Application Of Phosphate-solubilizing Bacteria Research Articles

Mitigating the effects of water-deficit stress on potato growth and photosynthesis using mycorrhizal fungi and phosphate-solubilizing bacteria

Abstract Biofertilizers, such as arbuscular mycorrhiza fungi and phosphate-solubilizing bacteria (PSB), have been reported to enhance plant growth under water stress conditions. This study aimed to investigate the effect of different biofertilizers on potato photosynthesis and growth under water deficit stress. The experiment was conducted over two crop years (2019 and 2020) using a randomized complete block design with three replications. Four irrigation intervals (70, 90, 110 and 130 mm of cumulative evaporation) and six biofertilizer treatments (PSB, Funneliformis mosseae [FM], Rhizoglomus fasciculatum [RF], PSB + FM, PSB + RF and no use) were applied. Severe moisture stress (130 mm evaporation) compared to no stress (70 mm evaporation) increased substomatal carbon dioxide concentration. The application of biofertilizers improved tuber yield under severe moisture stress, with FM showing the highest increase (62.9%), followed by RF (59.8%) and PSB (48.4%). The use of PSB along with mycorrhizae led to a significant decrease in mycorrhizal colonization percentage at all irrigation levels. The highest percentage of colonization and net photosynthesis was obtained from the application of both mycorrhizal species under irrigation conditions after 70 mm of evaporation. The application of PSB alone resulted in a 14.6% increase in the transpiration rate, additionally, the use of mycorrhiza led to an 18.7% increase in stomatal conductivity compared to no-biofertilizer. The results suggest that the simultaneous use of PSB and mycorrhizae can be effective in mild moisture stress, but in severe moisture stress, the use of mycorrhizal species alone is more effective.

Effects of Priestia aryabhattai on Phosphorus Fraction and Implications for Ecoremediating Cd-Contaminated Farmland with Plant-Microbe Technology.

The application of phosphate-solubilizing bacteria has been widely studied in remediating Cd-contaminated soil, but only a few studies have reported on the interaction of P and Cd as well as the microbiological mechanisms with phosphate-solubilizing bacteria in the soil because the activity of phosphate-solubilizing bacteria is easily inhibited by the toxicity of Cd. This paper investigates the phosphorus solubilization ability of Priestia aryabhattai domesticated under the stress of Cd, which was conducted in a soil experiment with the addition of Cd at different concentrations. The results show that the content of Ca2-P increased by 5.12-19.84%, and the content of labile organic phosphorus (LOP) increased by 3.03-8.42% after the addition of Priestia aryabhattai to the unsterilized soil. The content of available Cd decreased by 3.82% in the soil with heavy Cd contamination. Priestia aryabhattai has a certain resistance to Cd, and its relative abundance increased with the increased Cd concentration. The contents of Ca2-P and LOP in the soil had a strong positive correlation with the content of Olsen-P (p < 0.01), while the content of available Cd was negatively correlated with the contents of Olsen-P, Ca2-P, and LOP (p < 0.05). Priestia aryabhattai inhibits the transport of Cd, facilitates the conversion of low-activity P and insoluble P to Ca2-P and LOP in the soil, and increases the bioavailability and seasonal utilization of P in the soil, showing great potential in ecoremediating Cd-contaminated farmland soil with plant-microbe-combined technology.

Characterization and evaluation of potential halotolerant phosphate solubilizing bacteria from Salicornia fruticosa rhizosphere.

Soil salinization is a significant abiotic factor threatening agricultural production, while the low availability of phosphorus (P) in plants is another worldwide limitation. Approximately 95-99% of the P in soil is unavailable to plants. Phosphate-solubilizing bacteria (PSB) transform insoluble phosphates into soluble forms that plants can utilize. The application of PSB can replace or partially reduce the use of P fertilizers. Therefore, selecting bacteria with high solubilization capacity from extreme environments, such as saline soils, becomes crucial. This study aimed to identify twenty-nine bacterial strains from the rhizosphere of Salicornia fruticosa by sequencing the 16S rDNA gene, evaluate their development in increasing concentrations of NaCl, classify them according to their salinity response, and determine their P solubilization capability. The bacteria were cultivated in nutrient agar medium with NaCl concentrations ranging from 0.5% to 30%. The phosphate solubilization capacity of the bacteria was evaluated in angar and broth National Botanical Research Institute (NBRIP) media supplemented with calcium phosphate (CaHPO4) and aluminum phosphate (AlPO4), and increased with 3% NaCl. All bacterial strains were classified as halotolerant and identified to the genera Bacillus, Enterobacter, Halomonas, Kushneria, Oceanobacillus, Pantoea, Pseudomonas, and Staphylococcus, with only one isolate was not identified. The isolates with the highest ability to solubilize phosphorus from CaHPO4 in the liquid medium were Kushneria sp. (SS102) and Enterobacter sp. (SS186), with 989.53 and 956.37 mg·Kg-1 P content and final pH of 4.1 and 3.9, respectively. For the solubilization of AlPO4, the most effective isolates were Bacillus sp. (SS89) and Oceanobacillus sp. (SS94), which raised soluble P by 61.10 and 45.82 mg·Kg-1 and final pH of 2.9 and 3.6, respectively. These bacteria demonstrated promising results in in vitro P solubilization and can present potential for the development of bioinput. Further analyses, involving different phosphate sources and the composition of produced organic acids, will be conducted to contribute to a comprehensive understanding of their applications in sustainable agriculture.

Effect of application of phosphate solubilizing bacteria and organic fertilizers on soil phosphorus solubility and growth of maize (Zea mays var. saccharata Sturt L.) on andisols

Phosphate solubilizing microbes are a group of soil microbes that have the ability to extract P from bonds with Al, Fe, Ca, and Mg, so that they can dissolve P that is not available to become available for plants. This is because these microbes release organic acids which can form stable complexes with P-binding cations in the soil. The aim of this experiment was to study application of phosphate solubilizing bacteria and organic fertilizer to increase solubility of soil P through mineralization process of organic P to inorganic P and also solubility of P which adsorbed so that increase P available of Andisols and also increase of plant growth of maize. Design experiment of Randomized Block Design (RBD) was used in green house experiment, consisted of 12 treatments and three replications. The treatment consisted of three isolates (based on selection result) i.e. control (without both isolate and organic manure), Bacillus mycoides, B macerans, and Pseudomonas pseudoalcaligenes, respectively, combined with organic manure (cow manure and compost derived from bamboo leaf) and applied on Andisols soil. The result of experiment revealed that application of PSB and organic manure significantly increased of phosphatase activity and available P, decreased of soil organic P, but did not significant effect growth of maize on Andisols from Lembang. Inoculation of P. pseudoalcaligenes combined with compost gave significant effect on increase of available P and decrease of organic P.

Enhancing phosphate availability and growth of C. asiatica in andisols through phosphate-solubilizing bacteria application

Centella asiatica is a medicinal plant containing asiaticoside bioactive, this is considerably higher if grown in the highlands generally on Andisols. Conversely, phosphorus was deficient in Andisol soils. The experiment aimed to study effect of phosphate solubilizing bacteria (PSB) isolates from the rhizosphere of C. asiatica which can dissolve P, produce plant growth promoters, increase growth of C. asiatica and fertilization efficiency. The research was done at Soil Biology Laboratory, Agriculture Faculty, Universitas Padjadjaran and at the experimental field of Agricultural Technology Research and Assessment Installation Manoko, Lembang District, West Java, Indonesia. The research used a factorial randomized block design with three replications and two factors. The first factor were application techniques: control, root soaking, and soil watering. The second factor were dose of NPK fertilizer and soil conditioner: control, P fertilizer dose of 100%, soil conditioner, P fertilizer dose 75% + soil conditioner, and P fertilizer dose of 100% + soil conditioner. Three superior isolates were isolated from C. asiatica rhizosphere and have been identified as: Paraburkholderia caribensis strain MNL-133, Paraburkholderia caribensis strain DSM 13236, and Pseudomonas aeruginosa strain K19PSE24. The results showed that the application of PSB combined with a dose of P fertilizer and soil conditioner on C. asiatica affected the soil P available, the number of leaves, the number of stolons and plant dry weight.ABSTRAKPegagan (Centella asiatica) salah satu komoditas tanaman obat yang memiliki kandungan bioaktif asiatikosida. Asiatikosida lebih tinggi jika ditanam di dataran tinggi umumnya ordo Andisols. Defisiensi hara fosfor salah satu kendala budi daya pada tanah Andisol. Penelitian ini bertujuan mengkaji pengaruh bakteri pelarut fosfat (BPF) unggul yang diisolasi dari roofer tanaman pegagan yang mampu melarutkan P dan menghasilkan pemacu pertumbuhan tanaman pengaruhnya terhadap peningkatan pertumbuhan tanaman pegagan dan efisiensi pemupukan. Penelitian dilaksanakan di Laboratorium Biologi Tanah, Fakultas Pertanian UNPAD dan di kebun percobaan Instalasi Penelitian dan Pengkajian Teknologi Pertanian (IP2TP) Manoko, Lembang menggunakan Rancangan Acak Kelompok Faktorial dengan tiga ulangan. Faktor pertama adalah teknik aplikasi BPF: kontrol; perendaman akar; penyiraman pada tanah. Faktor kedua yaitu dosis pupuk NPK dan pembenah tanah, yaitu perlakuan kontrol, pupuk P dosis 100%, pembenah tanah, pupuk P dosis 75% + pembenah tanah, dan pupuk P dosis 100% + pembenah tanah. Isolasi BPF dari rhizosfer pegagan menghasilkan isolat unggul yaitu Paraburkholderia caribensis strain MNL-133, Paraburkholderia caribensis strain DSM 13236, and Pseudomonas aeruginosa strain K19PSE24. Hasil menunjukkan pemberian BPF dikombinasikan dengan dosis pupuk P dan pembenah tanah pada tanaman pegagan memberikan pengaruh terhadap P tersedia, jumlah daun, jumlah stolon, dan berat kering tanaman.

To Study the Effect of Cow Dung and Phosphate Solubilizing Bacteria on Growth and Yield of Potato (Solanum tuberosum L.)

Field investigation was carried out to study the effect of cow dung (CD) and phosphate solubilizing bacteria (PSB) on growth and yields parameters in potato cultivar Kufri chipsona-3 at School of Agriculture and Environmental Sciences, Shobhit University, Gangoh Saharanpur, Uttar Pradesh, condition during 2016?2017 and 2017?2018. The experiment was conducted in a randomized block design with four nutrient management practices CD, and their combination with biofertilizers (PSB). Growth parameters such as plant height, number of compound leaves per plant, number of stolon per plant, number of branches per plant, and yield attributing parameters such as fresh and dry weight of tubers per plant, number of tuber per plant, and total yield per hectare increased with the application of PSB in different combination rates was much better than applying of CD one and using of cow with PSB them in tries combination were the most effective treatments comparing with the others. However, the highest values for the number of tuber per plant and per plot as well as tuber yield per plot and per hectare were recorded on application of CD @ 10 t/ha + PSB @ 10 kg/ha was the most effective treatment both the years, followed by PSB @ 10 kg/ha, respectively.. KEYWORDS :Cow dung, phosphate solubilizing bacteria, growth and yield

Effects of application of phosphate and phosphate-solubilizing bacteria on bacterial diversity and phosphorus fractions in a Phaeozems

The aim of this study is to improve the utilization of phosphorus (P) in soil, and to study the effects of phosphate-solubilizing bacteria (PSB) on P fractions and bacterial communities. In this experiment, we reduced the amount of P fertilizer by 30 % and 40 % respectively to studied the effects of combined application of bacterial fertilizers on soil microbial community and phosphate transformation process under different fertilization rates. The results showed that the application of PSB affected the transformation process of different P fractions. PSB had the most significant impact on organic phosphorus (p < 0.05). Correlation analysis showed that the abundance of bacteria was significantly correlated to the P fractions, indicating that the application of PSB had affected the bacterial community structure. In addition, Structural Equation Model (SEM) analysis showed that there was a causal relationship between the various visual variables. SEM confirmed the response relationship between bacterial communities and P components. Based on these results, we concluded that the application of PSB increased the sensitivity of P components, especially Olsen-P and MBP, to soil microorganisms. The application of PSB is an effective method to improve P utilization.

Effect of phosphate solubilizing bacteria and blue green algae on yield and NPK content in hybrid rice

A pot experiment was conducted during kharif season of 2020 on sandy loam soil in texture and classified as mixed hyperthermic typic haplustepts to investigate the impact of phosphate solubilizing bacteria (PSB) and blue green algae (BGA) on crop yield and NPK nutrient uptake in hybrid rice cultivation. Thirteen treatments laid in completely randomized design with two different doses of chemical fertilizers (100% and 75%), two isolates of PSB (Enterobacter cloacae strain BAU3 and Bacillus aryabhattai strain BAUMS8) and blue green algae had been used in the study. The grain and straw yield of hybrid rice and nutrient uptake in both grain and straw increased significantly when supplied with 100% recommended dose of inorganic fertilizers (RDF) + PSB @ 750 ml ha-1 + BGA @ 10 kg ha-1 as compared to 100% RDF. It had been observed that combined application of PSB and BGA along with 100% RDF, enhanced grain and straw yield upto 11.17 and 6.53 percent, respectively in comparison to 100% RDF. Increase in the concentration of grain and straw N in treatment T8 was 8.65% and 11.42%, respectively, when compared with treatment T2 (100% RDF). The concentration of grain P in treatment T8 were 5.80% when compared with treatment T2 (100% RDF) while the magnitude of increase in rice straw was 7.28 percent. A similar trend of result was obtained in the case of K content in grain and straw of hybrid rice but the K concentration was higher in straw. Finally, application of 100% RDF along with PSB @ 750 ml ha-1 + BGA @ 10 kg ha-1 significantly augmented the yield and nutrient content in hybrid rice.

Effects of rice husk biochar (RHB) with combined inoculation of arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) on growth of maize (Zea mays)

For optimal plant growth and productivity, agricultural activity is dependent on soil quality and nutrient availability. Soil amendment such as rice husk biochar (RHB), which abundantly found in Malaysia, are capable of improving soil fertility due to its longevity and other benefits to soil biota, including beneficial soil fungi and bacteria such as arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB). AMF are well-known for their capacity to improve plant nutrient uptake, particularly P, which is essential for plant growth. Similarly, PSB, which is a beneficial bacteria, are able to solubilize phosphate into soluble form thus enhance the P availability for plant. However, the combination effect of AMF and PSB in the presence of RHB is not known. Thus, in order to assess the effects of AMF and PSB in the presence of RHB on soil properties and maize growth, a pot experiment was done. Randomized completely block design (RCBD) arrangement was applied to the following treatments: T1 (control), T2 (RHB), T3 (AMF), T4 (PSB), T5 (+RHB, +AMF), T6 (+AMF, +PSB), T7 (+RHB, +PSB) and T8 (+RHB, +AMF, +PSB). About 10 t/ha RHB was added to the soils for treatments T2, T5, T7, and T8. Ten grams of AMF inoculum and double application of PSB were applied to their respective treatments. Plant growth and soils sampling were done at 45 days after planting (DAP). Results showed that T7 gave 137% root biomass and 123% P uptake higher than control. Our findings were in line with our hypothesis (application of RHB, AMF or PSB or their combination would improve maize growth compared to control, in which T8 gave highest root volume and 150% higher than control. The results suggested that there were positive and synergistic effects of beneficial soil microorganisms (AMF or/and PSB) either with or without RHB. Thus, these combined inoculations and RHB application could be used in biofertilizer formulations to increase the maize growth and yield in sustainable agriculture system.

Rock Phosphate Solubilization by Plant Growth-Promoting Bacillus velezensis and Its Impact on Wheat Growth and Yield

Application of phosphate solubilizing bacteria for improvement of existing pools of phosphate in soil is important for plant growth. From rain fed area of Mansehra, 14 microbes were isolated. Among these, three isolates Bacillus velezensis, Bacillus subtilis, and Bacillus safensis exhibited strong phosphate solubilizing potential, indole acetic acid (IAA) and organic acid production, and antibacterial and antibiotic resistances. Due to better phosphate solublization potential, plant growth-promoting rhizobacteria, B. velezensis was used as bio-inoculant on wheat var. Pir sabaq alone, with rock phosphate (RP) and with 50%, 75%, and 100% single super phosphate (SSP) and urea. Application of RP with B. velezensis increased 50% phosphate and nitrate in soil and 80% in leaves. Plants treated with 100% SSP + urea and B. velezensis showed 50% higher P in soil and 90% in leaves. Application with RP showed significant increases on growth indices of wheat and results were more pronounced in RP + B. velezensis and 100% SSP + urea + B. velezensis treatments. Soluble protein and sugar contents of leaves were 46% and 24% higher in RP + B. velezensis, while IAA and gibberellic acid (GA) were 34% and 54% higher. Highest increases in protein (56%), sugar (30%), IAA (50%), and GA (90%) were found in 100% SSP + urea + B. velezensis. Spike length, seeds per spike, and weight of 1000 seed were 19%, 32%, and 26% higher in RP + B. velezensis, while these increases were 39%, 52%, and 33%, respectively in 100% SSP + urea + B. velezensis treatment. Bio-inoculation of B. velezensis with RP and chemical fertilizer may be helpful for improving productivity of cereal crops and sustainable agriculture.

Phosphate Solubilizing Bacteria (PSB) Improve Phosphorus Availability from Various Sources in Alkaline Soils

Phosphorus (P) is one of the major essential macronutrients for plants, applied to soil in the form of phosphatic fertilizers and organic manures. The application of PSB to soils can replace or partially reduce use of inorganic P fertilizers and could be one of the cost effective, highly efficient, and sustainable approaches to conserve P resources. The aim of the study was to evaluate the role of PSB in phosphorus (P) availability from organic, mineral and natural sources. For this purpose, a laboratory incubation experiment was conducted at the University of Agriculture Peshawar.  The experiment was consisting of four sources of P [poultry manure (PM), farm yard manure (FYM), rock phosphate (RP) and single supper phosphate (SSP)] for obtaining 45 mg P2O5 kg-1 and two types of inoculation (control and PSB) arranged in two factorial complete randomized design with three replications. Resultantly, PSB inoculation significantly improved. P availability at all incubation interval except day zero. A 3.4%, 5.4%, 12% and 16 % increased were observed in P as compared to control, at day 7, 14, 28 and 56 respectively.  Similarly, significant differences were observed in P release for P sources at all incubation intervals. Initially higher P release was observed for SSP but at day 14 onward PM and FYM proved to be the best P releasable sources as compared to mineral P sources. RP released the lowest P at all incubation intervals however it performed statistically at par to SSP at 56 days.  The significant interactive effect of P sources and PSB at day 28 and 56 demonstrated that soil receiving P from organic sources inoculated with PSB released higher P than other treatments combination. Thus, it is suggested that P must be applied from organic P sources (PM and FYM) along with PSB inoculation for better P nutrition and crop yield.

UAV Multispectral Data: A Reliable Approach for Managing Phosphate-Solubilizing Bacteria in Common Bean

Remote sensing can offer stakeholders opportunities to make precise and accurate decisions on agricultural activities. For instance, farmers can exploit aircraft systems to acquire survey-level, high-resolution imagery data for crop and soil management. Therefore, the objective of this study was to analyze whether an unmanned aerial vehicle (UAV) allows for the assessment and monitoring of biofertilization of the common bean upon vegetation indices (VIs). The biological treatment of the legume crop included its inoculation with phosphate-solubilizing bacteria (PSB), namely Bacillus subtilis and B. megaterium. Indicators of photosynthetic performance, such as chlorophylls (a and b) and carotenoids, were measured from actively growing leaves to determine effectiveness. In addition, images were acquired in the field, both spatially and temporally, to establish functional relationships between biometric and computational features. Microorganisms manifested as growth-promoting agents to the crop as they significantly increased its quantities of light-harvesting pigments. VIs allowed for predicting their impact on photosynthetic performance, making them on-site markers of PSB. Therefore, this research can provide insights into the remote, non-destructive mapping of spectral changes in the common bean upon the application of PSB. Imagery data from UAV would enable producers to generate information on the crop to intervene in the field at the right time and place for improved utilization of biofertilizers.

Global perspective of phosphate solubilizing microbes and phosphatase for improvement of soil, food and human health

Soil microbial flora has a pivotal role in the phyto-availability of phosphorus and other necessary minerals and nutrients. The primary class of Rhizobacteria involved in the solubilization of phosphate from non-available forms to available forms is Phosphate solubilizing bacteria (PSB). The application of Phosphate solubilizing bacteria increased phosphorus availability, which is one of the major factors responsible for the increase in the yield of crops. The phosphorus content is higher in the seeds than in the other plant parts; it helps plants in disease resistance and stress management such as winter rigors and improves the quality of fruits, vegetables, and cereal crops. Application of PSB as the biofertilizers positively affects the secretion of siderophores, nitrogen fixation, Indole acetic acid (IAA), 1-aminocylopropane-1-carboxylate (ACC) deaminase, chitinase, and protease. PSB can solubilize useful phosphate from rock phosphate and phosphate present in the combined state in lower to higher pH range (4 to 10), lower to a higher temperature (20 to 40 0C), and even in the higher salt ranges (0 to 7.5 % NaCl). Microbes help in the assimilation of phosphates and hydrocarbons by the secretions of different phosphatases such as monoesterase, diesterases, C-P lyase, and phosphatase and phytases. Using chemical P fertilizer in sustainable agricultural methods needs to be reduced. For this purpose, alternative and inexpensive technology are required so that plants can be provided with a sufficient amount of P. Phosphate solubilizing microbes can be an excellent option to replace chemical P fertilizers for improved agricultural production and soil fertility. The fertility of farm fields can be improved by using PSB as the bio-fertilizer and it will enhance the nutritional quality of plants and plant products which are directly or indirectly taken as food. Applying these microbes to soil/seeds makes good quality fruits and can help to fulfill the nutritional hunger of the world.

Influence of Different Doses and Methods of Phosphorous Solubilizing Bacteria and Phosphorus Levels on the Phosphorus Solubilizing Bacteria Population and Phosphorous Use Efficiency in Sunflower and Chickpea

A field experiment was conducted to study The effect of the application method and different doses of phosphate solubilizing bacteria (PSB) application and the phosphorus levels on sunflower during Rabi, 2020 at College of Agriculture, PJTSAU, Rajendranagar, Hyderabad. The experiment was laid out in Randomized Block Design, comprising eleven treatments with three replications. Initial soil parameters of experimental site indicated that the soil belongs to sandy loam texture, with alkaline in soil reaction, non-saline, low in O.C, low in available nitrogen, medium in available phosphorus, available potassium and available sulphur. The results showed that due to addition of PSB in powdered and liquid form there was an increase in PSB population in the soil, the increase in population is with the application of 75% phosphorus + PSB at 6 kg/ha in both crops. The increase in population is more with the soil application than the Drenching. Due to this there is also an increase in the phosphorous use efficiency. The above study indicated that combined application of PSB with reduced P levels could help in saving fertilizer dose to the extent of 25% in sunflower and 50% in chickpea.

Phosphate solubilizing bacteria optimize wheat yield in mineral phosphorus applied alkaline soil

Limited availability of phosphorus (P) in agricultural soils is a major cause of poor growth and yield of crops throughout the world. Optimization of crops productivity can be achieved by increasing the bioavailability of P via phosphate solubilizing bacteria (PSB), however, their effectiveness may vary with changing agro-climatic conditions That’s why current experiment was conducted to evaluate the potential of phosphate solubilizing bacteria (with PSB and without PSB) in improving growth and yield of wheat under different P levels (0, 25, 50, and 100 % of recommended P). The PSB with 100% recommended P significantly enhanced wheat tillers m −2 , grains spike -1 , grains and biological yield compared to the rest of the treatment’s combination. A significant improvement in 100 grains weight and rate of photosynthesis also validated the efficacious functioning of PSB and full recommended P. Furthermore, PSB were effective in optimizing wheat yield attributes at respective P level compared to Without PSB. Our findings imply that, PSB application along with 100% recommended P as inorganic phosphorus has potential to enhance wheat growth and yield over sole application of P fertilizers or PSB.

UJI AKTIVITAS BAKTERI PELARUT FOSFAT TERHADAP KELARUTAN FOSFAT PADA TANAH SALIN

The high salt content in saline soils is the main cause of low salinity soil fertility, especially phosphorus nutrients. The application of phosphate-solubilizing bacteria in saline soil is one method to increase phosphate availability in saline soils. The study consisted of two tests, namely (1) qualitative and quantitative testing of phosphate-solubilizing bacteria in saline conditions and (2) testing of the activity of phosphate solubilizing bacteria in saline soil. This study used Pseudomonas sp. and Bacillus valezensis (Soil Biology Laboratory collection), Inceptisol saline soil from Banongan and Agel Situbondo. The study aimed to determine the activity of phosphate-solubilizing bacteria on the solubility of phosphate in saline soil. The results showed that: (1) Pseudomonas sp. and Bacillus valezensis have a solubility index of 1.25 to 2.68 on solid Pikovskaya medium with some NaCl concentration. Quantitatively test on liquid Pikovskaya medium, water-soluble phosphate concentration about 4.84 ppm to 14.18 ppm and soluble phosphate (extract Bray) between 15.91 ppm to 21.58 ppm. In addition, (2) on saline soil showed that Pseudomonas sp. and Bacillus valezensis could increase phosphate availability by 11.61% to 72,89%. Based on the study results, the genus Pseudomonas sp. and Bacillus valezensis have the potential to increase phosphate availability in saline soils.

Phosphate solubilizing bacteria inoculated low-grade rock phosphate can supplement P fertilizer to grow wheat in sub-tropical inceptisol

Soil phosphorus (P) despite being an important element for plant growth, its high reactivity and low solubility has challenged the farming community for its efficient utilization. P fertilizers are produced from high grade rock phosphates. Reserve of this non-renewable resource is getting exhausted very rapidly. That establishes the need of using non-conventional P sources to grow crops. In this study, low grade rock phosphates (LGRP) were used as alternate P source to grow wheat in Inceptisol. Different quantities of phosphate solubilizing bacteria (PSB) inoculated LGRP were applied in incubation and pot experiments and were compared with a commercial P fertilizer. It was hypothesized that PSB inoculation would increase P solubility from LGRP and reduce P fixation in soil, thus improve supply parameter and increase P availability to the crop. Short term P dynamics at three different growth stages of wheat, enzyme activities, P-fixation and adsorption chemistry were studied. Incubation experiment established that PSB inoculated LGRP can supply significantly higher amount of P as compared to untreated LGRP. It also proved the potentiality of PSB inoculated LGRP treatment to maintain better supply of P in soil for long term. Pot experiment revealed that combined application of PSB inoculated LGRP + di-ammonium phosphate (DAP) can supplement 50% P fertilizer and maintain similar yield and P uptake as compared to DAP treatment. Applied PSB solubilized P from LGRP and soil, also prevented P fixation in soil by producing organic acids, siderophores, phosphatase enzymes. Thereby, application of PSB inoculated LGRP provided steady supply of available and saloid P for wheat throughout the growth stages and synchronised P supply with its demand. Application of PSB inoculated LGRP reduced the value of P adsorption maxima by ∼18% and bonding energy related constant of P-fixation by ∼11%; while value of P supply parameter enhanced by ∼14% over no PSB application. The PSB inoculated LGRP application enhanced inherent microbial activities by 10–24%, slashed P-fixation capacity by altering P adsorption chemistry and optimised P supply parameter. Thus, application of PSB inoculated LGRP could be recommended to crops to save ∼50% of the commercial P-fertilizer without affecting crop yields.

Insight into soil nitrogen and phosphorus availability and agricultural sustainability by plant growth-promoting rhizobacteria.

Nitrogen and phosphorus are critical for the vegetation ecosystem and two of the most insufficient nutrients in the soil. In agriculture practice, many chemical fertilizers are being applied to soil to improve soil nutrients and yield. This farming procedure poses considerable environmental risks which affect agricultural sustainability. As robust soil microorganisms, plant growth-promoting rhizobacteria (PGPR) have emerged as an environmentally friendly way of maintaining and improving the soil's available nitrogen and phosphorus. As a special PGPR, rhizospheric diazotrophs can fix nitrogen in the rhizosphere and promote plant growth. However, the mechanisms and influences of rhizospheric nitrogen fixation (NF) are not well researched as symbiotic NF lacks summarizing. Phosphate-solubilizing bacteria (PSB) are important members of PGPR. They can dissolve both insoluble mineral and organic phosphate in soil and enhance the phosphorus uptake of plants. The application of PSB can significantly increase plant biomass and yield. Co-inoculating PSB with other PGPR shows better performance in plant growth promotion, and the mechanisms are more complicated. Here, we provide a comprehensive review of rhizospheric NF and phosphate solubilization by PGPR. Deeper genetic insights would provide a better understanding of the NF mechanisms of PGPR, and co-inoculation with rhizospheric diazotrophs and PSB strains would be a strategy in enhancing the sustainability of soil nutrients.

Multi-Omics Reveal the Efficient Phosphate-Solubilizing Mechanism of Bacteria on Rocky Soil.

Phosphate-solubilizing bacteria (PSB) can alleviate available phosphorus (AP)-deficiency without causing environmental pollution like chemical phosphate fertilizers. However, the research and application of PSB on the barren rocky soil is very rare. We screened six PSB from sweetpotato rhizosphere rocky soil. Among them, Ochrobactrum haematophilum FP12 showed the highest P-solubilizing ability of 1,085.00 mg/L at 7 days, which was higher than that of the most reported PSB. The assembled genome of PSB FP12 was 4.92 Mb with P-solubilizing and plant growth-promoting genes. In an AP-deficient environment, according to transcriptome and metabolomics analysis, PSB FP12 upregulated genes involved in gluconic acid synthesis and the tricarboxylic acid cycle, and increased the concentration of gluconic acid and malic acid, which would result in the enhanced P-solubilizing ability. Moreover, a series of experiments in the laboratory and field confirmed the efficient role of the screened PSB on significantly increasing AP in the barren rocky soil and promoting sweetpotato yield. So, in this study, we screened highly efficient PSB, especially suitable for the barren rocky soil, and explored the P-solubilizing mechanism. The research will reduce the demand for chemical phosphate fertilizers and promote the environment-friendly agricultural development.

Integrated Use of Biofertlizers with Organic and Inorganic Phosphorus Sources Improve Dry Matter Partitioning and Yield of Hybrid Maize

ABSTRACT Phosphorus (P) unavailability and lack of organic matter in calcareous soils under semiarid climates are major reasons for low maize productivity grown in these conditions. The hypothesis was tested that integrated use of biofertilizers (BF) and P-sources could improve dry matter (DM) partitioning and yield of hybrid maize (CS-200) in the semiarid climate of Peshawar. A field trial was conducted to investigate the impact of two BF-sources, and eight organic and inorganic P-sources combinations (P) on DM partitioning, yield, and yield components of hybrid maize. The research was conducted at the Agronomy Research Farm of The University of Agriculture Peshawar, during summer 2017. Experiment was laid out in randomized complete block design with split plot arrangement, using four replications. Combination of inorganic-P [single super phosphate (SSP) and rock phosphate (RP)] and organic-P (compost and biochar) sources was used as factor-A, and BF [Phosphate Solubilizing Bacteria (PSB) and Trichoderma (TD)] as factor-B. Phosphorus was applied at the uniform rate of 120 kg ha−1 from different sources (08 treatments). The results revealed that P sources and BF had significantly affected all parameters under study. As compared with TD, application of PSB had significantly increased total plant dry weight (TDW), leaf dry weight (LDW), cob dry weight (CDW), husks dry weigh (HDW), stem dry weight (SDW), and roots dry weight (RDW) at both silking and physiological maturity. The highest ear length (EL), more number of grains per row (NGPR), number of rows per ear (NRPE), number of grains per ear (NGPE), heavy thousand grains weight (TGW), higher total biological yield above ground (BY), grain yield (GY), stover yield (SY), harvest index (HI), and shelling percentage (SP) were obtained with application of PSB over TD. As compared with sole biochar (T3), application of organic-P in the form of sole compost (T4) had significantly increased plant TDW (188.8 g & 312.9 g), LDW (34.3 g & 29.0 g), CDW (41.9 g & 176.1 g), HDW (25.9 g & 21.7 g), SDW (85.4 g & 65.6 g), RDW (26.9 g & 15.2 g) at silking and physiological maturity, respectively. Significantly higher yields (GY, SY, BY, HI & SP) and yield components (EL, NGPE, NRPE & TGW) were recorded with sole compost application (T4) or combined application of compost + SSP (T6). Among all possible interactions of BF and treatments (2 x 8 = 16 combinations), the integrated use of PSB x T4, and PSB x T6 was found to the most beneficial combinations for improving DM partitioning, yield and yield components of hybrid maize in the study area. Interestingly, the integrated use of BF with RP (T7 & T8) had more positive effect on DM partitioning, yield and yield components of hybrid maize than sole application of RP (T2).