Azospirillum Research Articles

Microalgae–bacteria interaction: a catalyst to improve maize (Zea mays L.) growth and soil fertility

AbstractBiofertilisers harbouring living organisms hold allure due to their prospective favourable influence on plant growth, coupled with a diminished environmental footprint and cost-effectiveness in contrast to conventional mineral fertilisers. The purpose of the present study was to evaluate the capacity of a specific microalga (MACC-612, Nostoc linckia) biomass and plant growth-promoting bacteria (PGPB) separately and together to improve crop growth and promote soil health. The research used a factorial design within a completely randomised block framework, featuring four replications for three consecutive years across different fields. The experiment utilised three levels of microalga (control, 0.3 g/L of N. linckia, MACC-612, and 1 g/L of N. linckia, MACC-612) and three levels of bacterial strains (control, Azospirillum lipoferum and Pseudomonas fluorescens). The result demonstrated that the use of N. linckia and PGPB separately or jointly as soil treatment resulted in a substantial improvement in chlorophyll, plant biomass, soil humus, and nitrogen, depending on the environmental conditions of the years. The combined use of N. linckia and PGPB results in an improvement in dry leaf weight by 35.6–107.3% at 50 days after sowing (DAS) and 29.6–49.8% at 65 DAS, compared to the control group. Furthermore, the studies show that the synergistic application of N. linckia at 0.3 g/L, in conjunction with A. lipoferum, significantly improved total nitrogen and (NO3− + NO2−)-nitrogen, registering increases of 20.7–40% and 27.1–59.2%, respectively, during the study period. The most effective synergistic combination was identified through the application of 0.3 g/L of N. linckia along with A. lipoferum. Hence, application of biofertilisers through synergistic combinations of two or more microorganisms, such as microalgae and bacteria, holds promise in improving crop chlorophyll, growth, and soil nitrogen.

Nutritional enhancement in black seed (Nigella sativa L.) using bacteria‐based biofertilizers

AbstractNigella sativa L. is an aromatic spice, utilized as an original and peculiar flavoring ingredient in a variety of culinary applications and pharmaceuticals. Black seed (Nigella sativa L.) belongs to the family Ranunculaceae. It is an undercultivated crop in Pakistan. The present study was planned keeping in mind sustainable development goals SDG 3 (good health and well‐being) and SDG 15 (life on land). The effects of several rhizospheric bacterial strains and synthetic fertilizers on the development of N. sativa and nutrition were studied using a completely randomized experimental design. For this purpose, plant growth‐promoting effects of different strains (Azospirillum brasilense, Azospirillum lipoferum, and Pantoea agglomerans) and synthetic fertilizers (nitrogen and phosphorus) were assembled to check their effects individually and in combination form. Azospirillum lipoferum and Pantoea agglomerans inoculation significantly enhanced the morphological characteristics of N. sativa, whether applied individually or in combination, with positive effects on seedlings, plant height, number of branches, number of leaves, number of flowers, stamens numbers, follicles number, number of tentacles and seed production. N. sativa plants that were simultaneously inoculated with Azospirillum lipoferum and Pantoea agglomerans showed the highest potential for antioxidant activity, particularly in petroleum ether extracts. In the methanolic extract, a higher amount of radical scavenging was observed as compared to positive and negative control. There was also increase in fat, moisture and carbohydrate contents of the combination inoculated plant. So, from the present study, in Pakistan, the technique is recommended to enhance the yield and nutritional value of N. sativa.

Effects of biofertilizer on the production of bell pepper (Capsicum annuum L.) in greenhouse

Biological fertilizers are useful sources of plant nutrients that enhance crop growth and quality, produce plant hormones, and contribute to sustainable crop production by maintaining soil fertility. The effect of arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPRs) applications in greenhouses on bell pepper (Capsicum annuum L. Nervin) has been studied by conducting a split plot experiment in three replications using a randomized complete block design. The biofertilizers included AMF inoculations (Rhizophagus irregularis + Funneliformis mosseae), and three different bacterial inoculations (Azotobacter chroococcum + Azospirillum lipoferum; Enterobacter cloacae + Pseudomonas putida; Bacillus subtilis + Bacillus amyloliquefaciens) and non-inoculation as a control with two levels of organic fertilizers (with and without).The organic treatment fertilizer, in combination with the inoculation of E. cloacae + P. putida or A. chroococcum + A. lipoferum, as well as AMF, significantly increased the microbial population within the rhizosphere compared to the control. In all treatments, fruit yield increased, with the highest value (15.94 kg m−2) recorded in the AMF treatment, indicating an increase of 18% over the control. All inoculations significantly increased total phenol and ascorbic acid levels in fruit when organic fertilizer was applied. The most significant N uptake was observed in A. crococcum + A. lipoform inoculation, while the most significant Fe uptake was observed in AMF. It was found that all inoculations significantly increased P, K, and Zn uptake. In conclusion, A combination of organic fertilizer and mycorrhizal or (Azotobacter chroococcum + Azospirillum lipoferum) inoculations increased the productivity and quality of bell peppers grown in greenhouses.

Energy and Economic Efficiency of Integrated Nutrient Management (INM) under Upland Paddy Cultivation at High Elevations of North-East India

Background: The study looks at integrated nutrient treatments’ energy requirements and the link between energy input and output and economic benefits. The experiment was conducted during 2019 to 2020 to compare the energy budget and monetary returns under INM modules in upland paddy. Methods: A total of 12 organic, inorganic and INM modules were evaluated employing randomised block design. Fertilizers, organic manures, bio-fertilizers viz., Azospirillum lipoferum, phosphorus solubilizing bacteria, potassium mobilizing bacteria, Glomus and zinc solubilizing bacteria were used. Result: Energy output and net energy were highest with INM treatments (T10 - 100% recommended doses of fertilizers (RDF) + Farm Yard Manure + Azospirillum lipoferum + PSB + KMB + Glomus + ZnSB), while energy use efficiency, energy productivity and energy efficiency ratio were highest in control (T1) in 2019 and in 2020 recorded the highest in T11 (Azospirillum lipoferum + PSB + KMB + Glomus + ZnSB). Other treatments, except T11 and T12 - FYM + Azospirillum lipoferum + PSB + KMB + Glomus + ZnSB, were at par. Although in T10 benefit cost ratio was lower than T9 (100% of RDF + Azospirillum lipoferum + PSB + KMB + Glomus + ZnSB), T10 produced maximum returns than other treatments. Due to its high returns, despite the need for non-renewable resources and low energy use efficiency, integration of various soil amendments were significant for maintaining production sustainability. However, long term experimentation needed to ascertain the overall benefit of INM practices in upland paddy in hilly regions of North East India.

Isolation of Azospirillum spp and Evaluation of its Plant Growth Promoting Abilities

Background: This study aimed to isolate Azospirillum species from the soil environment and assess their plant growth-promoting abilities. Soil samples were collected from 10 different agricultural sites. The bacteria were isolated by serially diluting the soil samples and each aliquot was transferred into a Nitrogen-free bromothymol blue medium and then incubated for 7 days at 37°C. The isolates were further screened based on their morphological, biochemical and plant growth phytohormone production. The Fourier Transform Infrared Spectrophotometer will be used to elucidate the functional groups present in the isolates. Furthermore, the isolates were subjected to molecular identification. The results showed that Seventeen (17) bacteria were isolated from the soil samples of different crop plants using nitrogen-free bromothymol blue medium with all forming a white subsurface pellicle and they were further screened to seven (7) isolates, based on their morphological, biochemical, and plant growth phytohormones production characteristics, they include A1, A2, A3, A4, A5, A6 and A7. Three of the isolates (A1, A3, and A6) were randomly selected for molecular identification. The Fourier Transform Infrared Spectrophotometer identified the functional groups that are present in the Azospirillum strains to be aromatic compounds. All isolates showed ammonium production potential with A7 having the highest production of 781.3 µg/ml. Only four (4) isolates showed the ability to solubilize Calcium triphosphate with A7 having the highest solubilization (776 µg/ml). Furthermore, all isolates exhibited the ability to produce Indole acetic acids in the growth medium with A6 having the highest production (798.5 µg/ml). The molecular analysis and the sequence analysis of the three isolates 16SrRNA showed two of the isolates to be Azospirillum brasilense (A1, A3) and the other Azospirillum lipoferum (A6). Therefore, this study shows that this strain of Azospirillum has a high ability to produce Indole Acetic Acids, which aids in the production of phytohormones such as Auxins, Solubilize Calcium triphosphate and hence proffer a sustainable solution to improving plant growth.

Harnessing the Synergy of the Cyanobacteria-Plant Growth Promoting Bacteria for Improved Maize (Zea mays) Growth and Soil Health

Intensive use of chemicals in agriculture harms the soil, disrupts the ecological balance, and impacts microorganisms. Biofertilizers are gaining traction due to their eco-friendly and cost-effective benefits. This study evaluates the potential of the cyanobacterium MACC-612 (Nostoc piscinale) and plant growth-promoting bacteria (PGPB) (Azospirillum lipoferum, Pseudomonas fluorescens) in enhancing crop growth, yield, and soil health. A two-year field study was conducted using a factorial approach and a completely randomized block design, comprising four replications. The three levels of the cynobacterium (0, 0.3, or 1 g/L of N. MACC-612) and different bacteria strains were used in the experiments. The results demonstrated substantial enhancements in seed number per ear, kernel weight, and yield when using N. piscinale and PGPB, whether used individually or in combination. The soil pH, humus, (NO3− + NO2−)-nitrogen, and soil microbial biomass showed significant increases across both years. The combining application of the N. piscinale (0.3 g/L) with A. lipoferum increased grain yield by 33.20% in the first year and 31.53% in the second. The humus and (NO3− + NO2−)-nitrogen content significantly rose in treatments involving N. piscinale at 0.3 g/L combined with A. lipoferum at about 20.25% and 59.2%, respectively, in comparison to the untreated control. Hence, the most effective approach was the combined use of N. piscinale and A. lipoferum, which enhanced maize growth and soil fertility.

Ecotoxic effect of agriculture and environmental important bioinoculant effective microorganism (EM) derived metabolites on microbial agro active agents

AbstractEffective microorganism (EM) – a mixture of beneficial microbial formulation are extensively utilized worldwide in agriculture as plant growth promotor and biocontrol agent. Because of their wide spectrum usage, it is necessary to study the non‐target effect against the beneficial organisms used in crop production. Though, the wider applications of EM in agriculture and the environment have revealed, the environmental quality management of EM mainly metabolites‐ biochemical compounds derived from EM have yet to be studied. With this objective, the present study is undertaken to evaluate the compatibility of EM derived metabolites on the selected microbial biofertilizers, biocontrol agents including biopesticidal agents. Metabolites were extracted from the culture‐free broth of EM culture using various solvents and the extracted metabolites were characterized by the gas chromatography‐ mass spectroscopy (GC‐MS). The food poisoning technique was adapted for the screening of toxic effects. Toxic effect of the metabolites derived from the respective solvent was confirmed by measuring the growth of the respective microbial strain's vegetative growth and sporulation efficacy by dual plate assay, dual liquid assay, and spore germination microscopic slide assay. Active principles of the metabolites were readily extracted in all the solvents and the possible presence of bioactive metabolites were characterized by GC‐MS. There was no significant difference between the control and extract recorded. In the case of Rhizobium leguminosarum, the colony diameters of ethyl acetate and acetone extract were 1.6 and 1.8 cm, respectively, as in control (1.8 cm). Similar findings were also recorded for Azospirillum lipoferum, Phosphobacterium sp., and Pseudomonas flurescens. However, growth inhibition including spore germination was recorded in petroleum ether and acetone extract. Further study will be useful to exploit the principles of EM and EM derived metabolites in agriculture and environment without affecting non target beneficial organism.

Integrated Action of Rhizobacteria with Aloe vera and Moringa Leaf Extracts Improves Defense Mechanisms in Hibiscus sabdariffa L. Cultivated in Saline Soil.

Osmotic stress is a serious physiological disorder that affects water movement within the cell membranes. Osmotic stress adversely affects agricultural production and sustainability and is largely caused by soil salinity and water stress. An integrated nitrogen-fixing bacteria (NFB) soil amendment and an exogenous foliar application of Aloe vera leaf extract (ALE), and moringa leaf extract (MLE) were evaluated on roselle (Hibiscus sabdariffa L.) growth, calyx yield, secondary metabolites, and tolerance to osmotic stress in salt-affected soil. The osmotic stress markedly decreased above- and below-ground development of the roselle plant, but integrated NFB soil amendment with ALE or MLE foliar application significantly alleviated its negative impacts. Broadly, an improvement was observed in chlorophyll, carbohydrates, and protein levels following NFB and extracts foliar application, as well as a significant enhancement in antioxidant production (total phenols, ascorbic acid, and FRAP), which decreased peroxide production and increased stress tolerance in plants. Under osmotic stress, the roselle calyx revealed the highest anthocyanin levels, which declined following NFB soil amendment and foliar extract application. Additionally, an enhancement in nitrogen (N), phosphorus (P), and potassium (K) contents and the K/Na ratio, along with a depression in sodium (Na) content, was noticed. The integrated application of Azospirillum lipoferum × ALE exhibited the best results in terms of enhancing above- and below-ground growth, calyx yield, secondary metabolites, and tolerance to osmotic stress of the roselle plants cultivated in the salt-affected soil.

Evaluation of Suitable Polymers for the Development of High-Concentrated Liquid Biofertilizers

An improvement in the present liquid formulation of biofertilizer is essential to expand its shelf life and enhance the bioefficacy potential of the inoculated crops. Here, we screened ten different water-soluble polymers for their feasibility as cell protectants in liquid biofertilizers for the duration of three months. The physio-chemical properties and Escherichia coli survival assay experiments identified five potential polymers: hydroxypropyl methylcellulose, polyvinyl alcohol, and natural polymers extracted from seaweed, red algae, and brown algae. These five polymers' aqueous solutions comply with the standard parameters of liquid biofertilizers. Further, these polymers were compared with standard liquid biofertilizer diluting medium (phosphate buffer with glycerol) for the shelf life of two biofertilizer strains, viz., Azospirillum lipoferum (Az204) and Bacillus megaterium var. phosphaticum (Pb1). All the polymers had high cell viability up to 60 days after incubation. In conclusion, the results suggest that these polymers could be effective encapsulating agents to improve the quality of liquid biofertilizers.

Innovative Spring Barley Cultivation Technology Based on the Use of Microbial Products Together with Living Mulch in Organic Farming

Field research was conducted in Poland in 2019–2021 to determine the effect of microbial products and living mulches on grain yield and grain yield structure elements as well as the biological index of soil fertility (BIF) in spring barley grown in organic agriculture. Two factors were examined: I. microbial products: control (no treatment with microbial products), inoculation with phosphorus-releasing bacteria (Bacillus megaterium var. phosphaticum, Arthrobacter agilis), and co-inoculation (simultaneous inoculation) with phosphorus-releasing bacteria (Bacillus megaterium var. phosphaticum, Arthrobacter agilis) and nitrogen-fixing bacteria (Azospirillum lipoferum Br17, Azotobacter chroococcum); II. living mulch: control (no living mulch—spring barley grown in a pure stand), red clover, red clover and Italian ryegrass, and Italian ryegrass. The study results demonstrated that the highest grain yield at 4.5 t ha−1 with superior structure was produced by spring barley following co-inoculation with phosphorus-releasing bacteria (Bacillus megaterium var. phosphaticum, Arthrobacter agilis) and nitrogen-fixing bacteria (Azospirillum lipoferum Br17, Azotobacter chroococcum). The highest value of the biological index of soil fertility (BIF II) determined at the flowering stage was obtained in plots with spring barley cultivated with the living mulch of red clover mixed with Italian ryegrass or red clover following inoculation with phosphorus-releasing bacteria and nitrogen-fixing bacteria 6.9 and 5.7, respectively.

Seed pre-sowing treatments and essential trace elements application effects on wheat performance

Current study was conducted to evaluate the effects of different seed priming and foliar spray of micronutrients on bread wheat performance in semi-arid region in Northwest of Iran. Pre-sowing treatments were S1: no pre-sowing treatment (intact seeds), S2: hydro-priming, S3: bio-priming (seed inoculation with plant promoting rhizobacteria consortium: Azotobacter chroococcum + Azospirillum lipoferum), S4: micronutrient seed priming and foliar feeding include, check (0): distilled water spray, Fe: foliar spray of iron, Zn: foliar spray of zinc. All seed priming treatments significantly increased plant height, tiller number, canopy width, total biomass, spike mass, seed number per spike and seed yield compared to intact seeds. A brief comparison of the effect of seed priming and fertilizer treatments showed that the effects of priming treatments on improving growth and seed yield was more obvious than fertilizer treatments. The greatest increase in seed yield and yield components was recorded for plants grown from bio-fortified seeds by essential trace elements. However, comparison of fertilizer treatments showed that growth parameters were significantly affected by Zn application. From the present study, it may be concluded that combined seed priming through pre-sowing hydration, soaking in micronutrients and microbial inoculation is useful to enhance wheat production and agricultural sustainability for smallholder farmers in semi-arid region.

De novo biosynthesis of 2′-fucosyllactose in a metabolically engineered Escherichia coli using a novel ɑ1,2-fucosyltransferase from Azospirillum lipoferum

Human milk oligosaccharides are complex, indigestible oligosaccharides that provide ideal nutrition for infant development. Here, 2′-fucosyllactose was efficiently produced in Escherichia coli by using a biosynthetic pathway. For this, both lacZ and wcaJ (encoding β-galactosidase and UDP-glucose lipid carrier transferase, respectively) were deleted to enhance the 2′-fucosyllactose biosynthesis. To further enhance 2′-fucosyllactose production, SAMT from Azospirillum lipoferum was inserted into the chromosome of the engineered strain, and the native promoter was replaced with a strong constitutive promoter (PJ23119). The titer of 2′-fucosyllactose was increased to 8.03 g/L by introducing the regulators rcsA and rcsB into the recombinant strains. Compared to wbgL-based strains, only 2′-fucosyllactose was produced in SAMT-based strains without other by-products. Finally, the highest titer of 2′-fucosyllactose reached 112.56 g/L in a 5 L bioreactor by fed-batch cultivation, with a productivity of 1.10 g/L/h and a yield of 0.98 mol/mol lactose, indicating a strong potential in industrial production.

Integrated Nutrient Management Boosts Productivity and Help Maintaining Sustained Yield of Upland Paddy under Jhum Cultivation in Hilly Region of Northeast India

Background: Replenishing the lost nutrients through the use of various soil amendments is vital in order to maintain soil fertility for sustained productivity in jhumlnd. Integrated Nutrient Management, can boost the upland rice productivity in jhumland by building up the lost soil nutrients. Methods: The study was conducted to evaluate the impact of integrated nutrient management on growth and yield of upland paddy (Oryza sativa L.) in Lai-Lad, Jirang Block of Ri-Bhoi District, Meghalaya, India; during 2019 and 2020. Randomised block design with 12 treatments was applied for the trial with 3 replications. Result: Application of 100% recommended doses of fertilizers + farmyard manure + Azospirillum lipoferum + phosphorus solubilizing bacteria + potassium mobilising bacteria + Glomus + zinc solubilizing bacteria (T10) significantly increased plant growth in both years of cultivation. Grain yield, harvest index and benefit cost ratio of upland paddy were at par among the treatments and were higher in 2nd cropping year. Integrated nutrient management could increase the growth characters, maintain sustained yield and economic profitability of upland paddy in hilly terrains of north-east India, under jhum cultivation.

Engineering D-glucose utilization in Azospirillum brasilense Sp7 promotes rice root colonization.

Bacteria of the genus Azospirillum include several plant associated bacteria which often promote the growth of their host plants. Although the host range of Azospirillum brasilense Sp7 is much wider than its close relative Azospirillum lipoferum 4B, it lacks the ability to efficiently utilize D-glucose for its growth. By comparing the genomes of both the species, the genes of A. lipoferum 4B responsible for conferring D-glucose utilization ability in A. brasilese Sp7 were identified by cloning individual or a combination of genes in a broad host range expression vector, mobilizing them in A. brasilense Sp7 and examining the ability of exconjugants to use D-glucose as sole carbon source for growth. These genes also included the homologs of genes involved in N-acetyl glucosamine utilization in Pseudomonas aeruginosa PAO1. A transcriptional fusion of the 5 genes encoding glucose-6-phosphate dehydrogenase and 4 components of glucose phosphotransferase system were able to improve D-glucose utilization ability in A. brasilense Sp7. The A. brasilense Sp7 strain engineered with D-glucose utilization ability showed significantly improved root colonization of rice seedling. The improvement in the ability of A. brasilense Sp7 to colonize rice roots is expected to bring benefits to rice by promoting its growth. KEY POINTS: • Genes required for glucose utilization in Azospirillum lipoferum were identified. • A gene cassette encoding glucose utilization was constructed. • Transfer of gene cassette in A. brasilense improves glucose utilization and rice root colonization..

Impact of Gypsum and Bio-Priming of Maize Grains on Soil Properties, Physiological Attributes and Yield under Saline–Sodic Soil Conditions

In order to enhance soil qualities and boost crop output, gypsum, plant-growth-promoting rhizobacteria (PGPR), and chitosan are all viable solutions. This study’s goal was to find out how different amounts of chitosan—0, 25, 50, 75, and 100 mg L−1—in combination with gypsum and PGPR inoculation (Azospirillum lipoferum + Bacillus subtilis), affected the yield of maize plants growing in saline–sodic soil. Field tests were carried out in triplicate across two growing seasons, 2020 and 2021, using a split plot design. According to the findings, applying the gypsum + PGPR + 50 mg L−1 chitosan treatment (T8) considerably improved plant physiology (chlorophyll, carotenoids, and proline levels), nutrient indicators (N, K+ and K+/Na+ ratio), soil enzyme activity (dehydrogenase, urease, amylase, and invertase), cation exchange capacity (CEC), and porosity. On the other hand, we revealed positive effects on Na+, bulk density (BD), electrical conductivity (EC), and the proportion of exchangeable sodium (ESP), thus, enhancing the productivity compared to the alternative treatment. Therefore, it might be inferred that using gypsum, microbial inoculation, and 50 mg L−1 chitosan may be a key strategy for reducing the detrimental effects of salinity on maize plants.

Enhancing <em>in vitro</em> growth of wheat seedlings under water stress using biopriming

Purpose: Providing food for the world, growing population becomes more difficult with the increase of abiotic stresses due to climate change. The production of wheat, which is a major crop is under the threat of drought stress. The aim of this experiment was to find out to what extent biopriming reduced the effects of drought on wheat (Triticum aestivum L. cv. Slemani-2) seedling growth under in vitro conditions. Research Method: In vitro planted seedlings were subjected to drought conditions using three different watering regimes (normal [control], ½ reduced, and ¾ reduced) after biopriming the seeds with Azospirillum lipoferum, Frateuria aurantia, and Chlorella saccharophila. Physiological traits and growth characteristics were measured. ANOVA was performed according to the factorial layout in completely randomized experimental design with three replications using Microsoft Windows based COSTAT software (version 6.3). Findings: The experiment results showed that biopriming had reduced the effect of drought on chlorophyll concentration and root characteristics, especially under ½ reduced water application. A. lipoferum and C. saccharophila were more beneficial for the seedlings than F. aurantia. Physiological and growth characteristics such as chlorophyll concentration were enhanced using biopriming, hence photosynthesis, root characters, and nutrient uptake. Research Limitations: The availability of previous studies and data on the microorganisms used werethe main constrain in the study. Conducting a study under controlled greenhouse conditions until harvest might provide more information as more parameters will be measured and data collected, especially at the anthesis stage as it is a crucial stage. Originality/ Value: This research provides a possible method to reduce drought impact on wheat crops by suggesting biopriming with new microorganisms.

ISOLATION, CHARACTERIZATION AND MANAGEMENT OF Alternaria solani CAUSING EARLY BLIGHT IN TOMATO THROUGH DIFFERENT BACTERIAL STRAINS

Tomato is grown widely in almost 140 countries having annual production of 151 million tons and is mostly grown in South America. Pure culture of Alternaria solani isolated from twig and leaf samples was prepared. The fungal colonies were cultured in Broth of MEA and PDA for 5-7 days at 25oC. Cetyl-trimethyl-ammonium-bromide (CTAB) extraction technique was applied for DNA extraction of A. solani with little modification. Molecular identification with ITS primers of isolated fungi was undertaken and a 594bp size of the band was obtained. The DNA sequence was submitted to Gen Bank having Gene Bank no. MN200940. The sequenced data was 100% similar to the Alternaria isolate Alt-C81 of Gen Bank accession code MN044802. Biological control agents were applied and data were collected at an interval of 3, 5, 7 and 10 days. The maximum inhibition percentage after 3 days (84.23%) was recorded by Azospirillum lipoferum (RB-38) while the lowest inhibition (44.84%) was recorded by Bacillus subtilis (RB-59). After 7 days of incubation, the highest inhibition (89.13%) was observed by using A. lipoferum (RB-38) and the lowest (60.57%) by Bacillus spp. (RB-43), respectively. After 10 days of incubation, the highest inhibition percentage (95.91%) was recorded by B. subtilis (RB-59) and the lowest by Bacillus thuringiensis (RB-16) with PI of 13.71% respectively. These results suggest that the bacterial isolates studied have a good potential to be used as biocontrol agents of A. solani in tomato plants for the sustainable production of tomatoes without using fungicides. It not gives a good perspective for sustainability and also reduce the environmental pollution.

Effect of Plant Growth Promoting Microorganisms on Pepper Plants Infected with Tomato Brown Rugose Fruit Virus

Symbiotic interaction between plants and microorganisms in the rhizosphere is an important factor affecting plant growth and fitness. Arbuscular mycorrhiza fungi symbiosis increases resistance of the plants to stress factors, including pathogens. Tomato brown rugose fruit virus (ToBRFV) is an important destructive virus damaging tomatoes and peppers with losses that can reach 100%. It is listed on the list of current quarantine organisms in the Czech Republic. The aim of this study was to evaluate influence of root colonization with Funneliformis mosseae or/and Azospirillum brasilense on ToBRFV symptoms and viral titre reduction. Plants treated with arbuscular mycorhizal fungi (AMF) had lower symptom emergence after 14 dpi, however there was no difference in symptoms emergence after 21 dpi within all treatments. The highest colonization intensity by Funneliformis mosseae was detected in ToBRFV negative plants treated with both AMF and Azospirillum (AZO) and the lowest in ToBRFV positive plants with the same treatment (AMF + AZO). Colonization intensity of Azospirillum brasilense in all treated variants went from 20% to 41%. Results suggest that the combination of those two beneficial microorganisms in ToBRFV-infected plants negatively affected AMF colonization.

The Impact of Inoculation with Azotobacter and Azospirillum Bacteria and Chemical Fertilizer on Barley Growth (Hordeum Vulgare L.)

To investigate the effect of using bio-inoculation and chemical fertilizers on barley Hordeum vulgare L. growth, one experiment was applied using sterile soil with a silty clay loam at the Agriculture College Research Station, Tikrit University, Tikrit, Iraq. Completely Random Design (CRD) with two factors, bio and chemical fertilizers, and four levels for each was used to layout the experiment. The biofertilizers treatments were non as a check (NC), Azotobacter (AZ), Azospirillum (AS), Azotobacter and Azospirillum (ASAZ) while the chemical fertilizers levels were 0, 50, 75, and 100 % of barley fertilizers recommendation, which was 120 kg. h-1 NPK. the biofertilizers with ASAZ increased barley plant height, 33.28 cm, dry weight, 5.73 g. plant-1, root weight, 4.86 g. plant-1, and absorbent N, 2.97%, P, 0.35%, K, 2.61% for barley, which were higher than other treatments. Also, the results showed the interaction ASAZ with 75% of barley’s fertilizers recommendation had a higher average for all traits. In short, using biofertilizers reduced 25% of the chemical fertilizer cost.

Rhizosphere Engineering of Rice with Plant Growth Promoting Rhizobacteria (PGPR) Elicits Crop Growth and Soil Microcosm in Blue-R Dye Contaminated Soil

ABSTRACT This investigation was conducted to determine the ability of plant growth-promoting rhizobacteria (PGPR) to elicit growth of rice plants (var. CO51) in soil incubated with Blue-R textile dye. Two commercial strains of PGPR, nitrogen-fixing Azospirillum lipoferum Az204 and phosphorus-solubilizing Bacillus megaterium var phosphaticum PSB1, were used to prepare a carrier and liquid-based formulations. Seed biotization of carrier-based PGPR consortium followed by a foliar spray substantially resulted in a higher plant biomass, germination percent, and vigor index as compared to non-inoculated plants in Blue-R-amended soil. The photosynthetic efficiency is also higher, which is evident by the total chlorophyll content in PGPR-treated seedlings. Similarly, the carrier-based PGPR inoculated plants revealed higher nutrient uptake as well as N, P, and K content in shoots as compared to the non-inoculated plants. PGPR inoculation through seeds showed better survival and colonization of A. lipoferum Az204 and B. megaterium PSB1 in the rhizosphere. A. liopferum Az204 remarked good colonization in inner tissues of roots, stems, and leaves. It was concluded that PGPR application through seeds enhances crop fitness, modulates rhizosphere services, and alleviates oxidative stress caused by Blue-R in rice plants. Therefore, rhizosphere engineering by PGPR through seeds followed by subsequent foliar sprays can be used as a sustainable strategy for textile wastewater-irrigated soils.