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Keywords = plant-growth-promoting rhizobacteria

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22 pages, 680 KB  
Review
The Rhizosphere Microbiome: A Key Mediator of Crop Responses to Fertilization Strategies
by Zhihui Zhao, Qihua Wu, Zerong Sun, Wenling Zhou and Junhua Ao
Plants 2026, 15(17), 2711; https://doi.org/10.3390/plants15172711 - 3 Sep 2026
Viewed by 135
Abstract
The rhizosphere microbiome, the plant’s “second genome” is pivotal for crop nutrient acquisition, health, and stress responses. While fertilization ensures high agricultural yields, a key challenge is reshaping this microbiome to boost crop performance. This review synthesizes how mineral, organic, and bio-organic/microbial inoculant [...] Read more.
The rhizosphere microbiome, the plant’s “second genome” is pivotal for crop nutrient acquisition, health, and stress responses. While fertilization ensures high agricultural yields, a key challenge is reshaping this microbiome to boost crop performance. This review synthesizes how mineral, organic, and bio-organic/microbial inoculant fertilizers affect rhizosphere microbial structure, diversity, and function. Long-term excessive mineral fertilizers (especially nitrogen) reduce microbial diversity, diminish beneficial groups (e.g., diazotrophs, PGPR), and disrupt microbial networks via soil acidification and altered root exudates, causing continuous cropping obstacles. In contrast, organic fertilizers improve soil microenvironments, maintaining high microbial diversity, enriching beneficial taxa (e.g., Proteobacteria, Actinobacteria), and enhancing community complexity. Bio-organic fertilizers/microbial inoculants “engineer” the microbiome by introducing exogenous beneficial microbes (e.g., Bacillus, Pseudomonas, AMF), directly promoting growth, suppressing diseases, and “reconditioning” indigenous beneficial communities. We also clarify how fertilization regulates plant-microbe dialog via root exudates and rhizosphere chemistry (e.g., pH, ion balance), discuss current challenges (causality, lab-to-field translation, genotype-microbiome-fertilization interactions), and outline future directions. Integrating rhizosphere microbiome management into fertilization is crucial for reducing chemical fertilizer reliance and advancing agricultural green transformation. Full article
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26 pages, 37305 KB  
Article
Potassium Humate and Bacillus aryabhattai Modulate Osmotic and Oxidative Homeostasis and Promote Cowpea Yield Under Drought
by Eulália Margarethe da Costa Melo, Agda Malany Forte de Oliveira, Semako Ibrahim Bonou, Priscylla Marques de Oliveira Viana, Igor Eneas Cavalcante, Guilherme Félix Dias, Ana Clara da Silva Dantas, Túlio William da Silva Gonçalves, Emmanuelly Silva Dias de Farias, Jessica Agra Guimarães, Liziane Maria de Lima and Alberto Soares de Melo
Plants 2026, 15(17), 2629; https://doi.org/10.3390/plants15172629 - 28 Aug 2026
Viewed by 290
Abstract
Global climate change has intensified prolonged droughts, making the development of sustainable agricultural technologies essential. Although potassium humate (KH) and Bacillus aryabhattai (BA) are recognized individually as effective biostimulants, their joint application represents an innovative, unexplored complementary strategy to mitigate drought stress in [...] Read more.
Global climate change has intensified prolonged droughts, making the development of sustainable agricultural technologies essential. Although potassium humate (KH) and Bacillus aryabhattai (BA) are recognized individually as effective biostimulants, their joint application represents an innovative, unexplored complementary strategy to mitigate drought stress in cowpea (Vigna unguiculata L. Walp.). This study aimed to evaluate the effects of these bio-inputs on mitigating water stress in the cowpea (Vigna unguiculata L. Walp.) cultivar ‘BRS Verdejante’. The experiment was conducted under greenhouse conditions using a completely randomized design in a 2 × 8 factorial arrangement, with two water regimes (100% and 50% crop evapotranspiration—ETc) and eight biostimulant combinations of KH and BA. While BA alone (T4) intensified osmotic adjustment via proline accumulation and APX activation, the combined treatment T5 (10 mg kg−1 soil KH + 4 mL kg−1 seed BA containing 1 × 108 CFU mL−1) achieved the best overall performance under drought (50% ETc). T5 effectively enhanced superoxide dismutase activity, preserved leaf relative water content, and reduced cell membrane electrolyte leakage by 42.6% compared to untreated stressed plants. These physiological adaptations protected reproductive organs, resulting in a 51.6% increase in pod number per plant under drought. The strategic co-application of low-dose potassium humate (10 mg kg−1 soil) and B. aryabhattai (4 mL kg−1 seed) effectively regulates osmotic and oxidative homeostasis, maintaining pod formation (+51.6%) and securing cowpea grain yield per plant under drought stress, thus serving as a promising strategy to mitigate drought stress in cowpea under controlled greenhouse conditions. Full article
(This article belongs to the Section Plant Response to Abiotic Stress and Climate Change)
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25 pages, 7847 KB  
Article
Relevant Probiotic and Functional Properties of Lactic Acid Bacteria Isolated from Aquaculture Environments on the Ivory Coast for Potential Aquaponic Applications
by Wahauwouélé Hermann Coulibaly, Tano Marie-Ange Sakia Mian, Yabo Majoie Géroxie Tohoyessou, Muiz O. Akinyemi, Bassey Ebenso, Ange Olivier Parfait Yao, Cécile Meex, Paul-Alexandru Popescu, Thierry Fievez, Phillipe Maesen and Hary Razafindralambo
Microorganisms 2026, 14(9), 1906; https://doi.org/10.3390/microorganisms14091906 - 28 Aug 2026
Viewed by 261
Abstract
Aquaponics combines aquaculture and hydroponics, offering an integrated and sustainable food production system. This study investigated the probiotic properties, plant growth-promoting (PGP) activity, and nitrifying capacity of twelve lactic acid bacteria (LAB) strains isolated from an aquaculture farm environment on the Ivory Coast [...] Read more.
Aquaponics combines aquaculture and hydroponics, offering an integrated and sustainable food production system. This study investigated the probiotic properties, plant growth-promoting (PGP) activity, and nitrifying capacity of twelve lactic acid bacteria (LAB) strains isolated from an aquaculture farm environment on the Ivory Coast for their potential application in aquaponic systems. All isolates demonstrated antagonistic activity against key pathogenic indicator strains, except Vibrio cholerae, and displayed varying levels of surface hydrophobicity (5.50 ± 0.70% to 22.83 ± 1.17%) and auto-aggregation (32.50 ± 0.08% to 52.89 ± 0.39%) after 24 h. Antioxidant activity was significantly higher in cell-free supernatants (~71–79%) than in intact cells (~30–33%). Bile salt tolerance (0.3%, 4 h) ranged from 2.13 ± 0.76% to 40.87 ± 2.12%, and survival under pH 1.5 with pepsin for 3 h varied from 4.84 ± 0.26% to 53.98 ± 13.28%. All isolates produced lactic, acetic, citric, malic, and propionic acid and exhibited amylase and cellulase activity; none showed hemolytic activity. Only LAB 11 produced indole-3-acetic acid (17.72 ± 0.06 μg/mL), siderophores, and phosphate-solubilization activity for PGP traits, and this group significantly enhanced maize seed germination (86.66 ± 5.77%) and radicle length (7.00 ± 0.52 mm) compared to the control (63.33 ± 32.14% and 4.94 ± 1.52 mm), respectively. LAB 1 and LAB 10 demonstrated the highest ammonia-oxidizing capacity in vitro and in trout pond water. LAB 1, LAB 10, and LAB 11 were confirmed by whole genome sequencing analysis to be Enterococcus faecalis strains with a favorable-safety genomic profile and probiotic characteristics. These three strains therefore represent promising candidates for consortium-based applications in aquaponics systems. Full article
(This article belongs to the Section Plant Microbe Interactions)
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37 pages, 2195 KB  
Review
Functional Roles of Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Rhizobacteria in Pistachio: Implications for Stress Tolerance, Nutrient Acquisition and Disease Suppression
by Luis Vera, Jorge Retamal-Salgado, Gonzalo Tortella, Gustavo Santoyo and Mauricio Schoebitz
Plants 2026, 15(17), 2575; https://doi.org/10.3390/plants15172575 - 24 Aug 2026
Viewed by 317
Abstract
Pistachio (Pistacia vera L.) is among the most economically important nut crops worldwide. They are increasingly exposed to the environmental constraints associated with climate change, including drought, salinity, nutritional imbalances, and heightened disease pressure. These stressors compromise plant growth, physiological performance, nutrient [...] Read more.
Pistachio (Pistacia vera L.) is among the most economically important nut crops worldwide. They are increasingly exposed to the environmental constraints associated with climate change, including drought, salinity, nutritional imbalances, and heightened disease pressure. These stressors compromise plant growth, physiological performance, nutrient acquisition, and orchard productivity, highlighting the need for sustainable strategies to enhance crop resilience. This review critically examines the current knowledge on the functional roles of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) in pistachio production. Evidence indicates that AMF and PGPR contribute to plant performance through multiple complementary mechanisms, including improved nutrient mobilization and uptake, maintenance of ionic homeostasis, enhancement of water-use efficiency, stimulation of antioxidant defenses, modulation of stress-related signaling pathways, and suppression of phytopathogens. AMF primarily enhance phosphorus acquisition, water relations, and soil structural stability, whereas PGPR contribute to nutrient solubilization, biological control, and induction of plant defense responses. Despite promising experimental results, most studies have been conducted under controlled conditions, limiting the translation of microbial inoculation strategies to commercial orchards in the field. We identified the key knowledge gaps and research priorities required to improve the consistency, scalability, and field validation of microbiome-based approaches for sustainable pistachio production under increasingly challenging environmental conditions. Full article
(This article belongs to the Special Issue Microorganisms for Improving Plant Resilience and Soil Health)
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17 pages, 1413 KB  
Article
Optimization and Validation of a Multitrait Physiological Drought Mitigation Index (PDMI) for Screening PGPR-Induced Drought Tolerance in Strawberry
by Tymoteusz Miller, Grzegorz Mikiciuk, Małgorzata Mikiciuk, Anna Kisiel and Dominika Paliwoda
Agronomy 2026, 16(17), 1623; https://doi.org/10.3390/agronomy16171623 - 24 Aug 2026
Viewed by 167
Abstract
Drought mitigation by plant growth-promoting rhizobacteria (PGPR) is commonly assessed using individual physiological traits, although plant responses to water deficit are intrinsically multivariate. We developed a Multitrait Physiological Drought Mitigation Index (PDMI) to summarize PGPR-specific physiological responses in strawberry (Fragaria × ananassa [...] Read more.
Drought mitigation by plant growth-promoting rhizobacteria (PGPR) is commonly assessed using individual physiological traits, although plant responses to water deficit are intrinsically multivariate. We developed a Multitrait Physiological Drought Mitigation Index (PDMI) to summarize PGPR-specific physiological responses in strawberry (Fragaria × ananassa) while separating drought-specific effects from general performance under optimal moisture. The balanced two-season experiment comprised 240 plant-level observations and 10 complete matched replication sets per season. The primary PGPR analysis excluded the non-bacterial magnesium-sulfate comparator (CMg) and included four PGPR strains, the uninoculated control, 200 plant-level observations, and 80 replication-level difference-in-differences (DiD) profiles. Nine nonredundant physiological traits were direction-aligned and standardized using the 2021 development season and aggregated with equal weights; all parameters were then applied unchanged to the 2022 holdout season. Block-adjusted MANOVA confirmed a joint inoculation variant × moisture interaction (Pillai’s trace = 0.533, F(36,664) = 2.835, p < 0.001). Block-restricted PERMANOVA detected a small multivariate strain effect (pseudo-F = 0.995, R2 = 0.0378, p = 0.0289), whereas PERMDISP was nonsignificant (p = 0.273). In 2021, DLGB 2 obtained the highest PDMI (0.160) and had a 66.3% bootstrap probability of rank 1 and an 88.3% probability of inclusion in the top two. In the 2022 holdout, AJ 1.2 ranked first; cross-season rank agreement was positive but uncertain (Spearman’s ρ = 0.60, p = 0.40). The best individual trait, water-use efficiency, showed greater within-season rank stability than PDMI (P(rank 1) = 0.998), demonstrating that the composite did not universally outperform single measurements. PDMI was not significantly associated with holdout yield mitigation (R2 = 0.0458; block-clustered p = 0.127; within-block permutation p = 0.341). PDMI should, therefore, be interpreted as a transparent integrative descriptor of coordinated physiological response rather than a definitive classifier, a universally superior screening metric, or a standalone yield predictor. Full article
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20 pages, 684 KB  
Article
Metabolic and Morphological Reprogramming in Ocimum basilicum L. Inoculated with a Beneficial Synthetic Community
by Renée Abou Jaoudé, Anna Grazia Ficca and Maurizio Ruzzi
Horticulturae 2026, 12(8), 1047; https://doi.org/10.3390/horticulturae12081047 - 21 Aug 2026
Viewed by 324
Abstract
Sweet basil (Ocimum basilicum L.) is a popular aromatic and medicinal crop cultivated globally. While its essential oils possess inherent antimicrobial properties, the plant remains highly susceptible to various pathogens. This study investigated the impact of a beneficial synthetic microbial community (SynCom)—composed [...] Read more.
Sweet basil (Ocimum basilicum L.) is a popular aromatic and medicinal crop cultivated globally. While its essential oils possess inherent antimicrobial properties, the plant remains highly susceptible to various pathogens. This study investigated the impact of a beneficial synthetic microbial community (SynCom)—composed of eight strains with proven antimicrobial and plant growth-promoting activities—on basil growth, ecophysiology, and metabolic profile in an aeroponic system. Although SynCom inoculation significantly enhanced photochemical efficiency, it did not yield significant gains in total biomass. Instead, inoculated plants exhibited a strategic reallocation of resources toward structural and chemical defenses. This physiological shift was physically manifested as denser plant canopies and lower specific leaf area (SLA). Untargeted metabolomic profiling identified 167 significantly altered metabolites. Notably, SynCom inoculation increased abscisic acid (ABA) turnover and redirected tryptophan metabolism from growth-promoting auxins to defense-related indoles and kynurenine derivatives. Furthermore, inoculation enriched the leaves with essential amino acids and a diverse array of protective secondary metabolites, including phenylpropanoids, flavonoids, and terpenoids. These findings demonstrate that specialized microbial inoculants can induce a transition toward fortified phenotypes and likely enhance plant resilience, even in the absence of traditional biomass gains. Full article
(This article belongs to the Special Issue Horticultural Plant Disease Management Using Advanced Biotechnology)
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18 pages, 1700 KB  
Review
Rhizobacteria-Mediated Reprogramming of Phytohormone Landscapes for Mitigating Salinity Stress in Plants
by Arghyadeepa Moharana, Lochan Dhruw, Armita Chakraborty, Preeti Pashwan, Sanjida Sultana Keya, Md. Mezanur Rahman, Archita Singh, Mamta Bhardwaj, Lam-Son Phan Tran and Aarti Gupta
Int. J. Mol. Sci. 2026, 27(16), 7494; https://doi.org/10.3390/ijms27167494 - 21 Aug 2026
Viewed by 373
Abstract
Salinity stress is one of the major stressors that limits yield potential in field crops. Salinity-led imbalances in ionic and water potential, as well as oxidative damage, impair photosynthesis. Plant-growth-promoting rhizobacteria (PGPRs) have been demonstrated to mitigate salinity-stress-induced damage through various mechanisms such [...] Read more.
Salinity stress is one of the major stressors that limits yield potential in field crops. Salinity-led imbalances in ionic and water potential, as well as oxidative damage, impair photosynthesis. Plant-growth-promoting rhizobacteria (PGPRs) have been demonstrated to mitigate salinity-stress-induced damage through various mechanisms such as biofilm and exopolysaccharide production, modulation of plant root architecture or molecular signaling involving modulation of sodium/potassium efflux transporters. PGPRs are known to induce biosynthesis and signaling of various phytohormones in plants. PGPR-derived phytohormones can in turn regulate molecular signaling involved in maintaining ion fluxes, preventing salinity-induced senescence, and reinforcing plant root architecture, thereby maintaining plant growth and development under saline conditions. In this review, we provide comprehensive advances on how PGPRs modulate and integrate biosynthesis and/or signaling of various phytohormones, such as auxins, cytokinins, gibberellin, ethylene, abscisic acid, salicylic acid, jasmonates, brassinosteroids and strigolactones, to reshape plant architecture, physiological and biochemical responses in plants under salinity. We integrate molecular evidence with morpho-physiological studies and propose a phytohormone-centric framework to select strains that optimize growth, ion homeostasis and plant stress resilience under salinity. Full article
(This article belongs to the Special Issue Plant Stress Biology)
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26 pages, 5450 KB  
Review
Microbial Biostimulants as Powerful Catalysts for Next-Generation Integrated Pest Management in Botanical Gardens
by Ayaz Ahmad, Mian Muhammad Ahmed, Muhammad Saud Khan, Syeda Maira Hamid, Muqaddas, Muhammad Shahbaz Gul, Sumbal Ayaz, Muzmil Iqbal, Muhammad Asim, Muhammad Masood Nabi, Shuihong Chen and Muhammad Bilal Khan
J. Zool. Bot. Gard. 2026, 7(3), 33; https://doi.org/10.3390/jzbg7030033 - 19 Aug 2026
Viewed by 370
Abstract
Botanical gardens are highly heterogeneous plant systems characterized by high taxonomic diversity, with numerous plant taxa represented within confined areas, and complex ecological interactions that create unique challenges for pest management. Conventional IPM strategies, designed for simplified agroecosystems, often fail to address complex [...] Read more.
Botanical gardens are highly heterogeneous plant systems characterized by high taxonomic diversity, with numerous plant taxa represented within confined areas, and complex ecological interactions that create unique challenges for pest management. Conventional IPM strategies, designed for simplified agroecosystems, often fail to address complex pest pressures in curated environments. Microbial biostimulants have emerged as promising components of sustainable IPM strategies by enhancing plant defense responses, improving stress resilience, and reducing reliance on chemical inputs. This review synthesizes current knowledge on microbial biostimulants, including plant growth-promoting rhizobacteria, arbuscular mycorrhizal fungi and endophytic microorganisms, in modulating plant defense against insect herbivores. These beneficial microbes enhance plant resistance through multiple mechanisms. They activate induced systemic resistance and modulate key phytohormones, including jasmonic acid, salicylic acid, and ethylene. Additionally, they regulate calcium-dependent and reactive oxygen species-mediated defenses. Microbially induced changes in plant secondary metabolites and volatile organic compounds further influence herbivore behavior and trophic interactions. Emphasis is placed on integrating microbial biostimulants into IPM frameworks tailored to botanical gardens. This highlights compatibility with biological control agents and reduced reliance on synthetic pesticides. Despite promising advances, challenges remain, including context-dependent efficacy, host specificity and limited long-term validation. Overall, microbial biostimulants offer a promising tool for enhancing IPM in biodiversity-rich botanical gardens, although further long-term validation is needed to fully assess their sustainability and effectiveness. Full article
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18 pages, 9661 KB  
Article
Rhizosphere Engineering Using a Native Pseudomonas veronii Improves Soil Functioning in Degraded Calcisol
by Gani Kalymbetov, Bakhytzhan Kedelbayev, Nortoji Khujamshukurov and Sagadat Turebayeva
Agriculture 2026, 16(16), 1774; https://doi.org/10.3390/agriculture16161774 - 19 Aug 2026
Viewed by 331
Abstract
The degradation of Calcisols in the arid regions of Central Asia constrains sustainable agricultural production because of low organic matter content, poor aggregate stability, nutrient limitations, and increasing climatic stress. This study evaluated a rhizosphere engineering approach based on the native plant growth-promoting [...] Read more.
The degradation of Calcisols in the arid regions of Central Asia constrains sustainable agricultural production because of low organic matter content, poor aggregate stability, nutrient limitations, and increasing climatic stress. This study evaluated a rhizosphere engineering approach based on the native plant growth-promoting bacterium Pseudomonas veronii Ps-S/Sh-1503/2022 for the rehabilitation of degraded Calcisols. Four-year field experiments (2022–2025) using Sorghum bicolor assessed plant growth, rhizosphere microbial indicators, physiological responses, pathogen suppression, crop productivity, and implementation feasibility through economic and environmental assessments. Inoculation with P. veronii increased root depth by 45%, improved aboveground biomass, increased the ratio of culturable bacteria to Fusarium spp. from 6.1 to 10.3, and reduced Fusarium abundance by 29.4%. Structural equation modeling suggested that trophic support (42.1%), aggregate stabilization (27.4%), biocontrol (23.3%), and defense-related responses (7.2%) were the principal pathways associated with soil rehabilitation. Economic assessment indicated that the combined inoculation and mineral fertilization treatment provided the highest profitability, while environmental assessment estimated potential reductions in mineral fertilizer use and greenhouse gas emissions. These findings suggest that rhizosphere engineering using a native P. veronii strain represents a promising, economically viable, and climate-smart approach for improving the biological functioning of degraded Calcisols and supporting sustainable agricultural production. Full article
(This article belongs to the Section Agricultural Soils)
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21 pages, 7877 KB  
Article
PGPR-Treated Spent Mushroom Substrate Enhances Lignocellulose Degradation, Enzyme Activities, and Microbial Restructuring to Sustain Blueberry Rhizosphere Fertility
by Mengjiao Wang, Ningqiang Li, Yinku Liang, Zhimin Xu and Haicui Wu
Microorganisms 2026, 14(8), 1827; https://doi.org/10.3390/microorganisms14081827 - 18 Aug 2026
Viewed by 297
Abstract
Spent mushroom substrate (SMS) is a major agricultural byproduct whose complex lignocellulosic matrix hinders direct reuse and poses environmental risks when stockpiled. This study evaluated whether pretreatment with plant growth-promoting rhizobacteria (PGPR) could enhance SMS as a soil amendment for blueberry cultivation. Two [...] Read more.
Spent mushroom substrate (SMS) is a major agricultural byproduct whose complex lignocellulosic matrix hinders direct reuse and poses environmental risks when stockpiled. This study evaluated whether pretreatment with plant growth-promoting rhizobacteria (PGPR) could enhance SMS as a soil amendment for blueberry cultivation. Two PGPR-treated SMS formulations, along with raw SMS and a blank control, were applied to blueberry seedlings in a 10-month greenhouse experiment. Plant height, rhizosphere soil nutrients, enzyme activities, lignocellulose fractions, and the microbial communities were monitored over three growth phases and four sampling points. PGPR-treated SMS significantly increased blueberry height gain during the fast-growing phase (June–September) and sustained elevated levels of organic carbon, nitrogen, phosphorus, and potassium throughout the experiment. Activities of cellulase, xylanase, laccase, peroxidase, protease, and lipase were markedly enhanced, accompanied by reduced lignin and cellulose contents and persistently high glucose availability. The amendments reshaped bacterial and fungal communities, enriching Bacillota, Acidobacteriota, Acidibacter, and Hyphomicrobium, and increasing alpha diversity, with clear structural separation from controls in principal coordinate analysis. Correlation and principal component analyses linked improved plant growth to nutrient availability, enzyme stimulation, and specific microbial taxa. These findings indicate that PGPR-treated SMS acts as a multifunctional amendment that promotes lignocellulose degradation, sustains soil fertility, and restructures the rhizosphere microbiome, offering a sustainable recycling strategy for horticultural production. Full article
(This article belongs to the Special Issue Agricultural Microbial Ecology: Plant–Soil–Microbe Interactions)
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21 pages, 1114 KB  
Article
Synergistic Effects of Microbial Inoculation and Nitrogen Fertilization on Maize Performance and Yield Attributes
by Sajjad Hussain, Saeed Ahmad Qaisrani, Muhammad Mubeen, Hafiz Muhammad Rashad Javeed and Muhammad Tahir
Nitrogen 2026, 7(3), 87; https://doi.org/10.3390/nitrogen7030087 - 18 Aug 2026
Viewed by 383
Abstract
Partial replacement of chemical fertilizers, particularly nitrogen fertilizers, with biological fertilizers is considered an effective strategy for reducing the negative environmental impacts associated with excessive fertilizer use. This study aimed to optimize N use through the application of bacterial-based biofertilizer, specifically plant growth-promoting [...] Read more.
Partial replacement of chemical fertilizers, particularly nitrogen fertilizers, with biological fertilizers is considered an effective strategy for reducing the negative environmental impacts associated with excessive fertilizer use. This study aimed to optimize N use through the application of bacterial-based biofertilizer, specifically plant growth-promoting rhizobacteria (PGPR), in different maize cultivars under semi-arid conditions. A randomized complete block design (RCBD) arranged in a split-plot arrangement was used, with the three hybrids (Shahkar, Bumbus and DK 7024) assigned to the main plots and different N treatments allocated to sub-plots. The field experiment was conducted during two consecutive spring seasons (Feb to June 2024 and 2025). The N treatments were defined as follows: control, 100% recommended N (200 kg/ha), 100% N with Pseudomonas stutzeri, 100% N with Bacillus subtilis, 100% N with Enterobacter sp., 50% N with Pseudomonas stutzeri, 50% N with Bacillus subtilis, 50% N with Enterobacter sp., 100% Pseudomonas stutzeri, 100% Bacillus subtilis, and 100% Enterobacter sp. The N treatments included synthetic fertilizer alone at the 100% recommended N rate and a combination of 100%, 50% and 0% of recommended levels with three N-fixing bacterial strains. Among the hybrids, DK 7024 exhibited the highest 1000-grain weight (349 g and 362.5 g), grain yield (6756 and 6971 kg ha−1) and total dry matter (17,500 and 18,368 kg ha−1) in 2024 and 2025, respectively. Among N levels, maximum 1000-grain weight, grain yield and total dry matter were noticed in 100% N with Enterobacter sp.: 402 g, 8446 kg ha−1 and 21,656 kg ha−1 in 2024 and 421 g, 8684 kg ha−1 and 22,237 kg ha−1 in 2025. Nitrogen application increased grain yield and total dry matter production; however, the treatment combined with 100% recommended synthetic N fertilizer with biofertilizer (Enterobacter sp.) showed superior performance compared with 100% N applied through only the synthetic fertilizer. The interaction between maize hybrids and N levels was statistically non-significant, suggesting that 100% N plus biofertilizers could be an effective strategy for achieving higher yields across different maize cultivars. Additionally, the beneficial effects of PGPR may contribute to sustainable agricultural practices. Further research is recommended to evaluate strategies involving reduced-N inputs combined with biological fertilizer, including the application of 100% N with biofertilizer. The present study suggests that N application in combination with biofertilizers has the potential to improve crop growth while promoting sustainable crop production. Full article
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21 pages, 18620 KB  
Article
Microbacterium sp. Y107 Is Associated with Enhanced Lingonberry Root Growth and Transcriptional Changes Under Gnotobiotic Conditions
by Enze Yu, Yuzhe Wang, Yurong Liang, Jiayi Li, Zihan Liu, Fanchang Bu, Hongrui Pan, Xinjie Wang, Dunting Tie, Hu Lou and Jie Zhang
Horticulturae 2026, 12(8), 1027; https://doi.org/10.3390/horticulturae12081027 - 17 Aug 2026
Viewed by 361
Abstract
Lingonberry (Vaccinium vitis-idaea L.) has a weak root system and limited nutrient acquisition capacity. Plant growth-promoting rhizobacteria (PGPR) can promote plant growth by regulating rhizosphere nutrient cycling and host metabolism, but the underlying mechanisms in Ericaceae remain unclear. In this study, the [...] Read more.
Lingonberry (Vaccinium vitis-idaea L.) has a weak root system and limited nutrient acquisition capacity. Plant growth-promoting rhizobacteria (PGPR) can promote plant growth by regulating rhizosphere nutrient cycling and host metabolism, but the underlying mechanisms in Ericaceae remain unclear. In this study, the strain Microbacterium sp. Y107 was isolated from the rhizosphere of lingonberry. Using growth-promoting assays (with 9 independent biological replicates, each consisting of 3 plants per bottle as the experimental unit, an inoculum density of OD600 = 1.0, a cultivation period of 60 days, and whole-plant harvesting), GC–MS-based metabolite analysis, axenic coculture, analyses of the rhizosphere environment and gene expression, transcriptome sequencing (3 biological replicates per treatment), and qRT–PCR validation, we systematically evaluated the effects of strain Y107 on lingonberry growth, rhizosphere conditions, and host gene expression. CK (control) plants were defined as those inoculated with sterile LB liquid medium. Pearson correlation analysis was also used to assess the relationships among plant growth, soil traits, and physiological indices. Compared with the CK treatment, strain Y107 significantly promoted lingonberry growth (p < 0.05), increasing the fresh weight of the roots by 157.65% and the whole-plant fresh weight by 33.85%, respectively, and increasing peroxidase (POD) activity by 61.11%, while reducing the contents of reducing sugars and proline. Strain Y107 stably colonized the lingonberry root surface and formed biofilms. Y107 treatment resulted in detectable levels of soil microbial biomass carbon and nitrogen, indicating successful microbial colonization. The ammonium nitrogen content significantly increased, increasing nitrogen availability and promoting root nutrient uptake. Transcriptome analysis revealed that the expression of genes enriched in photosynthesis-related pathways, as well as those involved in carbon and nitrogen metabolism and redox regulation, was altered in strain Y107, which upregulated key photosynthesis-related genes such as psbP and ndhU and significantly enriched the cytosolic ribosomal large subunit gene set in a negative direction. Correlation analysis further revealed that strain Y107 optimized the association between lingonberry growth and soil nutrients. Overall, strain Y107 promoted lingonberry growth through stable colonization, enhanced nutrient cycling, promoted lingonberry growth, and altered the expression patterns of genes involved in photosynthesis-related pathways. Full article
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18 pages, 1859 KB  
Article
Combined Effects of Arbuscular Mycorrhizal Fungi, Plant Growth-Promoting Rhizobacteria, and Mineral Fertilization on the Physiological, Biochemical, and Nutritional Properties of Chilaca Chili Pepper (Capsicum annum L.)
by Jael González Flores, Angel Adrian Bernal Lopez, Mónica Andrea Valdez Solana, Patricia Vázquez López, Apolinar González Mancilla and Erick Sierra Campos
Crops 2026, 6(4), 79; https://doi.org/10.3390/crops6040079 - 12 Aug 2026
Viewed by 343
Abstract
Pepper fruits contain diverse primary and secondary metabolites, including ascorbic acid, carotenoids, phenolics, and flavonoids, which contribute to nutritional quality, antioxidant capacity, coloration, and consumer acceptance. Chilaca chili pepper (Capsicum annuum L.) is a Mexican cultivar valued for its distinctive flavor and [...] Read more.
Pepper fruits contain diverse primary and secondary metabolites, including ascorbic acid, carotenoids, phenolics, and flavonoids, which contribute to nutritional quality, antioxidant capacity, coloration, and consumer acceptance. Chilaca chili pepper (Capsicum annuum L.) is a Mexican cultivar valued for its distinctive flavor and pungency, representing a valuable resource for studying fruit quality and sustainable crop improvement. This study evaluated the individual and combined effects of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on growth, physiological responses, antioxidant activity, and fruit quality traits. Twelve treatments in a 3 × 2 × 2 factorial designs were evaluated for chlorophyll, soluble solids, biomass, APX and LOX activities, and vitamin C and capsaicin contents at three ripening stages (green, mid-red, and red). Enzyme activities were determined spectrophotometrically, and bioactive compounds were quantified from methanolic fruit extracts. Microbial inoculation primarily improved fruit physiological quality rather than vegetative growth. Biomass and growth traits showed no significant differences among treatments (p > 0.05), whereas biochemical responses exhibited distinct ripening-dependent patterns. APX activity, vitamin C, and capsaicin increased from green to mid-red stages and declined at full ripeness. Bacillus sp.-based treatments (T1 and T2) produced a significant transient increase in LOX activity during mid-ripening, while T7 showed a similar but weaker response. AMF progressively enhanced LOX activity and capsaicin accumulation in green fruits. PGPR effects were strain-dependent, with Bacillus sp. promoting early capsaicin accumulation and A. deleyi favoring higher levels during advanced ripening. Overall, AMF and PGPR differentially regulate antioxidant metabolism, vitamin C accumulation, and capsaicinoid biosynthesis while interacting with mineral fertilization to improve fruit quality. These findings support beneficial microorganisms as sustainable tools for enhancing nutrient-use efficiency and fruit nutritional and functional value without replacing mineral fertilization. Full article
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28 pages, 6506 KB  
Article
Integrated Bentonite, Humic Substances and Bacillus polymyxa Enhance Soil Functionality, Rhizosphere Processes, Nutrient Uptake and Fruit Quality of Siwi Date Palm Under Deficit Irrigation in Sandy Soil
by Nahed M. Rashed, Khairy H. Abd-El-Rahman, Doaa M. Abou Elyazid, Amal A. Matar, Amin K. Amin and Mohamed S. Gawish
Horticulturae 2026, 12(8), 994; https://doi.org/10.3390/horticulturae12080994 - 11 Aug 2026
Viewed by 458
Abstract
Arid sandy soils are characterized by poor water retention, low nutrient availability, and limited productivity, posing major constraints to sustainable date palm cultivation under increasing water scarcity. A three-year field experiment was conducted to evaluate the combined effects of bentonite (BN), humic substances [...] Read more.
Arid sandy soils are characterized by poor water retention, low nutrient availability, and limited productivity, posing major constraints to sustainable date palm cultivation under increasing water scarcity. A three-year field experiment was conducted to evaluate the combined effects of bentonite (BN), humic substances (HS), and Bacillus polymyxa (BP) under three irrigation regimes (70, 85, and 100% of crop evapotranspiration (ETc)) on soil hydro-physical properties, nutrient uptake, and fruit quality of ‘Siwi’ date palm (Phoenix dactylifera L.). Twelve treatment combinations (3 irrigation regimes × 4 soil amendment treatments) were evaluated over three consecutive growing seasons. The integrated application of BN, HS, and BP significantly improved soil hydro-physical properties by increasing field capacity and plant-available water while reducing bulk density. These improvements were associated with enhanced leaf N, P, and K concentrations and greater accumulation of total soluble solids, total and reducing sugars, phenolic compounds, flavonoids, and β-carotene compared with the untreated control. The combined application of BN (12 kg palm−1) + HS (1 L palm−1) + BP (28 mL palm−1) produced the most favorable overall responses. Moderate deficit irrigation (85% ETc) provided the best balance between fruit quality and water conservation, maintaining superior fruit biochemical quality while reducing irrigation water use by approximately 15% compared with full irrigation. Multivariate analyses further supported these findings by revealing strong positive associations among soil water availability, nutrient status, sugars, and antioxidant-related compounds, while climatic variables were closely associated with seasonal variation in fruit biochemical characteristics. Overall, the integrated application of bentonite, humic substances, and B. polymyxa under 85% ETc irrigation represents an effective management strategy for improving soil performance, enhancing fruit nutritional quality, and increasing water-use irrigation efficiency in sandy soils under arid conditions. Full article
(This article belongs to the Special Issue Soil Amendments and Organic Management for Horticultural Crops)
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24 pages, 15582 KB  
Article
Bacillus velezensis and Sinorhizobium meliloti Form a Functional Complementary Alliance to Alleviate the Impact of Salt Stress on Alfalfa Growth
by Jie Bai, Tuo Yao, Wenbo Xu, Yang Lei, Chen Zhang and Jiali Chai
Agronomy 2026, 16(16), 1515; https://doi.org/10.3390/agronomy16161515 - 7 Aug 2026
Viewed by 414
Abstract
Salt stress is a prevalent abiotic stress worldwide, which markedly inhibits crop growth and triggers yield losses. In this study, salt-tolerant plant-growth-promoting rhizobacteria of Cerasus humilisBacillus pumilus and B. velezensis, which possess nitrogen-fixing, phosphate-solubilizing, and indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate [...] Read more.
Salt stress is a prevalent abiotic stress worldwide, which markedly inhibits crop growth and triggers yield losses. In this study, salt-tolerant plant-growth-promoting rhizobacteria of Cerasus humilisBacillus pumilus and B. velezensis, which possess nitrogen-fixing, phosphate-solubilizing, and indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing traits—were co-inoculated with Sinorhizobium meliloti. The effects of these bacterial combinations on alfalfa (Medicago sativa L.) were systematically evaluated during seed germination and plant growth under salt stress simulated using NaCl, Na2SO4, NaHCO3, and Na2CO3 at varying intensities. The results showed that under salt stress, inoculation significantly increased the seed germination rate by 11.33–41.33%. Pot experiments further revealed that inoculation significantly enhanced symbiotic nitrogen fixation efficiency in alfalfa and effectively maintained K+/Na+ homeostasis (K+ concentration increased by 4.23–125.34%, while Na+ concentration decreased by 7.15–102.09%). Concurrently, inoculation upregulated antioxidant enzyme activities and promoted the accumulation of non-enzymatic antioxidants, thereby significantly reducing reactive oxygen species levels. Moreover, inoculation substantially increased the content of osmoregulatory substances such as proline and soluble protein; proline accumulation surged more than fivefold (39.97–551.05%) compared with the non-inoculated control, effectively alleviating cellular dehydration. Through these multi-pathway regulations mediated by Bacillus sp. and S. meliloti, the inhibitory effect of salt stress on alfalfa growth was significantly mitigated, with dry weight increasing by 45.9–92.4%. Principal component analysis indicated that inoculation with the B. velezensisS. meliloti microbial combination was the most promising strategy for promoting alfalfa growth and alleviating salt stress. The results provide a theoretical basis for developing microbial fertilizers and establishing alfalfa pastures in saline lands, thereby promoting their sustainable utilization. Full article
(This article belongs to the Section Farming Sustainability)
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