Phosphate Solubilizing Bacteria Research Articles

Intensive Citrus Cultivation Suppresses Soil Phosphorus Cycling Microbial Activity

Soil microbes are key drivers in regulating the phosphorus cycle. Elucidating the microbial mineralization process of soil phosphorus-solubilizing bacteria is of great significance for improving nutrient uptake and yield of crops. This study investigated the mechanism by which citrus cultivation affects the soil microbial acquisition strategy for phosphorus by measuring the abundance of the phoD gene, microbial community diversity and structure, and soil phosphorus fractions in the soils of citrus orchards and adjacent natural forests. The results showed that citrus cultivation could lead to a decrease in soil pH and an accumulation of available phosphorus in the soil, with a content as high as 112 mg·kg-1, which was significantly higher than that of natural forests (3.7 mg·kg-1). Citrus cultivation also affected the soil phosphorus fractions, with citrus soil having higher levels of soluble phosphorus (CaCl2-P), citrate-extractable phosphorus (Citrate-P), and mineral-bound phosphorus (HCl-P). The phosphorus fractions of natural forest soils were significantly lower than those of citrus soils, whereas the phoD gene abundance and alkaline phosphatase activity were significantly higher in natural forest soils than in citrus soils. High-throughput sequencing results showed that the Shannon diversity index of phosphate-solubilizing bacteria in citrus soils was 4.61, which was significantly lower than that of natural forests (5.35). The microbial community structure in natural forests was also different from that of citrus soils. In addition, the microbial community composition of phosphate-solubilizing bacteria in citrus soils was also different from that of natural forests, with the relative abundance of Proteobacteria being lower in natural forest soils than in citrus soils. Therefore, citrus cultivation led to a shift of soil microbial acquisition strategy for phosphorus, with external phosphorus addition being the main strategy in citrus soils, whereas microbial mineralization of organic phosphorus was the main strategy in natural forest soils to meet their growth requirements.

Innovative approaches: Exploring nano-biochar technology’s impact on soil properties, alachlor retention, and microbial populations

Pesticide contamination and soil degradation stand as critical challenges in the agricultural ecosystem. This study delves into the impact of nano-biochar (NBC) on soil properties, alachlor retention, and microbial populations, exploring concentrations of 1 %, 3 %, and 5 % w w−1 in both planted and unplanted alachlor-contaminated soil. A six-week black bean-pot experiment was conducted in planted soil. The NBC, distinguished by its substantial carbon content and remarkable surface area, pore volume, and diameter, resulted in significant enhancements in soil pH, moisture content (MC), and soil organic carbon (SOC). Over the 6-week period, NBC3% and NBC1 % consistently increased SOC content, while NBC5% displayed a declining trend after the 4th week. The application of NBC led to a remarkable acceleration in alachlor reduction, achieving efficiencies exceeding 77 % in unplanted soils and reaching an impressive 97.3 % in planted soils. The reduction dynamics, modeled by a first-order equation, revealed notably shorter half-lives of alachlor in NBC-treated soils compared to controls. Abundance in total plate count (TPC), phosphate-solubilizing bacteria (PSB), and nitrogen-fixing bacteria (NFB) increased with NBC1 % and NBC3 %, although NBC5 % showed a decline after the 2nd week. The findings suggest that NBC1 % and NBC3 % offer optimal outcomes for desired soil improvements, enhanced microbial activity, and effective soil pesticide removal.

Effect of phosphorus management on yield and economics under direct seeded rice (Oryza sativa) and blackgram (Vigna mungo) intercropping in a rainfed acidic upland soil

A field experiment was conducted during rainy (kharif) season of 2019 at ICAR-National Rice Research Institute (NRRI), Central Rainfed Upland Rice Research Station (CRURRS), Hazaribagh, Jharkhand to study the effect of phosphorus management on productivity and profitability under direct seeded rice (Oryza sativa L.) (DSR) and blackgram [Vigna mungo (L.) Hepper] intercropping in rainfed acidic upland soil. The experiment was laid-out in a split-plot design comprised 4 methods of cropping, viz. Sole DSR; Sole blackgram; DSR + blackgram (4:1); and DSR + blackgram (4:2) allotted to main-plots and 4 phosphorus management practices, viz. P control (P0 ); Recommended dose of phosphorus (RDP) @17.5 kg P/ha; 50% RDP + phosphate solubilizing bacteria (PSB) @500 g/ha + arbuscular mycorrhiza fungi (AMF) @12.5 kg/ha; and 25% lime requirement (LR) + PSB + AMF in sub-plots. Experiment consisted of 16 treatment combinations, replicated thrice. The rice variety ‘Sahabhagi’ and blackgram variety ‘Uttara’ were used. Among the cropping systems, the highest grain yield was recorded in sole rice (3.84 t/ha) and sole blackgram (1.14 t/ha) which was significantly higher than yields under intercropping in both the ratios. Gross (`96,879/ha) and net returns (`70,603/ha) of sole blackgram were significantly higher than other cropping systems and followed by DSR + blackgram (4:2). Net benefit:cost (B:C) of sole blackgram was maximum (`2.69) and lowest in sole rice (`1.01). Among phosphorus management treatments, 50% RDP + PSB + AMF gave significantly higher net return (`49,440) and net benefit:cost (`1.68). Application of 100% RDP and 25% LR + PSB + AMF gave at par returns and net benefit:cost. It may be suggested that under rainfed uplands of eastern India, farmers may adopt either sole blackgram or intercropping of rice and blackgram in 4:2 over sole DSR for higher productivity and monetary returns. For better phosphorus management in soil they should inoculate PSB and AM fungi along with 50% RDP at the time of sowing.

Preceding kharif crops and fertilizer influence on growth, yield and nutrient requirement of succeeding wheat (Triticum aestivum)

A field experiment was conducted during 2 consecutive rainy (kharif) and winter (rabi) season each of 2020–21 and 2021–22 at C.P. College of Agriculture, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, Gujarat to study the effect of preceding kharif crops and fertilizer on growth, yield, economics and nutrient requirement of succeeding wheat (Triticum aestivum L.) crop. The experiment was laid out in split plot design comprising of 4 kharif crops, viz. greengram [Vigna radiata (L.) R. Wilczek], sesame (Sesamum indicum L.), pearl millet [Pennisetum glaucum (L.) R.Br.] and fodder sorghum [Sorghum bicolor (L.) Moench] as main plots and 5 fertilizer treatments, viz. 100% RDF (120 kg N + 60 kg P2 O5 + 40 kg K2 O/ha); 75% RDF; 50% RDF; 75% RDF + Azotobacter + PSB (phosphate solubilizing bacteria); and 50% RDF + Azotobacter + PSB as sub plots with four replications. Wheat grown after kharif greengram had better growth parameters and yield attributes which was reflected in an increase in grain (4.78 t/ha) and straw (6.41 t/ha) yield of wheat. Among different fertilizer treatments, wheat fertilized with 100% RDF recorded significantly higher grain (4.60 t/ha) and straw yield (6.20 t/ha). Nutrient uptakes by grain and straw increased under wheat grown after greengram and fertilized with 100% RDF. Greengramwheat crop sequence and wheat fertilized with either 100% RDF or 75% RDF along with Azotobacter + PSB seed inoculation earned higher net realization and B:C ratio.

Microbial population and yield of rice–wheat system under variable irrigation and nutrient management

A field experiment was conducted during rainy (kharif) season of 2018–19 and winter (rabi) season of 2019–20 at the Water Management Research Farm of CSK Himachal Pradesh Agricultural University, Palampur, Kangra, Himachal Pradesh to study the effect of moisture and nutrient management practices on different soil microbial entities and crop yields in rice (Oryza sativa L.)–wheat (Triticum aestivum L.) system. Experiment was laid out in a split-plot design with 3 replications. Treatments comprised of 3 irrigation levels, viz. Recommended critical stages regimes; Irrigation at 0.8 CPE (cumulative pan evaporation) (rice) and 0.6 CPE (wheat); Irrigation at 1.0 CPE (rice) and 1.0 CPE (wheat) assigned to main-plots and 4 nutrient management practices, viz. Inorganic; Organic; Natural farming; and Integrated management allotted to sub-plots. Irrigation at critical stages resulted in significantly higher rice yield, bacterial, azotobacter, phosphate solubilizing bacteria (PSB), actinomycetes population. However, fungi population increased under higher moisture regimes. In case of wheat crop, irrigation at 1.0 CPE resulted in a significantly higher yield (7.5% higher over irrigation at critical stages) in both the years of study. Organic and integrated nutrient management practices being statistically at par with each other recorded significantly higher microbial population. A significantly higher fungi population was, however, recorded with natural farming. The highest crop yields were obtained with integrated nutrient management (3.4 t/ha rice and 3.6 t/ha wheat in second year). The best combination for rice was irrigation at critical stages along with integrated nutrient management. Whereas, for wheat irrigation at 1.0 CPE with same nutrient management proved to be the best. Hence it is recommended to follow integrated nutrient management and irrigation at critical stages in rice and at 1.0 CPE in wheat for higher productivity as well as for improved biological properties of soil.

Quantifying response of azospirillum and phosphate solubilizing bacteria liquid inoculants seed treatment on productivity and profitability of kharif grain sorghum (Sorghum bicolor)

A field study was carried out during 2017–19 at Sorghum Research Unit, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra to assess the effect of liquid bio-fertilizers inoculation over existing powder form inoculants on kharif grain sorghum [Sorghum bicolor (L.) Moench]. The experiment comprised of 6 treatments, viz. no bio-fertilizer control i.e. with RDF alone (T1 ); RDF + Azo. (Azospirillum) + PSB @50 g each/kg seed (T2 ); RDF + Azo. + PSB @2 ml each/kg seed (T3 ); RDF + Azo. @2 ml and PSB @4 ml/kg seed (T4 ); RDF + Azo. @4 ml + PSB @2 ml/kg seed (T5 ); and RDF + Azo. + PSB @4 ml each/kg seed (T6) conducted in randomized block design (RBD) with 4 replications. Pooled data revealed that seed inoculation with Azo. + PSB @2 ml each/kg seed (T3 ) has improved the sorghum biological, grain yield and net returns 21.13, 19.83 and 17.92% over their powder form of inoculants i.e. T2 (14.71 t/ha, 3.56 t/ha and 73,116). These enhancements in biomass, grain yields and net income was owing to liquid bio-fertilizer seed treatment. Liquid-based inoculants were found to boost growth and yield parameters, which was ascribed to the concomitant increase in plant height and number of grains/panicle, respectively. Increase in quantity of liquid bio-fertilizers beyond 2 ml/kg seed proved not-rewarding from both productivity and profitability point of view. Sorghum seed inoculation with liquid bio-fertilizers @2 ml each/kg seed proved to be a potential substitute for existing powder form without any additional cost.

Phosphate solubilizing Pseudomonas and Bacillus combined with rock phosphates promoting tomato growth and reducing bacterial canker disease.

Nowadays, sustainable agriculture approaches are based on the use of biofertilizers and biopesticides. Tomato (Solanum lycopersicum L.) rhizosphere could provide rhizobacteria with biofertilizing and biopesticide properties. In this study, bacteria from the rhizosphere of tomato were evaluated in vitro for plant growth promotion (PGP) properties. Five Pseudomonas isolates (PsT-04c, PsT-94s, PsT-116, PsT-124, and PsT-130) and one Bacillus isolate (BaT-68s), with the highest ability to solubilize tricalcium phosphate (TCP) were selected for further molecular identification and characterization. Isolates showed phosphate solubilization up to 195.42 μg mL-1. All isolates showed phosphate solubilization by organic acid production. The six isolates improved seed germination and showed effective root colonization when tomato seeds were coated with isolates at 106 cfu g-1 in axenic soil conditions. Furthermore, the selected isolates were tested for beneficial effects on tomato growth and nutrient status in greenhouse experiments with natural rock phosphate (RP). The results showed that inoculated tomato plants in the presence of RP have a higher shoot and root lengths and weights compared with the control. After 60 days, significant increases in plant Ca, Na, P, protein, and sugar contents were also observed in inoculated seedlings. In addition, inoculated tomato seedlings showed an increase in foliar chlorophyll a and b and total chlorophyll, while no significant changes were observed in chlorophyll fluorescence. In greenhouse, two Pseudomonas isolates, PsT-04c and PsT-130, showed ability to trigger induced systemic resistance in inoculated tomato seedlings when subsequently challenged by Clavibacter michiganensis subsp. michiganensis, the causal agent of tomato bacterial canker. High protection rate (75%) was concomitant to an increase in the resistance indicators: total soluble phenolic compounds, phenylalanine-ammonia lyase, and H2O2. The results strongly demonstrated the effectiveness of phosphate-solubilizing bacteria adapted to rhizosphere as biofertilizers for tomato crops and biopesticides by inducing systemic resistance to the causal agent of tomato bacterial canker disease.

Effects of probiotic on growth and production of brown midrib sorghum mutant line (Sorghum bicolor L. Moench) in ultisol

This study aims to observe the efficiency of probiotic inoculants on growth, soil fertility, and production of brown midrib (BMR) sorghum mutant lines. The experimental using a Randomized Block Design of four treatments and four blocks, P0: manure + (N, K, 0% P) + probiotic; P1: manure + (N, K, 50% P) + probiotic; P2: manure + (N, K, 75% P) + probiotic; P3: manure + (N, K, 100% P) without a probiotic (control). The dose of cow manure fertilizer is 10 tons/ha, and the doses of N, P, and K fertilizers are 120 kg/ha, 90 kg/ha, and 60 kg/ha, respectively, from urea, triple superphosphate (TSP), and potassium chloride (KCl). Parameters observed were plant morphology, biomass production, nutrient and fiber fraction content, and soil fertility. The treatment had no significant effect (P>0.05) on stem diameter, leaf length, and width, soil pH, fresh and DM production, the number of leaves, plant height, stem:leaf: panicle ratio, colony PSB, soil P-available, fiber and nutrient fractions of sorghum whole plant. The conclusion is that applying probiotics with lower phosphate fertilizer in sorghum cultivation produces growth, forage production, nutrition and fiber fraction content, and P-available and colony PSB, like 100% P fertilizer application. Probiotic bacteria could be applied as phosphate-solubilizing bacteria and reduce the application of P fertilizer on BMR sorghum in ultisol.

Effect of basal and foliar application of diammonium phosphate in cognizance with phosphate-solubilizing bacteria on growth, yield and quality of rainfed chickpea (Cicer arietinum)

A rainfed experiment was conducted during the winter (rabi) seasons of 2011–12 and 2012–13 at Kumarganj, Faizabad, Uttar Pradesh to study the effect of diammonium phosphate (DAP) applied through soil and foliage in conjunction with phosphate-solubilizing bacteria (PSB) on growth characters, yield attributes and yield, seed protein content, nutrient uptake and phosphorus-use efficiency (PUE) of chickpea (Cicer arietinum L.). The application of 50 kg DAP/ha as basal + 50 kg DAP/ha as foliar in 2 splits 45 and 60 days after sowing + PSB significantly increased the growth attributes (plant height, primary branches/plant, leaf area/plant, number and dry weight of nodules/plant, root and shoot dry weight/plant, root: shoot ratio), yield attributes and yield (pods/plant, 1,000-seed weight, seed yield, biological yield), seed protein content, N and P uptake and PUE of chickpea. However, seeds/ pod and harvest index were not affected significantly due to the application of DAP in cognizance with PSB. Thus, split application of 100 kg DAP/ha (½ through soil + ½ through foliage in 2 splits at 45 and 60 DAS) in conjunction with PSB proved effective in enhancing growth, yield (1,486 kg/ha; 102% increase over the control) and quality of chickpea grown under rainfed conditions.

Influence of Rhizobium Co-inoculated with Arbuscular Mycorrhiza and Phosphate Solubilizing Bacteria on the Growth of Peanut Tainan 9 variety

The study of rhizobium co-inoculated with arbuscular mycorrhiza and phosphate solubilizing bacteria on peanut growth in pot experiment was laid out on completely randomized design (CRD). The experiment consisted of 5 treatments; 1) control (without microorganism), 2) rhizobium (R: Rhizobium sp.),3) R + arbuscular mycorrhiza (R+AM),4) R + Phosphate Solubilizing bacteria (R+PSB: Rhizobium sp. + Bacillus sp.) and 5) R+AM+PSB with 4 replications. The results showed that co-inoculated of microorganisms (R+AM+PSB) provided the highest root length, and the highest fresh weight and dry weight of shoot and root. The treatment of R+AM showed the peak of nodules number (115 nodules/plant), nodules fresh weight and dry weight (0.65 and 0.16 g/plant). R+AM+PSB treatment increased the percentage of AM root length colonized at 26.64%. However, total nitrogen content in peanut shoot was highest in R+PSB. The concentrations of phosphorus and potassium in peanut shoot and root parts were not significant among treatments. Co-inoculate of R and PSB produced the highest nitrogen fixation at 87.73 mg N/plant.

Growth, nutrient removal, and lipid productivity promotion of Chlorella sorokiniana by phosphate solubilizing bacteria Bacillus megatherium in swine wastewater: Performances and mechanisms

Effects of a phosphorus-solubilizing bacteria (PSB) Bacillus megatherium on growth and lipid production of Chlorella sorokiniana were investigated in synthesized swine wastewater with dissolved inorganic phosphorus (DIP), insoluble inorganic phosphorus (IIP), and organic phosphorus (OP). The results showed that the PSB significantly promoted the algal growth in OP and IIP, by 1.10 and 1.78-fold, respectively. The algal lipid accumulation was also greatly triggered, respectively by 4.39, 1.68, and 1.38-fold in DIP, IIP, and OP. Moreover, compared with DIP, OP improved the oxidation stability of algal lipid by increasing the proportion of saturated fatty acids (43.8 % vs 27.9 %), while the PSB tended to adjust it to moderate ranges (30.2–41.6 %). Further, the transcriptome analysis verified the OP and/or PSB-induced up-regulated genes involving photosynthesis, lipid metabolism, signal transduction, etc. This study provided novel insights to enhance microalgae-based nutrient removal combined with biofuel production in practical wastewater, especially with complex forms of phosphorus.

Phosphate-solubilizing bacteria improve the antioxidant enzyme activity of Potamogeton crispus L. and enhance the remediation effect on Cd-contaminated sediment

Phosphorus-solubilizing bacteria (PSB) assisted phytoremediation of cadmium (Cd) pollution is an effective method, but the mechanism of PSB-enhanced in-situ remediation of Cd contaminated sediment by submerged plants is still rare. In this study, PSB (Leclercia adecarboxylata L1–5) was inoculated in the rhizosphere of Potamogeton crispus L. (P. crispus) to explore the effect of PSB on phytoremediation. The results showed that the inoculation of PSB effectively improved the Cd extraction by P. crispus under different Cd pollution and the Cd content in the aboveground and underground parts of P. crispus all increased. The μ-XRF images showed that most of the Cd was enriched in the roots of P. crispus. PSB especially showed positive effects on root development and chlorophyll synthesis. The root length of P. crispus increased by 51.7 %, 80.5 % and 74.2 % under different Cd pollution, and the Ca/Cb increased by 38.9 %, 15.2 % and 8.6 %, respectively. Furthermore, PSB enhanced the tolerance of P. crispus to Cd. The contents of soluble protein, MDA and H2O2 in 5 mg·kg−1 and 7 mg·kg−1 Cd content groups were decreased and the activities of antioxidant enzymes were increased after adding PSB. The results showed that the application of PSB was beneficial to the in-situ remediation of submerged plants.

Role of Hazelnut Husk Compost and Phosphate Solubilizing Bacteria in Improving Productivity and Quality Parameters of Wheat (Triticum aestivum L.) and Their Effects on Some Soil Biological Properties

ABSTRACT Implementing compost can assist in improving soil structure and enable nutrient mobilization to plants that initiate an appropriate soil balance. In a greenhouse experiment, the influence of hazelnut husk compost (HHC), both in single and in combination with the phosphate solubilizing bacteria (PSB) on the wheat yield, yield parameters, and soil biological properties were investigated. A significant increase in yield and its quality parameters was recorded when the soil was treated with different doses of compost and bacteria. It was observed copious improvements in the soil biological properties with these applications. The microbial biomass carbon and total organic carbon ratios (Cmic:Corg) ranged from 1.51 to 2.09, were also remarkable in the organic amended soils. However, in all the treatments, the co-inoculation of bacteria with compost enhanced all the parameters significantly more than their individual applications. The highest yield increase over control (22.12%) was recorded from the integrated application of organic source and bio-fertilizer. This reflects a synergistic relationship between the compost and bacteria that eventually enhanced wheat production. It is therefore concluded that using HHC and PSB in soil can unfold promising possibilities for better soil health, which in the long run can contribute to sustainable food production.

Effects of organic amendments, biofertilisers and biodynamic preparations on soil properties and leaf nutrient concentrations in grapevine

ABSTRACT Excessive and unbalanced use of chemical fertilisers can lead to depletion of physical and chemical properties of the soil and have negative impacts on the environment. This investigation was conducted at Mizoram University, Aizawl, Mizoram, India and aimed to evaluate effects of organic amendments, biofertilisers and biodynamic preparations on soil properties and leaf nutrient status of grapevine. The experiment was laid out in randomised block design with 14 treatments consisting of different combinations of organic amendments, biofertilisers and biodynamic preparations viz. farmyard manure (FYM), vermicompost (VC), pig manure (PIM), neem cake (NC), Azospirillum, phosphate solubilising bacteria (PSB), potash solubilising bacteria (KSB), Trichoderma harzianum, cow pat pit (CPP) and biodynamic preparations BD500 and BD501. The results demonstrated that the use of organic amendments in combination with biofertilisers and biodynamic preparations enhanced leaf nutrient status as well soil properties in the vineyard. Among all the tested combinations, the highest concentrations of Mn, Zn, chlorophyll a, b and total chlorophyll in the leaves and concentrations of soil organic carbon, inorganic carbon, total carbon, total N, available N, P, K, Mn and Zn, cation exchange capacity (CEC) and abundance of bacteria and Actinomycetes in the soil were recorded with application of PIM + Azospirillum + PSB + KSB + T. harzianum + CPP + BD 500 + BD 501. This treatment was therefore recommended as a suitable option to meet the demand for long-term maintenance of soil fertility as well agroecosystem conservation and sustainability.

Relationships between soil compaction and soil physical-chemical-biological characteristics: A case study from volcanic agricultural soils of Entisol and Ultisol in North Maluku Province of Indonesia

Soil compaction has been recognized as a form of soil degradation that mostly deteriorates agricultural soil health worldwide from various climatic conditions and soil management. Heavy compaction can occur in agricultural soils due to intensive tillage, where its effects on soil properties have been the focus of many studies. The present study was undertaken to assess whether soil compaction occurs in agricultural soils adopting no-tillage systems and how the link between soil compaction and chemical-biological characteristics could be. A field investigation was carried out in two different locations that have different soil types, Entisol in Maitara Island and Ultisol in Halmahera Island, North Maluku Province. Sixteen undisturbed and disturbed soil samples were collected from each location grown with cassava and taken to the laboratory for analysis. Soil components observed included soil texture, bulk density, particle density, total porosity, soil permeability, soil organic matter (SOM), total nitrogen (N), phosphorous (P) availability, and phosphate-solubilizing bacteria (PSB). The findings revealed linear relationships between soil compaction and sand fraction, SOM, PSB, and available P, but none were found in soil total N. These results confirmed the importance of soil compaction management in food crop agricultural systems, particularly when soil carbon is low, to promote soil health. As the inconsistent correlation of soil compaction and chemical-biological properties was found in these two soil types, further investigation is necessary.

Response of green gram [Vigna radiata (L) Wilczek] to application of biofertilizers and phosphorus

The present study was carried out at the Crop Research Centre, Carrier Point University, Kota (Rajasthan), during the kharif season of 2020 and 2021 to assess the effect of phosphorus, rhizobium and phosphate solubilizing bacteria on growth and yield attributes of green gram. Significantly increase in growth, yield attributes and yield of green gram were recorded with the application of phosphorus 50 kg P2 O5 /ha. In case of biofertilizers (PSB, Rhizobium and PSB + Rhizobium), all growth and yield attributes and yield were increased significantly. However, among treatment combinations, the maximum values of these parameters were observed with 50 kg P2 O5 /ha + biofertilizers (PSB + Rhizobium) in comparison to all other treatment combinations. The net returns and B: C ratio were also higher under 50 kg P2 O5 /ha + biofertilizers (PSB + Rhizobium).

Comparison of bio-beads combined with Pseudomonas edaphica and three phosphate materials for lead immobilization: Performance, mechanism and plant growth

Phosphate materials (PMs) combine with phosphate solubilizing bacteria play an essential roles in lead (Pb) immobilization, but their resulting ability to reduce Pb bioavailability may vary depending on PMs used. In this study, Pseudomonas edaphica GAU-665 and three PMs: tricalcium phosphate, calcium phytate and nano-hydroxyapatite were respectively encapsulated into bio-beads by sodium alginate, which immobilization efficiency of Pb2+ were 99.11%, 97.76% and 99.02% at initial Pb2+ concentration of 200 mg L−1, respectively. The Pb2+ immobilization performance of bio-beads under different conditions and their organic acids secreted were examined. Most Pb2+ was immobilized by bio-beads through combined functions of adsorption, precipitation, ion exchange and biomineralization, accompanied by the formation of more stable compounds such as Pb3(PO4)2, Pb5(PO4)3OH and Pb5(PO4)3Cl. Meanwhile, pot experimental results indicated that the inoculation of CPhy (calcium phytate) bio-beads with PSB have highest biomass and root growth of oat (Avena sativa L.) in Pb-stressed compared with CK, which increased the content of chlorophyll b (167.51%) in shoot. In addition, the CPhy bio-beads enhance the peroxidase, catalase activities and reduce the malondialdehyde content to alleviating lead physiological toxicity in oat, which reductions the Pb accumulation in shoot (52.06%) and root (81.04%), and increased the residual fraction of Pb by 165.80% in soil. These findings suggest the bio-beads combined with P. edaphica GAU-665 and calcium phytate is an efficient Pb immobilization material and provided feasible way to improve safety agricultural production and Pb-contaminated soil remediation.

In Vitro Evaluation of Phosphate Solubilizing Bacteria as Antagonists for Bacterial Leaf Blight Disease (Xanthomonas oryzae pv. oryzae)

Rice is an important food crop in Indonesia, where more than 50% of the Indonesian population consumes rice as a staple food. Rice has decreased productivity by 50-80% due to bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo). The rapid spread and damaging effects of pesticide use on the environment are the main obstacles in the treatment of these bacteria. Alternative control is to use biological agents in the form of phosphate solubilizing bacteria (PSB). Phosphate solubilizing bacteria are part of the growth-promoting bacteria that have other abilities, namely biocontrol. The purpose of this study was to develop the ability of acid soil phosphate solubilizing bacteria to inhibit growth in vitro. The test was carried out using the dual culture technique with the zone of inhibition method. The results showed that ten isolates of PSB had inhibition against Xoo with various diameters of inhibition. The four highest inhibitory isolates were EF.NAP 3 (5.267 ± 0.189 mm), Pseudomonas GSP 6 (4533 ± 0.772 mm), EF.NAP 4 (3,424 ± 0.161 mm) and EF. NAP 9 (3.167±0.136 mm). The ability of PSB to inhibit Xoo can be used as an alternative in controlling bacterial leaf blight in rice plants. This indicates that the PSB isolate acts as a biostimulant in the dissolution of phosphate in the soil and as a bioprotectant.

Integrated nutrient module: an efficient tool for sustainable farming of cape gooseberry (Physalis peruviana L.)

Cape gooseberry is a nutrient loving crop. But excessive use of inorganic fertilizers may leads to health hazards, ecological vulnerabilities and diminution of soil physico-chemical characteristics. Hence, a trial was conducted for substituting inorganic fertilizers with biofertilizer in cape gooseberry to maintain the yield potential with soil fertility status too. The experimental plants were treated with azotobacter, phosphate and potash solubilizing bacteria (PSB and KSB) at 10 g plant-1 each with reduced dose of recommended fertilizer (RDF) (100- 60%) for two consecutive growing season. Total harvestable fruit plant-1 with highest yield was recorded in 90% RDF + Azotobacter, PSB and KSB treatment with par value in 60% RDF + Azotobacter, PSB and KSB treatment. Quality of ripped fruit with respect to TSS (15.90 °B), total sugar (11.29%), ascorbic acid (60.03 mg 100 g-1) and carotenoid content (49.25 µg 100 g-1) was also improved significantly in 60% RDF + Azotobacter, PSB and KSB treatment. Soil physico-chemical properties of the field was not varied significantly over initial reading. However, microbial population viz. bacteria, fungi and actinomycetes count was improved significantly in all the nutrient modules. Hence, it can be concluded that integrated nutrient module comprising 60% RDF of NPK + Azotobacter, PSB and KSB at 10 g plant-1 is the best treatment module for improving the production system of cape gooseberry in sustainable manner for long run without hampering the soil health and quality. Bangladesh J. Bot. 53(1): 83-90, 2024 (March)

Seed Coating Treatments and Foliar Spray of Micronutrients Enhance Quality of Harvested Seeds in Garden Pea (Pisum sativum L.)

To study the effect of different seed coating treatments and foliar application of micronutrients on quality seed production in pea, analysis of harvested seed was done at laboratory of the Department of Seed Science and Technology, Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan (HP). Seeds from field experiment were harvested and were evaluated in the laboratory conditions based on the different parameters. In field experiment, there were seven different treatments comprising, seed coating with Rhizobium, Phosphate solubilizing bacteria, iron, zinc, carbendazim along with control and foliar application of micronutrients. From the investigation, it was observed that seed coating with Rhizobium @ 30 g + PSB @ 30 ml kg-1 seed and two foliar sprays of ZnSO4 @ 0.3 % + FeSO4 @ 0.3 % at 50 per cent flowering and 15 days later, significantly improved the germination (96.00 %), seedling length (19.29 cm), seedling dry weight (34.80 mg), SVI-I (1851.62), SVI-II (3341.38), germination in accelerated ageing test and in cold test (77.75 % and 80 %, respectively) and resulted in the lowest EC (16.75 μS cm-1) of harvested seeds. Hence, it was concluded that seed coating with Rhizobium @ 30 g + PSB @ 30 ml kg-1 seed and two foliar sprays of ZnSO4 @ 0.3 % + FeSO4 @ 0.3 % performed best among all the treatments tested for quality seed production and it could be recommended for getting quality seeds in garden pea.