Poor Phosphorus Research Articles

Cardiovascular and fracture events analysis and intervention strategies in patients undergoing parathyroidectomy with secondary hyperparathyroidism.

Chronic kidney disease (CKD), especially end-stage renal disease (ESRD), is the most common cause of secondary hyperparathyroidism (SHPT), and SHPT is the most severe complication of ESRD. This study aimed to analyze the influencing factors of cardiovascular and fracture events in patients with SHPT which are the leading causes of death in patients with CKD, and provide a reference for selecting patients for whom surgery is more suitable. Patients who underwent parathyroidectomy (PTX) for SHPT at The First Affiliated Hospital, Zhejiang University School of Medicine from September 2021 to April 2024 were selected as the study object, with the inclusion and exclusion criteria as followed. They were divided into rural and urban residents for comparison as a cross-sectional study. The study evaluated the comorbidities, socioeconomic status, and postoperative complications diagnosed by radiography of patients undergoing surgery for SHPT. A total of 119 patients were included, among whom, 71 were from rural areas and 48 were from urban areas. Compared with urban residents, rural residents had poorer economic conditions, a longer interval from disease onset to PTX, and a higher incidence of cardiovascular and fracture events and concurrent nephrolithiasis, all of which were statistically significant. Multivariate analysis indicated that place of residence, age, and duration of uremia were independent risk factors of cardiovascular/fracture events. Medical staff in ESRD outpatient clinics should pay attention to patients with SHPT. ESRD patients should have better surveillance especially for rural, elder and poor phosphorus control patients, and promptly assess surgical intervention measures.

Disassembly-reassembly-phosphating strategy to fabricate hydrothermally-stable hierarchical P@ZSM-5 zeolite for efficient methanol-to-propylene

Available hierarchization and phosphorization of ZSM-5 zeolite as one of methanol-to-propylene (MTP) catalysts have improved reactive stability and propylene selectivity, but are subjected to the problems of poor phosphorus stabilization efficiency and inhomogeneous dispersion. Herein, we fabricate a series of hierarchical P@ZSM-5 zeolites via one-step disassembly-reassembly-phosphating strategy of ZSM-5 zeolite using successfully self-created asymmetric quaternary phosphonium hydroxides and elucidate the mechanism of mesoporous formation and the interaction of phosphorus with framework aluminum. Delightfully, reconstructively tetracoordinated PIV-O-AlIV structure endows excellent hydrothermal and Brønsted acid stability of hierarchical P@ZSM-5 zeolites. The MTP tests show that the P@ZSM-5(TBuCP) catalyst prepared by disassembly-reassembly-phosphating of tributylhexadecylphosphine hydroxide (TBuCPOH) exhibits superior propylene selectivity (48.9 %) and remarkedly long lifetime (32.5 h, WHSV=6h−1). Such enviable MTP performance is benefited from the join hands of the zeolitic hierarchization and suitable Brønsted acid strength conferred by its phosphorus-aluminum interaction that are conducive to olefinic cycle process. These findings afford value-filled opportunities in novel MTP catalysts with high reactive stability and propylene selectivity, and the understandings for phosphorus-zeolite chemistry.

Predicting phosphorus accumulation and proposing conditions needed for an algal-based phosphorus uptake process

ABSTRACT Algal-based waste stabilisation ponds (WSP) are a common wastewater treatment system for small communities but have poor phosphorus removal. Under certain conditions algae in WSPs will perform ‘luxury uptake’ increasing their phosphorus content to over 3% (gP/gSS) by storing polyphosphate. For the first time in the literature this paper presents a systematic study which determines the conditions needed to maximise phosphorus accumulation within WSP biomass taking into account the interactions between key variables. The key variables of temperature, phosphorus concentration, light intensity, mixing intensity, organic load, and pH were evaluated in 40 batch factorial experiments using a WSP algal culture. All six variables examined had significant main effects or interactions on the phosphorus content of the biomass. These were incorporated into a regression equation which was successfully validated against independent data sets from the literature. The conditions required to maximise the phosphorus content of the biomass were predicted for both summer (high light and high temperature) and winter (low light and low temperature) scenarios. The required conditions were revealed to be high phosphorus concentration, high mixing intensity, no supplementary CO2 addition, and low organic load. Interestingly, these conditions were consistent for both summer and winter suggesting that year-round treatment is possible. Practical methods of achieving these conditions were proposed. While further work will be needed to evaluate the effect of growth and potential influence of algal species, the findings presented provide a vital step towards developing a new phosphorus removal treatment process based on an enhanced understanding of environmental biotechnology.

Investigation of filtration performance and phosphorus removal in an electric field controlled dynamic membrane bioreactor

Dynamic membrane bioreactor (DMBR) offers several advantages over traditional membrane bioreactor, including cheaper costs, less resistance, and easier cleaning. Membrane fouling and poor phosphate removal performance restrict the application of DMBR. To address it, this study creatively combined electric field with DMBR and investigated the mechanisms. The results showed that applying an electric field significantly decreased membrane fouling rate in electric dynamic membrane bioreactor with Ti anode (E-DMBR-Ti). The median membrane fouling rate of E-DMBR-Ti was 2.28 kPa/h, which was 48.99 % lower than that of control group (4.47 kPa/h) during stable operation period. However, hydrogen bubbles formed on the cathode blocked membrane during membrane formation period. The enrichment of electroactive and denitrifying microorganisms (e.g., Lactococcus, Hydrogenophaga) in E-DMBR-Ti, which consumed electrons that would flow to the hydrogen evolution reaction, alleviated the negative impact. To address the issue of poor phosphorus removal efficiency of DMBR, based on the previous research, we replaced the titanium mesh of the anode with aluminum plates, and innovatively using the electrocoagulation technology which named E-DMBR-Al. At 2.4 A/m2 current density, E-DMBR-Al showed the highest phosphorus removal efficiency, with a median of 94.69 %, which was 37.69 % higher than that of DMBR. Furthermore, the enrichment of electroactive microorganisms (e.g., Lactococcus) and polyphosphate-accumulating organisms (e.g., unclassified_f__Comamonadaceae) on membrane contributed to the excellent phosphorus removal performance of E-DMBR-Al.

Phosphorus uptake mechanisms associated with phosphorus application levels in two cotton cultivars

Poor phosphorus utilization is a common limitation of sustainable cotton production. Even so, the intrinsic potential for efficient phosphorus acquisition of the roots remains unclear. In this study, we aimed to explore if phosphorus acquisition in cotton is affected by interactions that could possibly be associated with root morphology and gene expression, between genotype and application rates. A pot experiment was conducted with seven phosphorus application rates: 0, 12.5, 25, 50, 75, 150, and 300 mg P kg−1. The agronomic characters, root morphology, and expression of the PHT1 gene in the roots of cotton varieties with different phosphorus acquisition efficiencies were measured. According to the results, the phosphorus acquisition efficiency in cultivar XLZ19 was higher than in XLZ13 for phosphorus uptake because of the upregulation of GhPTs gene expression that increased the total root length and proportion of fine roots. The Olsen-P levels in the soil ranged from 20 to 30 mg kg−1 at the seedling stage and from 15 to 25 mg kg−1 at the flowering stage, suggesting better root growth and phosphorus supply. The conversion of phosphorus fertilizers to soil Olsen-P decreased when the phosphorus application rate exceeded 50–75 mg kg−1. The phosphorus acquisition–efficient XLZ19 phenotype owes its efficiency to high GhPTs expression and morphological changes in the roots. Finally, with these crops that are highly efficient in phosphorus acquisition, agricultural practices in sustainable cotton production may consume less phosphorus fertilizers.

Optimization and mechanism of phosphorus removal in plant-biofilm oxidation ditches: Plant uptake, iron plaque adsorption, and rhizosphere regulation

Poor phosphorus removal capacity has always been a Chinese wall to the development of oxidation ditch. Here, plant-biofilm oxidation ditch (PBOD) was proposed with different aeration conditions and plant types to investigate the parameter optimization of PBOD and internal mechanism of accelerated phosphorus removal. The results showed that the combination of aeration and plants was demonstrated as effective to enhance the PBOD capacity for sewage purification and phosphorus removal, since they can jointly promote the change of Fe2+ into Fe3+. Subsequently, part of Fe3+ and phosphate ions formed phosphate precipitation, and the other part of Fe3+ formed iron membrane on root surface, which can effectively adsorb phosphorus in sewage, so as to reduce the content of iron and phosphorus in sewage. Plant species did not play an important role in the removal effect of phosphorus but in the removal pathway: Canna generalis absorbed more phosphorus in the plant tissue than Zizania caduciflora, whereas Zizania caduciflora adsorbed more phosphorus on the root surface than Canna generalis. This is due to (a) Canna generalis roots released more organic acids, which may promote the conversion of insoluble inorganic phosphorus into soluble phosphate ions for plant uptake, and may reduce the amount of iron plaque on the root surface by generating organic acid chelated iron; (b) Zizania caduciflora has strong root oxygen secretion capacity and is easier to form iron plaque on the root surface, so it attaches more phosphorus.

Electrolysis-integrated constructed wetland with pyrite filler for simultaneous enhanced phosphorus and nitrogen removal

Constructed wetlands (CWs) have been widely applied for tail water treatment. However, conventional CWs usually encounter poor phosphorus and nitrogen removal performance due to limited adsorption capacity of fillers and insufficient electron donors. In this study, an electrolysis-integrated CW using pyrite as filler surrounding electrodes (e-PCW) was developed. After around 140 days’ operation with various voltages (5, 10 and 15 V), synergistic effects of pyrite filler and electrolysis process were observed. The optimal removal efficiencies of NH4+-N, TN and TP achieved at 5 V were 42.6 ± 3.5%, 68.2 ± 1.8% and 75.8 ± 2.5%, respectively. O2 generated at anode in e-PCW promoted oxidation of FeS2 in pyrite to release Fe3+, which could form FePO4 for phosphorus removal. At cathode, the produced H2 together with FeS2 could serve as electron donors, driving autotrophic denitrification to improve nitrogen removal. The results also showed that inputting 10 and 15 V voltages caused acidification in anodic area due to water electrolysis. Although minerals like CaMg(CO3)2 in pyrite could partially neutralize acidification, low pH (5–6) still inhibited nitrification process and led to desorption of phosphorus from fillers. Based on microbial community analysis, main functional bacteria were Desulfomicrobium (13.43%) and Thauera (4.66%) in cathodic area of e-PCW, which could reduce SO42− to S2− and afterwards drive sulfur-based autotrophic denitrification respectively. This work provided a novel and competitive technology for advanced wastewater treatment.

Differential Plant Growth Promotion Under Reduced Phosphate Rates in Two Genotypes of Maize by a Rhizobial Phosphate-Solubilizing Strain

The biotechnological manipulation of phosphate-solubilizing bacteria (PSB) is gaining prominence to improve the poor phosphorus (P) availability in the soil and maintain crop yields. In this study, we investigated howRhizobiumsp. B02 inoculation influences maize crop development and whether its use reduces phosphate fertilizer rates. We conducted growth promotion assays using P fertilizer doses in two maize genotypes under greenhouse conditions. Morphometric, physiological, and productivity parameters were assessed in three phenological stages: tillering (V5), tassel (VT), and maturity (R6). Maize response was significantly influenced by both inoculation and plant genotype, showing that the plant-promoting effect of inoculation is substantially more prominent in the white endosperm than in the yellow endosperm maize genotype. The development of maize in all phenological stages was promoted by inoculation withRhizobiumsp. B02. The most significant influence of inoculation was observed on shoot dry weight, relative chlorophyll content, shoot P concentration, leaf area, photosynthetic rate, 1,000-grain weight, and grain yield. A 17% gain in grain yield, representing 20 g plant−1, was obtained by inoculation with 50% diammonium phosphate (DAP) compared with the control treatment at the same dose. The complete fertilization control was phenocopied by the white endosperm inoculated at 50% DAP in all productivity parameters. Therefore, half of the P fertilization in white endosperm was replaced by inoculation withRhizobiumsp. B02. Herein, we report the potential of aRhizobiumstrain in a non-legume crop to improve P management.

Screening Selected Maize Single Crosses for Tolerance to Low P in Acidic Soils of Bumala and Maseno

Generally, 13% of Kenya’s arable land mass (7.5 million ha) is acidic and prone to poor phosphorus (P) availability and soil acidity. This results in crop yield losses due to the direct adverse effects Aluminium toxicity and P deficiency due to fixation of this element in the soil. The objective of this study was to develop and select P efficient maize single crosses developed by crossing as per North Carolina II mating design. Sixty maize genotypes, among them 34 single crosses were screened under acidic soils in Bumala and Maseno in a randomised complete block design. Sixty-seven percent of these single crosses were efficient, while 33% were inefficient. Two percent were efficient and responsive, 14% were inefficient but responsive, and the 79% were efficient but non-responsive. Generally, GY had a positive correlation with EH (0.45) and PH (0.61), while PH and EH had a positive correlation (r = 0.86) for the single crosses. The addition of P had significant effect on the grain yield, plant height, ear height and flowering of the genotypes at Bumala and Maseno. However, the effect of 26 kgP/ha was marginal at Maseno as compared to Bumala. The sites and genotypes varied significantly with regard to soil analysis and grain yield respectively, with the efficient and responsive genotypes selected for use in low input farming systems. Also, some of the efficient but non-responsive lines can also be selected for low input farming.

Liming and Phosphate Application Influence Soil Carbon and Nitrogen Mineralization Differently in Response to Temperature Regimes in Allophanic Andosols

Andosols are characterized by high organic matter content and play a significant role in carbon storage. However, they have low phosphorus fertility because of the high phosphate-fixing capacity of active aluminum. For agricultural use of Andosols, it is necessary to ameliorate its poor phosphorus fertility by applying lime and high doses of phosphate fertilizers. The objective of the present study was to clarify how such soil amendments affect the mineralization of soil organic carbon (C) and nitrogen (N) in allophanic Andosols under different temperature regimes. The soil was treated using combinations of liming and heavy phosphate application, followed by incubation under different temperature conditions. The N mineralization and the soil CO2 evolution rate were measured periodically. The patterns of N mineralization were analyzed by fitting them to first-order kinetics. Liming increased C and N mineralization irrespective of temperature, and the increase was further enhanced by phosphate application. Kinetic analysis of the N mineralization curve indicated lowering of the activation energy of N mineralization reactions with phosphate application, suggesting that P application may accelerate N mineralization at lower temperatures. These findings provide a basis for developing soil management strategies to reduce the loss of soil organic matter.

Unmodified cassava starches with high phosphorus content

Our study was based on the fact that physiological changes in the plant resulting from the growth conditions alter the properties of the starch. An experimental trial was installed with cassava plants in poor phosphorus soil. A part of plants received phosphate fertilization at a level three times higher than the recommended dose, in order to provide high availability of phosphorus in the soil. The plants grew for two years and the starches were isolated at three times in the second vegetative cycle. The starches had A-type X-ray pattern. Starches isolated from cassava plants grown in soils with high phosphorus had increases of more than 100% in the content of bound phosphorus, which caused changes in the size of the granules, amylose, swelling power, solubility, pasting and thermal properties. These results indicate possibilities of increasing the commercial value of native cassava starch due to the expansion of use, considering the range of uses of phosphate starches for food and non-food purposes.

Recovery of nitrogen and phosphorus fertilizer from pig farm biogas slurry and incinerated chicken manure fly ash

There is insufficient land to use the large amount of nitrogen-rich biogas slurry, a potential agricultural nonpoint source pollutant, produced by anaerobic digestion of pig manure on large-scale pig farms in South China, and biochemical treatments of this product are often insufficient for meeting discharge standards. In addition, a large amount of phosphorus-rich fly ash (FA), which has poor phosphorus bioavailability and cannot be directly used in agriculture, is produced by chicken manure incineration. Therefore, there is an urgent need to find a way to treat this solid waste. This study explores the possibility of synergistic management and comprehensive utilization of these two wastes. The results indicated that the leaching effect of sulfuric acid was better than that of hydrochloric acid, citric acid and oxalic acid in phosphorus extraction from FA. When the amount of sulfuric acid used was 0.75 mol/L, L/S was 10, and the leaching time was 120 min, 87.33% of the phosphorus in FA was extracted; when the wastewater pH was 9.5 and the molar ratio of Mg:N:P was 1:1:2, 95.43% of ammonia nitrogen was recovered from the pig farm biogas slurry. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses indicated that the main component of the resulting NP fertilizer was struvite, and pot experiments showed that this NP fertilizer was more effective than superphosphate (SP) for plant growth. The residual wastewater met discharge standards after SBR treatment. The present research shows that two different agricultural wastes from one farm, N-rich biogas slurry and P-rich FA, can be treated together to yield recycled NP fertilizers and that the residual wastewater meets the standards for discharge. This study provides an innovative method for the comprehensive treatment and resource utilization of waste in modern and large-scale farms.

Global actions for a sustainable phosphorus future.

Food security and healthy freshwater ecosystems are placed at jeopardy by poor phosphorus management. Scientists are calling for transformation across food, agriculture, waste and other sectors — mobilized through intergovernmental action, which has been missing thus far.

Effect of the Influent C/P Ratio on the Nutrient Removal Characteristics of the SNEDPR System

This study focuses on the nitrogen (N) and phosphorus (P) removal characteristics in a simultaneous nitrification-endogenous denitrification and phosphorus removal (SNEDPR) system at different influent C/P ratios. An extended anaerobic/low aerobic (dissolved oxygen:0.5-1.0 mg·L-1) sequencing batch reactor (SBR) fed with municipal sewage was studied by adjusting different C/P ratios (10, 15, 20, 30, and 60). The experimental results show that the proper reduction of the influent C/P ratio (C/P ratio reduced from 60 to 30) enhances the competitive advantages of phosphorus-accumulating organisms (PAOs) in the SNEDPR system. The highest phosphorus removal efficiency was achieved at a C/P ratio of 30, with the anaerobic phosphorus release rate (PRR) and aerobic phosphorus uptake rate (PUR, used as P/MLSS) reaching 3.5 mg·(g·h)-1 and 4.2 mg·(g·h)-1 respectively, and an average effluent PO43--P concentration below 0.3 mg·L-1. The percentage of PAOs contributing to the storage of endogenesis carbon (PPAO, An) reached 88.1%. However, a poor phosphorus removal performance was observed with further reduction of the influent C/P ratios to 10; both the PO43--P removal efficiency and PPAO, An decreased from 38.1% and 82.4% to 3.1% and 5.3%, respectively. The PRR and PUR were 0.2 mg·(g·h)-1 and 0.24 mg·(g·h)-1, respectively. The COD removal performance was not affected by the decreasing influent C/P ratios; the average COD removal efficiency stabilized at 85%. In addition, the nitrification performance became worse with decreasing C/P ratios (from 60 to 20) because the effluent NH4+-N and NO2--N concentrations increased from 0 and 6.9 mg·L-1 to 5.1 mg·L-1 and 16.2 mg·L-1, respectively. The nitrificaton performance recovered when the C/P ratios further decreased to 10, but the nitrite accumulation was disturbed as both the effluent NH4+-N and NO2--N concentrations reduced to 0. The effluent NO3--N concentration increased from 0.08 mg·L-1 to 14.1 mg·L-1. The SNED efficiency first decreased from 62.1% to 36.4% and then increased to 56.4%. The advantageous competition of glycogen accumulating organisms (GAOs) improved when the influent C/P ratio was lower than 15. The enhancement of the endogenous denitrification ability of GAOs might explain the recovery denitrification performance of the system when the influent C/P ratios decreased from 20 to 10.

Determining variables that influence the phosphorus content of waste stabilization pond algae

Waste stabilization ponds (WSP) are one of the most common forms of wastewater treatment for smaller communities globally, but have poor phosphorus removal. It is known that WSP algae can accumulate polyphosphate within their cells in excess of that needed for cell function. If polyphosphate accumulation could be triggered at the higher range of WSP cell concentrations, phosphorus removal from domestic wastewater could be significantly improved. However, this phenomenon is sporadic and still not fully understood. With a view of building a fundamental understanding to underpin the engineering of a new phosphorus removal process, this paper examines eight previously untested variables that may influence the cellular phosphorus content of WSP biomass. Although calcium, magnesium, and potassium are key constituents of polyphosphate granules, the concentrations tested were not limiting to polyphosphate accumulation. While literature also pointed to inoculum characteristics as potentially having an impact, no significance was found in this research. Conversely, three important new triggers where identified that significantly (90% confidence) affected the cellular phosphorus content of WSP biomass. An increase in cellular phosphorus content was triggered by decreasing the organic load, or allowing the pH to increase as compared to pH control. By contrast, the presence of mixing decreased the phosphorus content of the WSP biomass.

Patient-Reported Factors Associated With Poor Phosphorus Control in a Maintenance Hemodialysis Population

The purpose of this study was to determine the influence of patient-reported medication adherence and phosphorus-related knowledge on phosphorus control and pharmacy-reported adherence to phosphorus binding medication among patients on maintenance hemodialysis. Retrospective, cross-sectional cohort study. Seventy-nine hemodialysis patients (mean age 64.2 years, SD = 14 years; 46.8% female) in a stand-alone hemodialysis unit within an integrated learning healthcare system. Ten percent (10%) of subjects were Caucasian, 42% Latino, 19% African American, and 29% Asian. Forty-eight percent had diabetes; 72% had BMI ≥ 30. Inclusion criteria included the provision of survey data and having medication refill data available in the pharmacy system. 77.2% had mean phosphorus levels ≤ 5.5 mg/dL; 22.8% had mean phosphorus levels > 5.5 mg/dL. Subjects were administered the 8-item Morisky Medication Adherence Scale (MMAS-8) and also reported on their phosphorus-related knowledge. Phosphorus levels within an adequate range. The mean serum phosphorus level was 4.96 mg/dL (SD = 1.21). In the well-controlled group, mean phosphorus was 4.44 mg/dL (SD = 0.76). In the poorly controlled group, mean phosphorus was 6.69 mg/dL (SD = 0.74). A total of 61% of patients reported at least some unintentional medication nonadherence, and 48% reported intentional medication nonadherence. Phosphorus-specific knowledge was low, with just under half of patients reporting that they could not name two high-phosphorus foods or identify a phosphorus-related health risk. Phosphorus binder-related nonadherence was substantially higher in the uncontrolled than the controlled group. Adjusting for age, individuals with poorer self-reported binder adherence were less likely to have controlled phosphorus levels (odds ratio = 0.71, P = .06). Phosphorus-related non-adherence, but not low phosphorus-specific knowledge, was associated with poorer phosphorus control. Such findings provide important information for the development of evidence-based strategies for improving phosphorus control among patients on dialysis.

Biological nutrient removal in a sequencing batch membrane bioreactor treating municipal wastewater

This study aimed to evaluate the performance of a sequencing batch membrane bioreactor (SBMBR) in wastewater treatment for nutrient removal. The reactor, which was built at a pilot scale with a volume of 15 L, was operated for 240 d and fed with municipal wastewater. The SBMBR was operated under a sequencing batch mode, with a total cycle time of 4 h, including the feeding, anoxic/anaerobic, and aeration/filtration phases. The membrane bioreactor presented high performance on chemical oxygen demand, ammonium, and total nitrogen removal during the whole experimental period, with average removals efficiencies of around 97, 99, and 82%, respectively. Regarding total phosphorus, SBMBR reached the average removal efficiency of 48%. The poor phosphorus removal performance was attributed to the low availability of organic matter during the anoxic/anaerobic phase due to denitrification activity, which limited the P-release process and subsequent P-uptake during aerobic phase. Furthermore, the temperature increase during the summer period further hindered the enhanced biological phosphorus removal process, in which a decrease in the P-release values was observed. Fluorescence in situ hybridization analysis revealed a large presence of glycogen-accumulating organisms population on the SBMBR sludge, which contributes to explain the low efficiency obtained in phosphorus removal.

English

In India, soybean is the third largest oilseed crop but its productivity is lower and that can mainly be related to low fertilizer phosphorus usage, poor phosphorus use efficiency and flower and bud drop. In this backdrop, to achieve sustained higher soybean productivity, twenty seven treatments [three doses: 20, 30 and 40 kg P2O5 ha-1; three sources: single super phosphate (SSP), phosphorus rich organic manure (PROM) and di-ammonium phosphate (DAP) and three plant growth regulators (PGRs): water spray, benzyl adenine 50 ppm and naphthalene acetic acid (NAA) 100 ppm] were evaluated in a split plot design having three replications on medium clay loam soils of Udaipur (India) during rainy seasons of 2009 and 2010. Results conclude that 40 kg P2O5 ha-1, SSP and NAA  recorded significantly higher pooled plant height (51.65, 50.82 and 51.17 cm), branches plant-1 (4.56, 4.43 and 4.48), oil content (21.40, 20.91 and 21.20%), oil yield (558.89, 528.75 and 521.79 kg ha-1), seed protein yield (1111.56, 1039.96 and 1045.60 kg ha-1), grain yield (25.95, 25.12 and 24.23 q ha-1) and stover yield (37.37, 36.23 and 35.73 q ha-1) over their corresponding treatments. Use of NAA and benzyl adenine were statistically indifferent, however, they recorded significantly early setting of 50% flowering and substantially extended the crop maturity period over water spray. However, various levels and sources of phosphorus were indifferent in periods of 50% flowering and maturity. Use of 40 kg P2O5 ha-1 and NAA recorded significantly higher pooled seed protein content over their corresponding counterparts but phosphorus sources were indifferent.     Key words: Oil content, phosphorus levels, phosphorus sources, plant growth regulators (PGRs), protein content, soybean productivity.

English

Colombia is a tropical country with high diversity and an agricultural economy, yet their soils are characterized by low pHs and poor phosphorus concentrations. Soil supplementation with chemical fertilizers containing soluble phosphorus is a costly and contaminating practice and for this reason, the aim of this study was to isolate actinobacteria that are able to release soluble phosphate from wild plants of the Eastern Cordillera of Colombia and select strains with high phosphorus solubilizing activity. To screen the isolates of actinobacteria, we used two qualitative assays to determine the efficiency of solubilization by measuring the halo of hydrolysis in a Pikovskaya’s agar plate (PVK). A second assay was performed on broth with National Botanical Research Institute's phosphate growth (NBRIP) medium containing bromophenol blue (BPB). Finally, the released soluble phosphate by actinobacteria was quantified using insoluble Ca3(PO4)2 or AlPO4 as sole sources of P. Only five of the tested strains were the best solubilizing strains in the two qualitative assays. The strains T1C, T1H, T3A, T3C, P3E, F1A, F2A and V2B solubilized significantly more phosphorus than the other strains, which was shown for the quantitative assay. Strains T1C, T3A, T3C and F1A are candidates for future studies and to evaluate other plant growth promoting activities.   Key words: Screening, phosphate solubilizing, actinobacteria, Colombia.

Phosphorus Availability and Proton Efflux of Nodulated-root Varies among Common-bean Genotypes (Phaseolus vulgaris) in Rhizobox

In this study we compared between six RILs of (Phaseolus vulgaris L.) in growth, nodulation, phosphorus use efficiency for N2 fixation and proton release in response to two levels of P in nutrient solution. For plants grown at 250 and 75 ìmol P pl−1 week−1 for 42 days. For this propose Glass house experiment in rhizobox was conducted to evaluate six common bean genotypes for their growth behavior at two levels of soil phosphorus, deficient (75 μmol week−1 plant−1) and sufficient (250 μmol week−1 plant−1) using 24g soil per rhizobox. Genotypes showed differential behavior at both P levels for all parameters. Shoot biomass and nodule biomass were observed higher in sufficient P than in deficient P. Difference for phosphorus utilization efficiency and phosphorus uptake were also observed where RILs 34,75 and 147 were the higher efficient in use and uptake of P under sufficient P than deficient P. and also greater in H+ efflux for these RILs under sufficient than deficient P. It concluded that these RILs have the possibility to enrich the poor phosphorus soils by available P and improve the soil fertility.