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At least 163 records · Page 9Linked to original sources
PubMed2003

Influence of early stages of arbuscular mycorrhiza on uptake of zinc and phosphorus by red clover from a low-phosphorus soil amended with zinc and phosphorus.

In a pot experiment, red clover (Trifolium pratense) was grown in sterilized Zn-amended low available P soil (0, 50 or 400 mg Zn kg(-1)) with or without 100 mg kg(-1) added P and with or without inoculation with the arbuscular mycorrhizal (AM) fungus G. mosseae. When the plants were harvested after 40 days, AM colonization of the roots was still at an early stage, with only 14-38% of total root length colonized on average. AM colonization was highest in low-P soil, and was lowest in soil amended with 400 mg Zn kg(-1). Shoot yields were highest in AM plants with added P, but root yields were unaffected by AM inoculation. Shoot and root yields were higher with 100 mg added P kg(-1) soil, but lower with 400 mg Zn kg(-1) than 50 mg Zn kg(-1) or controls unamended with Zn. Shoot and root P concentrations were seldom higher in AM plants, but shoot P offtakes were higher in AM plants with added P. Concentrations of Zn and Cu were much higher in the roots than in the shoots. Shoot and root Zn and shoot Cu were lower, but root Cu was higher, in AM plants. Soil residual pH after plant growth was higher in AM treatments, and residual total Zn was also higher, indicating lower Zn uptake by AM plants. Soil solution pH was higher in AM treatments, and soil solution Zn was lower in the presence of mycorrhiza. The results are discussed in terms of AM protection of the plants against excessive shoot Zn uptake.

Copper↗
PubMed2006

Toxicological responses of red-backed salamanders (Plethodon cinereus) to subchronic soil exposures of 2,4-dinitrotoluene.

Dinitrotoluenes are used as propellants and in explosives by the military and as such have been found at relatively high concentrations in the soil. To determine whether concentrations of 2,4-dinitrotoluene (2,4-DNT) in soil are toxic to amphibians, 100 red-backed salamanders (Plethodon cinereus) were exposed to either 1500, 800, 200, 75 or 0mg 2,4-DNT/kg soil for 28 days and evaluated for indicators of toxicity. Concentrations of 2,4-DNT were less than targets and varied with time. Most salamanders exposed to concentrations exceeding 1050 mg/kg died or were moribund within the first week. Salamanders exposed to soil concentrations exceeding 345 mg/kg lost >6% of their body mass though no mortality occurred. Overt effects included a reduction in feed consumption and an increase in bucco-pharyngeal oscillations in salamanders. These results suggest that only high soil concentrations of 2,4-DNT have the potential to cause overtly toxic effects in terrestrial salamanders.

Animals↗
PubMed1995

Improving feeding management and work performance of Mashona oxen through strategic supplementation with cobsheath-groundnut stover.

Six pairs of Mashona oxen ploughed dry, red clay soils in August (winter) and in mid-November (spring). Between September and November the oxen were randomly assigned to 3 feeding groups: no supplement (control), 400 g/head per day of cobsheath-groundnut stover for 70 days and 800 g/head per day of the same supplement for 35 days. Cobsheath-groundnut stover was fed in order to determine its potential as supplementary feed for draught oxen during the dry season. The liveweight (LW) lost by heavy oxen during winter ploughing was lower (P < 0.001) than that of light oxen. During spring ploughing heavy oxen again lost less (P < 0.001) LW than light ones. In addition, non-supplemented oxen lost more LW than those supplemented. Therefore feeding strategies for Mashona draught oxen should aim at providing adequate nutrients to at least maintain LW during the dry season. Heavy oxen outperformed (P < 0.001) light ones during winter ploughing. Work output of supplemented oxen in spring was also significantly greater (P < 0.05) than that of non-supplemented ones. This result demonstrated the benefits of supplementary feed during the dry season. Concentrations of lactate and free fatty acids in plasma, heart rates and rectal temperatures increased (P < 0.05) markedly during work. The increases were higher (P < 0.05) for light oxen, particularly those not fed supplement.

Animal Feed↗
PubMed2005

Preparation and application of the sol-gel-derived acrylate/silicone co-polymer coatings for headspace solid-phase microextraction of 2-chloroethyl ethyl sulfide in soil.

Three types of novel acrylate/silicone co-polymer coatings, including co-poly(methyl acrylate/hydroxy-terminated silicone oil) (MA/OH-TSO), co-poly(methyl methacrylate/OH-TSO) (MMA/OH-TSO) and co-poly(butyl methacrylate/OH-TSO) (BMA/OH-TSO), were prepared for the first time by sol-gel method and cross-linking technology and subsequently applied to headspace solid-phase microextraction (HS-SPME) of 2-chloroethyl ethyl sulfide (CEES), a surrogate of mustard, in soil. The underlying mechanisms of the coating process were discussed and confirmed by IR spectra. The selectivity of the three types of sol-gel-derived acrylate/silicone coated fibers was studied, and the BMA/OH-TSO coated fibers exhibited the highest extraction ability to CEES. The concentration of BMA and OH-TSO in sol solution was optimized, and the BMA/OH-TSO (3:1)-coated fibers possessed the highest extraction efficiency. Compared with commercially available polyacrylate (PA) fiber, the sol-gel-derived BMA/OH-TSO (3:1) fibers showed much higher extraction efficiency to CEES. Therefore, the BMA/OH-TSO (3:1)-coated fibers were chosen for the analysis of CEES in soil matrix. The reproducibility of coating preparation was satisfactory, with the RSD 2.39% within batch and 3.52% between batches, respectively. The coatings proved to be quite stable at high temperature (to 350 degrees C) and in different solvents (organic or inorganic), thus their lifetimes (to 150 times) are longer than conventional fibers. Extraction parameters, such as the volume of water added to the soil, extraction temperature and time, and the ionic strength were optimized. The linearity was from 0.1 to 10 microg/g, the limit of detection (LOD) was 2.7 ng/g, and the RSD was 2.19%. The recovery of CEES was 88.06% in agriculture soil, 92.61% in red clay, and 101.95% in sandy soil, respectively.

Acrylates↗
PubMed2001

Enhanced transport of pesticides in a field trial with treated sewage sludge.

This study was designed to provide high-density data on spatial distribution of three herbicides with different physiochemical characteristics in a sludge-amended and non-amended control field over the course of an irrigation season. The field experiment was carried out on a sandy loam Hamra Red Mediterranean soil (Rhodoxeralf) at Bet Dagan, Israel. After a single 50 mm irrigation event, the mean centers of mass (COM) in the control field were at 15.6, 14.9, and 17 cm for bromacil, atrazine and terbuthylazine, respectively; in the sludge-amended field, mean COMs were at 28.8, 31.2, and 34.1 cm, respectively. After 500 mm of irrigation in the control field, the COM depth distribution of the three pesticides was inversely correlated with octanol-water (Kow) distribution coefficients and soil sorption coefficients (Koc), and positively correlated with aqueous solubilities. After 500 mm irrigation in the sludge-amended field, the mean terbuthylazine COM was at 19.8 cm versus 13.8 cm for the control field, demonstrating a sustained enhanced effect on terbuthylazine transport. Downward transport of atrazine was also enhanced by sludge amendment, albeit less than terbuthylazine. Bromacil was preferentially accumulated in the upper soil layers of the sludge-amended field as compared with the control field after 500 mm irrigation. The enhanced transport of all three pesticides in the sludge-amended field after a single irrigation event is attributed to development of preferential flow pathways around hydrophobic clods of sludge. Enhanced transport of terbuthylazine, and to a lesser extent, atrazine, throughout the irrigation season, is attributed to their transport as complexes with dissolved, colloidal and suspended organic matter derived from sludge degradation.

Agriculture↗
PubMed2002

Local treatment of hemorrhoidal disease and perianal eczema. Meta-analysis of the efficacy and safety of an Escherichia coli culture suspension alone or in combination with hydrocortisone.

The objective of this paper was to assess the available clinical data on the efficacy and safety of ointments containing either a bacterial culture suspension (BCS) from Escherichia coli or a combination of BCS with hydrocortisone (CAS 50-23-7) (BCS: Posterisan, and BCS + HC: Posterisan forte). The BCS is assumed to act by immunomodulation in hemorrhoidal disease and perianal eczema. Six randomized, double-blind trials are reported: three of them using BCS ointment and one using BCS + HC, against ointment base, and two trials using BCS + HC against hydrocortisone ointment alone. Patients with hemorrhoids and/or perianal eczema were included and treated over 2 weeks with weekly assessments. Efficacy parameters included score changes for burning, itching, redness and soiling as well as the investigators' overall efficacy rating. Safety was assessed from adverse drug reactions and an overall safety rating. Out of 1,070 patients (mean age 50 years), 273 received BCS and 229 BCS + HC; 568 patients were given the various controls. In the overall efficacy rating, BCS ointment was significantly superior to the ointment base in all three studies (p = 0.028, p = 0.016, and p = 0.045). Moreover, BCS + HC was superior to the ointment base (p < 0.001) and to hydrocortisone alone (p = 0.156 and p = 0.021), confirming the distinct effect of the E. coli suspension. Satisfactory results were achieved in 83% of patients after the BCS + HC combination, 77% after BCS-containing ointment, 75% after hydrocortisone ointment and 52% after ointment base. Symptom scores decreased consistently more after administration of BCS than after the ointment base (p = 0.095, p = 0.006, and p = 0.029), and likewise, the combination of BCS + HC was significantly superior to the ointment base (p < 0.001) and to hydrocortisone alone (p = 0.036 and p = 0.019). Adverse events were less frequent for BCS and BCS + HC than for the ointment base. It can therefore be concluded that ointments containing either only E. coli BCS or a combination of BCS and hydrocortisone provide significant relief in perianal eczema as well as in early stages of hemorrhoidal disease.

Adult↗
PubMed2006

Economic costs of endemic non-filarial elephantiasis in Wolaita Zone, Ethiopia.

BACKGROUND: Endemic non-filarial elephantiasis or podoconiosis is a chronic and debilitating geochemical disease occurring in individuals exposed to red clay soil derived from alkalic volcanic rock. It is a major public health problem in countries in tropical Africa, Central America and North India. OBJECTIVE: To estimate the direct and the average productivity cost attributable to podoconiosis, and to compare the average productivity time of podoconiosis patients with non-patients. METHODS: Matched comparative cross sectional survey involving 702 study subjects (patients and non-patients) supplemented by interviews with key informants in Wolaita Zone, southern Ethiopia. RESULTS: Total direct costs of podoconiosis amounted to the equivalent of US$ 143 per patient per year. The total productivity loss for a patient amounted to 45% of the total working days per year, causing a monetary loss equivalent to US$ 63. In Wolaita zone, the overall cost of podoconiosis exceeds US$ 16 million per year. CONCLUSIONS: Podoconiosis has enormous economic impact in affected areas. Simple preventive measures (such as use of robust footwear) must be promoted by health policy makers.

Adolescent↗
PubMed2000

Levels of racism: a theoretic framework and a gardener's tale.

The author presents a theoretic framework for understanding racism on 3 levels: institutionalized, personally mediated, and internalized. This framework is useful for raising new hypotheses about the basis of race-associated differences in health outcomes, as well as for designing effective interventions to eliminate those differences. She then presents an allegory about a gardener with 2 flower boxes, rich and poor soil, and red and pink flowers. This allegory illustrates the relationship between the 3 levels of racism and may guide our thinking about how to intervene to mitigate the impacts of racism on health. It may also serve as a tool for starting a national conversation on racism.

Disease↗
PubMedDate not supplied

Application of calorimetry to microbial biodegradation studies of agrochemicals in oxisols.

Calorimetry was used to monitor the inhibitory effect caused by the bipyridynium diquaternary salts paraquat, diquat, and phosphamidon on microbial activity in a Red Latosol soil (Oxisol). The thermal effect was recorded on samples composed of 1.50 g of soil, 6.0 mg of glucose, 6.0 mg of ammonium sulfate, and different masses of an inhibitor ranging from zero to 8.00 mg, under a controlled moisture content of 35%. Thermal effects of each pollutant on the degradation curves of glucose in the soil were compared. Increasing amounts of the inhibitor caused a decrease in the thermal effect from -2234 to -1987 kJ mol(-1) for paraquat, -1670 to -1306 kJ mol(-1) for diquat, and -2239 to -589 kJ mol(-1) for phosphamidon. The last xenobiotic agent caused a significant inhibitory effect on the microbial activity of the soil. The results of relative efficiency, eta = deltaH/deltaH', referring to the enthalpic value with (deltaH) and without (deltaH') agrochemical in the soil, exhibited a significant correlation. From this correlation obtained for the ranges 2.00 to 8.00, 1.30 to 8.00, and 1.20 to 5.80 mg of the agrochemicals paraquat, diquat, and phosphamidon, respectively, the following eta values were calculated: 0.993 to 0.894, 0.668 to 0.522, and 0.896 to 0.236, respectively, during the degradation of glucose in the soil. The largest relative efficiency for paraquat implies that this agrochemical can be metabolized by microbial activity.

Biodegradation, Environmental↗
PubMed2006

[Effects of potassium application rate and its supplemental proportion on dry matter accumulation and potassium absorption of flue-cured tobacco].

A field trial with flue-cured tobacco conducted on a red paddy soil showed that the dry matter accumulation in the tobacco reached a peak in 50-60 days after transplanting, but was lower within 30 days or over 80 days after transplanting. The dry matter accumulation was increased with increasing K application rate and its supplemental proportion. The K content in the tobacco got its peak in 30-50 days after transplanting, and then went down, with the K content at maturing stage being as half as that in the peak period. The K content of the tobacco in each growth stage was obviously higher with 315 kg x hm(-2) K application than with 225 kg x hm(-2) K application. At maturing stage, the dry matter and K contents in the tobacco decreased with 225 kg x hm(-2) K application, but increased with 315 kg x hm(-2) K application, and the K content was higher with 70% K supplemental proportion than with 50% and 30% K supplemental proportion.

Absorption↗
PubMed1991

[Nitrogen composition of the fruit juice of the Persian lime in Cuba].

In 1987 to 1989 the composition was studied of the nitrogen compounds (nitrogen and free amino acids) in the fruit juice of Persian lime during its commercial harvesting period. Adult Persian lime trees grafted on Citrus macrophylla and C. volkameriana were used, planted on a groundwater-affected red ferrilytic soil in the La Habana Province. Determination of the total nitrogen and of the free proline was carried out in May to July of each experimental year. The amino acid spectrum was established from juice samples in May 1987 and in July 1988. With the nitrogen concentrations varying between 14 and 90 mg/100 ml of juice, no consistent behaviour or pattern could be detected either in the total nitrogen content or the proline content in the juice during the 3 experimental years. 14 free amino acids were found, with about 90% of the total content formed from asparagine acid, glutamic acid, alanine, proline, gamma-aminobutyric acid, and arginine, regardless of the experimental year or the grafting basis.

Amino Acids↗
PubMed1981

Endemic elephantiasis of the lower legs in the United Cameroon Republic.

Evidence for an association of endemic non-filarial elephantiasis of the lower legs with areas of red clay soils around volcanoes has been noted in several countries bordering the Rift Valley in East Africa. It was of interest to observe whether the association is also present in an area of endemic prevalence of the disease in West Africa. Such an area occurs in the Cameroon highlands where it has been suggested that onchocerciasis might be an etiological factor. The present study describes the results of a survey in this area. There was no statistical evidence of a relationship with onchocerciasis and the content of mineral microparticles in lymphatic tissues of the lower legs was again established. Climatic, geological and soil characteristics were similar to those in East Africa. It is considered that the disease in the two widely separated non-bancrofti areas is of similar etiology and it is proposed that it may be interpreted as silicosis of peripheral lymphatics of the lower legs.

Adult↗
PubMed2003

The role of arbuscular mycorrhiza in zinc uptake by red clover growing in a calcareous soil spiked with various quantities of zinc.

Three pot experiments were conducted to investigate the role of arbuscular mycorrhiza (AM) in Zn uptake by red clover. Plants inoculated with Glomus mosseae and uninoculated controls were grown in a sterile calcareous soil in 'Plexiglas' (Acrylic) containers with two nylon net partitions (30 microm mesh) to separate the central root zone from the two outer hyphal zones. The effects of mycorrhiza on plant growth and Zn uptake changed dramatically with increasing Zn addition level (range 0-1200 mg kg(-1)) in the root zone. With Zn addition levels <300 mg kg(-1), added Zn did not affect plant yield and above the critical level plant yield gradually decreased but was always higher for mycorrhizal than for controls. Below the critical Zn application rate (50 mg kg(-1)), Zn uptake was enhanced while above this level Zn translocation to the shoots decreased. At all Zn addition levels, mycorrhizal colonization increased Zn absorption and accumulation in the roots, and this may help to explain the alleviation of Zn toxicity at high Zn application rates. As expected, AM colonization enhanced P nutrition and hence yield at all added Zn levels studied. Efforts were made to obtain direct evidence for hyphal contribution to Zn uptake by applying both Zn to the hyphal growth zone and additional P to the root zone to avoid the 'growth dilution effect'. The data demonstrate that mycorrhizal hyphae could absorb Zn directly from the soil and then transfer it to the plant roots. The hyphal contribution to Zn uptake by the host plant reached its maximum value at the Zn addition level of 50 mg kg(-1), in which Zn uptake via the extramatrical hyphae comprised 22% of total uptake, thus confirming the critical Zn application level found previously.

Hyphae↗
PubMed1982

Competitiveness of Rhizobium trifolii Strains Associated with Red Clover (Trifolium pratense L.) in Mississippi Soils.

Five strains of Rhizobium trifolii were evaluated in competition with indigenous populations in nodulating red clover (Trifolium pratense L.) cv. Kenland in two different soils in Mississippi. Double antibiotic resistance acquisition was used to measure the proportion of nodules occupied by the introduced mutant strains. In vertisol soil, strains RP113-7, 162BB1, LM1, and 162P17 were recovered in at least 94% of the assayed nodules, whereas TA1 was found in 83.8% of the nodules. At an ultisol location, significant differences were detected within the introduced rhizobia. Strain RP113-7 was recovered at very high rates (99.2% of the assayed nodules), whereas strains 162BB1, LM1, 162P17, and TA1 were all found in 84.9 to 96.0% of the nodules sampled. Forage yield and percent crude protein levels were lower with the less effective but competitive strain (TA1) at both locations. Results indicated that more effective strains of R. trifolii can increase red clover production and symbiotic nitrogen fixation under different environmental conditions in Mississippi.

Journal Article↗
PubMed2007

Organic agriculture and nitrous oxide emissions at sub-zero soil temperatures.

In the Red River Valley of the upper midwestern United States, soil temperatures often remain below freezing during winter and N2O emissions from frozen cropland soils is assumed to be negligible. This study was conducted to determine the strength of N2O emissions and denitrification when soil temperatures were below zero for a manure-amended, certified organic field (T2O) compared with an unamended, conventionally managed field (T2C). Before manure application, both fields were similar with respect to autotrophic and heterotrophic N2O production and N2O flux at the soil surface (0.15+/-0.05 mg N2O-N m-2 d-1 for T2O and 0.12+/-0.06 mg N2O-N m-2 d-1 for T2C). After application of pelletized, dehydrated manure, average daily flux (based on time-integrated fluxes from 20 November to 8 April), was 1.19+/-0.34 mg N2O-N m-2 d-1 for T2O and 0.47+/-0.37 mg N2O-N m-2 d-1 for T2C. Denitrification for intact cores measured in the laboratory at -2.5 degrees C was greater for organically managed soils, although only marginally significant (p<0.1). Cumulative emissions for all winter measurements (from 16 November to 8 April) averaged 1.63 kg N2O-N ha-1 for T2O and 0.64 kg N2O-N ha-1 for T2C. Biological N2O production was evident at sub-zero soil temperatures, with winter emissions exceeding those measured in late summer. Late autumn manure application enhanced cumulative N2O-N emissions by 0.9 kg ha-1.

Agriculture↗
PubMed1997

Seasonal air and soil temperature effects on photosynthesis in red spruce (Picea rubens) saplings.

Net photosynthesis and stomatal conductance were measured in ten red spruce (Picea rubens Sarg.) saplings, growing near Ithaca, New York, throughout the early spring and late-fall growing periods. Gas exchange and daily minimum and maximum soil and air temperatures were also measured. Linear regression analysis showed that rates of net photosynthesis were positively correlated with both minimum daily soil and air temperatures but that minimum soil temperature was a better predictor of net photosynthesis. Moreover, net photosynthesis was more sensitive to changes in soil temperature than to changes in air temperature, and photosynthesis was approximately twice as sensitive to temperature changes during the fall than during the spring.

Journal Article↗
PubMed2006

Cessation of tillering in spring wheat in relation to light interception and red : far-red ratio.

BACKGROUND AND AIMS: The production of axillary shoots (tillering) in spring wheat (Triticum aestivum) depends on intraspecific competition. The mechanisms that underlie this competition are complex, but light within the wheat canopy plays a key role. The main objectives of this paper are to analyse the effects of plant population density and shade on tillering dynamics of spring wheat, to assess the canopy conditions quantitatively at the time of tillering cessation, and to analyse the relationship between the tiller bud and the leaf on the same phytomer. METHODS: Spring wheat plants were grown at three plant population densities and under two light regimes (25 % and 100 % light). Tiller appearance, fraction of the light intercepted, and red : far-red ratio at soil level were recorded. On six sampling dates the growth status of axillary buds was analysed. KEY RESULTS: Tillering ceased earlier at high population densities and ceased earlier in the shade than in full sunlight. At cessation of tillering, both the fraction of light intercepted and the red : far-red ratio at soil level were similar in all treatments. Leaves on the same phytomer of buds that grew out showed more leaf mass per unit area than those on the same phytomer of buds that remained dormant. CONCLUSIONS: Tillering ceases at specific light conditions within the wheat canopy, independent of population density, and to a lesser extent independent of light intensity. It is suggested that cessation of tillering is induced when the fraction of PAR intercepted by the canopy exceeds a specific threshold (0.40-0.45) and red : far-red ratio drops below 0.35-0.40.

Photosynthesis↗
PubMed2003

The effect of lead-contaminated soil from Canadian prairie skeet ranges on the neutral red retention assay and fecundity in the earthworm Eisenia fetida.

The sublethal effects of lead (Pb) on the earthworm Eisenia fetida were evaluated in the laboratory using freshly spiked soil and soil collected from Canadian prairie skeet ranges. After a four-week exposure to soil spiked with lead acetate, earthworm neutral red retention time (NRRT). soil Pb concentrations, and earthworm Pb body burdens were measured. Lysosomal NRRT was reduced in a concentration-dependent manner (p < 0.0001), and NRRT was negatively correlated with earthworm Pb body burdens (r = -0.80, p < 0.0001). To evaluate the effects of aged Pb, earthworms were exposed to soil from three skeet ranges, and responses were compared with three matched reference sites. After a four-week exposure, NRRT, growth, fecundity, soil total Pb levels, and earthworm Pb body burdens were measured. The potentially bioavailable fraction of Pb in these sites was measured using a Ca(NO3)2 extraction. Growth and fecundity did not differ significantly between any of the skeet ranges and their reference sites. However, NRRT was significantly reduced in all three ranges compared with their respective reference sites (p < 0.05), indicating that the neutral red retention assay (NRRA) may be useful for detecting toxicity and potential hazards at Pb-contaminated sites. Lysosomal NRRT was negatively correlated with soil Ca(NO3)2-extractable Pb (r = -0.80, p < 0.0001) and soil total Pb (r = -0.73, p = 0.001). Lysosomal NRRT was negatively correlated (r = -0.67, p < 0.002) with earthworm Pb tissue levels.

Animals↗