Phosphate Solubilizing Microorganisms Research Articles

The combined application of salt-alkali tolerant phosphate solubilizing microorganisms and phosphogypsum is an excellent measure for the future improvement of saline-alkali soils.

The combined application of salt-alkali tolerant phosphate solubilizing microorganisms and phosphogypsum is an excellent measure for the future improvement of saline-alkali soils.

Isolation of Phosphate Solubilizing Fungi from Soil and Their Application in Plant Growth Promotion

Phosphorus plays a significant role in numerous physiological and metabolic processes in plants. Soil phosphorus is immobilized due to the formation of insoluble complexes. The use of efficient phosphate-solubilizing microorganisms opens up a new prospect for better crop productivity and for greater yield performance without affecting the soil health. Phosphate-solubilizing fungi (PSF) enhance available phosphorus released from soil, which contributes to P requirement of plants. Hence, the present study was designed to evaluate the utilization of PSF as a biofertilizer. Pikovskaya's Agar medium was used to isolate fungal species from compost and open dumpsite soil. Isolated fungi were labelled as PSF-X, PSF-Y, and PSF-Z. A pot experiment was carried out to determine the effect of isolated fungal strains. The isolated fungal strain was introduced to the developed potting media which contained compost and soil at 1:1 ratio. Soya bean was selected as the experimental plant. Plant growth parameters (shoot length and root length) were measured to determine the effect of isolated fungal strains. Plant growth parameters were recorded after 21days. Fungi inoculated pots showed a significant increase in both shoot and root lengths in comparison to the control (n=9, p<0.05). Potting media consisting of PSF-X showed the best result. The highest root length (4.7±0.1 cm) and shoot length (35.8±1.2 cm) were recorded in pots inoculated with PSF-
 
 Hence, isolated PSF-X, PSF-Y, and PSF-Z are recommended as suitable biofertilizer strains for potting medium.
 
 
 Keywords: Fertilizer, Fungi strain, Phosphorus, Plant growth

Phosphate solubilizing microorganisms: a sustainability strategy to improve urban ecosystems.

Intensification of urban construction has gradually destroyed human habitat ecosystems. Plants, which serve as the foundation of ecosystems, require green, low-cost, and effective technologies to sustain their growth in stressful environments. A total of 286 keywords and 10 clusters from the bibliometric analysis of 529 articles (1999-2023) indicate the increasing importance of research on microbial functionality in landscape ecosystems. Phosphate solubilizing microorganisms (PSMs) also improve plant disease resistance, adaptability, and survival. PSMs are widely used to promote plant growth and improve ecological quality. They can increase the availability of phosphorus in the soil and reduce the dependence of plants on chemical fertilizers. Microorganisms regulate phosphorus as key tools in landscape ecosystems. Most importantly, in urban and rural landscape practices, PSMs can be applied to green spaces, residential landscapes, road greening, and nursery planting, which play significant roles in improving vegetation coverage, enhancing plant resistance, improving environmental quality, and mitigating the heat island effect. PSMs are also helpful in restoring the ecological environment and biodiversity of polluted areas, such as brownfields, to provide residents with a more liveable living environment. Therefore, the multiple efficacies of PSM are expected to play increasingly important roles in the construction of urban and rural landscape ecosystems.

Bibliometric analysis of soil phosphate solubilizing microorganisms research using VOSviewer

Bibliometric analysis of soil phosphate solubilizing microorganisms research using VOSviewer

Phosphate solubilization and plant growth properties are promoted by a lactic acid bacterium in calcareous soil.

On the basis of good phosphate solubilization ability of a lactic acid bacteria (LAB) strain Limosilactobacillus sp. LF-17, bacterial agent was prepared and applied to calcareous soil to solubilize phosphate and promote the growth of maize seedlings in this study. A pot experiment showed that the plant growth indicators, phosphorus content, and related enzyme activity of the maize rhizospheric soils in the LF treatment (treated with LAB) were the highest compared with those of the JP treatment (treated with phosphate solubilizing bacteria, PSB) and the blank control (CK). The types of organic acids in maize rhizospheric soil were determined through LC-MS, and 12 acids were detected in all the treatments. The abundant microbes belonged to the genera of Lysobacter, Massilia, Methylbacillus, Brevundimonas, and Limosilactobacillus, and they were beneficial to dissolving phosphate or secreting growth-promoting phytohormones, which were obviously higher in the LF and JP treatments than in CK as analyzed by high-throughput metagenomic sequencing methods. In addition, the abundance values of several enzymes, Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology, and Carbohydrate-Active Enzymes (CAZys), which were related to substrate assimilation and metabolism, were the highest in the LF treatment. Therefore, aside from phosphate-solubilizing microorganisms, LAB can be used as environmentally friendly crop growth promoters in agriculture and provide another viable option for microbial fertilizers. KEY POINTS: • The inoculation of LAB strain effectively promoted the growth and chlorophyll synthesis of maize seedlings. • The inoculation of LAB strain significantly increased the TP content of maize seedlings and the AP concentration of the rhizosphere soil. • The inoculation of LAB strain increased the abundances of the dominant beneficial functional microbes in the rhizosphere soil.

Biofertilizer based on fish waste increases the yield of Vigna unguiculata L. Walp, Zea mays L., and the rhizospheric microbiota

Crops of Vigna unguiculata L. “cowpea” and Zea mays L. “corn” require chemical fertilizers for proper growth and development; however, its inadequate application contaminates the environment, creating the need to search new alternatives that reduce its impact. Due to this, the objective of this research was to determine the effect of a biofertilizer from fish wastes on the yield of cowpea and corn, and its effect on their rhizospheric microbiota. The physicochemical and biological characteristics of the biofertilizer were determined, and then was applied on the field under a completely randomized block design with six treatments: absolute control, chemical control, biofertilizer at 1%, 1.25%, 1.5% and 1.25% plus chemical fertilizer. The application of biofertilizer at 1, 1.25 and 1.5% increased the height, root length and yield of cowpea; however, the increase percentages were lower than those obtained with chemical fertilizer and the biofertilizer at 1.25% plus chemical fertilizer. In the case of corn, all treatments with biofertilizer increased the growth and yield of aerial biomass compared to the control, and the percentages of increase exceeded the chemical fertilizer in terms of the number of leaves, length and root biomass. In addition, the biofertilizer increased the microbial fertility of the soil expressed as the number of colony-forming units of nitrogen-fixing and phosphate-solubilizing microorganisms per gram of soil in both crops. In conclusion, a positive effect of the biofertilizer from fish wastes was evidenced, which increased the yield of cowpea and corn, as well as an increase in soil microbial fertility.

Using Bacillus megaterium as a bio-fertilizer alleviates salt stress, improves phosphorus nutrition, and increases cauliflower yield

The traditional crop production system involves the use of large amounts of chemical fertilizers, which negatively impacts the ecological environment by increasing soil degradation and salinity, threatening sustainable agricultural production. Therefore, there is an urgent need for agricultural practices that increase plant productivity and reduce negative impacts on the environment. Phosphate-solubilizing microorganisms can enhance nutrient availability and plant uptake. This study investigated the effect of Bacillus megaterium as a bio-fertilizer (inoculated and non-inoculated) combined with phosphorus fertilizer (40, 60, and 80 kg. ha−1) on the growth and yield of cauliflower grown under saline conditions, saline soil (9.68 dS.m−1) and saline irrigation water (7.12 dS.m−1). Salt-stressed cauliflower inoculated with Bacillus and fertilized with 60 or 80 kg. ha−1 P2O5 showed improved growth and higher yield compared to other treatments, without significant differences between them. However, Bacillus-treated plants fertilized with 60 P2O5 showed increases in superoxide dismutase (SOD) by 29.3%, catalase (CAT) by 13.9, chlorophyll by 10.4%, N by 7.8%, and P by 8.6%, while Na decreased by 7.8%, resulting in significant increases in cauliflower yield (head weight by 9.3%, and total yield by 8.3%) compared with the control treatment (recommended P fertilizer, 80 kg P2O5. ha−1). The results indicated that the inoculation of salt-stressed plants with Bacillus megaterium is a promising and feasible approach to reduce phosphorus fertilizer use by up to 25% and enhance membrane stability (MSI), relative water content (RWC), nutrient availability, and growth performance, thus mitigating the adverse effects of salt stress exacerbated by climate change.

Livestock movement driven phosphorus transitions as core drivers of grassland vegetation dynamics

The Banni grasslands, located in the Kachchh district of India, have experienced significant degradation and a decrease in grassland productivity. Phosphorus is a crucial nutrient for grassland productivity, and its availability is often limited in these ecosystems. The study is a maiden attempt to understand the link between phosphorus availability, measured by the phosphorus activation coefficient (PAC), phosphate solubilizing microorganisms (PSM), vegetation patterns, indicated by normalized difference vegetation index (NDVI) and its relationship with livestock movement. Soil samples were collected from 45 locations spread across the three divisions of Banni grassland, and various soil parameters including phosphorus content, organic carbon, and microbial activity were analyzed. The results showed that the concentration of available phosphorus (AP) varied significantly among different divisions of the grassland, with division 1 having the highest AP concentration. The phosphorus activation coefficient (PAC) was also highest in division 2. Additionally, PSM diversity was significantly different among divisions, with division 2 exhibiting the highest PSM values. The NDVI values, representing vegetation density, varied across divisions, with division 1 having the highest overall NDVI. Statistical analysis revealed significant positive correlations between PAC, PSM, and NDVI. The research emphasizes the significance of PSM driven phosphorus availability in influencing vegetation dynamics within the Banni grassland ecosystem. The movement of livestock emerges as a key factor in introducing organic matter and phosphate solubilizing microorganisms, thereby facilitating the conversion of total phosphorus (TP) into forms accessible to plants. The study indicates that implementing effective phosphorus management practices, taking into account livestock movement and organic contributions, could enhance grassland productivity and ensure the long-term sustainability of the ecosystem. These findings offer valuable insights for more holistic and nuanced understanding of the complex relationships between phosphorus availability, phosphate solubilizing microorganisms, vegetation patterns, and sustainable management in the Banni grasslands and potentially in other ecosystems facing similar challenges.

Phosphorus Solubilizing Microbes: Propitious Strategy For Biofertilization

Phosphorus (P) is crucial for plant growth and development, it is a macroelement that is required for plants to function physiologically. Even though there are a lot of P-containing organic and inorganic molecules in soil, most of them are inert, making them unavailable to plants. Phosphorus (P) deficiency is widely acknowledged as a critical constraining factor in agricultural production, primarily due to its essential role in various biochemical pathways, including ATP synthesis, nucleic acid formation, and energy transfer processes within plant cells. In rhizosphere soil a diverse community of plant-growth-promoting rhizobacteria (PGPR), particularly phosphate-solubilizing bacteria (PSB) are present, by increasing nutrient bioavailability—especially in the case of phosphate—these bacteria have a beneficial effect on plant growth, increasing total plant productivity and yield. Phosphate-solubilizing microorganisms (PSMs) aid in the hydrolysis of resistant organic and inorganic phosphate (P) forms into soluble forms that are easily absorbed by plants. Despite decades of research on PSMs, the practical implementation of PSM-based strategies to enhance soil phosphorus fixation and improve crop yields at the field scale remains largely undeveloped. This review aims to deepen our comprehension of the pivotal role played by PSMs as biofertilizers in the context of crop production.

Uranium bioprecipitation mediated by a phosphate-solubilizing Enterobacter sp. N1-10 and remediation of uranium-contaminated soil

Uranium (U) pollution in soils is prevalent worldwide and poses a significant health risk that will require remediation approaches. However, traditional U bioreduction by sulfate reducing bacteria (SRB) are sensitive to oxygen and are not suitable for treating aerobic topsoil. Bioprecipitation of U into uranyl phosphate (UP) mediated by phosphate-solubilizing microorganism (PSM) is not affected by oxygen. In this study, PSM strains were isolated and used for U-contaminated soil remediation. Microbial metabolites and the mechanism of PSM bioprecipitation were revealed. The results showed that strain Enterobacter sp. N1-10 had the highest phosphate-solubilizing capacity (dissolved P was 409.51 ± 8.48 mg/L). Uranium bioprecipitation was investigated by culturing the bacterium in the presence of 50 mg/L U and in the cell-free culture supernatant. The results showed that strain N1–10 had a high U removal rate (99.45 ± 0.43 %) after adding 50 mg/L U to the culture medium. A yellow precipitate was immediately formed when uranyl nitrate solution was added to the cell-free culture supernatant. The analysis indicated that bacterium produced lactic acid (37.58 mg/L), citric acid (4.76 mg/L), succinic acid (2.03 mg/L), and D-glucuronic acid (1.94 mg/L); the four organic acids solubilized Ca3(PO4)2 to form stable uranyl phosphate precipitate. The application of strain N1-10 and Ca3(PO4)2 significantly decreased the bioavailability of soil U (43.54 ± 0.52 %). In addition, pot experiments showed that PSM N1-10 and Ca3(PO4)2 promoted plant growth and markedly reduced U accumulation by pakchoi. These results demonstrate that PSM N1-10 and Ca3(PO4)2 exhibit a great potential for U bioremediation.

Effect of ammonium stress on phosphorus solubilization of a novel marine mangrove microorganism Bacillus aryabhattai NM1-A2 as revealed by integrated omics analysis

BackgroundPhosphorus is one of the essential nutrients for plant growth. Phosphate-solubilizing microorganisms (PSMs) can alleviate available P deficiency and enhance plant growth in an eco-friendly way. Although ammonium toxicity is widespread, there is little understanding about the effect of ammonium stress on phosphorus solubilization (PS) of PSMs.ResultsIn this study, seven PSMs were isolated from mangrove sediments. The soluble phosphate concentration in culture supernatant of Bacillus aryabhattai NM1-A2 reached a maximum of 196.96 mg/L at 250 mM (NH4)2SO4. Whole-genome analysis showed that B. aryabhattai NM1-A2 contained various genes related to ammonium transporter (amt), ammonium assimilation (i.e., gdhA, gltB, and gltD), organic acid synthesis (i.e., ackA, fdhD, and idh), and phosphate transport (i.e., pstB and pstS). Transcriptome data showed that the expression levels of amt, gltB, gltD, ackA and idh were downregulated, while gdhA and fdhD were upregulated. The inhibition of ammonium transporter and glutamine synthetase/glutamate synthase (GS/GOGAT) pathway contributed to reducing energy loss. For ammonium assimilation under ammonium stress, accompanied by protons efflux, the glutamate dehydrogenase pathway was the main approach. More 2-oxoglutarate (2-OG) was induced to provide abundant carbon skeletons. The downregulation of formate dehydrogenase and high glycolytic rate resulted in the accumulation of formic acid and acetic acid, which played key roles in PS under ammonium stress.ConclusionsThe accumulation of 2-OG and the inhibition of GS/GOGAT pathway played a key role in ammonium detoxification. The secretion of protons, formic acid and acetic acid was related to PS. Our work provides new insights into the PS mechanism, which will provide theoretical guidance for the application of PSMs.

Microbial Solutions to Soil Health: The Role of Biofertilizers in Sustainable Agriculture

Soil health is fundamental to sustainable agriculture, influencing plant growth, nutrient availability, and ecosystem stability. However, the overuse of chemical fertilizers, monoculture practices, and soil erosion have led to a significant decline in soil fertility, necessitating the exploration of alternative agricultural practices. In this context, biofertilizers—formulated with living microorganisms—have emerged as effective microbial solutions to enhance soil health. They work by promoting nutrient availability, stimulating plant growth, and improving soil structure. This review explores the various types of biofertilizers, such as nitrogen-fixing bacteria, phosphate-solubilizing microorganisms, and mycorrhizal fungi, detailing their mechanisms of action and specific applications in agriculture. Furthermore, the review highlights the numerous benefits of biofertilizers, including their role in reducing chemical fertilizer dependence, enhancing crop yields, and fostering sustainable agricultural practices. Despite their potential, several challenges hinder the widespread adoption of biofertilizers, including limited awareness among farmers, quality control issues, and the need for effective application techniques. By addressing these challenges, biofertilizers can significantly contribute to environmentally friendly farming practices, underscoring their importance in achieving sustainable agricultural systems and promoting long-term soil health.

The Role of Phosphate-Solubilizing Microorganisms in Soil Health and Phosphorus Cycle: A Review

The role of phosphate-solubilizing microorganisms (PSM) in soil health and Phosphorus (P) cycle is a crucial aspect of agricultural productivity. Recent research has emphasized the importance of microorganisms in maintaining soil health. Phosphorus is an essential macronutrient for plant growth and development and significantly affects crop productivity. The PSM solubilize phosphate by producing metabolites such as organic acids, inorganic acids, hydrogen sulphide, exopolysaccharide, and siderophore. Studies have shown that the combination of PSM with phosphate fertilizers increase the efficiency of the fertilizers in soils. The efforts have been made to integrate exogenous soil microorganisms into P cycling models. This review highlights the critical role of microorganisms in maintaining soil health and promoting P cycle, emphasizing the importance of incorporating them into soil management practices.

Organic and natural farming improve microbial diversity and dehydrogenase activity in clusterbean-tomato cropping sequence

ABSTRACT Organic (OF) and natural farming (NF) may help to overcome drawbacks of chemical farming. A field experiment was conducted to investigate the microbial diversity and dehydrogenase activity in clusterbean-tomato cropping sequence with different farming systems over 3 years. An increase in bacterial population in OF (73.6%) and NF (55.4%) over conventional farming practice (PoP) and 90.8% (OF) and 62.1% (NF) over farmers’ practice (FP) was recorded. Fungal population in OF and NF increased by 32.8% and 12%, respectively over PoP and 76.8% (OF) and 47% (NF) over FP. Increase in actinomycetes population of 34% (OF) and 18.1% (NF) over PoP and 60.9% (OF) and 41.8% (NF) over FP was observed. Phosphate solubilizing microorganisms (PSM) population increased to 62.8% (OF) and 33.4% (NF) over PoP and 103.1% (OF) and 66.4% (NF) over FP. Population of N-Fixers also found enhanced in OF (31.4%) and NF (9.7%) compared to PoP and FP (OF: 97.4% and NF: 58%). The higher dehydrogenase activity of 41.4% (OF) and 25.5% (NF) was recorded over PoP and OF (62%) and NF (43.8%) over FP. It can be concluded that OF and NF enhanced microbial diversities and dehydrogenase activity.

Influence of biosurfactants in the recovery of REE from monazite using Burkholderia thailandensis

The demand of rare earth elements (REE) has grown over the past decades due to their importance in high technology devices such as wind turbines, superconductors, rechargeable batteries, autocatalytic converters, magnets, or LED lighting. The development of clean mining processes is gaining interest and the biomining of REE is mainly focused on monazite using phosphate solubilizing microorganisms. The members of the genus Burkholderia can dissolve phosphorous from inorganic rocks. Furthermore, several species of Burkholderia are able to produce biosurfactants named rhamnolipids. Nevertheless, rhamnolipid interactions with REE have been poorly investigated.The aim of the present work is the study of the solubilization of monazite and the recovery of REE using the bacterium Burkholderia thailandensis, and the influence of the rhamnolipids produced by the bacteria in the REE mobilization. B. thailandensis grown in nutrient broth with 1% monazite (w/v) reached 8.3 mg·l−1 REE after 15 days.To produce rhamnolipids, B. thailandensis was grown in medium supplemented with 10% glycerol and the biosurfactants were extracted. The critical micelle concentration (CMC) was determined: 94.45 mg·l−1 for commercial rhamnolipids and 60.41 mg·l−1 for purified rhamnolipids. The maximum REE solubilization was obtained at CMC reaching 9.36 mg·l−1 with commercial rhamnolipids and 5.13 mg·l−1 with rhamnolipids produced by B. thailandensis E264.

Pigeon Pea (Cajanus cajan L.) Based Intercropping System: A Review

Pigeon pea (Cajanus cajan L.) is a tropical and subtropical leguminous crop it is rich in protein and has high nutrient content and India is the largest producer. Pigeon pea is grown in a sole cropping system as well as with intercropping system it is majorly intercropped with legumes, cereal, and oilseed crops. Intercropping depends upon the interaction of crop species and their management. Intercropping is done between different types of cereals, pulses, and oilseed crops. Some successful cereal and pulse intercropping systems like (mung bean + maize) where, a larger equivalent yield is obtained by seeding maize following four rows of mung beans than by closer spacing. Wheat is mostly intercropped with chickpea, mustard and barley but in irrigated conditions when wheat intercropped with mustard proved more profitable than wheat intercropped with chickpea. In the Mediterranean nation, common vetch (Vicia sativa) is popularly grown with cereals. When maize and cowpea were intercropped in southern Africa, the quantity of nitrogen, phosphate, and potassium in the soil was enhanced. Maize and beans are popular in eastern Africa. However, there are many challenges while adopting intercropping for the survival of the plant. In intercropping of pigeon pea when two or more than crops are sown, they show a synergetic effect, and when it is treated with the biofertilizers like Rhizobium, arbuscular mycorrhizal fungi (AMF), phosphate-solubilizing microorganisms (PSM) and plant growth-promoting rhizobacteria (PGPR), it enhances the growth of the plant, fixes atmospheric nitrogen in the soil, availability of phosphorus to the plant increases the uptake of other micro-nutrient to the plant and plant beneficial microbes. When dual inoculation of Rhizobium and AMF is done, chlorophyll content increases in the plant.

Effect of Trichoderma viride on insoluble phosphorus absorption ability and growth of Melilotus officinalis

Phosphorus (Pi) deficiency is a major factor of limiting plant growth. Using Phosphate-solubilizing microorganism (PSM) in synergy with plant root system which supply soluble Pi to plants is an environmentally friendly and efficient way to utilize Pi. Trichoderma viride (T. viride) is a biocontrol agent which able to solubilize soil nutrients, but little is known about its Pi solubilizing properties. The study used T. viride to inoculate Melilotus officinalis (M. officinalis) under different Pi levels and in order to investigate the effect on Pi absorption and growth of seedlings. The results found that T. viride could not only solubilizate insoluble inorganic Pi but also mineralize insoluble organic Pi. In addition, the ability of mineralization to insoluble organic Pi is more stronger. Under different Pi levels, inoculation of T. viride showed that promoted the growth of aboveground parts of seedlings and regulated the morphology of roots, thus increasing the dry weight of seedlings. The effect of T. viride on seedling growth was also reflected the increasing of chlorophyll fluorescence parameters and photosynthetic pigment content. Moreover, compared to the uninoculated treatments, inoculation of T. viride also enhanced Pi content in seedlings. Thus, the T. viride was a beneficial fungus for synergistic the plant Pi uptake and growth.

Implications of Below-Ground Allelopathic Interactions of Camelina sativa and Microorganisms for Phosphate Availability and Habitat Maintenance.

Toxic breakdown products of young Camelina sativa (L.) Crantz, glucosinolates can eliminate microorganisms in the soil. Since microorganisms are essential for phosphate cycling, only insensitive microorganisms with phosphate-solubilizing activity can improve C. sativa's phosphate supply. In this study, 33P-labeled phosphate, inductively coupled plasma mass spectrometry and pot experiments unveiled that not only Trichoderma viride and Pseudomonas laurentiana used as phosphate-solubilizing inoculants, but also intrinsic soil microorganisms, including Penicillium aurantiogriseum, and the assemblies of root-colonizing microorganisms solubilized as well phosphate from apatite, trigger off competitive behavior between the organisms. Driving factors in the competitiveness are plant and microbial secondary metabolites, while glucosinolates of Camelina and their breakdown products are regarded as key compounds that inhibit the pathogen P. aurantiogriseum, but also seem to impede root colonization of T. viride. On the other hand, fungal diketopiperazine combined with glucosinolates is fatal to Camelina. The results may contribute to explain the contradictory effects of phosphate-solubilizing microorganisms when used as biofertilizers. Further studies will elucidate impacts of released secondary metabolites on coexisting microorganisms and plants under different environmental conditions.

Growth Promoting Potential of Phosphate Solubilizing Enterobacter Cloaca and Enterobacter Hormaechei on Maize and Cowpea Seedlings

Introduction: Phosphorus plays a range of functions in the proper growth and development of plants. Numerous microbial species, including bacteria, fungi, actinomycetes, and even algae have been found to play a crucial role in the solubilization of phosphate. This study was therefore aimed at exploring the growth-promoting potential of phosphate solubilizing Enterobacter species on maize and cowpea seedlings. Methods: Five strains that showed remarkable phosphate solubilization potential were used for the study. The bacterial isolates consist of three strains of Enterobacter cloaca and two strains of Enterobacter hormaechei. Growth promotion studies were carried out under laboratory conditions (in blotters) and green house (soil environment). In the blotter study, percent germination, germination index, germination time, germination rate, and vigor index were estimated, while shoot and root lengths, number of leaves, and wet weight were estimated in the greenhouse study. Results: In both seedlings, percent germination, germination index, and vigor index showed significantly higher values in seeds primed with the isolates than in the water-treated seeds (p≤ 0.05). Throughout the period of planting, the shoot and root lengths of the isolate-treated seedlings showed significantly higher values than the untreated control setups. This observation was irrespective of the maize and cowpea seedlings. In both seedlings, shoot and root lengths were directly proportional to days of growth. The bacterial strains showed significantly higher growth promoting potential on the seedlings. Conclusion: Therefore, the availability of these phosphate solubilizing microorganisms in the soil could enhance the growth of the seeds.

Combining Fully Acidulated Phosphates with Phosphate-Solubilizing Microorganisms for Urochloa brizantha Fertilization

Aimed to evaluate the productive, morphological and nutritional characteristics, in addition to the accumulation of nutrients in the aerial part of Urochloa brizantha cv. Marandu subjected to phosphorus chemical sources and its interaction with phosphate-solubilizing inoculant. The experiment was developed in Colorado do Oeste, RO, Brazil, being adopted a randomized block design with three replications. The treatments consisted of different phosphate fertilizer doses associated or not with phosphate-solubilizing microorganisms (PSM): 0% P; 50% P; 100% P; 50% P + 250 mL ha-1 PSM; 50% P + 500 mL ha-1 PSM; 50% P + 750 mL ha-1 PSM; and 50% P + 1000 mL ha-1 PSM. Triple superphosphate was used as a chemical fertilizer, and fertilization with chemical fertilizer and PSM occurred on November 19th, 2021. The results for the morphological characteristics and yields of Marandu grass showed significant differences. The different arrangements and phosphate doses influenced the green matter yield and dry matter yield, both using the 50% P + 1000 mL ha-1 PSM presented higher yields (3,642.75 kg ha-1 and 1,049.10 kg ha-1, respectively). Higher crop growth rate results in green matter were also found when employing a combination of 50% P + 500 mL ha-1 PSM and 50% P + 1000 mL ha-1 PSM. Dry matter had a significant effect on the bromatological composition, with higher results observed when using 50% P alone (34.55%). Regarding the accumulation of nutrients in the aerial part, the highest P accumulation in Marandu grass was observed when utilizing 100% P, resulting in an accumulation of 15.4 kg P ha-1. Inoculation with PSM for fertilization of U. brizantha cv. Marandu grass does not have adverse effects on the increase in P availability to the plant, resulting in adequate yield and crop development associated with the productive potential of the area.