Search

Peanut is a staple crop suitable for mechanized harvest and a source of plant proteins and fatty acids. It is widespread in Asia and North America, while there is limited cultivation in Europe despite potentially favorable climatic conditions. To test the adaptability of peanut in the Mediterranean area, a two-year field trial was carried out with one Spanish-type and one Virginia-type genotype cultivated under two water regimes (full irrigation and half irrigation supply). In order to test the response to fertilization management, three treatments were carried out, including an unfertilized control, a N-fertilized treatment, and a N-fertilized treatment inoculated with a commercial mixture of plant-growth promoting microorganisms, including two Bacillus species, Trichoderma and arbuscular mycorrhizal fungi (AMF). Microbiological soil analysis assessed the robustness of bacilli and their viability in soil. The Virginia-type genotype showed a better adaptability, with a positive response to irrigation and biofertilization. In particular, the inoculated treatment led to the highest agricultural crop water productivity, with important implications for sustainability. The impact of agronomic strategies was evaluated also in relation to storage proteins. The expression of 7s vicilin fraction showed a variability associated with water supply. [ABSTRACT FROM AUTHOR]

Background: The required amounts of chemical fertilizers (NPK) are determined by plant yield, and product quality is given less consideration. The use of PGPRs is an environmentally friendly approach that, in addition to increasing yield, also improves fruit quality. This study examined the role of specific Streptomyces strains in aiding cucumber plants to 1) use fewer NPK fertilizers in the same quantity 2) improve the quality of cucumber fruit, and 3) promote growth and defense system. Results: In this study, the effect of 17 Streptomyces strains on the vegetative traits of cucumber seedlings of the Sultan cultivar was evaluated as the first test. Four strains of Streptomyces with the highest root and shoot dry weight were selected from the strains. This experiment was performed to determine the interaction effect of selected strains and different amounts of NPK on cucumber yield, quality, physiological and biochemical responses of plants. The first experiment's results revealed that strains IC6, Y7, SS12, and SS14 increased significantly in all traits compared to the control, while the other strains dramatically improved several characteristics. Analysis of variance (ANOVA) revealed significant differences between the effect of strains, NPK concentrations, and their interactions on plant traits. The treatments containing 75% NPK + SS12, yielded the most fruit (40% more than the inoculated control). Antioxidant enzymes assay showed that SS12 substantially increased the activity of POX, PPO, and the expression of the genes related to these two enzymes. Hormone assay utilizing HPLC analysis revealed that various strains employ a specific mechanism to improve the immune system of plants. Conclusions: Treatment with strain SS12 led to the production of cucumbers with the highest quality by reducing the amount of nitrate, and soluble sugars and increasing the amount of antioxidants and firmness compared to other treatments. A specific Streptomyces strain could reduce 25% of NPK fertilizer during the vegetative and reproductive growth period. Moreover, this strain protected plants against possible pathogens and adverse environmental factors through the ISR and SAR systems. [ABSTRACT FROM AUTHOR]

Continuous discovery of novel in vitro plant culture practices is always essential to promote better plant growth in the shortest possible cultivation period. An alternative approach to conventional micropropagation practice could be achieved through biotization by inoculating selected Plant Growth Promoting Rhizobacteria (PGPR) into the plant tissue culture materials (e.g., callus, embryogenic callus, and plantlets). Such biotization process often allows the selected PGPR to form a sustaining population with various stages of in vitro plant tissues. During the biotization process, plant tissue culture material imposes developmental and metabolic changes and enhances its tolerance to abiotic and biotic stresses, thereby reducing mortality in the acclimatization and pre-nursery stages. Understanding the mechanisms is, therefore crucial for gaining insights into in vitro plant-microbe interactions. Studies of biochemical activities and compound identifications are always essential to evaluate in vitro plant-microbe interactions. Given the importance of biotization in promoting in vitro plant material growth, this review aims to provide a brief overview of the in vitro oil palm plant-microbe symbiosis system. [ABSTRACT FROM AUTHOR]

Human activities, industrialization and civilization have deteriorated the environment which eventually has led to alarming effects on plants and animals by heightened amounts of chemical pollutants and heavy metals in the environment, which create abiotic stress. Environmental conditions like drought, salinity, diminished macro-and micro-nutrients also contribute in abiotic stress, resulting in decrement of survival and growth of plants. Presence of pathogenic and competitive microorganisms, as well as pests lead to biotic stress and a plant alone can not defend itself. Thankfully, nature has rendered plant's rhizosphere with plant growth promoting rhizobacteria which maintain an allelopathic relationship with host plant to defend the plant and let it flourish in abiotic as well as biotic stress situations. This review discusses the mechanisms behind increase in plant growth via various direct and indirect traits expressed by associated microorganisms in the rhizosphere, along with their current scenario and promising future for sustainable agriculture. It also gives details of ten such bacterial species, viz. Acetobacter, Agrobacterium, Alcaligenes, Arthrobacter, Azospirillum, Azotobacter, Bacillus, Burkholderia, Enterobacter and Frankia, whose association with the host plants is famed for enhancing plant's growth and survival. [ABSTRACT FROM AUTHOR]

In order to study the effects of nanoparticles and biofertilizers on chlorophyll fluorescence indices and some physiological traits of triticale (Triticosecale Wittmack) under salinity stress, a factorial experiment was conducted based on a randomized complete block design with three replications in the research greenhouse of Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardebili in 2021. Experimental factors included salinity (non-saline control, 35, and 70 mM NaCl), application of biofertilizers (PGPR) (biofertilizers-free control, application of Azospirilum, Pseudomonas, combined application Azospirilum and Pseudomonas) and nanoparticles foliar application (foliar application with water as control, nano iron oxide foliar application, nano silicon, combined foliar application of nano iron-silicon oxide). The results showed that both application of PGPR and foliar application of nanoparticles under non-saline condition increased quantum yield (64%), maximum fluorescence (69%), variable fluorescence (175%), chlorophyll index (48.1%), leaf nitrogen content (35.3%), leaf relative water content (49.7%) and stomatal conductance (81.4%) and grain yield per plant (44.5%) in comparison with biofertilizers-free and nanoparticles foliar application under 70 mM salt condition. Maximum of minimum fluorescence (178) and electrical conductivity (126) were obtained at the highest salinity level, i.e. 70 mM NaCl. Based on the results of this study, it seems that application of bio fertilizers and nanoparticles foliar application may improve the grain yield of triticale under salinity stress.

Abstract Background Plant growth promoting rhizobacteria (PGPR), such as Bradyrhizobium japonicum IRAT FA3, are able to improve seed germination and plant growth under various biotic and abiotic stress conditions, including high salinity stress. PGPR can affect plants’ responses to stress via multiple pathways which are often interconnected but were previously thought to be distinct. Although the overall impacts of PGPR on plant growth and stress tolerance have been well documented, the underlying mechanisms are not fully elucidated. This work contributes to understanding how PGPR promote abiotic stress by revealing major plant pathways triggered by B. japonicum under salt stress. Results The plant growth-promoting rhizobacterial (PGPR) strain Bradyrhizobium japonicum IRAT FA3 reduced the levels of sodium in Arabidopsis thaliana by 37.7%. B. japonicum primed plants as it stimulated an increase in jasmonates (JA) and modulated hydrogen peroxide production shortly after inoculation. B. japonicum-primed plants displayed enhanced shoot biomass, reduced lipid peroxidation and limited sodium accumulation under salt stress conditions. Q(RT)-PCR analysis of JA and abiotic stress-related gene expression in Arabidopsis plants pretreated with B. japonicum and followed by six hours of salt stress revealed differential gene expression compared to non-inoculated plants. Response to Desiccation (RD) gene RD20 and reactive oxygen species scavenging genes CAT3 and MDAR2 were up-regulated in shoots while CAT3 and RD22 were increased in roots by B. japonicum, suggesting roles for these genes in B. japonicum-mediated salt tolerance. B. japonicum also influenced reductions of RD22, MSD1, DHAR and MYC2 in shoots and DHAR, ADC2, RD20, RD29B, GTR1, ANAC055, VSP1 and VSP2 gene expression in roots under salt stress. Conclusion Our data showed that MYC2 and JAR1 are required for B. japonicum-induced shoot growth in both salt stressed and non-stressed plants. The observed microbially influenced reactions to salinity stress in inoculated plants underscore the complexity of the B. japonicum jasmonic acid-mediated plant response salt tolerance.

Soil pollution caused by petroleum hydrocarbons is a serious threat for human life, as it affects the groundwater, cause economical losses after decreasing the agricultural production, and create other ecological issues. Here, we are reporting the isolation and screening of rhizosphere bacteria possessing biosurfactant producing potential and capable of enhancing plant growth under petrol stress as well as possessing. Efficient biosurfactant producers having plant growth promoting traits were characterized morphologically, physiologically, and phylogenetically. These selected isolates were identified as Bacillus albus S2i, Paraclostridium benzoelyticum Pb4, and Proteus mirabilis Th1 based on 16S rRNA sequence analysis. These bacteria possessed plant growth promoting attributes as well as exhibited positive activity toward the assays based on hydrophobicity, lipase activity, surface activity, and hydrocarbon degradation that indicated the production of biosurfactants. Fourier transform infrared spectroscopy of crude biosurfactants extracted from bacterial strains revealed that the biosurfactants from Pb4 and Th1 might belong to glycolipid or glycolipopeptide class whereas the biosurfactants from S2i could be from phospholipid class. Scanning electron micrographs exhibited group of exopolymer matrices interconnecting the cells forming a complex network of mass, while energy dispersive X-ray analysis has shown elemental composition of biosurfactants with dominance of nitrogen, carbon, oxygen, and phosphorous. Further, these strains were then used to ascertain their effect on the growth and biochemical parameters including stress metabolites and antioxidant enzymology of Zea mays L. plants grown under petrol (gasoline) stress. Significant increments in all studied parameters were observed in comparison with control treatments that might be due to petrol degradation by bacteria and also by secreting growth stimulating substances released by these bacteria in soil ecosystem. To the best of our knowledge, this is the first report in which Pb4 and Th1 were studied as surfactant producing PGPR and further their role as biofertilizer for the significant improvement in phytochemical constituents of maize plants grown under petrol stress was assessed. [ABSTRACT FROM AUTHOR]

Plants exude secondary metabolites from the roots to shape the composition and function of their microbiome. Many of these compounds are known for their anti-microbial activities and play a role in plant immunity, such as the indole-derived phytoalexin camalexin. Here we studied the dynamics of camalexin synthesis and exudation upon interaction of Arabidopsis thaliana with the plant growth promoting bacteria Pseudomonas sp. CH267 or the bacterial pathogen Burkholderia glumae PG1. We show that while camalexin accumulation and exudation is more rapidly but transiently induced upon interaction with the growth promoting bacteria, the pathogen induces higher and more stable camalexin levels. By combination of experiments with cut shoots and roots, and grafting of wild-type plants with mutants in camalexin synthesis, we showed that while camalexin can be produced and released by both organs, in intact plants exuded camalexin originates in the shoots. We also reveal that the root specific CYP71A27 protein specifically affects the outcome of the interaction with the plant growth promoting bacteria and that its transcript levels are controlled by a shoot derived signal. In conclusion, camalexin synthesis seems to be controlled on a whole plant level and is coordinated between the shoots and the roots. [ABSTRACT FROM AUTHOR]

Plant-microbe interactions are a phenomenal display of symbiotic/parasitic relationships between living organisms. Plant growth-promoting rhizobacteria (PGPR) are some of the most widely investigated plant-beneficial microbes due to their capabilities in stimulating plant growth and development and conferring protection to plants against biotic and abiotic stresses. As such, PGPR-mediated plant priming/induced systemic resistance (ISR) has become a hot topic among researchers, particularly with prospects of applications in sustainable agriculture. The current study applies untargeted ultra-high performance liquid chromatography-high-definition mass spectrometry (UHPLC-HDMS) to investigate PGPR-based metabolic reconfigurations in the metabolome of primed wheat plants against Puccinia striiformis f. sp. tricti (Pst). A seed biopriming approach was adopted, where seeds were coated with two PGPR strains namely Bacillus subtilis and Paenibacillus alvei (T22) and grown under controlled conditions in a glasshouse. The plants were infected with Pst one-week postgermination, followed by weekly harvesting of leaf material. Subsequent metabolite extraction was carried out for analysis on a UHPLC-HDMS system for data acquisition. The data was chemometrically processed to reveal the underlying trends and data structures as well as potential signatory biomarkers for priming against Pst. Results showed notable metabolic reprogramming in primary and secondary metabolism, where the amino acid and organic acid content of primed-control, primed-challenged and non-primed-challenged plants were differentially reprogrammed. Similar trends were observed from the secondary metabolism, in which primed plants (particularly primedchallenged) showed an up-regulation of phenolic compounds (flavonoids, hydroxycinnamic acids-HCAs- and HCA amides) compared to the non-primed plants. The metabolomics-based semi-quantitative and qualitative assessment of the plant metabolomes revealed a time-dependent metabolic reprogramming in primed-challenged and primed-unchallenged plants, indicating the metabolic adaptations of the plants to stripe rust infection over time. [ABSTRACT FROM AUTHOR]

It is known that members of the bacterial genus Azospirillum can promote the growth of a great variety of plants, an ability harnessed by the industry to create bioproducts aimed to enhance the yield of economically relevant crops. Its versatile metabolism allows this bacterium to adapt to numerous environments, from optimal to extreme or highly polluted. The fact of having been isolated from soil and rhizosphere samples collected worldwide and many other habitats proves its remarkable ubiquity. Azospirillum rhizospheric and endophytic lifestyles are governed by several mechanisms, leading to efficient niche colonization. These mechanisms include cell aggregation and biofilm formation, motility, chemotaxis, phytohormone and other signaling molecules production, and cell-to-cell communication, in turn, involved in regulating Azospirillum interactions with the surrounding microbial community. Despite being infrequently mentioned in metagenomics studies after its introduction as an inoculant, an increasing number of studies detected Azospirillum through molecular tools (mostly 16S rRNA sequencing) as part of diverse, even unexpected, microbiomes. This review focuses on Azospirillum traceability and the performance of the available methods, both classical and molecular. An overview of Azospirillum occurrence in diverse microbiomes and the less-known features explaining its notorious ability to colonize niches and prevail in multiple environments is provided. [ABSTRACT FROM AUTHOR]

Industrialization and urbanization are important for economic development which makes the human life easy by providing different job opportunities, increasing the production level of cheaper goods and standard of living. Despite its many positive effects, industrialization has had a negative impact on the natural ecosystem through environmental pollution. It is responsible for a greater input of potentially toxic and non-toxic substances into essential environmental components such as air, soil and water. Continuous industrialization has resulted in significant environmental problems due to the release of pollutants and extremely difficult treatment of contaminated areas. This review focuses on the recent literature dealing with the role of Plant Growth Promoting Microbes (PGPMs), i.e. bacteria and Arbuscular mycorrhizal Fungi (AMF) in the remediation of polluted sites. [ABSTRACT FROM AUTHOR]

Plant growth-promoting rhizobacteria (PGPR), is a consortium of such bacteria which colonizes the roots of plants and show beneficial effects on growth and yield of plant. Pseudomonas is found to be most potent PGPR, occurring globally and having positive effect on productivity of plant. This review unravels severassl species of Pseudomonas which enhance growth and yield of spinach and can be used as biofertilizer. Certain species of Pseudomonas have been discovered which in absence of any chemical fertilizer can increase productivity of spinach alone. Investigation of such PGPR in case of spinach is quiet important as spinach cultivation make use of large amount of chemical fertilizers which are deleterious to health of crop, environment and human beings altogether. ssThis review also introduces certain methods of inoculation of Pseudomonas sp. which encourages colonization around root or seeds of spinach, hence upgrading its association with spinach and yield in short. Thus, this review draws attention to explore more about Pseudomonas in case of green leafy spinach, inorder to gain large scale productivity and field application of it, which promotes organic farming and goodness of well-being. [ABSTRACT FROM AUTHOR]

Several studies have described the potential use of volatile organic compounds (VOCs) emitted by soil microorganisms, specifically of the genus Bacillus , as a sustainable solution for disease management in plants. The Bacillus species have been extensively studied as biocontrol agents (BCAs) due to their ability to inhibit pathogens, trigger induced systemic resistance (ISR) in plants, and enhance plant growth. The ability of the Bacillus species to produce long-lasting resting structures, such as endospores, makes them particularly appealing as BCAs. In recent years, there has been a growing body of research on the effects of Bacillus -emitted VOCs on plant pathogen growth and the triggering of ISR. This review aims to highlight recent advances in the understanding of the biological activities of Bacillus -emitted VOCs, identify new subjects for VOCs research, and stimulate interest in the academic and agri-business sectors for developing pre- and post-harvest application methods. [ABSTRACT FROM AUTHOR]

Dryland lacks water, unfulfilled nutrient supply, lack of abiotic and biotic elements, and very little rainfall. The area of dry land in Indonesia reaches 144.47 × 106 ha. About 99.65 × 106 ha are dry land with potential for agriculture, and around 44.82 × 106 ha are dry land with no possibility for agriculture. Many arid lands in Indonesia cause significant problems, especially in the agricultural sector. The problem often occurs due to the constraints of plant growth factors, including planting media, water, light, wind, and nutrients. This study aims to determine the resistance of bacteria to drought stress and high salinity as well as their ability to produce IAA (Indole Acetic Acid). The method used is in vitro. The results obtained are various kinds of bacteria, the nature of bacteria in binding gram, and osmoprotectant bacteria. Bacteria tested from the dry land of annual plants could effectively survive on PEG 6000 media NaCl even at high concentrations. The best bacteria that can survive in the saline conditions were B7, B8, B9, B10, while the potential as plant growth hormone bacteria are B6, B7, B8, B9, B10. [ABSTRACT FROM AUTHOR]

Tomato is one of the world's most commonly grown and consumed vegetables. However, it can be attacked by the Gram-positive bacterium Clavibacter michiganensis subsp. michiganensis (Cmm), which causes bacterial canker on tomato plants, resulting in significant financial losses in field production and greenhouses worldwide. The current management strategies rely principally on the application of various chemical pesticides and antibiotics, which represent a real danger to the environment and human safety. Plant growth-promoting rhizobacteria (PGPR) have emerged as an attractive alternative to agrochemical crop protection methods. PGPR act through several mechanisms to support plant growth and performance, while also preventing pathogen infection. This review highlights the importance of bacterial canker disease and the pathogenicity of Cmm. We emphasize the application of PGPR as an ecological and cost-effective approach to the biocontrol of Cmm, specifying the complex modes of biocontrol agents (BCAs), and presenting their direct/indirect mechanisms of action that enable them to effectively protect tomato crops. Pseudomonas and Bacillus are considered to be the most interesting PGPR species for the biological control of Cmm worldwide. Improving plants' innate defense mechanisms is one of the main biocontrol mechanisms of PGPR to manage bacterial canker and to limit its occurrence and gravity. Herein, we further discuss elicitors as a new management strategy to control Cmm, which are found to be highly effective in stimulating the plant immune system, decreasing disease severity, and minimizing pesticide use. [ABSTRACT FROM AUTHOR]

The natural soil environment is considered one of the most diverse habitats containing numerous bacteria, fungi, and larger organisms such as nematodes, insects, or rodents. Rhizosphere bacteria play vital roles in plant nutrition and the growth promotion of their host plant. The aim of this study was to evaluate the effects of three plant growth-promoting rhizobacteria (PGPR), Bacillus subtilis, Bacillus amyloliquefaciens, and Pseudomonas monteilii for their potential role as a biofertilizer. The effect of the PGPR was examined at a commercial strawberry farm in Dayton, Oregon. The PGPR were applied to the soil of the strawberry (Fragaria × ananassa cultivar Hood) plants in two different concentrations of PGPR, T1 (0.24% PGPR) and T2 (0.48% PGPR), and C (no PGPR). A total of 450 samples from August 2020 to May 2021 were collected, and microbiome sequencing based on the V4 region of the 16S rRNA gene was conducted. The strawberry quality was measured by sensory evaluation, total acidity (TA), total soluble solids (TSS), color (lightness and chroma), and volatile compounds. Application of the PGPR significantly increased the populations of Bacillus and Pseudomonas and promoted the growth of nitrogen-fixing bacteria. The TSS and color evaluation showed that the PGPR presumptively behaved as a ripening enhancer. The PGPR contributed to the production of fruit-related volatile compounds, while the sensory evaluation did not show significant differences among the three groups. The major finding of this study suggests that the consortium of the three PGPR have a potential role as a biofertilizer by supporting the growth of other microorganisms (nitrogen-fixing bacteria) as part of a synergetic effect and strawberry quality such as sweetness and volatile compounds. Key points: Application of the PGPR significantly increased the population of the Bacillus and Pseudomonas genus. Application of the PGPR induced the growth of other beneficial bacteria. The PGPR have potential role as a ripening enhancer. [ABSTRACT FROM AUTHOR]

Rice production in the Central Plains of Thailand plays a key role in the country's food security. However, the overuse of inputs coupled with the rising production costs are making it increasingly difficult for smallholder rice farming to remain economically and environmentally sustainable. Replicated production-scale field trials of Cost Reduction Operating Principles (CROP)—Thailand's national package of best management practices for rice production—were established in tandem with laser land leveling (LLL), mechanical drum seeder, and the application of two biofertilizer products (i.e., PGPR II, that contains Azospirillum brasilense Sp. TS29 and Burkholderia vietnamiensis S45; and LDD #12, that contains Azotobacter tropicalis, Burkholderia unamae and Bacillus subtilis) and compared with farmer's practices (FP). Performance indicators (PI) promoted by the Sustainable Rice Platform (SRP) were used to assess economic and environmental indicators. CROP + PGPR had significantly higher net income (79%) and nitrogen-use efficiency (57%) compared with FP. Pesticide use (28%), seed (60%), inorganic fertilizer N (41%) and total production costs (19%) were reduced in all CROP treatments compared with FP. These results demonstrate that the application of CROP, LLL, mechanical drum seeder, and biofertilizers can substantially improve the economic and environmental sustainability of rice production in the Central Plains of Thailand. [ABSTRACT FROM AUTHOR]

Plant nutrition through mineral fertilizers is commonly used in soilless culture systems. Our study aims to replace intensive mineral fertilizers with bio-fertilizers, at least partially. We supplemented 50% of the mineral fertilizers with Chlorella vulgaris microalgae, a mix of beneficial bacteria and mycorrhiza. In addition, we investigated how to enhance spinach quality by implementing a sustainable and eco-friendly production method. Our research focused on analyzing the parameters of leaf quality and nitrate accumulation of baby spinach grown in a floating culture system utilizing biofertilizers. When mycorrhiza, algae, and bacteria supplemented 50% of mineral fertilizers, 17.5%, 20%, and 21.9% fewer leaf yields than 100% mineral fertilizers (5270 g m−2) were achieved. However, biofertilizers improved the internal leaves' quality of hydroponically grown baby spinach. The highest amount of total phenolic (356.88 mg gallic acid 100g−1), vitamin C (73.83 mg 100 g−1), total soluble solids (9.4%), phosphorus (0.68%), and iron (120.07 ppm) content were obtained by using mycorrhiza. Bacteria induced the lowest nitrate content (206 mg kg−1) in spinach leaves, while 100% mineral fertilizers showed the highest nitrate (623 mg kg−1) concentration. Moreover, bacteria provided the highest SPAD-chlorophyll (73.72) and titrable acidity (0.31%). The use of microalgae, Chlorella vulgaris, induced the highest amount of potassium (9.62%), calcium (1.64%), magnesium (0.58%), zinc (75.21 ppm), and manganese (64.33 mg kg−1). In conclusion, our findings demonstrate that the utilization of biofertilizers has the potential to significantly reduce the reliance on mineral fertilizers by up to 50%. Furthermore, an improvement in the quality of baby spinach, as evidenced by an increase in health-beneficial compounds, is possible. Thus, implementing biofertilizers in the cultivation of soilless baby spinach presents a promising approach to achieving both environmental sustainability and improved crop quality. [ABSTRACT FROM AUTHOR]

Agricultural areas exhibiting numerous abiotic stressors, such as elevated water stress, temperatures, and salinity, have grown as a result of climate change. As such, abiotic stresses are some of the most pressing issues in contemporary agricultural production. Understanding plant responses to abiotic stressors is important for global food security, climate change adaptation, and improving crop resilience for sustainable agriculture, Over the decades, explorations have been made concerning plant tolerance to these environmental stresses. Plant growth-promoting rhizobacteria (PGPR) and their phytohormones are some of the players involved in developing resistance to abiotic stress in plants. Several studies have investigated the part of phytohormones in the ability of plants to withstand and adapt to non-living environmental factors, but very few have focused on rhizobacterial hormonal signaling and crosstalk that mediate abiotic stress tolerance in plants. The main objective of this review is to evaluate the functions of PGPR phytohormones in plant abiotic stress tolerance and outline the current research on rhizobacterial hormonal communication and crosstalk that govern plant abiotic stress responses. The review also includes the gene networks and regulation under diverse abiotic stressors. The review is important for understanding plant responses to abiotic stresses using PGPR phytohormones and hormonal signaling. It is envisaged that PGPR offer a useful approach to increasing plant tolerance to various abiotic stresses. However, further studies can reveal the unclear patterns of hormonal interactions between plants and rhizobacteria that mediate abiotic stress tolerance.

This study aimed to assess the ability of bacteria living in bamboo roots to suppress the pathogen Phytophthora infestans in Solanum tuberosum L. cv. Granola Kembang—G2. The research was conducted in Pujon Village, Malang Regency, East Java, from March to June 2022, using a factorial experiment arranged at random groups. The first factor is Plant Grow Promoting Rhizobacteria (PGPR), i.e. P1, PGPR derived from bamboo (Bambusa vulgaris Schrad. ex J.C.Wendl) roots; and P2, PGPR from Biopharma. The second factor is the concentration of PGPR, namely 10 mg L–1 (C1), 20 mg L–1 (C2), and 30 mg L–1 (C3). There was no significant interaction between the PGPR source and the PGPR concentration treatment on the observed variables except tuber weight ha–1. The PGPR source did not show significant differences in the intensity of disease attacks, the number of tubers plant–1, and the percentage of tuber damage. PGPR concentrations showed significant differences in these three variables. The concentration of PGPR, which effectively and efficiently suppresses disease, is 20 mg L–1 (C2), which is suitable for potato tuber production is 30 mg L–1 (C3).

Hydroponics is a contemporary agricultural system providing precise control over growing conditions, potentially enhancing productivity. Biofertilizers are environmentally friendly, next-generation fertilizers that augment product yield and quality in hydroponic cultivation. In this study, we investigated the effect of three bio-fertilizers in a hydroponic floating system, microalgae, plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF), combined with a 50% reduction in mineral fertilizer, on lettuce yield and quality parameters including antioxidants: vitamin C, total phenols and flavonoids. The treatments tested were: 100% mineral fertilizer (control 1), 50% mineral fertilizer (control 2), 50% mineral fertilizer with microalgae, 50% mineral fertilizer with PGPR and 50% mineral fertilizer with AMF. The research was conducted during the winter months within a controlled environment of a glasshouse in a Mediterranean climate. The PGPR comprised three distinct bacterial strains, while the AMF comprised nine different mycorrhizal species. The microalgae consisted of only a single species, Chlorella vulgaris. AMF inoculation occurred once during seed sowing, while the introduction of PGPR and microalgae occurred at 10-day intervals into the root medium. Our findings revealed that the treatment with PGPR resulted in the highest growth parameters, including the lettuce circumference, stem diameter and fresh leaf weight. The 100% mineral fertilizer and PGPR treatments also yielded the highest lettuce production. Meanwhile, the treatment with AMF showed the highest total phenol and flavonoid content, which was statistically similar to that of the PGPR treatment. Furthermore, the PGPR recorded the maximum range of essential nutrients, including nitrogen (N), potassium (K), iron (Fe), zinc (Zn) and copper (Cu). Thus, the inclusion of PGPR holds promise for optimizing the lettuce growth and nutrient content in hydroponic systems. In conclusion, PGPR has the potential to enhance nutrient availability in a floating hydroponic system, reducing the dependence on chemical fertilizers. This mitigates environmental pollution and fosters sustainable agriculture.

Biocontrol agents are microbiological-based alternatives to agrochemicals due to their effective and sustainable attributes in controlling phytopathogens. This research highlights the formulation of biocontrol agents using sugarcane-bagasse as a carrier matrix and the evaluation of the formulants in phytopathogen management. The isolated rhizospheric bacteria were screened for the antibiosis trait responsible for biocontrol activity using the agar streak method. Bacterial isolates with antibiosis potential were further identified phenotypically. The carrier was prepared by oven drying the sugarcane-bagasse at 90 °C for three days while grinding and sieving using a mesh sieve of 1.16 mm was done afterwards. For the biocontrol formulation, 200 mL of biocontrol inoculum was added to 20 g of sugarcane-bagasse for each organism to form the final products. Water and adhesion capacities were conducted on the three formulations and, the antagonistic potential of the formulants were evaluated using the maize growth profile after 21 days. A total of nine isolates were obtained; only three (3) showed antibiosis antagonistic activity and were further utilized for the formulations branded ZEEMYC (Mycobacterium spp.), ZEEPAS (Pseudomonas spp.), and ZEEBAC (Bacillus spp.), respectively. The water capacities of the three formulations were between 6.9 g and 9.9 g, respectively, while adhesion capacity was also observed. On day five (5), maize seeds planted in all pots sprouted, except diseased seeds without a biocontrol agent (DSs). On day 11, plant height, shoot length, and root length ranged between 36.5 cm and 39 cm, 31 cm and 34 cm, and 5 cm and 7 cm for plants with a biocontrol agent. Those of the control (healthy seeds without biocontrol) were 42 cm, 34.5 cm, and 7.5 cm, while barely visible growth was observed in the DSs. This study displays the potential of natural-based biocontrol agents in controlling the phytopathogen Aspergillus niger and contributes significantly to SDG 2.

Abstract Glycyrrhiza uralensis Fisch. is an important, perennial medicinal plant whose root microbiome is considered to play an important role in promoting accumulation of effective medicinal ingredients (liquiritin and glycrrhizic acid). Here, we report a comprehensive analysis of the microbial community structural composition and metabolite-plant-microbes association of G. uralensis Fisch. We collected both soil and rhizosphere samples of G. uralensis from different environmental conditions (cultivated and wild) and growth years (grown for one year and three years). Our data revealed higher species diversity in the wild group than in the cultivated group. The core rhizosphere microbiome of G. uralensis comprised 78 genera, including Bacillus, Pseudomonas, Rhizobium, some of which were potential plant beneficial microbes. Our results suggest that the growth of G. uralensis has a correlation with the root-associated microbiota assemblage. Integrated analysis among rhizosphere microbial taxa, plant gene expressions, and liquiritin and glycrrhizic acid accumulation showed that the liquiritin and glycrrhizic acid accumulation exhibited associations with the rhizosphere microbial composition at the genus level. The results provide valuable information to guide cultivation of G. uralensis, and potentially to harness the power of the root-associated microbiota to improve medicinal plant production.

Plant-microbe interactions are a phenomenal display of symbiotic/parasitic relationships between living organisms. Plant growth-promoting rhizobacteria (PGPR) are some of the most widely investigated plant-beneficial microbes due to their capabilities in stimulating plant growth and development and conferring protection to plants against biotic and abiotic stresses. As such, PGPR-mediated plant priming/induced systemic resistance (ISR) has become a hot topic among researchers, particularly with prospects of applications in sustainable agriculture. The current study applies untargeted ultra-high performance liquid chromatography-high-definition mass spectrometry (UHPLC-HDMS) to investigate PGPR-based metabolic reconfigurations in the metabolome of primed wheat plants against Puccinia striiformis f. sp. tricti (Pst). A seed bio-priming approach was adopted, where seeds were coated with two PGPR strains namely Bacillus subtilis and Paenibacillus alvei (T22) and grown under controlled conditions in a glasshouse. The plants were infected with Pst one-week post-germination, followed by weekly harvesting of leaf material. Subsequent metabolite extraction was carried out for analysis on a UHPLC-HDMS system for data acquisition. The data was chemometrically processed to reveal the underlying trends and data structures as well as potential signatory biomarkers for priming against Pst. Results showed notable metabolic reprogramming in primary and secondary metabolism, where the amino acid and organic acid content of primed-control, primed-challenged and non-primed-challenged plants were differentially reprogrammed. Similar trends were observed from the secondary metabolism, in which primed plants (particularly primed-challenged) showed an up-regulation of phenolic compounds (flavonoids, hydroxycinnamic acids-HCAs- and HCA amides) compared to the non-primed plants. The metabolomics-based semi-quantitative and qualitative assessment of the plant metabolomes revealed a time-dependent metabolic reprogramming in primed-challenged and primed-unchallenged plants, indicating the metabolic adaptations of the plants to stripe rust infection over time.

Plant diseases are still the main problem for the reduction in crop yield and a threat to global food security. Additionally, excessive usage of chemical inputs such as pesticides and fungicides to control plant diseases have created another serious problem for human and environmental health. In view of this, the application of plant growth-promoting rhizobacteria (PGPR) for controlling plant disease incidences has been identified as an eco-friendly approach for coping with the food security issue. In this review, we have identified different ways by which PGPRs are capable of reducing phytopathogenic infestations and enhancing crop yield. PGPR suppresses plant diseases, both directly and indirectly, mediated by microbial metabolites and signaling components. Microbial synthesized anti-pathogenic metabolites such as siderophores, antibiotics, lytic enzymes, hydrogen cyanide, and several others act directly on phytopathogens. The indirect mechanisms of reducing plant disease infestation are caused by the stimulation of plant immune responses known as initiation of systemic resistance (ISR) which is mediated by triggering plant immune responses elicited through pathogen-associated molecular patterns (PAMPs). The ISR triggered in the infected region of the plant leads to the development of systemic acquired resistance (SAR) throughout the plant making the plant resistant to a wide range of pathogens. A number of PGPRs including Pseudomonas and Bacillus genera have proven their ability to stimulate ISR. However, there are still some challenges in the large-scale application and acceptance of PGPR for pest and disease management. Further, we discuss the newly formulated PGPR inoculants possessing both plant growth-promoting activities and plant disease suppression ability for a holistic approach to sustaining plant health and enhancing crop productivity.

Soil salinity, a growing issue worldwide, is a detrimental consequence of the ever-changing climate, which has highlighted and worsened the conditions associated with damaged soil quality, reduced agricultural production, and decreasing land areas, thus resulting in an unsteady national economy. In this review, halo-tolerant plant growth-promoting rhizo-microbiomes (PGPRs) are evaluated in the salinity-affected agriculture as they serve as excellent agents in controlling various biotic-abiotic stresses and help in the augmentation of crop productivity. Integrated efforts of these effective microbes lighten the load of agro-chemicals on the environment while managing nutrient availability. PGPR-assisted modern agriculture practices have emerged as a green strategy to benefit sustainable farming without compromising the crop yield under salinity as well as salinity-affected supplementary stresses including increased temperature, drought, salinity, and potential invasive plant pathogenicity. PGPRs as bio-inoculants impart induced systemic tolerance (IST) to plants by the production of volatile organic compounds (VOCs), antioxidants, osmolytes, extracellular polymeric substances (EPS), phytohormones, and ACCdeaminase and recuperation of nutritional status and ionic homeostasis. Regulation of PGPR-induced signaling pathways such as MAPK and CDPK assists in salinity stress alleviation. The "Next Gen Agriculture" consists of the application of designer crop microbiomes through gene editing tools, for instance, CRISPR, and engineering of the metabolic pathways of the microbes so as to gain maximum plant resistance. The utilization of omics technologies over the traditional approaches can fulfill the criteria required to increase crop yields in a sustainable manner for feeding the burgeoning population and augment plant adaptability under climate change conditions, ultimately leading to improved vitality. Furthermore, constraints such as the crop specificity issue of PGPR, lack of acceptance by farmers, and legal regulatory aspects have been acknowledged while also discussing the future trends for product commercialization with the view of the changing climate. [ABSTRACT FROM AUTHOR]

In order to study the effects of nanoparticles and biofertilizers on chlorophyll fluorescence indices and some physiological traits of triticale (Triticosecale Wittmack) under salinity stress, a factorial experiment was conducted based on a randomized complete block design with three replications in the research greenhouse of Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardebili in 2021. Experimental factors included salinity (non-saline control, 35, and 70 mM NaCl), application of biofertilizers (PGPR) (biofertilizers-free control, application of Azospirilum, Pseudomonas, combined application Azospirilum and Pseudomonas) and nanoparticles foliar application (foliar application with water as control, nano iron oxide foliar application, nano silicon, combined foliar application of nano iron-silicon oxide). The results showed that both application of PGPR and foliar application of nanoparticles under non-saline condition increased quantum yield (64%), maximum fluorescence (69%), variable fluorescence (175%), chlorophyll index (48.1%), leaf nitrogen content (35.3%), leaf relative water content (49.7%) and stomatal conductance (81.4%) and grain yield per plant (44.5%) in comparison with biofertilizers-free and nanoparticles foliar application under 70 mM salt condition. Maximum of minimum fluorescence (178) and electrical conductivity (126) were obtained at the highest salinity level, i.e. 70 mM NaCl. Based on the results of this study, it seems that application of bio fertilizers and nanoparticles foliar application may improve the grain yield of triticale under salinity stress. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of plant growth-promoting rhizobacteria (PGPR) and compost, applied alone or in combination, on tomato resistance to vascular wilt caused by Verticillium dahliae. Improved management of vascular wilt is important for enhanced productivity of greenhouse-grown susceptible tomato plants. The application of compost and PGPR resulted in a reduction in infection parameters compared with untreated plants inoculated with the pathogen, as well as activation of plant defence mechanisms. In the presence of the pathogen, compost application significantly improved the total fresh and dry weights by 97% and 71%, respectively, compared with pathogen-inoculated controls. The combination of compost with PGPR significantly increased chlorophyll fluorescence and stomatal conductance compared with the infected-control. In addition, the combination of compost and PGPR reduced the accumulation of stress markers such as malondialdehyde and hydrogen peroxide by 48% and 77%, respectively, and promoted the activity of antioxidant enzymes. Fruit yield and quality were also significantly improved relative to the control. The results suggest that compost applied alone or in combination with PGPR helps to suppress vascular wilt and to improve the yield and quality of tomatoes. [ABSTRACT FROM AUTHOR]

Plants are frequently exposed to adverse environments during their life span. Among them drought stress is one of the major threats to agricultural productivity. In order to survive in such unstable environment, plants have developed mechanisms through which they recognize the severity of the stress based on the incoming environmental stimuli. To combat the detrimental effects of drought, the plants have evolved various strategies to modulate their physio-hormonal attributes. These strategies that can be modulated by shade and microbes contribute to enhancing tolerance to drought and reducing yield loss. Plant hormones, such as abscisic acid, auxin and ethylene have a major role in the shade- and microbe-associated improvement of drought tolerance through their effects on various metabolic pathways. In this process, the CLAVATA3/EMBRYOSURROUNDING REGION-RELATED 25 peptide has a major role due to its effect on ABA synthesis as shown in our regulatory model. [ABSTRACT FROM AUTHOR]

Combined stressors (high soil salinity and saline water irrigation) severely reduce plant growth and sugar beet yield. Seed inoculation with plant growth-promoting rhizobacteria (PGPR) and/or foliar spraying with silica nanoparticles (Si-NP) is deemed one of the most promising new strategies that have the potential to inhibit abiotic stress. Herein, sugar beet (Beta vulgaris) plants were treated with two PGPR (Pseudomonas koreensis MG209738 and Bacillus coagulans NCAIM B.01123) and/or Si-NP, during two successive seasons 2019/2020 and 2020/2021 to examine the vital role of PGPR, Si-NP, and their combination in improving growth characteristics, and production in sugar beet plants exposed to two watering treatments (fresh water and saline water) in salt-affected soil. The results revealed that combined stressors (high soil salinity and saline water irrigation) increased ion imbalance (K+/Na+ ratio; from 1.54 ± 0.11 to 1.00 ± 0.15) and declined the relative water content (RWC; from 86.76 ± 4.70 to 74.30 ± 3.20%), relative membrane stability index (RMSI), stomatal conductance (gs), and chlorophyll content, which negatively affected on the crop productivity. Nevertheless, the application of combined PGPR and Si-NP decreased oxidative stress indicators (hydrogen peroxide and lipid peroxidation) and sodium ions while increasing activities of superoxide dismutase (SOD; up to 1.9-folds), catalase (CAT; up to 1.4-folds), and peroxidase (POX; up to 2.5-folds) enzymes, and potassium ions resulting in physiological processes, root yield, and sugar yield compared to non-treated controls under combined stressors (high soil salinity and saline water irrigation). It is worth mentioning that the singular application of PGPR improved root length, diameter, and yield greater than Si-NP alone and it was comparable to the combined treatment (PGPR+Si-NP). It was concluded that the combined application of PGPR and Si-NP has valuable impacts on the growth and yield of sugar beet growing under combined stressors of high soil salinity and saline water irrigation. [ABSTRACT FROM AUTHOR]

Ocimum basilicum L. and its derived products are primarily consumed by humans; hence, agrochemical use seems inappropriate for its cultivation. However, farmers are accustomed to using rampant inorganic fertilizers to augment crop productivity, which has unintendedly engendered severe environmental perturbations. Concomitantly, farmers will soon have to confront the challenges of growing crops under suboptimal conditions driven by global climate change. Consequently, to develop a clean, sustainable, and resilient production technology, field experiments spanning over two years (2020 and 2021) were conducted, comprising three biostimulants, viz., vermicompost (0, 4, and 8 Mg ha-1), biofertilizer (uninoculated and inoculated), and liquid seaweed extract (without and at 7 ml L-1) in the Indian western Himalaya for the first time. Soil health indicators, leaf photosynthetic pigments, gaseous exchange, mineral contents, essential oil (EO) quantity, and composition were evaluated. Soil microbial respiration (SMR), microbial biomass carbon (MBC), organic carbon (OC), dehydrogenase (DHA), alkaline phosphatase (ALP), and b-glucosidase activities were increased by 36.23, 83.98, 30.61, 42.69, 34.00, and 40.57%, respectively, when compared with the initial soil status. The net photosynthetic rate (Pn) was significantly increased with the highest (8 Mg ha-1) and moderate (4 Mg ha-1) vermicompost dosages by 13.96% and 4.56%, respectively, as compared with the unfertilized control (0 Mg ha-1). Likewise, the biofertilizer and seaweed extract also enhanced Pn by 15.09% and 10.09%, respectively. The crop's key EO constituents, viz., methyl chavicol and linalool, were significantly improved with the highest and moderate vermicompost rates of 2.71, 9.85%, and 1.18, 5.03%, respectively. Similarly, biofertilization and seaweed application also boosted methyl chavicol and linalool by 3.29, 8.67%, and 1.93, 3.66%, respectively. In both years, significantly higher herbage (8.86 and 11.25 Mg ha-1) and EO yield (113.78 and 154.87 kg ha-1) were recorded with a congregate treatment of the highest vermicompost dose, biofertilizer, and liquid seaweed extract. In conclusion, the integrated use of biostimulants having complementary properties can sustainably maximize the quantity and quality of O. basilicum and concomitantly ameliorate soil health. This study can inspire scientific communities and industries to develop second-generation biostimulant products, delivering better sustainability and resilience for a renaissance in agriculture. [ABSTRACT FROM AUTHOR]

Simple Summary: Wheat is a vital source of food, and its production is increasingly threatened by drought episodes. Moreover, its cultivation under water deficit situations along with zinc deficient soils is a major concern of declined wheat grain quantity and quality. Drought-linked changes in nutrient use efficiency, photosynthetic mechanisms, and chemical composition of wheat plants ultimately led to poorer harvest. Therefore, we aimed to understand the drought-ameliorating and grain nutritional improving effects in wheat by rhizobacteria (Azospirillum brasilense) and ZnO nanoparticles (NPs) under various growth stage-based drought stress episodes. Rhizobacteria colonized the host plant rhizosphere and provided growth promotion and stress amelioration. ZnO NPs were recognized as a potential water and zinc deficiency alleviator, and general growth promoter by triggering nitrogen metabolism, chlorophyll synthesis, membrane integrity, and grain zinc biofortification activities. Physio-biochemical observations indicated significantly higher positive effects under co-application over the sole use of either microbial or nanomaterials. Based on our research, it was concluded that co-applied Azospirillum brasilense and ZnO NPs generally increase wheat productivity under drought episodes with low operational cost to growers. Further, plausible synergistic physiological enhancement by NPs and rhizobacteria interaction may contribute towards sustainable wheat crop management under abiotic stresses. Drought is a major abiotic factor and affects cereal-based staple food production and reliability in developing countries such as Pakistan. To ensure a sustainable and consistent food supply, holistic production plans involving the integration of several drought mitigation approaches are required. Using a randomized complete block design strategy, we examined the drought-ameliorating characteristics of plant growth-promoting rhizobacteria (PGPR) and nanoparticles (NPs) exclusively or as a combined application (T4) through three stages (D1, D2, and D3) of wheat growth (T1, control). Our field research revealed that Azospirillum brasilense alone (T2) and zinc oxide NPs (T3) improved wheat plant water relations, chlorophyll, proline, phenolics and grain quality, yield, and their allied traits over the stressed treatments. Specifically, the best outcome was observed in the combined treatment of PGPR and ZnO NPs (T4). Interestingly, the combined treatment delivered effective drought mitigation through enhanced levels of antioxidants (15% APX, 27% POD, 35% CAT, 38% PPO and 44% SOD) over controls at the grain-filling stage (GFS, D3 × T1). The 40% improvements were recorded under the combined treatment at GFS over their respective controls. Their combined usage (PGPR and ZnO NPs) was concluded as an effective strategy for building wheat resilience under drought, especially in arid and semi-arid localities. [ABSTRACT FROM AUTHOR]

While horticulture tools and methods have been extensively developed to improve the management of crops, systems to harness the rhizosphere microbiome to benefit plant crops are still in development. Plants and microbes have been coevolving for several millennia, conferring fitness advantages that expand the plant's own genetic potential. These beneficial associations allow the plants to cope with abiotic stresses such as nutrient deficiency across a wide range of soils and growing conditions. Plants achieve these benefits by selectively recruiting microbes using root exudates, positively impacting their nutrition, health and overall productivity. Advanced knowledge of the interplay between root exudates and microbiome alteration in response to plant nutrient status, and the underlying mechanisms there of, will allow the development of technologies to increase crop yield. This review summarizes current knowledge and perspectives on plant–microbial interactions for resource acquisition and discusses promising advances for manipulating rhizosphere microbiomes and root exudation. [ABSTRACT FROM AUTHOR]

In this study, a hydroponic experiment was performed to investigate the effects of exogenous methyl jasmonate（MeJA） and plant growth promoting rhizobacteria（Sphingomonas sp.D36） on cadmium toxicity and cadmium accumulation of tomato plants. The results showed that MeJA,D36 alone or their combination significantly alleviated the Cd-induced growth inhibition of tomato seedlings, and increased the root length, plant height, fresh weight and dry weight of tomato plants, especially that Cd+MeJA+D36 increased the dry weight of aboveground and underground parts by 35.54% and 44.62%,respectively.Cd+MeJA+D36 inoculation increased photosynthetic pigment content in tomato leaves and decreased malonyldialdehyde level in tomato roots as compared with Cd-stressed plants（p<0.05）.Meanwhile, the activities of SOD and APX increased by 28.17% and 44.89% in the underground part, and the activities of POD increased by 25.58% in the aboveground part. In addition, the Cd content in roots, stems and leaves decreased by 18.57%,15.49% and 44.80%,respectively.Taken together, the results showed that MeJA and D36 could alleviate the Cd toxicity in tomato plants by enhancing antioxidant response and decreasing the uptake of Cd.This study provids theoretical basis and practical guidance for applying MeJA and plant growth promoting rhizobacteria to alleviate heavy metal stress in tomato plants, it also provid a basis for establishing a way of using plant growth regulators and bacteria to control heavy metal toxicity. [ABSTRACT FROM AUTHOR]

【Objective】The present study aimed to investigate the effects of different PGPR containing ACC deaminase on double-flower lily ‘Double Surprise’, which would provide theoretical support for the rational application and development of strains as additively in fertilizers. 【Method】A pot experiment was conducted to study the effects of different PGPR that produce ACC deaminase on double-flower lily ‘Double Surprise’ by measuring plant height, stem diameter, flowering period antioxidase activity. 【Result】G Qiao W6 strain was the best strain tested in promoting the plant height, 13.12% higher than that of CK and reached extreme significant difference with CK (P<0.05); M Sa W11 strain was the best strain tested in promoting the stem diameter, 3.66% higher than that of CK and had a significant difference with CK (P<0.05); F strain had the best effect on increasing leaf area, prolonging single flower period and whole plant flowering period, reducing ethylene release content, 57.17%, 16.19%, 11.45% and 74.23% higher than that of CK, and all reached significant differences with CK (P<0.05); Sn-2 strain was the best strain tested in increasing the number of flower buds, 19.06% higher than that of CK and had a significant difference with CK (P<0.05); G Ka Wa strain was the best effect on improving the diameter of bulbs and the activities of SOD and POD. The diameter of bulbs was 23.01% longer than that of CK and reached a significant difference with CK (P<0.05); XG strain was the best effect on increasing the weight of bulb and reducing the content of MDA. The weight of bulbs was 74.23% higher than that of CK and reached extreme significant difference with CK (P<0.05). The weight of bulbs was significantly negatively correlated with plant height, and extremely significantly negatively correlated with the flowering period of a single flower and the whole plant; Ethylene was negatively correlated with leaf area; The florescence of the whole plant was positively correlated with that of a single flower. 【Conclusion】F strain had the best growth promoting effects on double-flower lily ‘Double Surprise’ and the higher the plant height and the longer the flowering period, the smaller the weight of the bulbs; The larger the leaf area, the greater the ethylene release. [ABSTRACT FROM AUTHOR]

The population growth is one of the most important global problems that researchers must overcome. So, application of plant growth promoting rhizobacteria (PGPR) can play a significant role in enhancing the agricultural production through facilitating water and nutrient uptake for plants under various conditions as an important and alternative strategy to overcome overpopulation all over the world. Plant growth promoting rhizobacteria can used as low-cost and environmentally safe biofertilizer to improve crop growth and development by regulating hormonal balance, maintaining nutrients and producing plant growth regulators, however, the chemical fertilizers can harm the ecosystem and human health severely. PGPR treatments may positively affect physiological, biochemical and anatomical features resulting in improve various morphological characters such as number of leaves, leaf area and stem height. Additionally, chlorophyll a and b, carotenoids, relative water content (RWC), antioxidant enzymes and plant hormones as well as crop yield were increased in many plants with the application of PGPR. Moreover, application of PGPR led to improve the anatomical characters of stems and leaves such as stem diameter, lamina thickness, phloem thickness, xylem vessels diameter and number of xylem vessels. Previous studies also reported that PGPR can mitigate the adverse effects of several biotic and abiotic stresses resulted in improve plant growth and yield in many stressed plants. This review article gives an overview on the impacts of PGPR in enhancing morphological, physio-biochemical and anatomical characters through improving the antioxidant enzymes activity, producing plant hormones and consequently crop production. [ABSTRACT FROM AUTHOR]

Wheat root rot, caused by Bipolaris sorokiniana , is a significant and extensive soilborne disease. Streptomyces sp. NEAU-KT41 was isolated from healthy wheat root soil and possessed strong antifungal activity against B. sorokiniana. Findings from the pot test indicated that strain NEAU-KT41 (108 CFU/mL) and its 10 % cell-free culture filtrate had significant biocontrol efficiency against wheat root rot, with 66.67 % and 64.4 %, respectively, resulting in significant increases in biomass and chlorophyll content. For 108 CFU/mL spore suspension, the plant height increased by 167.52 %; root length by 141.64 %, fresh weight by 65 %, chlorophyll a by 13.43 %, and chlorophyll b by 51.02 % under disease stress. For the 10 % cell-free culture filtrate, the plant height increased by 21.93 %, root length by 17.92 %, dry weight by 29.35 %, chlorophyll a by 17.92 %, and chlorophyll b by 82.15 % under disease stress. Moreover, strain NEAU-KT41 could produce proteases, amylases, lipases, and ACC deaminase, and had the ability to decompose organic phosphorus and fix nitrogen. The cell-free culture filtrate affected B. sorokiniana in several manners, including increasing the cell membrane permeability, diminishing the soluble protein content in the mycelia, impeding conidia germination and germ tube extension, and affecting B. sorokiniana invasion of plants. Briefly, Streptomyces sp. NEAU-KT41 is a prospective biocontrol agent that can be used to manage root rot in wheat and has potential applications. • Streptomyces sp. NEAU-KT41 possessed strong antifungal activity against B. sorokiniana. • Strain NEAU-KT41 and its cell-free culture filtrate had significant biocontrol effect on wheat root rot. • Strain NEAU-KT41 and its cell-free culture filtrate increased the biomass and chlorophyll content of plants. • Strain NEAU-KT41 produced a variety of hydrolase, decomposed organic phosphorus and fixed nitrogen. • The cell-free culture filtrate affected the cell membrane permeability of B. sorokiniana and impeded the infection. [ABSTRACT FROM AUTHOR]

A 7-month glasshouse study was conducted to assess the growth responses, nutrient status, and non-enzymatic antioxidant properties of E. guineensis seedlings grown on infertile Ultisol which were subjected to different combinations of chemical fertilizers (CF) and commercial biofertilizer (IBG) as follows: [T1] 100% CF [T2] 70% CF + 30% IBG biofertilizer [T3] 50% CF + 50% IBG biofertilizer [T4] 70% CF only and [T5] Absolute Control. A combination of CF70 and IBG30 led to 15.8% increase in the growth of seedlings as compared to CF100, presenting significantly higher fresh shoot and root weights as well as an ideal root-to-shoot ratio. Absolute control seedlings on the other hand, showed less desirable phenotypical traits across all the observed parameters. Significantly higher levels of relative chlorophyll were recorded for the seedlings treated with CF70 + IBG30, which positively correlated with the chlorophyll a /b ratio. Moreover, the biofertilizer and chemical fertilization allowed increased uptake of nutrients where higher uptake of B and P was positively correlated (p < 0.05) with enhanced frond production, while larger roots mass was associated with primary growth traits. The positive impacts of the combined IBG biofertilizer and chemical fertilizer application were likely attributed to enhanced accumulation of non-enzymatic antioxidants to counteract the effects of soil infertility, with seedlings in CF70 + IBG30 mostly recorded the highest phenolic, anthocyanin, flavonoid, photosynthetic pigments, DPPH radical activity and proline levels. • Combined application of chemical and biofertilizer improves oil palm seedlings growth. • 30% biofertilizer can complement 70% chemical fertilizer addition. • Higher P, K, Mg, and Ca uptake by seedlings was observed in CF70 + IBG30. • A correlation was observed between B and P uptake and fronds production. • TPC, TAC, TFC, AsA and proline were found higher in bio-chemical fertilized seedlings. [ABSTRACT FROM AUTHOR]

Clonal plantation involves the rooting of cuttings from superior genotypes selected for their hybrid vigor and desired qualities. However, the cuttings of some Eucalyptus species and their hybrid genotypes present difficulties in their rooting capacity. Applying PGPR to cutting growth medium as a root stimulating agent has not been extensively studied for Eucalyptus tree species. We aimed to assess the rooting capacity of cuttings taken from two poor-rooting Eucalyptus hybrid clones of E. grandis × E. nitens through the application of PGPR in nursery trials. Seven rhizospheric bacterial species that demonstrated the ability to produce indole-3-acetic acid and to solubilise phosphate were used to prepare two rhizospheric consortium inoculums in which Pseudomonas-Bacillus strains and non-Pseudomonas-Bacillus were grouped. Inoculums were tested for their rooting stimulating capacity on cuttings of the hybrids GN 018B and GN 010 and compared to the nursery standard indole-3-butyric acid. A total of 320 cuttings were treated. Both hybrid clones demonstrated significant (p < 0.0001) genotype differences for all three growth responses, i.e., total, root, and shoot length. Cuttings of both hybrids demonstrated high survival rates and rooting percentage. Although several rooting architectural configurations were prevalent, the Pseudomonas-Bacillus consortium promoted adventitious root development and fibrosity in GN 018B hybrids.