Plant Growth-promoting Rhizobacteria Treatments Research Articles

Plant growth-promoting rhizobacteria modulate induced corn defense against Spodoptera litura (Lepidoptera: Noctuidae).

Common cutworm, Spodoptera litura is an important pest of corn causing significant crop yield loss. Synthetic insecticides have mostly been used to combat this pest, raising human and environmental health concerns. Plant-growth promoting rhizobacteria (PGPR) could compensate for or augment the harmful effects of agrochemicals. Herein, we aimed to assess whether PGPR-induced defenses in corn plants impact the host-plant selection behavior of S. litura. Headspace volatile organic compounds (VOCs) were analyzed using Gas chromatography-mass spectrometry (GC-MS). Larvae fed inoculated corn exhibited lower weights and RGR than non-inoculated plants. Under choice experiments, PGPR-treated plants significantly reduced percentage leaf damage area and oviposition rate compared to untreated plants. VOC ratio emission varied significantly between control and PGPR treatments, which, in part, explains feeding and oviposition deterrence in PGPR-treated plants. The results demonstrate that PGPR inoculation can enhance corn resistance to S. litura, making it a promising candidate for crop protection strategies.

The Potential of Burkholderia sp. from Zea mays Roots as Plant Growth Promoting Rhizobacteria

Plant Growth-Promoting Rhizobacteria (PGPR) plays a crucial role in enhancing plant health, while Burkholderia sp. has been identified and has potential as a promising PGPR for maize plants. Recognizing the essential role of PGPR in plant health, this study explores how L-TRP addition might improve PGPR performance for better plant growth. Employing a completely randomized design, the study assesses the effects of Burkholderia sp. as PGPR on maize growth across three treatment groups: PGPR with L-TRP, PGPR without L-TRP, and a control group. The evaluation focuses on plant growth metrics, plant hormone production (auxin and gibberellin), and siderophore activity to gauge plant iron availability. Statistical analysis highlights that L-TRP supplementation notably increases auxin production in the PGPR + L-TRP group, surpassing the PGPR without L-TRP and control groups. Although both PGPR treatments elevate gibberellin levels compared to the control, auxin increase is the most significant outcome, indicating no substantial difference in gibberellin levels between the two PGPR groups. Enhanced siderophore production suggests improved iron assimilation for plants. The findings demonstrate that L-TRP supplementation with PGPR, particularly Burkholderia sp., effectively boosts maize growth, primarily through increased auxin and siderophore production. This combination presents a promising strategy for augmenting agricultural yields, especially for maize productivity, by leveraging the synergistic effects of soil microbes and nutrient supplementation.

Interactive effect of ambient and elevated levels of tropospheric ozone, nutrition and PGPR on growth and yield of chickpea (Cicer arietinum)

An experiment was conducted during 2020 and 2021 at ICAR-Indian Agricultural Research Institute, New Delhi, to study the interactive effect of nutrient and PGPR (Plant growth promoting rhizobacteria) on growth and yield of chickpea (Cicer aeritinum L.) cv. Pusa 3043 under ambient and elevated levels of ozone in FAOE (Free air ozone enrichment). A loss of 15–16% in dry matter production was observed under elevated ozone (EO3) when compared to ambient ozone (AO3) conditions. Seed treatment with PGPR was found to compensate for this loss as an increase in seed yield 18–19% was observed over untreated seeds. In terms of seed yield, the PGPR treatments with 75% nitrogen showed significant improvement compared to the recommended dose of fertilizer (RDF) application. A yield increase of 12% and 14% was observed with PGPR like RPAN8 (Anabena laxa) and An-Rh (Anabena torulosa with Mesorhizobium ciceri) (chickpea rhizobium) respectively, suggesting an advantage of an–Rh over RPAN8 under EO3. A combination of both PGPRs outperformed the individual PGPR, showing a 19% yield increase over RDF. This proves the potential of seed treatment with PGPR (RPAN8 and An-Rh) in ameliorating tropospheric ozone-induced stress in chickpea plants.

Enhancing nutrient uptake and grapefruit (Citrus paradisi) growth through soil application of beneficial bacteria (Bacillus spp.)

The term plant growth-promoting rhizobacteria (PGPR) refers to a root-associated bacteria that possesses several benefits for soil and the plant. The increasing demand for sustainable food production necessitates a shift towards agricultural practices that mitigate adverse environmental impacts. Excessive use of chemical fertilizers and pesticides has raised concerns, prompting a surge of interest in harnessing the potential of beneficial soil microorganisms, particularly plant growth-promoting rhizobacteria. This study explores the impact of soil inoculation with PGPR treatments on grapefruit seedlings, including a commercial strain of Bacillus velezensis, a fresh inoculum of Bacillus amyloliquefaciens, a mixture of three selected citrus endophytic Bacillus spp. isolates, inorganic fertilizers, and combinations thereof. The aim was to test their ability to enhance growth and nutrient uptake reducing the input of chemical fertilization. Results indicated that the combination of Bacillus velezensis and inorganic fertilization significantly improved soil nutrient availability and enhanced plant growth, surpassing both negative (water) and positive (inorganic fertilization) controls. Shoot and root system biomass showed significant increases from Bacillus velezensis plus inorganic fertilization compared to other treatments. These findings provide insights into management methods that can reduce chemical inputs while promoting plant productivity. The demonstrated benefits of PGPR on grapefruit seedlings highlight a promising approach for future research and applications in sustainable citrus cultivation.

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

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

Combined Application of Biochar and Plant Growth-Promoting Rhizobacteria Improves Heavy Metal and Drought Stress Tolerance in Zea mays.

Plants are often exposed to multiple stresses, including heavy metals (HM) and drought, which limit the plant growth and productivity. Though biochar or plant growth-promoting rhizobacteria (PGPR) have been widely used for alleviating HM or drought stress in plants, the study of the effects of combined treatment with biochar and PGPR under simultaneous HM and drought stress is limited. This study investigated individual and combined effects of groundnut shell biochar (GS-BC) and PGPR Bacillus pseudomycoides strain ARN7 on Zea mays growth, physiology, and HM accumulation, along with their impact on soil enzymes under HM (Ni and Zn), drought, or HM+drought stress. It was observed that even under HM+drought stress, Z. mays growth, total chlorophyll, proteins, phenolics, and relative water contents were increased in response to combined GS-BC and ARN7 treatment. Furthermore, the combined treatment positively influenced plant superoxide dismutase, ascorbate peroxidase, and catalase activities, while reducing electrolyte leakage and phenolics, malondialdehyde, and proline under HM, drought, or HM+drought stress. Interestingly, the combined GS-BC and ARN7 treatment decreased HM accumulation and the bioaccumulation factor in Z. mays, highlighting that the combined treatment is suitable for improving HM phytostabilization. Additionally, GS-BC increased soil enzymatic activities and ARN7 colonization irrespective of HM and drought stress. As far as we know, this study is the first to illustrate that combined biochar and PGPR treatment could lessen the adverse effects of both HM and drought, suggesting that such treatment can be used in water-deficient HM-contaminated areas to improve plant growth and reduce HM accumulation in plants.

Exploiting the role of plant growth promoting rhizobacteria in reducing heavy metal toxicity of pepper (Capsicum annuum L.).

Microorganisms are cost-effective and eco-friendly alternative methods for removing heavy metals (HM) from contaminated agricultural soils. Therefore, this study aims to identify and characterize HM-tolerant (HMT) plant growth-promoting rhizobacteria (PGPR) isolated from industry-contaminated soils to determine their impact as bioremediators on HM-stressed pepper plants. Four isolates [Pseudomonas azotoformans (Pa), Serratia rubidaea (Sr), Paenibacillus pabuli (Pp) and Bacillus velezensis (Bv)] were identified based on their remarkable levels of HM tolerance in vitro. Field studies were conducted to evaluate the growth promotion and tolerance to HM toxicity of pepper plants grown in HM-polluted soils. Plants exposed to HM stress showed improved growth, physio-biochemistry, and antioxidant defense system components when treated with any of the individual isolates, in contrast to the control group that did not receive PGPR. The combined treatment of the tested HMT PGPR was, however, relatively superior to other treatments. Compared to no or single PGPR treatment, the consortia (Pa+Sr+Pp+Bv) increased the photosynthetic pigment contents, relative water content, and membrane stability index but lowered the electrolyte leakage and contents of malondialdehyde and hydrogen peroxide by suppressing the (non) enzymatic antioxidants in plant tissues. In pepper, Cd, Cu, Pb, and Ni contents decreased by 88.0-88.5, 63.8-66.5, 66.2-67.0, and 90.2-90.9% in leaves, and 87.2-88.1, 69.4-70.0%, 80.0-81.3, and 92.3%% in fruits, respectively. Thus, these PGPR are highly effective at immobilizing HM and reducing translocation in planta. These findings indicate that the application of HMT PGPR could be a promising "bioremediation" strategy to enhance growth and productivity of crops cultivated in soils contaminated with HM for sustainable agricultural practices.

The Impact of Integrated Nutrient Management on Trifolium alexandrinum Varietal Performance in the Indo-Gangetic Plains: A Comparative Yield and Economic Analysis

The importance of selecting an appropriate berseem variety and implementing effective nutrient management practices is crucial for maximizing both the production and economic potential of forage crops. This was clearly demonstrated in a field experiment conducted during the rabi seasons of 2019–2020 and 2020–2021. The experimental setup was a factorial randomized block design incorporating five berseem varieties (Mescavi, HB-1, HB-2, BL-10, and BL-42) and five integrated nutrient management practices: 100% recommended dose of fertilizers (RDF) or NM-1, 75% RDF + plant growth-promoting rhizobacteria (PGPR) or NM-2, 75% RDF + municipal solid waste compost (MSWC) or NM-3, 75% RDF + farmyard manure (FYM) + PGPR or NM-4, and 50% RDF + MSWC + PGPR or NM-5. The objective of the experiment was to evaluate the physio-morphological responses, biomass yield, and economic efficiencies of different berseem varieties under various nutrient management practices. The experimental results highlighted the superior performance of the BL-42 variety in terms of growth and yield attributes compared to the other tested berseem varieties. Specifically, BL-42 showed an enhancement in total green fodder yield by 17.10%, 26.60%, 37.75%, and 28.04% over the varieties BL-10, HB-2, HB-1, and Mescavi, respectively. Moreover, the application of the 75% RDF + FYM + PGPR treatment (NM-4) significantly boosted the total green fodder yield by 13.08%, 14.29%, 34.48%, and 39.02% over the 75% RDF + MSWC, 100% RDF, 75% RDF + PGPR, and 50% RDF + MSWC + PGPR treatments, respectively. In terms of economic returns, BL-42 achieved a significantly higher gross return (GR) and net return (NR) of 194,989 ₹/ha and 145,142 ₹/ha, respectively, compared to the GR and NR of BL-10 (166,512 and 116,665 ₹/ha, respectively). Similarly, the nutrient management practice of 75% RDF + FYM + PGPR recorded the highest GR and NR (191,638 and 137,346 ₹/ha, respectively) compared to the 100% RDF treatment (167,593 and 120,716 ₹/ha, respectively). These findings underscore the critical role of variety selection and tailored nutrient management in optimizing both the yield and economic gains in forage crop cultivation. The significant differences in production and returns highlight the potential of targeted agronomic strategies to enhance the profitability and sustainability of forage farming.

Analyzing Single and Combined Cultures of Plant Growth-Promoting Rhizobacteria Isolates from Afghanistan as a Potential Biofertilizer for Rice Growth and Development

Developing multi-functional, environmentally friendly biofertilizers can help reduce chemical fertilizer usage. This study examined single and combined application effects of four plant growth-promoting rhizobacteria (PGPR) strains: AF124 (Rhizobium daejeonense), AF74 (Enterobacter cloacae), AF96 (Pseudomonas putida), and AF42 (Enterobacter cloacae), isolated from alkaline salt-stressed soils from Afghanistan. Physiological features such as nitrogen (N2) fixation, indole-3-acetic acid (IAA), organic acid production, and P and K solubilization of bacteria in single or combined cultures in vitro were examined. A single application of AF124 and AF74 showed significantly higher IAA production than the combined application of dual, triple, and quadruple PGPR treatments. Regarding acetylene reduction activity, an N2-fixation activity indicator, a single application of AF124 showed the highest value, followed by a triple application of AF124 + AF96 + AF42. The P-solubilization activity and organic acid production were lower in the single application of AF124 but higher with other strains in the combined applications, which resulted in the secretion of multiple organic acids into the medium. The highest solubilized K value was obtained from the quadruple application compared to other treatments. In the rice inoculation test, all single and combined PGPR treatments increased its growth parameters, such as root length and root and shoot dry biomass. The present results indicate that these four PGPR strains can potentially contribute to developing multi-functional bio-fertilizer formulations.

Enhancing the Yield, Quality and Antioxidant Content of Lettuce through Innovative and Eco-Friendly Biofertilizer Practices in Hydroponics

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.

Plant growth promoting rhizobacterium Bacillus sp. BSE01 alleviates salt toxicity in chickpea (Cicer arietinum L.) by conserving ionic, osmotic, redox and hormonal homeostasis.

Soil salinity leading to sodium toxicity is developing into a massive challenge for agricultural productivity globally, inducing osmotic, ionic, and redox imbalances in plants. Considering the predicted increase in salinization risk with the ongoing climate change, applying plant growth-promoting rhizobacteria (PGPR) is an environmentally safe method for augmenting plant salinity tolerance. The present study examined the role of halotolerant Bacillus sp. BSE01 as a promising biostimulant for improving salt stress endurance in chickpea. Application of PGPR significantly increased the plant height, relative water content, and chlorophyll content of chickpea under both non-stressed and salt stress conditions. The PGPR-mediated tolerance towards salt stress was accomplished by the modulation of hormonal signaling and conservation of cellular ionic, osmotic, redox homeostasis. With salinity stress, the PGPR-treated plants significantly increased the indole-3-acetic acid and gibberellic acid contents more than the non-treated plants. Furthermore, the PGPR-inoculated plants maintained lower 1-aminocyclopropane-1-carboxylic acid and abscisic acid contents under salt treatment. The PGPR-inoculated chickpea plants also exhibited a decreased NADPH oxidase activity with reduced production of reactive oxygen species compared to the non-inoculated plants. Additionally, PGPR treatment led to increased antioxidant enzyme activities in chickpea under saline conditions, facilitating the reactive nitrogen and oxygen species detoxification, thereby limiting the nitro-oxidative damage. Following salinity stress, enhanced K+ /Na+ ratio and proline content were noted in the PGPR-inoculated chickpea plants. Therefore, Bacillus sp. BSE01, being an effective PGPR and salinity stress reducer, can further be considered to develop a bioinoculant for sustainable chickpea production under saline environments.

Response of Growth and Yield of Sweet Corn Plants in Rainfed Land to Providing Plant Growth Promoting Rhizobacteria Bamboo Roots

Sweet Corn is an important food crop that functions as a source of food, feed, and industrial raw materials. Efforts to increase corn production require technological input to increase yields and be environmentally friendly. One way is by using Plant Growth Promoting Rhizobacteria (PGPR). This research aims to determine the response of growth and yield of sweet corn plants on rainfed land to the application of PGPR bamboo root plants and to determine the appropriate PGPR concentration for the growth and yield of sweet corn plants. This research was carried out from February to June 2020 in Rantau Panjang, Sambaliung District, Berau Regency. East Kalimantan, Indonesia. The research used a Randomized Completely Block Design (RCBD) consisting of 6 treatments of bamboo root PGPR concentration, namely treatment: p0 = control; p1 = 5.0 ml l-1 water; p2 = 7.5 ml l-1 water; p3 = 10.0 ml l-1 water; p4 = 12.5 ml l-1 water; and p5 = 15.0 ml l-1 water. Each treatment was repeated 4 times. The results of the research showed that: (1) The responses of cob diameter and cob production were significantly different, while the responses of plant height, number of leaves, age at flowering, cob length, and number of rows of seeds per cob were not significantly different to PGPR treatments; and (2) Giving PGPR with a concentration of 10 ml l-1 water (p3) resulted in high cob production, namely 12.80 Mg ha-1.

Perlakuan Air Panas dan Plant Growth Promoting Rhizobacteria untuk Menekan Cendawan Terbawa Benih pada Padi Varietas IPB-3S

Hot Water Treatment and Plant Growth Promoting Rhizobacteria to Suppress Seed-Borne Fungi on Rice Variety IPB-3S
 IPB-3S is a new rice variety which was developed to improve national rice production in Indonesia. This study aimed to determine seed-borne fungi associated with IPB-3S variety and to determine the potential of hot water and PGPR treatment to suppress the fungal infection. The study consisted of five experiments, i.e. seed health test by dry seed observation and by blotter test, pathogenicity test, seed treatment using hot water and plant growth promoting rhizobacteria (PGPR). Seven genera of fungi were found in IPB-3S seeds, namely Aspergillus, Penicillium, Rhizopus, Rhizoctonia, Curvularia, Fusarium and Colletotrichum. All of these fungi are pathogenic based on pathogenicity test. Seed treatment using hot water at 54 ℃ and PGPR reduced fungal infections and increased germination of IPB-3S seeds.

Plant growth promoting rhizobacteria and biochar production from Parthenium hysterophorus enhance seed germination and productivity in barley under drought stress.

Drought stress can significantly affect plant growth and development. Biochar (BC) and plant growth-promoting rhizobacteria (PGPR) have been found to increase plant fertility and development under drought conditions. The single effects of BC and PGPR in different plant species have been widely reported under abiotic stress. However, there have been relatively few studies on the positive role of PGPR, BC, and their combination in barley (Hordeum vulgare L.). Therefore, the current study investigated the effects of BC from Parthenium hysterophorus, drought tolerant PGPR (Serratia odorifera), and the combination of BC + PGPR on the growth, physiology, and biochemical traits of barley plants under drought stress for two weeks. A total of 15 pots were used under five treatments. Each pot of 4 kg soil comprised the control (T0, 90% water), drought stress alone (T1, 30% water), 35 mL PGPR/kg soil (T2, 30% water), 2.5%/kg soil BC (T3, 30% water), and a combination of BC and PGPR (T4, 30% water). Combined PGPR and BC strongly mitigated the negative effects of drought by improving the shoot length (37.03%), fresh biomass (52%), dry biomass (62.5%), and seed germination (40%) compared to the control. The PGPR + BC amendment treatment enhanced physiological traits, such as chlorophyll a (27.9%), chlorophyll b (35.3%), and total chlorophyll (31.1%), compared to the control. Similarly, the synergistic role of PGPR and BC significantly (p< 0.05) enhanced the antioxidant enzyme activity including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) to alleviate the toxicity of ROS. The physicochemical properties (N, K, P, and EL) of the soils were also enhanced by (85%, 33%, 52%, and 58%) respectively, under the BC + PGPR treatment compared to the control and drought stress alone. The findings of this study have suggested that the addition of BC, PGPR, and a combination of both will improve the soil fertility, productivity, and antioxidant defense systems of barley under drought stress. Therefore, BC from the invasive plant P. hysterophorus and PGPR can be applied to water-deficient areas to improve barley crop production.

Sub-optimal nutrient regime coupled with Bacillus and Pseudomonas sp. inoculation influences trichome density and cannabinoid profiles in drug-type Cannabis sativa.

Cannabis sativa remains under heavy legal restriction around the globe that prevents extensive investigations into agricultural applications for improving its development. This work investigates the potential of specific plant growth-promoting rhizobacteria (PGPR) to improve Cannabis cannabinoid yield through increased trichome densities on floral organs, and to determine if sub-optimal environmental conditions would affect the outcomes of PGPR presence by altering plant development and cannabinoid profiles. Here, Pseudomonas sp. or Bacillus sp. were applied to the root system either separately or in a consortium to determine the effect of this bacterial treatment on the density of stalked glandular trichomes. Further, a low nutrient regime was applied for the first half of plant development to determine if an environmental stressor interacts with the effects of the microbial treatments on stalked trichome densities. Following 8 weeks of flower development, trichome density on calyces and bracts of inflorescences were determined using microscopy. Our findings unexpectedly indicate that recommended nutrient levels were linked to a decreasing trend in trichome densities with PGPR inoculations, but a low nutrient regime coupled with PGPR treatment increased them. Cannabinoid content is partially consistent with these results, in that a low nutrient regime increased the abundance of key cannabinoids compared to recommended regimes, with Bacillus sp. inoculation linked to the greatest number of significant changes between the two nutrient regimes. Overall, this work provides insight into how PGPR presence affects Cannabis stalked trichome development and cannabinoid profiles, and how environmental stressors can affect, and even enhance, trichome densities and influence major cannabinoid production, thereby pointing towards avenues for reducing the reliance on synthetic fertilizers during plant production without compromising yield.

Pre-Harvest Application of Aminoethoxyvinylglycine, Salicylic Acid and Plant Growth Promoting Rhizobacteria on Fruit Quality of ‘Sweetheart’ Sweet Cherry

Sweet cherry, which affects consumers’ preferences with its aroma, taste and sensory properties, is a significant fruit species for human health with its bioactive compounds such as organic acids, vitamins and anthocyanins. However, its post-harvest shelf life is very short due to its sensitive fruit structure. Thus, the significant economic losses occur. In the study, effects of pre-harvest Aminoethoxyvinylglycine (AVG), Salicylic acid (SA) and plant growth promoting rhizobacteria (PGPR) applications on fruit quality characteristics and biochemical content in sweet cherry were determined. SA and PGPR treatments increased fruit size, but AVG decreased (If the fruit weight is 4.51 in the control application, 4.49 in the SA application and 4.10 in the PGPR, how can it be said that SA and PGPR increase the fruit weight). The fruits treated with SA, AVG and PGPR had higher fruit firmness values than the control’-fruits. Salisylic acid treatmens did not affect the rate of soluble solids content(SSC) in fruit, SSC rate was higher in PGPR treated-fruit, but AVG decreased the SSC. Titratable acidity (TA) was lower in PGPR treated-fruit, but was higher in the AVG and SA treated-fruit. Fruits treated with the SA and AVG had higher fruit color values than control fruits, while the lowest color values was obtained with PGPR treatment. In general; PGPR, SA and AVG were effective in the concentration of organic acids, but their effects varied depending on the organic acid compounds. As a result, AVG and SA delayed fruit ripening and fruit softening while PGPR, AVG and SA improved fruit quality (It is not clear how this idea was reached). These applications can be considered as a promising method for improving fruit quality at harvest and maintaining post-harvest fruit quality of sweet cherry.

Pengaruh Dosis Pupuk Kandang dan Konsentrasi Plant Growth Promoting Rhizobacteria (PGPR) Terhadap Pertumbuhan dan Hasil Tanaman Kedelai (Glycine max L.)

Soybean is one of the potential food crops that has a high vegetable protein content, which is around 40%. The aim of this study was to obtain an optimal combination of manure dose and PGPR (Plant Growth Promoting Rhizobacteria) concentration on the growth and yield of soybean (Glycine max L.). The study used a randomized block design (RBD) with two factors repeated three times. The first factor is the dose of manure: K1 = 0 tons ha-1, K2 = 10 tons ha-1, and K3 = 20 tons ha-1. The second factor was the concentration of PGPR, namely P0 = 0 ml l-1, P1 = 5 ml l-1, P2 = 10 ml l-1, and P3 = 15 ml l-1. The results showed that there was no interaction between the treatment dose of manure and the PGPR concentration. Separately, the treatment dose of manure and concentration of PGPR had a significant effect on the parameters of plant height, number of leaves, stem diameter, leaf area, plant dry weight, number of productive nodes, number of pods per plant, percent of filled pods, dry seed weight, and weight of 100 seeds. The dose of manure 20 tons ha-1, was able to increase the dry seed yield to 21.42 g plant--1 and 2.91 tons ha-1, and the weight of 100 seeds was 30.49 g plant-1. While the application of PGPR with a concentration of 15 ml l -1 resulted in a dry seed weight of 21.11 g plant-1 and 2.93 tons ha-1 and a weight of 100 seeds of 30.09 g plamt-1, which was higher than without PGPR treatment.

Utility of Plant Growth-Promoting Rhizobacteria for Sustainable Production of Bermudagrass Forage.

A two-year study was conducted in bermudagrass hay fields in central Alabama to estimate the potential of plant growth-promoting rhizobacteria (PGPR) as a tool for sustainable agriculture in forage management. This study compared the effects of two treatments of PGPR, applied with and without lowered rates of nitrogen, to a full rate of nitrogen fertilizer in a hay production system. The PGPR treatments included a single-strain treatment of Paenibacillus riograndensis (DH44), and a blend including two Bacillus pumilus strains (AP7 and AP18) and a strain of Bacillus sphaericus (AP282). Data collection included estimates of forage biomass, forage quality, insect populations, soil mesofauna populations, and soil microbial respiration. Applications of PGPR with a half rate of fertilizer yielded similar forage biomass and quality results as that of a full rate of nitrogen. All PGPR treatments increased soil microbial respiration over time. Additionally, treatments containing Paenibacillus riograndensis positively influenced soil mesofauna populations. The results of this study indicated promising potential for PGPR applied with lowered nitrogen rates to reduce chemical inputs while maintaining yield and quality of forage.

Role of PGPR and silver nanoparticles on the physiology of Momordica charantia L. irrigated with polluted water comprising high Fe and Mn

The current investigation designed to estimate the bioremediation potential of plant growth-promoting rhizobacteria (PGPR) and Ag-nanoparticles. Tube well and HIT water comprising Mn and Fe above recommended values were used as treatments while tap water irrigation was treated as control. The HIT water showed 24, 200, and 64.11% higher content of Na, K Ca over control. Seeds were sterilized in 95% ethanol and soaked for 3 h before sowing in 73 h old culture of Pseudomonas stutzeri (Kx574858) @ 108 cells/ml. Phytotoxic effect of Fe and Mn reduce plant biomass and suppress photosynthetic activity indicates. The carotenoids, proline, and proline activity were 366, 450, and 678% higher in tube well water with combined PGPR and Ag-nanoparticles treatments. Pseudomonas stutzeri was more effective than Ag-nanoparticles to reduce oxidative stress with higher production of carotenoids, flavonoids, proline content, and enzyme SOD and CAT activities in HIT water. It is contingent that the high Mn and Fe bearing waste water enhance PGPR bioremediation potential to reduce metal stress in plants with synergistic action of PGPR and organic matter to alleviate oxidative stresses under metal stress. The residual effect of P. stutzeri on organic matter content of the rhizosphere soil and germination rate was higher for Momordica charantia L.

Plant Growth Promoting Rhizobacteria (PGPR) and Arbuscular Mycorrhizal Fungi Combined Application Reveals Enhanced Soil Fertility and Rice Production

Rice (Oryza sativa L.) is an important crop that is grown worldwide to supply the world’s expanding food demand. In the current study, the effects of plant growth-promoting rhizobacteria (PGPR) and Arbuscular mycorrhizal fungi (AMF) on soil fertility and rice growth were explored. Rice plants were inoculated to evaluate how AMF fungi and PGPR affect various aspects of soil and plants, implicating abiotic stress tolerances. The experiment was carried out in a completely randomized design with three replicates under the controlled conditions. Results depicted that the plants that were inoculated with a mixture of AMF and PGPR had better yields and nutritional concentrations, while both AMF and PGPR lowered soil pH and organic matter differently. Similarly, AMF and PGPR treatments significantly increased the amount of N, P, K, and B in the post-harvest soil. The PGPR-inoculated plants had a 10–40% higher buildup of N in their tissues. Similarly, when they were compared with non-infected plants, AMF-inoculated treatments demonstrated a greater N accumulation in the rice tissue. The maximum P content in plant tissues was 0.149% in PGPR5-infected plants, either alone or in combination with AMF. In T12, AMF + PGPR5 inoculated rice plants, the maximum K uptake was 1.98%, which was 54% higher than the control treatment. The sole application of AMF raised K buildup in rice tissues by 38% compared with the control treatment. The improved productivity of plants with AMF and PGPR (especially with PGPR5) was attributed to the increased availability of nutrients in the soil. As a result, rice plant growth, yield, and essential element uptakes were boosted significantly. The present study’s results suggested using the combined application of AMF + PGPR5 for improving the rice yield and for sustaining the soil health.