Phosphate Solubilizing Bacteria Population Research Articles

Uji Kombinasi Pupuk Anorganik Dan Pupuk Bio-Organik P Terhadap Ketersediaan P Dalam Tanah, Serapan P Tanaman, Dan Populasi Bakteri Pelarut Fosfat Pada Tanaman Kedelai (Glycine Max L. Merrill)

The application of bio-organic P fertilizer alongside inorganic fertilizers plays a crucial role in increasing available phosphorus (P) for plants while also aiming to reduce and optimize the use of inorganic fertilizers. This combination is expected to enhance crop yields, balance nutrient availability, and improve soil structure. The objective of this research was to investigate the impact of the combination of inorganic and bio-organic P fertilizers on soil P availability, P uptake in soybean plants, and the population of Phosphate-Solubilizing Bacteria (PSB) during the vegetative phase. The research utilized an experimental approach with four treatments. Each treatment involved five randomly selected samples, resulting in a total of 20 experimental units. The study was conducted from March to July 2019 in paddy fields in Semoyang Village, Praya Timur Subdistrict, Central Lombok Regency. The treatments used were as follows: P1 (50% of the recommended inorganic fertilizer + 10 g of bio-organic P fertilizer per plant), P2 (75% of the recommended inorganic fertilizer + 10 g of bio-organic P fertilizer per plant), P3 (100% of the recommended inorganic fertilizer), and the control group (without any treatment). The parameters analyzed in this study were the available P content in the soil, soil pH, dry weight of biomass, P uptake in plants, and the population of Phosphate-Solubilizing Bacteria. The results demonstrated that the treatments involving the combination of inorganic and bio-organic P fertilizers showed improvements in all tested parameters compared to using only inorganic fertilizers. The soil pH ranged from 6.56 to 6.64, available soil P ranged from 13.2 to 17.33 ppm, dry weight of biomass ranged from 8.2 to 11.01 grams, P uptake in plants ranged from 10.69 to 16.76 mg per plant, and the population of PSB ranged from 1.14×106 cfu/g to 4.56×107 cfu/g.

POPULASI BAKTERI DAN RESPIRASI MIKROBA TANAH PADA RHIZOSFER TANAMAN JAGUNG ( Zea mays L.) YANG DIBERI PUPUK TERPADU DAN BIOCHAR SEKAM PADI PADA MASA VEGETATIF MAKSIMUM

This study aims to determine the Bacterial Population and Microbial Respiration in the rhizosphere of corn plants due to the application of integrated fertilizers and rice husk biochar soil amendments during the maximum vegetative period. This research was conducted using an experimental method with polybag experiments in a greenhouse from July to September 2021. The experiment was arranged using a completely randomized design (CRD) with 7 treatment combinations P0 (control treatment), P1 (Urea + phonska administration), P2 ( Giving Urea + Phonska + Biochar), P3 (Giving Urea + Phonska + BPF), P4 (Giving Urea + Phonska + Biochar + BPF), P5 (Giving Urea + Phonska + BPF + Compost), P6 (Giving Urea + Phonska + Biochar) + BPF + Compost). Each treatment was repeated 3 times, so as many as 21 units of experimental polybags were obtained. Parameters measured were total bacterial population, population of phosphate solubilizing bacteria, soil microbial respiration, pH, cation exchange capacity, and C-Organic. The results showed that the application of integrated fertilizers (inorganic, compost and biological-BPF) and rice husk biochar had a significant effect. on the total bacterial population, BPF and soil microbial respiration in the corn plant rhizosphere observed at the maximum vegetative period. From this study, it was concluded that the combination of inorganic fertilizer + organic fertilizer + bpf and biochar was the best combination in increasing the total population of bacteria, phosphate solubilizing bacteria and soil microbial respiration.

Isolation and characterization of indigenous phosphate solubilizing bacteria from calcareous soil of dry land ecosystems in Timor Tengah Selatan, East Nusa Tenggara, Indonesia

Abstract. Nur MSM, Benggu YI, Tae ASJA, Ishaq LF, Soetedjo INP. 2023. Isolation and characterization of indigenous phosphate solubilizing bacteria from calcareous soil of dry land ecosystems in Timor Tengah Selatan, East Nusa Tenggara, Indonesia. Intl J Trop Drylands 7: 66-72. Phosphate Solubilizing Bacteria (PSB) is a potential biofertilizer due to its ability to increase phosphorus (P) availability. That is important, especially in areas where P availability becomes a constraint for plant growth, such as calcareous soil in Timor Island, East Nusa Tenggara, Indonesia. The study was undertaken in three ecosystems, including mamar, farm, and coastal areas in Timor Tengah Selatan, with the objective was obtaining and characterizing PSBs from these ecosystems. Five soil samples from the rhizosphere of five plants were collected from each ecosystem for PSB occurrence and soil physicochemical properties. The results showed that PSB could be found in these three ecosystems observed, with the highest types of the isolate being in the coastal area ecosystem compared to mamar and farm ecosystems. PSBs were relatively low in the three ecosystems, possibly related to the soil properties. Despite the low population of PSBs obtained, 19 isolates of PSBs were found in this study. The study results provide initial information on the occurrence of PSBs in calcareous soil Timor. This study needs to be expanded to screen and identify the PSB isolates used as biofertilizers for calcareous soil in the region.

Effect of Different Phosphorus Sources on Soil Physico-Chemical Property Dynamics under Chickpea Crop

A field experiment was conducted during Rabi season of 2021-2022 to study the effect of rock phosphate (RP), poultry manure (PM) and phosphate solubilizing bacteria (PSB) on soil properties. The experiment was laid out in three replications with 9 treatments in Randomized Block design (RBD). Results revealed that the combined application of 50% P through RP + 50% P through PM + PSB (T9) significantly decrease the bulk density but, higher soil porosity was observed with application of 100% P through PM (T5) and 100% P through PM + PSB (T8) were at par. Whereas, improved in soil pH and organic carbon were reported with the application of T8. Also, the maximum available nitrogen (294.95 kg ha-1) was acquired under T8. However, the highest available phosphorus, potassium and available Fe, Mn, Cu and Zn content in soil were observed with T9. Similarly, higher PSB population and acid phosphatase activity was recorded with application of T9. Dehydrogenase activity was observed to be higher underT8 at harvest of chickpea crop. It was concluded that application of phosphate, poultry manure and phosphate solubilizing bacteria improve the soil properties.

Assessment of the Potentials of Water Hyacinth (Eichhornia crassipes) as Raw Material for Biofertilizer

This research investigated the potentials of water hyacinth as raw material for biofertilizers. Water hyacinth was collected from Alape River in Ilaje Local Government Area of Ondo State and processed for microbiological, proximate and physicochemical analyses by standard methods. Results revealed that the total heterotrophic bacterial and fungal populations were 5.0 x 107 (CFU/g) and 3.5 x 105 (CFU/g) and 3.6 x 102 SFU/g and 3.0 x 102 (SFU/g) for root and leaf parts respectively. The population of phosphate solubilizing bacteria, Azospirillum spp., Azotobacter spp. and Rhizobium spp. were 3.5 x 104 - 1.3 x 106 CFU/g, 1.4 x 103- 2.6 x 104 (CFU/g), 3.4 x 103 – 1.7 x 104 (CFU/g) and 1.2 x 103 – 1.1 x 104 (CFU/g) respectively. 16S rRNA gene sequencing revealed the presence of Enterobacter cloacae (LT 221670.1 -53%) and Bacillus safensis (AB711138.1 -99%), Pseudomonas mendocina (LN 881702.1 – 99%) and Aeromonas veroni (LC 487867.1 – 97%) from the root and leaf respectively. Aspergillus spp., Fusarium sp., Rhizopus sp., Trichoderma sp. Cladosporium sp. were among the fungi from the water weed parts. The proximate, nutrient and heavy metal constituents of water hyacinth vary among the leaf, stem and root. The proximate values for moisture (65.45%), protein (12.18%) and carbohydrate (5.30%) were highest in the leaf part compared to the stem and roots. Also, the highest values of ash (18.48%), fat (3.84%) and crude fibre (12.50%) were obtained in the plant root relative to leaf and stem. Apart from magnesium and phosphorous, mineral elements such as sodium, calcium and potassium were more abundant in the leaf. Among the heavy metal, Lead, Cadmium, Nickel, Arsenic and Cobalt had undetectable values for all parts. This study concludes that the presence of microbial biofertilizer and micro and macro nutrients on water hyacinth suggests its potential as raw material for biofertilizer and can be used to promote plant growth without negative consequences.

Chemical and Biological Properties of Potted-Soil for Strawberry Cultivation

Strawberries in tropical West Java are cultivated intensively in potted soil but the substrate condition received less attention. The objective of this descriptive research was to evaluate the chemical and macronutrient profile in potted-soils for strawberry cultivation, and to determine beneficial microbes’ population in root-free bulk soil and rhizosphere of potted-strawberry. The soil samples collected from 12-months and one-month-old potted strawberry; both contained Inceptisols soil order with 10 t/ha and 25 t/ha manure respectively. The proximate analysis was performed using Association of Official Analytical Chemists Method. The microbial enumeration was performed by Serial Dilution Plate Method in specific medium. The results showed that potted soils were not saline, but slightly acid, low in organic carbon and high in cation exchange capacity. The soil reactions were suitable for strawberry but the electrical conductivity was too low for strawberry growth. The potted soils have low to very low carbon to nitrogen ratio, but high in total nitrogen and very high in potential P2O5 and K2O. The population of phosphate-solubilizing bacteria, nitrogen-fixing Azotobacter, total bacteria and total fungi in old potted soil were low; but its counts were increased in manure-treated potted soil. The ratios of bulk soil to rhizosphere microbial count were only 1.0-1.25. The study verified that the doses of organic matter should be increased, while decreasing the chemical fertilizer level.

THE EFFECT OF AGRICULTURAL WASTE COMPOST ON THE POPULATION OF AZOTOBACTER, AZOSPIRILLUM, AND PHOSPHATE SOLUBILIZING BACTERIA IN CORN PLANT MEDIA ON INCEPTISOLS JATINANGOR

Plants require nutrients in order to grow. One method is to provide organic fertilizer in the form of compost. rice straw, Oil Palm Empty Fruit Bunch (OPEFB), and sugarcane bagasse can all be used as compost material. The purpose of this study is to see how different types of agricultural waste compost affect the population of beneficial bacteria such as Azotobacter sp., Azospirillum sp., and Phosphate Solubilizing Bacteria (PSB) on maize planting media in Jatinangor. The study was carried out at the screen house of Ciparanje Experimental Garden in Jatinangor District, utilizing a Randomized Block Design with 9 treatments and three replications. The treatments included a control (no treatment) and three dose levels (5 tons.ha-1 , 10 tons.ha-1 , and 15 tons.ha-1 ) of each type of compost (oil palm empty fruit bunch, sugarcane bagasse, and rice straw). The findings revealed that the use of various types of agricultural waste compost influenced the population of Azotobacter sp., Azospirillum sp., and PSB. When compared to the compost treatment of rice straw and bagasse, the application of OPEFB compost at a dose of 15 tons.ha-1 produced a greater population of Azotobacter sp. 106.43 x 107 cfu.g-1 . While the population of Azospirillum sp. increased by 2.20 x 107 cfu.g-1 as a result of the 15 tons.ha-1 compost of OPEFB, the effect was similar to that of rice straw and bagasse compost. PSB population increased at 15 tons.ha-1 of rice straw compost to 3.73 x 104 cfu.g-1 but not different from 15 tons.ha-1 of OPEFB compost. Compost can be used as an environmentally friendly fertilizing alternative to enhance the population of beneficial bacteria in corn growth media and increasing nutrient availability for plants.

ISOLATION AND MOLECULAR CHARACTERIZATION OF PHOSPHATE SOLUBILIZING BACTERIA FROM RHIZOSPHERIC SOILS OF TROPICAL LOWLAND RICE

Phosphate-solubilizing bacteria (PSB) can promote the dissolution of insoluble phosphorus in soil, enhancing the availability of soluble P and reducing the consumption of fertilizer and aid in sustainable agricultural development. The phosphate solubilising bacteria were isolated from the rhizospheric soils of the experimental site located in the ICAR-National Rice Research Institute's experimental farm in Cuttack, India. & the population of PSBs varied between 1-22.5 cfu/gm*104 and higher in DSR (Direct seeded rice) compared to TPR (Transplanted rice). Phosphate solubilization efficiency (PSE) of the isolates gave better result in Pikovskaya’s agar medium plates i.e. 188.9% in K6 (Kasalath, P80, DSR) rather than National Botanical Research Institute’s Phosphate growth medium (NBRIP) i.e. 73.3% for K6. The highest PSE% in C sources was found in lactose i.e. 166.7% for the isolate K9 (Kasalath, P0, DSR) and 180.0% for the isolate D17 (Dular, P80, TPR) for potassium nitrate as N source. The morphological study by staining characteristics showed that all the isolates were gram negative and cocci except D19 (Dular, P80, TPR) which was gram positive and rod shaped. Amplified fragments of oligonucleotide primers in RAPD characterization showed 51.81% polymorphism and 44.54% monomorphism. Based on dendrogram all the isolates were placed in group A except S11 (Dular, P80, TPR) which was placed in major group B showing great variation from all other isolates and group A consists of 6 minor groups in which minor group A6 was the largest containing 5 isolates i.e. Kasalath, P40, DSR (S13), Kasalath, P80, DSR (S14, S15, S16) & IR36, P40, DSR (S17).

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.

Combination of FOBIO biopesticide and Brassica rapa L. as remediator of heavy metal Pb in soil

Marginal soil is infertile soil caused by various factors, one of which is the excessive accumulation of heavy metals. FOBIO microorganism-based biopesticide formula containing phosphate solubilizing bacteria is expected to be used to reduce excess heavy metals in the soil. Brasica rapa L. is a variety resistant to Pb heavy metal stress and absorbs more heavy metals into root tissue than leaf tissue with the help of microorganisms. This study aimed to determine the combination of Brassica rapa L. and FOBIO biopesticide in absorbing Pb in the soil, determine the growth of Brassica rapa L. at each Pb concentration, and determine the population of phosphate-solubilizing bacteria in the soil at each level of Pb stress after remediation. This study used variations in the concentration of heavy metals, particularly Pb. Parameters observed included plant growth, Pb concentration in the soil before and after remediation, and the population of phosphate-solubilizing bacteria. The results showed that combining FOBIO biopesticides and Brassica rapa L. could reduce Pb concentration in the soil. The growth of Brassica rapa L. plants was significantly different after treatment. The findings confirmed that increasing, the concentration of Pb led to a decrease in the population of phosphate-solubilizing bacteria.

UJI EFEKTIVITAS KOMPOS KOTORAN SAPI DAN SEKAM PADI MENGGUNAKAN MIKROORGANISME LOKAL BATANG PISANG TERHADAP POPULASI BAKTERI PELARUT FOSFAT DAN PRODUKSI PAKCOY (Brassica rapa var. chinensis L.)

Management of agricultural land in Jabung District using inorganic fertilizers with high doses resulted in a decrease in soil quality, such as a low population of phosphate solubilizing bacteria that can release phosphate from Al-P and Fe-P bonds. Inceptisols in Jabung Subdistrict with low fertility still has the potential to cultivate pakcoy with the innovative application of cow manure and rice husk compost with banana stem MOL bioactivator as a source of bacterial culture and organic matter decomposers. This study was aimed to determine the effectiveness of the application of cow dung and rice husk compost on the population of phosphate solubilizing bacteria, the diversity of bacteria in dissolving phosphate based on the clear zone index, and the yield of pakcoy. This study used a randomized block design with six treatments and four replications. The results showed that cow dung and rice husk compost significantly increased the population of phosphate solubilizing bacteria by 27.7 × 106 CFU g-1, diversity of phosphate solubilizing bacteria based on the clear zone index as many as 23 isolates with the highest clear zone index 5,40 isolate code P52. The results also showed that the application of cow dung and rice husk compost significantly increased the wet weight by 15,520 kg ha-1 and the dry weight of pakcoy by 661.6 kg ha-1.

PENGARUH PEMBERIAN DOLOMIT DAN PUPUK ANORGANIK TERDAHAP SERAPAN FOSFAT, POPULASI BAKTERI PELARUT FOSFAT DAN PRODUKSI PADI

Excessive use of chemical fertilizers in rice fields can reduce soil pH. Elemental P in acid soils is generally not available to plants because it is bound by Fe and Al elements; therefore, it is necessary to make an effort to optimize the availability of P in the soil by improving soil pH with the addition of dolomite lime supported by inorganic fertilizers. This study aimed to determine the effect of dolomite and inorganic fertilizers on plant P uptake, the relationship between available P and phosphate-solubilizing bacteria population, and the effect of dolomite and inorganic fertilizer application on rice yield. This study used a randomized block design with eight treatments and three replications. The results showed that the application of dolomite and inorganic fertilizer had a significant effect on plant P uptake and dry grain weight. The population of phosphate-solubilizing bacteria was positively correlated with the availability of phosphorus in the soil.

PENGARUH APLIKASI KOMPOS DENGAN PUPUK ANORGANIK (NPK DAN UREA) TERHADAP POPULASI BAKTERI PELARUT FOSFAT DAN HASIL TANAMAN JAGUNG DI LAHAN KERING

The aim of this study was to explore the effect of a combination of manure and inorganic fertilizer (NPK and Urea) on the population of phosphate-solubilizing bacteria and the yield of maize. The study was carried out from June to October 2018 in the Kemantren Village, Alas Kulak Hamlet, Jabung District, Malang Regency. This study used a randomized block design consisting of 8 treatment levels and repeated three times. The results of the analysis of variance showed that the application of a combination of compost, fertilizer (NPK and Urea) gave significantly different results to the population of phosphate solubilizing bacteria C-organic, P-total, P-available, dry shelled weight and stover weight. The treatment of 2 t ha-1 compost + 100 kg ha-1 NPK + 50 kg gave the highest yield for the population of phosphate solubilizing bacteria with a value of 61×104 CFU.g-1. Maize production yields obtained treatment of 2 t ha-1 of compost + 400kg.ha-1NPK + 200 kg.ha-1 Urea reached a value of 8.65 t ha-1.

Soil microbial community dynamics as influenced by integrated nutrient management practices in sweet basil (Ocimum basilicum L.) cultivation

An experiment was conducted to study the effect of integrated nutrient management practices on the microbial community dynamics of soils under sweet basil (Ocimum basilicum L.) at ICAR - Indian Institute of Horticultural Research, Bengaluru during the Kharif season of 2015 and 2016. There were nine treatments replicated thrice in randomized complete block design. The results indicated that integrated application of FYM (10 t/ha) + 100% recommended N through FYM + bio-fertilizer i.e., T2 recorded the highest population of heterotrophic free-living N2 fixers (40.66 and 63.33 CFU ×103/ g), phosphate solubilizing bacteria (5.6 and 6.6 CFU ×103/ g) and fungal (6.4 and 5.33 CFU ×103/ g) while T9 with the application of NPK (160:80:80 kg /ha) + FYM (10 t/ha) recorded the highest population of actinomycetes (29.93 and 44.56 CFU ×103/ g) in the soil during 2015 and 2016, respectively. Application of recommended dose of FYM (10 t/ha) in T7 resulted in a reduction in the population of heterotrophic free-living N2 fixers (26.13 and 34 CFU ×103/ g) and actinomycetes (20 and 30.5 CFU ×103/ g) whereas, the application of a recommended dose of chemical fertilizer in T8 recorded the lowest population of phosphate solubilizing bacteria (3.9 CFU ×103/ g) and fungal (3.6 and 2.5 CFU ×103/ g) during 2015 and 2016, respectively. The highest organic carbon (0.63 and 0.66 %) content in the post-harvest soil samples was recorded with the application of NPK (160:80:80 kg /ha) + FYM (10 t/ha) while, the lowest organic carbon value (0.52 and 0.53%) was recorded in T8 during 2015 and 2016, respectively. Application of recommended FYM (10 t/ha) along with recommended NPK (160:80:80 kg/ha) in T9 recorded maximum herbage yield in the main crop (41.59 and 38.31 t/ha) and ratoon (20.97 and 17.77 t/ha) during 2015 and 2016, respectively. The results obtained from this study clearly demonstrated that integrated nutrient management can maximize soil microbial community dynamics which is considered as the driving force behind regulating soil processes that support sustainable sweet basil cultivation.

Soil microbial community dynamics as influenced by integrated nutrient management practices in sweet basil (Ocimum basilicum L.) cultivation

An experiment was conducted to study the effect of integrated nutrient management practices on the microbial community dynamics of soils under sweet basil (Ocimum basilicum L.) at ICAR - Indian Institute of Horticultural Research, Bengaluru during the Kharif season of 2015 and 2016. There were nine treatments replicated thrice in randomized complete block design. The results indicated that integrated application of FYM (10 t/ha) + 100% recommended N through FYM + bio-fertilizer i.e., T2 recorded the highest population of heterotrophic free-living N2 fixers (40.66 and 63.33 CFU ×103/ g), phosphate solubilizing bacteria (5.6 and 6.6 CFU ×103/ g) and fungal (6.4 and 5.33 CFU ×103/ g) while T9 with the application of NPK (160:80:80 kg /ha) + FYM (10 t/ha) recorded the highest population of actinomycetes (29.93 and 44.56 CFU ×103/ g) in the soil during 2015 and 2016, respectively. Application of recommended dose of FYM (10 t/ha) in T7 resulted in a reduction in the population of heterotrophic free-living N2 fixers (26.13 and 34 CFU ×103/ g) and actinomycetes (20 and 30.5 CFU ×103/ g) whereas, the application of a recommended dose of chemical fertilizer in T8 recorded the lowest population of phosphate solubilizing bacteria (3.9 CFU ×103/ g) and fungal (3.6 and 2.5 CFU ×103/ g) during 2015 and 2016, respectively. The highest organic carbon (0.63 and 0.66 %) content in the post-harvest soil samples was recorded with the application of NPK (160:80:80 kg /ha) + FYM (10 t/ha) while, the lowest organic carbon value (0.52 and 0.53%) was recorded in T8 during 2015 and 2016, respectively. Application of recommended FYM (10 t/ha) along with recommended NPK (160:80:80 kg/ha) in T9 recorded maximum herbage yield in the main crop (41.59 and 38.31 t/ha) and ratoon (20.97 and 17.77 t/ha) during 2015 and 2016, respectively. The results obtained from this study clearly demonstrated that integrated nutrient management can maximize soil microbial community dynamics which is considered as the driving force behind regulating soil processes that support sustainable sweet basil cultivation.

PENGARUH APLIKASI BAKTERI PELARUT FOSFAT DAN PUPUK ANORGANIK FOSFAT TERHADAP POPULASI BAKTERI PELARUT FOSFAT, P-TERSEDIA, DAN HASIL TANAMAN JAGUNG PADA ALFISOL

Fulfilment of nutrients for plants can be maximized when fertilization, but the application of inorganic fertilizers can cause damage to the soil if the dosage is excessive. The utilization of phosphate solubilizing bacteria is an effort to increase the efficiency of phosphate fertilization that can extract phosphate from an insoluble form that becomes available. This study aimed to obtain a combination of inorganic fertilization doses (SP-36 and NPK) and the application of biological fertilizers that utilize phosphate solubilizing bacteria (PSB) to increase the population of phosphate solubilizing bacteria and P-available in the soil, as well as corn crop yields. This study used a randomized block design with nine treatments and three replications. The result showed that the application of PSB and inorganic phosphate fertilizer shows a significant effect on the population of PSB, P-available, plant height, stover dry weight, cob weight with husk and cob weight without husk, but didn’t show a significant effect on 100 seeds weight and number of plant leaves. Based on the correlation analysis, the results show a positive correlation between soil chemical properties, P-available, and corn yield.

بررسی تأثیر باکتری تیوباسیلوس، کود گوگردی و فسفری بر جمعیت باکتری‌های حل‌کننده فسفات در خاک

Introduction: According to WHO and FAO studies, the diseases caused by contaminated foods are of the most widespread threats to human health in developing and developed countries. Therefore, in recent years, researchers have been trying to use soil microorganisms to solve this problem and maintain the health of plants and the environment. Phosphorus after nitrogen, is a major macronutrient in plants which controls the growth, seeding and fruit production and involves in basic biological functions such as cell division, nucleic acids synthesis, photosynthesis and respiration and energy transfer. However, high amount of soluble inorganic phosphate is annually applied to the soil as chemical fertilizer but a large portion of it is immobilized rapidly after application due to phosphate fixation by aluminum, calcium, iron, magnesium and soil colloids and becomes unavailable to plants. The use of biological agents especially phosphate solubilizing microorganisms, can play an important role in supplying plant nutrients and improves crop health and productivity without causing any harm in agricultural and natural ecosystems. Bacteria and fungi are the two important groups of phosphate solubilizing microorganisms. Phosphate solubilizing bacteria in soil include Rhizobium, Bacillus, Pseudomonas, Agrobacterium, Achromobacter, Enterobacter and Burkholderia, and the most important ones i.e., Bacillus sp. and Pseudomonas flourescens. Material and Methods: In order to evaluate the effect of Thiobacillus, sulfur and phosphorus applicationon population of phosphate solubilizing bacteria in soil, a field experiment was conducted at Zarghan Agricultural and Natural Resources Research Center of Iran in a factorial, based on complete randomized block design with 3 replications. Treatments consisted of three levels of sulfur fertilizer with biofertilizer containing Thiobacillus bacteria (without sulfur and biofertilizer containing Thiobacillus (S0), application of 500 kg S + 10 kg biofertilizer containing Thiobacillus (S1), 1000 kg S + 20 kg biofertilizer containing Thiobacillus (S2) and 2000 kg S + 40 kg biofertilizer containing Thiobacillus (S3) per hectare), three levels of triple super phosphate (without phosphorus (P0), 100% (P1) and 65% (P2) percent phosphorus recommended based on the soil test) in two corn planted and not planted states. After harvesting, 72 soil samples were collected from each plot and transferred to the biology laboratory of soil and water research institute of Karaj. Soil samples were stored in sterile conditions at 4◦C. In order to isolate phosphate solubilizing bacteria, 10 gram of soil from each sample was suspended in 90 ml of sterilized water to make 1:10 dilution. Then, series of dilution were made (101 – 107) and 0.1 ml of suspensions of the diluted soil sample were transferred to petri dishes containing pikovskaya medium and incubated at 28- 30˚C. To identify PSP from halos surrounding characterized colonies was used and counting was performed 1-14 days after cultivation. The colonies were isolated on the basis morphological characteristics such as shape, color and size and then purified by linear culture. Finally, 60 strains were purified that were used to compare phosphate solubilizing capability. Results and Discussion: The results of this study showed that the main and interaction effects of sulfur fertilizer and biofertilizer treatments of Thiobacillus, phosphorus and plants on the population of phosphate-solubilizing bacteria (cells per gram of dry soil) in Pikovskaya medium were significant at 0.01 level probability. The highest population of bacteria was obtained at the lowest level (S1). Increasing the level of sulfur fertilizer and Thiobacillus biofertilizer decreased the population of phosphate-solubilizing bacteria and the highest level of sulfur and Thiobacillus biofertilizer led to the lowest bacterial population. Also, the study of phosphorus application on the bacterial population showed that phosphorus fertilizer at both levels significantly increased the bacterial population compared to the control (no application phosphorus). The best fertilizer treatment for phosphorus application was P1 which had the greatest effect on bacterial population compared to P2 treatment in Pikovskaya environment. In this experiment, the population of bacteria in corn planted conditions was higher than in non-planted conditions and this population increase was observed in almost all different levels of sulfur and phosphorus fertilizers. The highest bacterial population was observed in combined treatment of S1P2 under corn planted conditions. The results of microscopic, physiological and biochemical tests of the strains showed that all 60 bacterial strains were capable to form clear zone in Pikovskaya medium. Among them, 15 strains (7, 3, 2 and 3 strains belonging to Bacillus megaterium, Bacillus subtilis, Bacillus cereus and Pseudomonas fluorescent, respectively) had higher phosphate solubility than the others.

Selection of efficient phosphorus solubilizing bacteria strains and mycorrhizea for enhanced cereal growth, root microbe status and N and P uptake in alkaline calcareous soil

ABSTRACT Calcareous, alkaline and kaolinite soils, despite external P fertilization, are low in plant extractable P because of their P fixing nature. Use of Arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) are eco-friendly technologies for enhancing plant P nutrition and total crop production. However, use of potentially viable amongst numerous strains is of significant importance. In this study, we isolated and characterized AMF and PSB strains from berseem, wheat and pasture rhizosphere at ten agricultural soils and evaluated their P nutrition potential on maize crop grown in pots. Two PSB strains (URF-B-4 and NP-B-4) were identified for their highest population density (3.2 × 108 g−1 CFU) and P solubility index (3.02) whilst a total of four AMF strains (Glomus Hoi, Glomus claroideum, Glomus mossai, and Glomus intrardices) were isolated from berseem rhizosphere. The isolated strains were used both in the presence and absence of vermicompost (VC) in order to evaluate their potential in low and high carbon soils. Results revealed that selected strains of AMF and PSB in vermicompost (VC) pots (AMF+PSB+VC) significantly increased the plant height and roots dry biomass (by 41 and 55%, respectively). Soil OM, AB-DTPA extractable P, soil total N, plant P concentrations and N and P uptake were also significantly (P < 0.05) higher with AMF+PSB+VC followed by PSB+VC over rest of the treatments. The AMF+PSB resulted in significantly higher plant N concentration while the AMF root colonization and spores density and PSB population density were maximum for AMF+PSB+VC followed by AMF+PSB. Results concluded that for improved plant growth, nutrients availability/uptake, microbial status, and fertility of the alkaline and calcareous soils, only the efficient AMF and PSB strains (URF-B-4 and NP-B-4) application along with vermicompost would pay back significantly in addition to routine inorganic P fertilizer application.

Effect of Long-Term Organic Fertilization in Flooded Rice Soil on Phosphorus Transformation and Phosphate Solubilizing Microorganisms

Phosphorus (P) is a major limiting factor for plant growth. Long-term organic fertilization increases P availability by improving soil microbial and chemical properties. To study this, rice was grown under different treatments, namely, control, farmyard manure (FYM), green manure (GM), FYM + GM (1:1) (FYGM), FYM + Azolla (1:1) (FYAZ), rice straw (5 t ha−1) + GM (GMRSF), Azolla + GM (1:1) (GMAZ) and rice straw (2.5 t ha−1) + GM (GMRSH), with the aim of comparative evaluation of microbiological and chemical changes occurring in the rice soil after 15 years of rice-fallow cycles. The results showed that organic fertilization increased dehydrogenase activity by 12–50% over the control. Both acid (166.1 μg PNP g−1 h−1) and alkaline phosphatase (46.1 μg PNP g−1 h−1) activities were found highest in GMRSH. Long-term application of organic fertilization increased the pools of active/labile C (microbial biomass carbon, readily mineralizable carbon), N (microbial biomass nitrogen) and P (microbial biomass phosphorus) in the soil. Bacterial and fungal populations were observed higher in the FYM treatment than in the control. However, the populations of phosphate solubilizing bacteria (PSB) and fungi (PSF) were observed highest in GMRSH and FYAZ, respectively. Non-occluded Al and Fe-P (125.94 kg ha−1) was highest in GMRSH, while occluded P (6.46 kg ha−1) was highest in GMRSF. Thus, long-term (15 years) organic fertilization improves PSB and PSF populations, contributing to better P transformation in the soil. GMRSH and GMRSF treatments were found to be effective organic fertilization in increasing enzymatic activities, available phosphate fractions and microbial biomass in soil.

Microbial exploration of the origin of the Pandeglang cocoa plant (Theobroma cacao L.) rhizosphere as potential biofertilizer

This study aimed to determine the ability of microorganisms originating from the root ecosystem (Rhizosphere) of cocoa (Theobroma cacao L) as a potential superior to biological agents. For the experiment, soil samples were observed from the rhizosphere of cocoa plants in Pandeglang Regency. At this stage, the research was focused on finding out the extent of microbe screening results from cocoa rhizosphere soil in producing phytohormones. The results from the initial selection showed a population of Azotobacter 2.8 x 105 cfu/mL, a population of Azospirillium of 0.3 x 102 cfu/mL, and a population of Phosphate-solubilizing bacteria (PSB) 4.1 x 107 cfu/mL. In the hemolysis test conducted for 9 isolates, only 1 isolate showed a negative result. From the test of the ability to produce phytohormones showed respectively from the highest values were IAA 5.467 mg/L, gibberellin 3.768 mg/L, zeatin 1.321 mg/L, and kinetin 0.886 mg/L. The land rhizosphere of Pandeglang cocoa plant had superior potential microbes which could be used as biological fertilizers.