity against pathogenic fungal strains (Alterneria brassicae, Alterneria brassicola, Verticillium longisporum, Fusarium oxysporum) than P. putida. They also synthesised plant growth regulators (PGRs) such as IAA (0.146,0.156μg/ml) and GA (2.062, 2.074 μg/ml). The co-inoculation of strains improved soil organic C, P, N, and K by 283.01 %, 100.42 %, 8.89 % and 40.38 %. Also, the interactive effect of Pp and Pf recovered dry matter content (DMC) by 18.13 % in comparison to Cd-stressed plants. Moreover, the strains reduced Cd-induced H2O2 production by DAB (340.38’-3’ diaminobenzidine) staining and hence restored membrane integrity. Also, in Cd-treated B. juncea plants, the anatomical characteristics were negatively affected. However, inoculated strains induce maximum recovery as indicated by well-developed vascular elements. Genes associated with PGPR traits were mined from the NCBI database. The information compiled thereafter indicated that the genes, galU, CadR, and pgl were responsible for biofilm formation, Cd resistance and lactone synthesis. In conclusion, we reported a promising consortium having PGPR traits, that improve soil and B. juncea health under Cd toxicities. Hence, the use of such bioinoculants can be a safer substitute for chemical fertilizers.

Plant growth promoting rhizobacteria (PGPR) application for coping with salinity and drought: a bibliometric network multi-analysis.

Rhizobacteria play a crucial role in plant growth and yield, stimulating primary production and improving stress resistance. Climate change has several consequences worldwide that affect arable land and agriculture. Studies on plant-soil-microorganism interactions to enhance plant productivity and/or resistance to abiotic stress may open new perspectives. This strategy aims to make agricultural-relevant plant species able to complete their biological cycle in extreme soils with the help of inoculated or primed plant growth-promoting rhizobacteria (PGPR). We provide an overview of the evolution of interest in PGPR research in the last 30 years through: (i) a quantitative search on the Scopus database; (ii) keyword frequencies and clustering analysis, and (iii) a keyword network and time-gradient analysis. The review of scientific literature on PGPR highlighted an increase in publications in the last 15 years, and a specific time gradient on subtopics, such as abiotic stresses. The rise in PGPR as a keyword co-occurring with salinity and drought stresses aligns with the growing number of papers from countries directly or partly affected by climate change. The study of PGPR, its features, and related applications will be a key challenge in the next decades, considering climate change effects on agriculture. The increased interest in PGPR leads to deeper knowledge focused specifically on researching agriculturally sustainable solutions for soils affected by salinity and drought.

Genetic and ecological inheritance of plant growth-promoting rhizobacteria

Abstract Background The utilization of beneficial (Rhizo) bacteria, as an alternative to traditional fertilizers, has emerged as an eco-friendly strategy for ameliorating sustainable agricultural production. This approach aims to reduce the use of agrochemicals and minimize environmental pollution. Scope This review provides an updated insight into the ecological impact of plant growth-promoting rhizobacteria (PGPR), focusing on the resident microbiome and its potential transferability to the next generation of plants. Conclusion In this context, PGPR are assumed to alter the rhizosphere microbiome by outcompeting the existing taxa through nutrient deprivation, acidification of the environment, metabolites production, and consequently, increasing the copiotrophic taxa. Such modifications can maximize the beneficial interactions of plant-PGPR by increasing the bioavailability of nutrients and handling diverse signaling pathways. The effects of interactions within the PGPR-root system can adjust the composition of root exudates and influence the release of bioactive molecules by the root, especially under stress conditions, which can act as signals to reactivate and recruit the beneficial microbes in the rhizosphere and endosphere in favor of the plants. Such changes in microbiome structure can occur gradually over time, even if the survival rate of PGPR in soil and their re-colonization efficiency inside plant tissue are limited. The aforementioned modifications in the rhizosphere and plant microbiome have the potential to increase the survival chances of the progeny plants growing under the same stress conditions. Establishing a comprehensive and robust knowledge framework that addresses all of these issues is critical for significantly advancing the field of microbe-plant interactions and for developing reliable applications of PGPR.

Effect of plant growth-promoting rhizobacteria (PGPR) on growth and yield of shallots on saline soils

Soil salinity is a limiting factor in agricultural productivity. One of the biological approaches to mitigate the impact of salt stress on plants is inoculating plant growth-promoting rhizobacteria (PGPR) to the plant roots. This study aimed to investigate the eff of PGPR dosage on the growth and yield of shallots at various salinity levels. This study was carried out in the experimental field of Poncokusumo, Malang. The treatments tested consisted of two factors. The first factor was soil salinity level, consisting of four levels: no salinity, NaCl 50 mM, NaCl 100 mM, and NaCl 150 mM. The second factor was PGPR concentration, consisting of four levels: no PGPR, PGPR 10 mL/L, PGPR 20 mL/L, and PGPR 30 mL/L. The sixteen treatment combinations were arranged in a randomized block design with three replications. The data obtained were subjected to the analysis of variance (ANOVA) at a significance level limit of 5%, followed by the Honestly Significant Difference (HSD) test at a 5% significance level for any significant differences. The results showed that the application of 30 mL/L of PGPR reduced EC of the soil and improved plant height, plant dry weight, leaf area, bulb diameter, bulb weight, and the number of bulbs per plant by 33%, 47.3%, 81%, 13%, 34.2%, 98.5%, and 31%, respectively, compared to the treatment without PGPR application under NaCl 150 mM salinity. The application of PGPR at 20 and 30 mL/L dosages significantly increased chlorophyll, flavonoid, and proline indices at NaCl at 100 mM and 150 mM salinity levels compared to the treatment without PGPR.

Improving Soil Quality and Yield of Intercropping-System Crops in a Dry Land Area through Plant Growth Promoting Rhizobacteria Application Frequency

The future of agriculture is prone to choose technology that can enhance the quality of the resources to support the sustainability of food production. Plant Growth Promoting Rhizobacteria (PGPR) is a reliable technology for future agriculture as it is environment-friendly, and able to optimize resource utilization and decrease external input. This research aimed to analyze the effect of PGPR (Pseudomonas fluorescens + Bacillus polymyxa) application frequency on chemical soil properties, a yield of an intercropping system in dry land, the in-between correlation of the parameters, and to determine the best PGPR application frequency. Randomized Complete Block Design (RCBD) was used in this research to put the treatment in the experimental unit properly. The treatments consisted of i) one-time application of PGPR at the planting time, ii) twice application of PGPR at the planting time and 15 Days After Planting (DAP), iii) three times application of PGPR at the planting time, 15 DAP and 30 DAP, iv) without application of PGPR as control. The results showed that PGPR application frequency improved chemical soil properties, yield, and total by-products as livestock feed. The activity of soil enzymes, nitrogenase, and phosphatase, was enhanced compared to the control. The application of PGPR in dryland areas is recommended to maintain soil fertility and support sustainable intercropping crop production. Further studies are needed to conduct mixed farming between agriculture, animal husbandry, clean energy (biogas), and organic fertilizer (residue from the biogas digester).

The use of combination plant growth promoting rhizobacteria to control chili leaf curl disease in the field

Plant growth-promoting rhizobacteria (PGPR) is a promising technology for controlling viral diseases, including pepper yellow leaf curl disease (PYLCD) of chili pepper caused by Begomovirus infection. The objectives of this research were to investigate the effectiveness of PGPR containing Pseudomonas fluorescens PF1 and Bacillus polymyxa BG25, as well as their combination with other protective agents, to control PYLCD under field conditions in an endemic region. The treatments consisted of a single application of PGPR (a mixture of P. fluorescens PF1 and B. polymyxa BG25), guano tea, endophytic fungus H5, and neem oil; combination of PGPR with guano tea, endophytic fungus H5, and neem oil; conventional pesticide that relies on synthetic chemical insecticide sprayed weekly; and untreated plots. The experiment was arranged in a randomized block design with four replications. Treatment with PGPR alone was able to delay disease onset by 2.25 weeks, but it caused only a slight reduction in disease incidence. The combination of PGPR + guano tea and PGPR + endophyte H5 provided the best results in controlling PYLCD. The combination of PGPR + guano tea and PGPR + endophyte H5 delayed disease onset by 2.75 weeks and 3.25 weeks, respectively, and reduced disease incidence with effectiveness rates of 52.72% and 52.08%, respectively. These two treatment combinations gave the best performance for plant growth and yield.

Plant Growth-Promoting Rhizobacteria: A Promising Strategy To Optimize The Development Of Schizolobium Parahyba

Objective: To investigate the efficacy of plant growth-promoting rhizobacteria (PGPR) in enhancing the early development stages of Schizolobium parahyba, a critical species for the timber industry, aiming to optimize reforestation and agroforestry practices for sustainable forestry. Theoretical Framework: The research is grounded in the exploration of symbiotic relationships between PGPR strains and plant species, focusing on their potential to improve seed germination, plant growth, and biomass production. The study examines how these interactions can be leveraged to enhance agricultural productivity and sustainability, with a specific emphasis on the benefits of employing PGPR in forestry. Method: The study utilized an experimental approach, assessing the impact of four PGPR strains (Serratia marcescens, Pseudomonas protegens, Enterobacter absuriae, and Acinetobacter calcoaceticus) on S. parahyba seedlings. These were cultivated in three different substrates, with variables such as germination rate, above-ground and root growth, and biomass production meticulously measured to evaluate the effects of bacterial inoculation. Results and Conclusions: The application of PGPR notably improved all measured growth parameters in S. parahyba seedlings, with A. calcoaceticus and P. protegens specifically enhancing stem and root development, respectively. A synergistic effect was observed in substrates containing peat, underscoring the significant potential of PGPR in boosting the productivity and sustainability of early-stage forestry cultivation. The findings advocate for further field studies to fine-tune these interactions, aiming to establish more resilient and ecologically sustainable agricultural practices. Originality/Value: This research contributes novel insights into the utilization of PGPR in forestry, highlighting its substantial promise in enhancing the early growth stages of Schizolobium parahyba. By demonstrating the specific benefits of PGPR strains and their interactions with different substrates, the study offers a promising strategy for improving the sustainability and productivity of reforestation and agroforestry efforts.

Application of Plant Growth Promoting Rhizobacteria on Vegetative Growth in Chili Plants (Capsicum frutescens L.)

Cayenne pepper is a significant plant in tropical regions, utilized not only as a culinary spice but also in the pharmaceutical industry. An effective strategy for enhancing the physical, chemical, and biological quality of soil is the employment of plant growth-promoting rhizobacteria (PGPR). PGPR, a soil microorganism that colonizes plant roots, can accelerate growth and protect against certain pathogens. The use of PGPR, particularly in biocontrol of plant pathogens and biofertilization, is prevalent across various global regions. This study evaluates the effectiveness of PGPR in boosting the growth of cayenne pepper and was conducted in Peresak Village, Narmada District, West Lombok Regency, NTB Province. The methodology implemented was a Completely Randomized Design (CRD) experiment with five treatments and five replications, totaling 25 plant units. The treatments included a control (P0 ml/L) and four PGPR concentrations: P1 (10 ml/L), P2 (20 ml/L), P3 (30 ml/L), and P4 (40 ml/L). Each PGPR dose was dissolved in 1 liter of water and administered at 200 ml per polybag. The findings indicated that PGPR application significantly impacted the growth of cayenne pepper plants, notably increasing plant height, leaf count, branch count, and flower count. The 30 ml/L PGPR concentration (P3) proved most effective in enhancing these growth parameters. The results underscore the substantial benefits of incorporating PGPR as a biofertilizer agent in agricultural practices to optimize crop yields.

Restoration of fumigated soil biota with plant growth-promoting rhizobacteria to counteract Meloidogyne incognita (Tylenchida: Heteroderidae) boosts eggplant growth and defenses

This study investigated the effectiveness of two plant growth-promoting rhizobacteria (PGPR) formulations, Bio Arc® 6% WP (BA, Bacillus megaterium) and BECTO Grow Roots® (BGR; Serratia marcescens, Pseudomonas putida, and P. fluorescens). Additionally, it focused on naturally infested soil that had undergone metam potassium fumigation to reduce root-knot nematode (RKN), specifically Meloidogyne incognita. It aimed to monitor eggplant response to soil biodiversity changes for 60 days of the experiment under greenhouse conditions. Our data showed that soil fumigation eliminated nematodes and reduced other microorganisms significantly. In sterilized soil, plant fresh root weight significantly decreased after the elimination of soil biota. Moreover, BGR achieved the highest plant growth vigor [fresh root (18.48%), fresh shoot (23.52%), and fresh plant weight (21.03%)], followed by BA [fresh root (11.98%), fresh shoot (20.77%), and fresh plant weight (16.38%), respectively]. Plant growth traits increased significantly following the second reinoculation of PGPR after a month. Also, the same data trend was observed in treatments inoculated with RKN + PGPR. Furthermore, BGR treatments exhibited consistent efficacy in controlling nematode infection, maintaining superior vegetative growth compared to BA treatments over time. However, BA treatments displayed a decline in plant growth when faced with repeated nematode infection. The range of gall, egg mass, and second-stage juvenile (J2s) numbers diminished after inoculation-infected plants with RKN and PGPR compared with infected plants alone. Biochemical changes in eggplant roots cultivated in sterilized soil exposed significant enhancement in total sugars, protein, and nonenzymatic antioxidants (flavonoids and phenolic content), with antioxidant activity enhanced upon inoculation of PGPR and RKN. Oppositely, the levels of enzymatic antioxidants (catalase, peroxidase, and superoxide dismutase) decreased significantly with single and double PGPR application. However, the decline was less pronounced in the BGR treatments than in BA. In contradiction of oxidative enzymes, reinoculated PGPR + RKN multiplied significantly in reinfested RKN treatments. Our findings support the use of PGPR combinations, in particular, for preventive inoculation against M. incognita. They also enhance plant growth-promoting factors and stimulate plant defenses against inevitable soil reinfestation following soil fumigation.

Real-Time PCR (qtPCR) to Discover the Fate of Plant Growth-Promoting Rhizobacteria (PGPR) in Agricultural Soils.

To optimize the application of plant growth-promoting rhizobacteria (PGPR) in field trials, tracking methods are needed to assess their shelf life and to determine the elements affecting their effectiveness and their interactions with plants and native soil microbiota. This work developed a real-time PCR (qtPCR) method which traces and quantifies bacteria when added as microbial consortia, including five PGPR species: Burkholderia ambifaria, Bacillus amyloliquefaciens, Azotobacter chroococcum, Pseudomonas fluorescens, and Rahnella aquatilis. Through a literature search and in silico sequence analyses, a set of primer pairs which selectively tag three bacterial species (B. ambifaria, B. amyloliquefaciens and R. aquatilis) was retrieved. The primers were used to trace these microbial species in a field trial in which the consortium was tested as a biostimulant on two wheat varieties, in combination with biochar and the mycorrhizal fungus Rhizophagus intraradices. The qtPCR assay demonstrated that the targeted bacteria had colonized and grown into the soil, reaching a maximum of growth between 15 and 20 days after inoculum. The results also showed biochar had a positive effect on PGPR growth. In conclusion, qtPCR was once more an effective method to trace the fate of supplied bacterial species in the consortium when used as a cargo system for their delivery.

Combined control of plant diseases by Bacillus subtilis SL44 and Enterobacter hormaechei Wu15

Co-incubation of plant growth promoting rhizobacteria (PGPRs) have been proposed as a potential alternative to pesticides for controlling fungal pathogens in crops, but their synergism mechanisms are not yet fully understood. In this study, combined use of Bacillus subtilis SL44 and Enterobacter hormaechei Wu15 could decrease the density of Colletotrichum gloeosporioides and Rhizoctonia solani and enhance the growth of beneficial bacteria on the mycelial surface, thereby mitigating disease severity. Meanwhile, PGPR application led to a reorganization of the rhizosphere microbial community through modulating its metabolites, such as extracellular polymeric substances and chitinase. These metabolites demonstrated positive effects on attracting and enhancing conventional periphery bacteria, inhibiting fungal pathogens and promoting soil health effectively. The improvement in the microbial community structure altered the trophic mode of soil fungal communities, effectively decreasing the proportion of saprotrophic soil and reducing fungal plant diseases. Certain combinations of PGPR have the potential to serve as precise instruments for managing plant pathogens.

Synergy of plant growth promoting rhizobacteria and silicon in regulation of AgNPs induced stress of rice seedlings

Silver Nanoparticles (AgNPs), as an emerging pollutant, have been receiving significant attention as they deepen the concern regarding the issue of food security. Silicon (Si) and plant growth-promoting rhizobacteria (PGPR) are likely to serve as a sustainable approach to ameliorating abiotic stress and improving plant growth through various mechanisms. The present study aims to evaluate the synergistic effect of Si and PGPRs on growth, physiological, and molecular response in rice seedlings (Oryza sativa) under AgNPs stress. Data suggested that under AgNPs exposure, the root and shoot growth, photosynthetic pigments, antioxidant enzymes (CAT and APX), expression of antioxidant genes (OsAPX and OsGR), silicon transporter (OsLsi2), and auxin hormone-related genes (OsPIN10 and OsYUCCA1) were significantly decreased which accompanied with the overproduction of reactive oxygen species (ROS), nitric oxide (NO) and might be due to higher accumulation of Ag in plant cells. Interestingly, the addition of Si along with the AgNPs enhances the level of ROS generation, thus oxidative stress, which causes severe damage in all the above-tested parameters. On the other hand, application of PGPR alone and along with Si reduced the toxic effect of AgNPs through the improvement of growth, biochemical, and gene regulation (OsAPX and OsGR, OsPIN10 and OsYUCCA1). However, the addition of L-NAME along with PGPR and silicon drastically lowered the AgNPs induced toxicity through lowering the oxidative stress and maintained the overall growth of rice seedlings, which suggests the role of endogenous NO in Si and PGPRs mediated management of AgNPs toxicity in rice seedlings.

The Coupling Effects of PGPR Inoculation and Foliar Spraying of Strigolactone in Mitigating the Negative Effect of Salt Stress in Wheat Plants: Insights from Phytochemical, Growth, and Yield Attributes

Salt stress has detrimental effects on wheat plants at several physiological, biochemical, and molecular levels. This stress leads to suppressed growth, reduced grain yield, and poor quality of harvested grains. However, two approaches have shown promise for improving wheat salt tolerance: using a synthetic strigolactone analog called GR24 and applying plant growth-promoting rhizobacteria (PGPR). GR24 plays a vital role in regulating plant growth and development and in defense against various stresses. Conversely, PGPR are beneficial bacteria that colonize the rhizosphere of plants and promote their growth through multiple mechanisms. In our study, we investigated the effects of salinity on the growth and yield traits of two different wheat cultivars and explored the combined role of PGPR and GR24 in mitigating the impact of salt stress. We created three different salinity levels using NaCl in pots (original, 5 dS m−1, and 10 dS m−1) and inoculated wheat seeds with a salt-tolerant Bacillus velezensis UTB96 strain. In addition, we applied 10 μM GR24 via foliar application during the pollination stage. Our observations showed that salt stress negatively affected wheat’s growth, yield, and phytochemical properties compared to the control. However, both single and combined applications of PGPR and GR24 mitigated the adverse effects of salinity. The combined treatment had a more substantial impact than either alone in inducing and improving biochemical and ionic characteristics. These included decreasing Na+ content in both leaves and roots, and EL, H2O2, and MDA content in leaves while increasing K+ content in both leaves and roots, growth and yield-related traits, RWC, chlorophyll pigments, total protein, soluble sugar, starch, proline, GB, and antioxidant enzyme activity (APX, POX, and CAT) of leaves. In conclusion, integrating PGPR and GR24 can efficiently induce salt tolerance and improve plant growth under stressed conditions. This combined approach has the potential for broad applicability in supporting plant growth in the presence of salt stress.

NanoBiofertilizer and its Application in Sustainable Agriculture, Crop Specific Nutrients Delivery and Environmental Sustainability: A Review

Probiotic bacteria are increasingly in demand in the food and feed industries. A growing population and finite resources require efficient ways to maximize yields. Probiotic bacteria are gaining popularity in the food and feed industries due to their unique combination of benefits and values, which include consumer health interests, sustainability values, food innovation, and potential business opportunities. The use of conventional fertilizers can increase crop production but can also cause runoff and toxicity issues. A nanobiofertilizer offers improved crop nutrition and reduces application rates. Slow-release properties minimize environmental losses while nanoscale particle size enhances nutrient absorption. If nanobiofertilizers are closely regulated, they can boost yields without destroying the soil and aquatic ecosystems. In recent years, nanobiofertilizers have received considerable attention. Plant extracts and microbes are used in green synthesis to produce eco-friendly nanoparticles. Crop-specific nutrient release can be tailored using modified nanoparticle surfaces. Controlled nutrient delivery is achieved by smart nanocarrier systems that adapt to changing soil moisture, pH, and microbial activity. Combined applications of plant growth-promoting rhizobacteria have been reported that they can enhance crop growth in synergy. This review presents an overview of the most recent studies on nanobiofertilizers, as well as the issues connected with their environmental implications, safety, and regulation, presenting a roadmap for the responsible use of nanobiofertilizers, which aims to enhance food security while protecting the environment for future generations.

Plant growth-promoting rhizobacteria (PGPR) improve the growth and quality of several crops

Plant growth-promoting rhizobacteria (PGPR) are known to have the effect of promoting plant growth. In this paper, three PGPR strains were selected from the previous work, which had plant growth-promoting activities such as phosphate solubilization, nitrogen fixation, phosphorus mobilization, etc. These strains named FJS-3(Burkholderia pyromania), FJS-7(Pseudomonas rhodesiae), and FJS-16(Pseudomonas baetica), respectively, were prepared into solid biological agents. Three widely planted commercial crops (tea plant, tobacco, and chili pepper) were selected for PGPR growth promotion verification. The results showed that the new shoots of tea seedlings under PGPR treatment were much more than the control. We also used tobacco, another important crop in Guizhou, to test the growth-promoting effect of individual bacteria, and the results showed that each of them could promote the growth of tobacco plants, and FJS-3(Burkholderia pyrrocinia) had the best effect. In addition, we carried out experiments on tobacco and pepper using multi-strain PGPR, the tobacco plants' height, fresh, and root weight increased by 30.15 %, 37.36 %, and 54.5 %, respectively, and the pepper plants' increased by 30.10 %, 56.38 % and 43.18 %, respectively, which both showed significantly better effects than that of a single strain. To further test the field performance, field trials were carried out in a mature Longjing43 tea plantation in Guizhou. There were four treatments: no fertilization (T1), combined application of PGPR biological agent and compound fertilizer (T2), only application of PGPR (T3), and only application of compound fertilizer (T4). In terms of yield, grouped with or without PGPR, there was a 15.38 % (T2:T4) and 92.31 % (T3:T1) increase between them, respectively. The tea's yield and tea flavor substances such as tea polyphenols, caffeine, and theanine were detected, and the T2 showed the most significant positive effect on both sides. Especially, an important indicator of Matcha green tea is the color, chlorophyll content was then tested, and PGPR application increased it and improved the appearance. All these results demonstrated that the PGPR we screened could significantly promote plant growth and quality improvement, and had good application potential in crop planting, which could contribute to environmental protection and economic growth.

The Effectiveness of Plant Growth Promoting Rhizobacteria (PGPR) on the Growth of Root Nodules of Peanut Genotypes under Water Deficit Condition

The deficiency of water sources and soil fertility are obstacles to producing peanuts in dry land. One of effort to increase production on dry land is the utilization of PGPR biofertilizers. This study aimed to determine the growth of plants and root nodules of several peanut genotypes applied with PGPR, to understand the interaction between several peanut genotypes and PGPR on plant growth and root nodules, and to examine the relationship between water deficit conditions and the formation of root nodules. This experiment used a Complete Randomized Design-split split-plot design with the main plots being D0 = optimal conditions (no water deficit) and D1 = water deficit. The subplots were P0 = no PGPR and P1 = with PGPR. The sub-subplots consisted of five peanut genotypes: V1 = Hypoma-I, V2 = Domba, V3 = Talam, V4 = Bison, and V5 = G300-II. The observations showed that the addition of PGPR resulted in higher plant growth compared to those without PGPR and had more effective root nodules in nitrogen fixation compared to treatments without PGPR. The application of PGPR and genotype did not show significant interaction on plant growth and root nodules under water deficit conditions. Water deficit significantly affected all parameters of plant growth and root nodules. PGPR significantly affected the parameters of leaf number rate, nodule number, and nodule weight. Genotype significantly affected the plant height rate. The interaction of water deficit and genotype significantly affected the leaf number rate, while the interaction of water deficit and PGPR, and the interaction of PGPR and genotype did not significantly affect all observation parameters.