Removal of Chlorpyrifos by Water Hyacinth (Eichhornia crassipes) and the Role of a Plant-Associated Bacterium

The objective of this research was to study the efficiency of water hyacinth (Eichhornia crassipes) and the role of any plant-associated bacteria in removing chlorpyrifos from water. The relative growth rate (RGR) of E. crassipes in the presence of 0.1 mg/L chlorpyrifos was not significantly different from that in its absence and only slightly decreased at concentrations of 0.5 and 1.0 mg/L by ～1.1- and ～1.2-fold, respectively, with an observed dry weight based RGR_DW for E. crassipes of 0.036–0.041 mg/g/d. The removal rate constants of chlorpyrifos in the absence of plants were low at 3.52, 2.29 and 1.84 h^?1 for concentrations of 0.1, 0.5 and 1.0 mg/L, respectively, but were some 3.89- to 4.87-fold higher in the presence of E. crassipes. Chlorpyrifos removal was markedly facilitated by the presence of a root-associated bacterium, preliminarily identified as Acinetobacter sp. strain WHA. The interaction of E. crassipes and Acinetobacter sp. strain WHA provide an efficient and ecological alternative to accelerate the removal and degradation of chlorpyrifos pollution from aquatic systems including wastewater.     

Assessment of plant growth attributes,bioaccumulation, enrichment,and translocation of heavy metals in water lettuce (Pistia stratiotes L.) grown in sugar mill effluent

This study was conducted to assess the pollutant uptake capability of water lettuce (Pistia stratiotes L.) in terms of bioaccumulation, enrichment, and translocation of heavy metals grown in sugar mill effluent. Results showed that the maximum fresh weight (328.48 ± 2.04 gm kg^?1), total chlorophyll content (2.13 ± 2.03 mg g^?1 fwt), and relative growth rate, RGR (11.89 gg^?1 d^?1) of P. stratiotes were observed at 75% concentration of the sugar mill effluent after 60 days of phytoremediation experiment. The bioaccumulation factor (B_F) of different heavy metals was greater than 1 with 50% and 75% concentrations of sugar mill effluent and this indicated that P. stratiotes was hyperaccumulator or phytoremediator of these metals. The enrichment factor (E_F < 2 for Cu, Fe, Cr, Pb, Zn, and Mn) and (E_F > 2 for Cd) indicated that P. stratiotes mineral enrichment deficient and it moderately enriched the different heavy metals. Moreover, translocation factor (T_F) was less than 1 which indicated the low mobility of metals in different parts (root and leaves) of P. stratiotes after phytoremediation. Therefore, P. stratiotes can be used for phytotreatment of sugar mill effluent up to 50% to 75% concentrations and considered as hyperaccumulator aquatic plant for different heavy metals and other pollutants from the contaminated effluents.     

Antioxidant and radioprotective effect of the active fraction of Pilea microphylla (L.) ethanolic extract

The ethanolic extract of Pilea microphylla (L.) was defatted, successively fractionated with acetone and the residue so obtained was found to be most potent when subjected to detailed free radical scavenging and in vivo radioprotection studies. The most active fraction reacts with free radicals, such as DPPH (50 microM), ABTS(.)(-) (100 microM) and (.)OH (generated by Fenton reaction) with IC(50) value of 23.15 microg/ml, 3.0 microg/ml and 310 microg/ml, respectively. The most active fraction inhibited iron-induced lipid peroxidation in phosphatidyl choline liposomes with an IC(50) of 13.74 microg/ml. The kinetics of scavenging of DPPH and ABTS(.)(-) radicals were followed at different concentrations of the fraction by employing stopped-flow studies. The observed first order decay rate constants at 200 microg/ml and 50 microg/ml of fraction with DPPH (50 microM) and ABTS(.)(-) (50 microM) were found to be 0.4s(-1) and 2.1s(-1), respectively. The fraction when screened for in vivo radioprotection in Swiss albino mice showed 80% protection at a dose of 900 mg/kg and with a DRF of about 1.12. The fraction was also found to protect livers of irradiated mice from depletion of endogenous antioxidant enzymes like glutathione, GST, SOD, catalase and thiols. The fraction also protected the villi height, increased the number of crypt cells while offering general protection to the intestine from acute radiation effects. The fraction also protected the hematopoietic system as assessed by endogenous spleen colony assay, contributing to the overall radioprotective ability.     

混配杀虫剂对美洲大蠊初孵若虫乙酰胆碱酯酶的活体in vivo抑制

研究了美洲大蠊初孵若虫乙酰胆碱酯酶（AChE）的最佳反应条件：蛋白含量40—50μg,pH7．4,底物浓度0．5mmol／L,反应温度37℃,保温时间15分钟。动力学参数Km和Vmax分别为5．64×10-4mol／L和55．5nmol／（min·mgprotein）。分析了顺式、反式氯氰菊酯与辛硫磷、马拉硫磷或毒死蜱以1：10比例混配对AChE的活体抑制。结果表明混配均能增强对AChE的抑制,其中顺式优于反式,与生测结果一致。认为拟除虫菊酯和有机磷混配增效的重要原因之一是提高了对靶标酶——AChE的抑制。     

In vitro and in vivo activity of meglumine antimoniate produced at Farmanguinhos-Fiocruz, Brazil, against Leishmania (Leishmania) amazonensis, L (L.) chagasi and L (Viannia) braziliensis

The leishmanicidal activity of four batches of meglumine antimoniate, produced in Farmanguinhos-Fiocruz, Brazil (TAMs), was assessed and compared to Glucantime(R)-Aventis Pharma Ltda. Using the amastigote-like in vitro model, the active concentrations of Sb v varied from 10microg/ml to 300 microg/ml for L. (L.) chagasi and from 50microg/ml to 300microg/ml for L. (L.) amazonensis, with no statistically significant differences among the four batches of TAMs and Glucantime(R). The inhibitory concentrations (IC50) determined by the amastigote-infected macrophage model for TAM01/03 and Glucantime(R) were, respectively: 26.3microg/ml and 127.6microg/ml for L. chagasi, 15.4microg /ml and 22.9microg/ml for L. amazonensis, and 12.1microg/ml and 24.2microg/ml for L. (V.) braziliensis. The activities of the four batches of TAMs were confirmed in an in vivo model by assessing, during eight weeks skin lesions caused by L. braziliensis in hamster that were treated with 20mg Sb v/Kg/day for 30 consecutive days. The meglumine antimoniate produced by Farmanguinhos was as effective as the reference drug, Glucantime(R)-Aventis, against three species of Leishmania that are of medical importance in Brazil.     

Phosphorus availability to rice (Oriza sativa L.)-wheat (Triticum estivum L.) in a Vertisol after eight years of inorganic and organic fertilizer additions

Integrated use of inorganic fertilizer N and well decomposed cattle manure (CM) or 30-35 days old Parthenium (Parthenium hysterophorus L.), a weed grown off site as green manure (GM) under repeated applications of fertilizer P and urea N for eight years in a rice (Oriza sativa L.)-wheat (Triticum estivum L.) sequence was studied on transformation of fertilizer P applied to soil at the National Research Center for Weed Science, Jabalpur, India. Based on the results, it appeared that, repeated applications of 52 kg super-phosphate P resulted in a marked increase in Olsen P linearly with time. Conjunctive use of urea fertilizer N with organic manure resulted in a larger increase in Olsen P in the Vertisol. Studies further revealed that the greater accumulation of fertilizer P applied in excess to crop removal occurred in inorganic P in the plots receiving only fertilizer N. However, plots receiving fertilizer N along with organic manures led to P accumulation predominantly in organic forms. The study suggests that these two pools of P acted as a sink when fertilizer P was applied in excess to crop removal and are bio-chemically active. The Olsen P status after 8 cycles of rice-wheat crops revealed that the average amount of fertilizer P required after adjusting for crop uptake to increase Olsen P by 1 mg kg(-1) soil was 7.2 kg Pha(-1) in the plots receiving only fertilizer N. Whereas, application of 5t FYM or 6t GM reduced it to 4.6 kg Pha(-1). The plots receiving manure always maintained a greater concentration of Olsen P. The application of CM or GM with fertilizer N enriched short-term inorganic P as well as long-term organic P fertility. After eight years, larger concentrations of organic P in the subsurface layer (16-30 cm), compared to initial values, indicates downward movement of P in organic forms.     

Bioactivity of alkamides isolated from Echinacea purpurea (L.) Moench.

Alkamides from the roots of Echinacea purpurea (L.) Moench were examined for anti-inflammatory activity in an in vitro model system. Cyclooxygenase-I (COX-I) and cyclooxygenase-II (COX-II) inhibitory activities were assessed at pH 7 for alkamides isolated from E. purpurea roots to compare inhibitory activities between the two cyclooxygenase isozymes. At 100 microg/ml, several E. purpurea alkamides inhibited COX-I and COX-II enzymes in the range of 36-60% and 15-46%, respectively, as compared to controls. Mosquitocidal activity was assessed at 100 and 10 microg/ml, with 100% mortality against Aedes aegyptii L. larvae noted for several E. purpurea alkamides at 100 microg/ml.     

Effect of Mechanical Stress on Sunflower (Helianthus annuus L.) Hypocotyl Growth

Etiolated seedlings of Sunflower (Helianthus annuus L.) weresubjected to mechanical stress by longitudinally compressingthe hypocotyl with approx. 0·05 N force (equivalent to0·025 MPa for a 1·6 mm diameter hypocotyl). Thisrelatively low compressive stress effected an increase in relativegrowth rates (RGR) of the hypocotyl for a period of 1-2 h, followingwhich RGR returned to the pretreatment rate. RGR was also increasedby an equivalent compressive stress treatment (0·025MPa) for 4 h in water or in 10^-10 mol l^-1 IAA. These resultsare discussed in the context of a possible role for mechanicallyinduced stress in the initiation and maintenance of nutationalgrowth movements.Copyright 1994, 1999 Academic Press Helianthus annuus, Sunflower, hypocotyl growth, mechanical stress, seedling growth, nutational growth movements, circumnutation     

Arsenic removal from waters by bioremediation with the aquatic plants Water Hyacinth (Eichhornia crassipes) and Lesser Duckweed (Lemna minor)

In this study the removal of arsenic by the Water Hyacinth (Eichhornia crassipes) and Lesser Duckweed (Lemna minor) was monitored under a concentration of 0.15mgL(-1) of the element. Plant densities were 1kg/m2 for Lesser Duckweed and 4kg/m2 for Water Hyacinth on a wet basis. The arsenic was determined in foliar tissue and water samples by hydride generation atomic absorption spectroscopy. The element was monitored as a function of time during 21 days. No significant differences were found in the bioaccumulation capability of both species. The removal rate for L. minor was 140mg As/had with a removal recovery of 5%. The Water Hyacinth had a removal rate of 600mg As/had and a removal recovery of 18%, under the conditions of the assay. The removal efficiency of Water Hyacinth was higher due to the biomass production and the more favorable climatic conditions. This specie represents a reliable alternative for arsenic bioremediation in waters.     

Potential use of Lemna minor for the phytoremediation of isoproturon and glyphosate

Pesticides are being detected in water bodies on an increasingly frequent basis. The present study focused on toxicity and phytoremediation potential of aquatic plants to remove phytosanitary products from contaminated water. We investigated the capacity of Lemna minor (L. minor) to eliminate two herbicides isoproturon and glyphosate from their medium. Since phytoremediation relies on healthy plants, pesticide toxicity was evaluated by exposing plants to 5 concentrations (0-20 microg L(-1) for isoproturon and 0-120 microg L(-1) for glyphosate) in culture media for 4 d using growth rate and chlorophyll a fluorescence as endpoints. At exposure concentrations of 10 microg x L(-1) for isoproturon and 80 microg x L(-1) for glyphosate, effects on growth rate and chlorophyll fluorescence were minor (< 25%), so that this initial concentration was selected to study herbicide removal After a 4-d incubation, removal yields were 25% and 8% for isoproturon and glyphosate, respectively.     

Seed germination and seedling performance of two Mediterranean tree species,holm oak (shape Quercus ilex L.) and Aleppo pine (shape Pinus halepensis Mill.): a multifactor experimental approach

A two-level multifactor experimental approach was used to compare seed germination and seedling performance of two Mediterranean tree species: the early successional Aleppo pine (Pinus halepensis Mill.) and the late successional holm oak (Quercus ilex L.). In a first experiment germination rate was evaluated under the combined effects of shade, nitrogen availability, and pine or holm oak leaf litter. In a second experiment we tested for the effects of shade, nutrient availability, and litter type on seedling survival, growth and biomass allocation. Holm oak showed higher germination rates under shaded than under unshaded conditions, while Aleppo pine showed no differences between shaded and unshaded conditions. Nitrogen availability and litter type had no significant effect on germination of either species. Both species showed increased RGR, but also higher mortality rates, when grown in an enriched nutrient environment. While Aleppo pine showed no differences in RGR and mortality rate under different shading levels, RGR decreased and mortality increased for holm oak in full light. Increased radiation decreased LAR, SLA and height:diameter ratio, and increased RWR and R/S in both species, although Aleppo pine showed more pronounced changes. Unlike Aleppo pine, holm oak responded to increased nutrient availability by decreasing R/S and increasing LAR. From these results, no seed-seedling conflicts were found in either species, but a trade-off does seem to exist for holm oak between biomass allocation traits deployed in response to increased nutrient availability and radiation. Aleppo pine outperformed holm oak under most environmental conditions tested and showed a wider regeneration niche.     

Oxidative stress of liver in hamsters infected with Leishmania (L.) chagasi

Oxidative stress as a mediator of hepatic tissue damage concurrent with Leishmania (L.) chagasi infection was investigated. Chemiluminescence in liver supernatant of hamsters infected with Leishmania (L.) chagasi showed a ratio of 1.53/ mg protein and 2.10/liver weight 90 days after infection when compared with the control. The malondialdehyde (MDA) levels also increased significantly both with and without addition of Fe3+/ascorbic acid in the reaction mixture, with a ratio of 2.12 and 1.55/mg protein or 2.91 and 2.12/liver weight, respectively. The parasite burden in the spleen, as a measure of infection severity, was 9.1+/-1.33 x 10(8) parasites/organ. On the 10th day of infection, the chemiluminescence also was significantly higher in infected hamsters than in the controls (ratio = 1.36/mg protein or 1.34/liver weight); however, the MDA levels were not different from those of controls. After 90 days of infection, significant correlations were observed between chemiluminescence and MDA concentration with and without the presence of Fe3+/ascorbic acid (r = 0.54, P = 0.0001; r = 0.56, P = 0.0001; respectively). The high infection/control ratio of both chemiluminescence and MDA concentration and the significant correlation between those events strongly indicate the occurrence of oxidative stress and lipid peroxidation as a mechanism of liver damage in cases of chronic infection by L. chagasi. The significant increase in chemiluminescence at 10 days of infection demonstrates that oxidative stress occurs very early, first consuming the antioxidants and then inducing lipid peroxidative damage later in the chronic stage of this disease.     

Capacity of Lemna gibba L. (duckweed) for uranium and arsenic phytoremediation in mine tailing waters

The potential of Lemna gibba L. to clean uranium and arsenic contamination from mine surface waters was investigated in wetlands of two former uranium mines in eastern Germany and in laboratory hydroponic culture. Water and plants were sampled and L gibba growth and yield were monitored in tailing ponds from the field study sites. Contaminant accumulation, growth and yield experiments were conducted in the laboratory using synthetic tailing water. Mean background concentrations of the surface waters were 186.0+/-81.2 microg l(-1) uranium and 47.0+/-21.3 microg l(-1) arsenic in Site one and 293.7+/-121.3 microg l(-1) uranium and 41.37+/-24.7 microg l(-1) arsenic in Site two. The initial concentration of both uranium and arsenic in the culture solutions was 100 microg l(-1). The plant samples were either not leached, leached with deionized H2O or ethylenediaminetetracetic (EDTA). The results revealed high bioaccumulation coefficients for both uranium and arsenic. Uranium and arsenic content of L gibba dry biomass of the field samples were as follows: nonleached samples > deionized H2O leached (insignificant ANOVA p = 0.05) > EDTA leached. The difference in both arsenic and uranium enrichment were significantly high between the nonleached and the other two lead samples tested at ANOVA p > 0.001. Estimated mean L gibba density in surface water was 85,344.8+/-1843.4 fronds m(-2) (approximately 1319.7 g m(-2)). The maximum specific growth rate was 0.47+/-0.2 d(-1), which exceeded reported specific growth rates for L gibba in the literature. Average yield was estimated at 20.2+/-6.7 g m(-2) d(-1), giving approximately 73.6+/-21.4 t ha(-1) y(-1) as the annual yield. The highest accumulations observed were 896.9+/-203.8 mg kg(-1) uranium and 1021.7+/-250.8 mg kg(-1) arsenic dry biomass for a 21-d test period in the laboratory steady-state experiments. The potential extractions from surface waters with L gibba L. were estimated to be 662.7 kg uranium ha(-1) yr(-1) and 751.9 kg arsenic ha(-1) yr(-1) under the above conditions.     

Gamma radiation and hormone treatment as tools to reduce salt stress in rice (Oryza sativa L.)

We investigated the effects of jasmonic acid (JA) and gamma irradiation on the growth and metabolic responses to salt stress in rice (Oryza sativa L.) plants. The relative growth rate (RGR), relative water content (RWC), and chlorophyll (Chl) content were lower in NaCI-treated plants than in the control, whereas the malondialdehyde content (MDA), electrolyte leakage (EL), and contents of proline and abscisic acid (ABA) were higher in the treated plants. When induced by the salt stress, those effects, however, were somewhat alleviated by the application of JA or gamma irradiation. The most significant response was manifested by the proline content, with relatively lower values for alleviation being recorded for the contents of RGR, RWC, Chl, and MDA, as well as EL. Moreover, although total Chl content was not significantly influenced by JA or gamma irradiation in plants under salt stress, an increase in the level of Chl a resulted in a markedly changed ratio of Chl a/b. The degree of alleviation, in terms of growth and metabolic responses, was more extensive for JA-treated plants than for those exposed to gamma irradiation.     

Flavonoid content in leaf extracts of the fig (Ficus carica L.), carob (Ceratonia siliqua L.) and pistachio (Pistacia lentiscus L.)

The total flavonoid content of leaf extracts (70% ethanol) from fig (Ficus carica L.), carob (Ceratonia siliqua L.) and pistachio (Pistacia lentiscus L.) plants were determined by using reverse phase high-performance liquid chromatography (HPLC)-and analyzed by UV/VIS array and electrospray ionization (ESI)-mass spectrometry (MS) detectors. As a base for comparison, flavonoid type and level were also determined in extracts from soybeans and grape seeds. It was found that the major flavonoids in Ficus are quercetin and luteolin, with a total of 631 and 681 mg/kg extract, respectively. In Ceratonia leaves, nine different flavonoids were detected. The major one was myricetin (1486 mg/kg extract), with a similar level in Pistacia (1331 mg/kg extract, myricetin). The present study is the first to report the presence of the isoflavone genistein in the Pistacia leaf, which was discovered to consist of about a third of the genistein level detected in soybean.     

In vitro antioxidant activity of Hedyotis corymbosa (L.) Lam. aerial parts

The methanolic extract of the aerial part of Hedyotis corymbosa (L.) Lam. (Rubiaceae) was screened for antioxidant activity using 1,1-diphenyl-2-picryl hydroxyl (DPPH) quenching assay, 2,2'-azinobis-3-ethylbenzothiozoline-6-sulfonic acid (ABTS) cation decolorization test, ferric reducing power (FRP), scavenging capacity towards hydroxyl ion (OH*) radicals and nitric oxide (NO) radical inhibition activity using established assay procedures. Total phenolics and total flavonoid contents were, also determined. The plant yielded 210 mg gallic acid equivalent/100 g phenolic content and 55 mg quercetin equivalent/100 g flavonoid content. The extract exhibited high antiradical activity against DPPH, ABTS, nitric oxide and hydroxyl radicals with EC50 value of 82, 150, 130, and 170 microg/ml, respectively. The FRP increased with increasing concentration of the sample. The antioxidant activity of the extract was comparable with that of the standard butylated hydroxyl toluene (BHT). High correlation between total phenolic/flavonoid contents and scavenging potential of different reactive oxygen species (R2 = 0.785-0.998) indicated the polyphenols as the main antioxidants.     

Techno-economic and environmental approaches of Cd2+ adsorption by olive leaves (Olea europaea L.) waste

Abstract

In this study, the techno-economic approach of olive leaves (Olea europaea L.) wastes for the removal of Cd²⁺ from aqueous solutions was demonstrated. The adsorption process was illustrated regarding batch experiments and scanning electron microscopy, energy dispersive X-ray, and Fourier-transform infrared characterization. The optimum pH and contact time were 6.6 and 123?min, respectively, giving Cd²⁺ removal efficiencies of 94.9% at C_o = 50?mg/L and 81.5% at C_o = 100?mg/L. The monolayer adsorption capacity of the Langmuir isotherm model was 32.6?mg/g (R² = 0.97). The adsorption mechanisms might be related to (a) ion exchange with cations (e.g., K⁺, Na⁺, and Ca²⁺), (b) formation of cadmium chloride complexes, (c) interaction with oxygen-containing functional groups, (d) physical agglomeration in the pore surface, and (e) precipitation interaction using inorganic minerals (i.e., carbonates, phosphates, and silicates). The total cost of the adsorption process for the treatment of ions-containing wastewater was 0.038 $USD/m³. Assuming a benefit-cost of tertiary treated water as 0.044 $USD/m³, the adsorption system could attain a payback period of 5.7?years. This period was shorter than the lifetime of the capital investment (i.e., 10?years), and hence, the project would be economically feasible for an application.     

The importance of FeEDTA for reversibility of phosphate-induced chlorosis in maize (Zea mays L.)

Chlorosis induced with a supraoptimum dose of phosphorus in nutrient solution (69 mg P l^-1) was reverted by spraying of leaves of chlorotio maize plants (Zea mays L.) with FeEDTA. Biomass formation, chlorophyll and iron content were decreased in the above-ground parts of plants grown under chlorosis-inducing conditions. Spraying always decreased content of inorganic phosphorus (P_i/Fe ratio was significantly changed), increased chlorophyll content in old plants and stimulated dry mass formation at supraoptimum phosphorus doses. FeEDTA application improved phosphate utilization (portion of phosphate in organic bonds was increased). This may be the basis of chlorosis-reverting effect of FeEDTA.     

The use of water lettuce (Pistia stratiotes L.) for rhizofiltration of a highly polluted solution by cadmium and lead

The effectiveness of heavy metal uptake from contaminated nutrient solution by four aquatic macrophytes (Pistia stratiotes L., Salvinia auriculata AubL, Salvinia minima Baker, and Azolla filiculoides Lam) was estimated in this study. The influence of cadmium (3.5 mg L(-1) and 10.5 mg L(-1)) and lead (25 mg L(-1) and 125 mg L(-1)) on the stress symptoms was observed through the determination of chlorophyll content and transpiration rate over 14 days of the experiment. The results of the present study showed extreme reductions in Cd and Pb concentrations in solution during the first 4 days. The accumulation of Pb in plant tissues was the highest during the first 4 days and was more than 10 times higher in the roots (42,862 mg kg(-1)) than in the leaves (3867 mg kg(-1)). The accumulation of Cd slowly increased and was the highest at the end of the experiment. Concentrations in roots (3923 mg kg(-1)) were roughly 6 times higher than in the leaves (624 mg kg(-1)). Results showed significant decrease in the transpiration rate at Pb treatment and a significant increase at Cd treatment during 48 hours of exposition.     

Phosphorus acquisition characteristics of cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.) and white lupin (Lupinus albus L.) under P deficient conditions

A rhizobox experiment was conducted to examine the P acquisition characteristics of cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.) and white lupin (Lupinus albus L.) under P-deficient conditions. We aimed to identify whether cotton is physiologically efficient at acquiring P through release of protons, phosphatases or carboxylates. Plants were pre-grown in the upper compartment of rhizoboxes filled with a sand and soil mixture to create a dense root mat against a 53 μm polyester mesh. For each species, two P treatments (0 and 20 mg P kg^?1) were applied to the upper compartment in order to create P-deficient and P-sufficient plants. At harvest, the upper compartment with intact plants was used for collection of root exudates while the lower soil compartment was sliced into thin layers (1 mm) parallel to the rhizoplane. Noticeable carboxylates release was only detected for white lupin. All P-deficient plants showed a capacity to acidify their rhizosphere soil to a distance of 3 mm. The activity of acid phosphatase was significantly enhanced in the soil-root interfaces of P-stressed cotton and wheat. Under P-deficient conditions, the P depletion zone of cotton from the lower soil compartment was narrowest (<2 mm) among the species. Phosphorus fractionation of the rhizosphere soil showed that P utilized by cotton mainly come from NaHCO₃–P_i and NaOH–P_o pools while wheat and white lupin markedly depleted NaHCO₃–P_i and HCl–P pools, and the depletion zone extended to 3 mm. Wheat also depleted NaOH–P_o to a significant level irrespective of P supply. The study suggests that acquisition of soil P is enhanced through P mobilization by root exudates for white lupin, and possibly proton release and extensive roots for wheat under P deficiency. In contrast, the P acquisition of cotton was associated with increased activity of phosphatases in rhizosphere soil.