scholarly journals A New Model Describing Copper Dose–Toxicity to Tomato and Bok Choy Growth in a Wide Range of Soils

2019 ◽  
Vol 16 (2) ◽  
pp. 264 ◽  
Author(s):  
Bao Jiang ◽  
Yibing Ma ◽  
Guangyun Zhu ◽  
Jun Li
Keyword(s):  
Soil Properties ◽  
Dose Response ◽  
Predictive Models ◽  
Contaminated Soils ◽  
Ethylenediaminetetraacetic Acid ◽  
Heavy Metal Concentration ◽  
Exposure Dose ◽  
Exchange Capacity ◽  
Response Curves ◽  
Wide Range

Phytotoxicity thresholds for heavy metals are derived from dose–response curves, which show the relationships between exposure dose and toxicity response. However, the results of tests or observations are commonly based on total heavy metal concentration, not the exposure dose that causes phytotoxicity; additionally, the phytotoxicity response differs with plant species. In the present study, the ethylenediaminetetraacetic acid (EDTA)-extractable copper (Cu) concentration was determined in order to evaluate Cu extractability. As two important horticultural food crops in Asia, tomato (Lycopersicon esculentum ‘Meifen No. 1’) and bok choy (Brassica rapa var. chinensis ‘Susheng 28’) were used to investigate Cu phytotoxicity in a wide range of Chinese soils with and without leaching treatment, after which relationships between Cu phytotoxicity thresholds based on EDTA-extractions and soil properties were established. The phytotoxicity thresholds showed that biomass of bok choy was more sensitive to Cu than tomato. Multiple linear regression analyses showed that soil factors, including organic carbon (OC), citrate dithionate extractable manganese (CD-Mn), cation exchange capacity (CEC), and CaCO3 explained over 85% of the variance in Cu phytotoxicity thresholds. The EDTA-extractable Cu dose–response relationships were further improved by incorporating soil properties. The new phytotoxicity predictive models indicated soil properties (soil pH, OC, CEC, and oxalate-extractable Mn) and EDTA-extractable Cu concentration explained more than 90% of the variance in the phytotoxicity response of tomato and bok choy biomass. The new phytotoxicity predictive models could be used to develop a reasonable remediation strategy for contaminated soils.

Modelling the effects of soil properties on the concentration of Cd extracted by 10 mM CaCl2 from soils of the Sydney Basin

Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 799 ◽  
Author(s):  
P. J. Milham ◽  
K. B. P. N. Jinadasa ◽  
D. Collins ◽  
P. J. Nicholls ◽  
C. A. Hawkins ◽  
...  
Keyword(s):  
Soil Properties ◽  
Contaminated Soils ◽  
Maximum Error ◽  
Exchange Capacity ◽  
Sorption Data ◽  
Final Model ◽  
Residual Variation ◽  
Low Concentrations ◽  
Wide Range ◽  
Median Error

Undisturbed surface soils on the peri-urban fringe of the Sydney Basin are mostly acidic, with low concentrations of total cadmium (Cdt) and a wide range of other properties. In taxonomically similar soils on vegetable farms, Cdt is typically about 20-fold greater and undesirably large concentrations of Cd occur in some of the vegetables. We used a sequence of multiple regression models to evaluate how soil properties, taxonomy, and farming affected the behaviour of Cd in surface composites (0–15 cm) from 29 farmed and 12 unfarmed sites in the Basin. The dependent variable was the log10 transformation of the concentration of Cd extracted in 1 h by 10 mm CaCl2 solution (log10 CdCa). The range of values of CdCa was 0.2–60 μg/L. The independent variables in the base model were pHCa and log10 Cdt (R2 = 0.885, r.s.d. = 0.245). The final model contained 2 additional log10-transformed soil properties: effective cation exchange capacity (ECEC) and oxalate-extractable Fe (Feox) (R2 = 0.974, r.s.d. = 0.121). The effect of log10 Feox was significant (P < 0.05), but only when pHCa was > 5.6, the approximate sorption edge for Cd on goethite. The effects of other soil properties could not be adequately tested because the residual variation was too small. The measured values of CdCa had a median error of ±17% and a maximum error of ±58% relative to the back-transformed fitted values from the final model. The coefficient of log10 Cdt in the final model was 1.33 ± 0.05 for the farmed soils and 1.01 ± 0.04 for the unfarmed soils, i.e. log10 CdCa was more sensitive to changes in log10 Cdt in the farmed than the unfarmed soils (P < 0.01). This difference is consistent with the effects of the greater load and briefer duration of contact for Cd in the farmed soils. The coefficients of pHCa and of log10 ECEC in our final model had values of 0.49 (± 0.03) and 0.69 (± 0.08). These values are remarkably similar to those obtained when we fitted our data, using a model that had been used to describe the effects of soil properties on a compilation of Cd-sorption data, and to those in a partitioning model based on the desorption of Cd from contaminated soils. That is, the behaviour of Cd may be influenced by the duration of contact between Cd and the soil, and perhaps the load; however, neither factor appears to change the effects of pHCa and log10 ECEC.

scholarly journals Relationship of soil properties to fractionation, bioavailability and mobility of lead and zinc in soil

2008 ◽  
Vol 53 (No. 5) ◽  
pp. 225-238 ◽  
Author(s):  
N. Finžgar ◽  
P. Tlustoš ◽  
D. Leštan
Keyword(s):  
Organic Matter ◽  
Regression Analysis ◽  
Soil Organic Matter ◽  
Soil Properties ◽  
Multiple Regression ◽  
Contaminated Soils ◽  
Organic Matter Content ◽  
Clay Content ◽  
Exchange Capacity ◽  
Matter Content

Sequential extractions, metal uptake by <i>Taraxacum officinale</i>, Ruby&rsquo;s physiologically based extraction test (PBET) and toxicity characteristic leaching procedure (TCLP), were used to assess the risk of Pb and Zn in contaminated soils, and to determine relationships among soil characteristics, heavy metals soil fractionation, bioavailability and leachability. Regression analysis using linear and 2nd order polynomial models indicated relationships between Pb and Zn contamination and soil properties, although of small significance (<i>P</i> < 0.05). Statistically highly significant correlations (<i>P</i> < 0.001) were obtained using multiple regression analysis. A correlation between soil cation exchange capacity (CEC) and soil organic matter and clay content was expected. The proportion of Pb in the PBET intestinal phase correlated with total soil Pb and Pb bound to soil oxides and the organic matter fraction. The leachable Pb, extracted with TCLP, correlated with the Pb bound to carbonates and soil organic matter content (<i>R</i><sup>2</sup> = 69%). No highly significant correlations (<i>P</i> < 0.001) for Zn with soil properties or Zn fractionation were obtained using multiple regression.

Evidence for existence of cortical androgen-stimulating hormone.

1979 ◽  
Vol 236 (6) ◽  
pp. E616 ◽  
Author(s):  
L N Parker ◽  
W D Odell
Keyword(s):  
Luteinizing Hormone ◽  
Dose Response ◽  
Thyroid Stimulating Hormone ◽  
Pituitary Hormone ◽  
Response Curves ◽  
Adrenal Androgen ◽  
Luteinizing Hormone Releasing Hormone ◽  
Response Slope ◽  
Wide Range ◽  
Stimulating Hormone

An animal model using dexamethosone-suppressed, castrated dogs was developed to test the hypothesis that a pituitary hormone other than ACTH modulates adrenal androgen (AA) secretion. Plasma samples were obtained every 15 min during infusions of saline, synthetic alpha 1-24 corticotropin, porcine 1-39 corticotropin (ACTH), or bovine pituitary gland extract (PE) in a wide range of doses. Androstenedione (A), dehydroepiandrosterone (DHA), and cortisol (F) were quantified by radioimmunoassay. When the ratio of AA levels was related to those of F, in order to correct for ACTH content in the PE, the slopes of the dose-response curves for corticotropin and PE were different at the 0.01 level. For A the dose-response slope for the PE was 0.18 +/- 0.5 SE, whereas that of ACTH was 0.02 +/- 0.01. For the DHA response the slopes were 0.17 +/- 0.04 for the PE and 0.04 +/- 0.03 for ACTH. Related studies showed no increase in AA levels in response to luteinizing hormone-releasing hormone, bovine growth hormone (GH), bovine prolactin, ovine thyroid-stimulating hormone (TSH), or synthetic aqueous arginine vasopressin (AVP). We conclude that a pituitary factor other than ACTH, prolactin, GH, luteinizing hormone, follicle-stimulating hormone, TSH, or AVP may be responsible for the observed increase in AA concentrations.

scholarly journals Correspondence of In Vitro and In Vivo Fluconazole Dose-Response Curves for Cryptococcus neoformans

2005 ◽  
Vol 49 (8) ◽  
pp. 3297-3301 ◽  
Author(s):  
Robert A. Larsen ◽  
Madeline Bauer ◽  
Ann M. Thomas ◽  
Alejandro Sanchez ◽  
Diane Citron ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Dose Response ◽  
Response Curve ◽  
Drug Susceptibility Testing ◽  
Response Curves ◽  
In Vitro Susceptibility ◽  
Drug Concentrations ◽  
Wide Range

ABSTRACT We conducted in vitro experiments to evaluate the susceptibility of a clinical isolate of Cryptococcus neoformans to a wide range of concentrations of fluconazole. In vitro susceptibility was tested using broth macrodilution methods modified to provide a numeric count of viable organisms. The association between the quantitative in vitro response and fluconazole drug concentrations was estimated using local nonparametric regression. Regression analysis was used to assess the correspondence between the in vitro fluconazole concentration-response curve and the murine dose-response curve observed in our previously reported murine model. The regression model was then used to predict the murine response. There was a strong correspondence between in vitro measures of response to fluconazole alone and the previously reported biologic effects seen in the mouse. In vitro antifungal drug susceptibility testing can reliably predict the murine response to fluconazole.

Soil Properties Influence Saflufenacil Phytotoxicity

Weed Science ◽  
2014 ◽  
Vol 62 (4) ◽  
pp. 657-663 ◽  
Author(s):  
Travis W. Gannon ◽  
Adam C. Hixson ◽  
Kyle E. Keller ◽  
Jerome B. Weber ◽  
Stevan Z. Knezevic ◽  
...  
Keyword(s):  
Organic Matter ◽  
Regression Analysis ◽  
Soil Properties ◽  
Texture Classification ◽  
Organic Matter Content ◽  
The United States ◽  
Exchange Capacity ◽  
Matter Content ◽  
Crop Tolerance ◽  
Wide Range

Saflufenacil, a pyrimidinedione herbicide, is used for contact and residual broadleaf weed control in various crops. Bioactivity of saflufenacil in soil was tested in greenhouse and laboratory studies on 29 soils representing a wide range of soil properties and geographic areas across the United States. A greenhouse bioassay method was developed using various concentrations of saflufenacil applied PPI to each soil. Whole canola plants were harvested 14 d after treatment, and fresh and dry weights were recorded. Nonlinear regression analysis was used to determine the effective saflufenacil doses for 50% (ED50,), 80% (ED80), and 90% (ED90) inhibition of total plant fresh weight. Bioactivity of saflufenacil in soil was strongly correlated to soil organic (R= 0.85) and humic matter (R= 0.81), and less correlated to cation exchange capacity (R= 0.49) and sand content (R= −0.32). Stepwise regression analysis indicated that organic matter was the major soil constituent controlling bioactivity in soil and could be used to predict the bioactivity of saflufenacil. Saflufenacil phytotoxicity was found to be dependent on soil property; therefore, efficacy and crop tolerance from PRE and PPI applications may vary based on soil organic matter content and texture classification.

EVALUATION OF SOIL EXTRACTANTS FOR THE PREDICTION OF PLANT-AVAILABLE POTASSIUM IN ONTARIO SOILS

1990 ◽  
Vol 70 (4) ◽  
pp. 607-615 ◽  
Author(s):  
LIANGXUE LIU ◽  
THOMAS E. BATES
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Predictive Models ◽  
Stepwise Regression ◽  
Exchange Capacity ◽  
Simple Correlation ◽  
K Uptake ◽  
Independent Variables ◽  
Medicago Sativa L ◽  
Extractable Soil

The effectiveness of five extractants, NaCl, AB-DTPA, NH4OAc, Mehlich 3 and HNO3 was evaluated on 72 Ontario soils for prediction of plant-available K to alfalfa (Medicago sativa L.) grown in a greenhouse. Total K uptake by four cuts of alfalfa was used to measure plant available soil K. The average amounts of K extracted were in ascending order: AB-DTPA < NaCl < = NH4OAc < Mehlich 3 < HNO3. The highest simple correlation with K uptake by alfalfa was obtained with HNO3 (r = 0.76) and the lowest with NaCl (r2 = 0.61). The K uptake by alfalfa was used as the dependent variable to develop predictive models using stepwise regression, with extractable soil K, exchangeable Mg and Ca, soil pH, organic matter, cation exchange capacity (CEC), and contents of silt and clay as independent variables. The best prediction of K uptake with extracted soil K and its square was AB-DTPA (R2 = 0.84), followed by HNO3 (0.81), NH4OAc (0.81), NaCl (0.78) and Mehlich 3 (0.77). Inclusion of soil properties improved the effectiveness of prediction. The models developed with the different extractants differ in the number of variables which contributed significantly at 5% probability. Based on the final R2 and ease of measurement of variables, the NH4OAc model is one of the best as a predictor of availability of K in Ontario soils when used along with other soil properties such as plant-available nonexchangeable K and soil organic matter. Key words: Potassium extractants, plant-available K, alfalfa

MELANOPHORE-STIMULATING HORMONE-MELATONIN ANTAGONISM IN RELATION TO COLOUR CHANGE IN XENOPUS LAEVIS

1971 ◽  
Vol 49 (4) ◽  
pp. 573-580 ◽  
Author(s):  
KAY DIERST-DAVIES ◽  
F. W. LANDGREBE ◽  
G. M. MITCHELL
Keyword(s):  
Xenopus Laevis ◽  
Dose Response ◽  
Colour Change ◽  
Response Curves ◽  
Low Concentrations ◽  
Wide Range ◽  
Dose Response Curves ◽  
Normal Light ◽  
Melanophore Stimulating Hormone ◽  
Stimulating Hormone

SUMMARY Experiments on colour change of Xenopus laevis were performed to investigate the possibility that melatonin is the physiological antagonist to melanophore-stimulating hormone (MSH). Various amounts of substandard (SS) extract of ox posterior pituitary plus melatonin were injected into the dorsal lymph sac of adult male Xenopus laevis. Normal light-adapted, completely hypophysectomized, and anterior lobectomized animals were used. Dose—response curves were obtained for different SS dosages over a wide range of melatonin concentrations. Melatonin at very low concentrations inhibited the darkening reaction to both injected SS and endogenous MSH. In all cases more melatonin was required to inhibit the effect of SS in hypophysectomized than in normal animals. The results indicate that melatonin may be a physiological MSH antagonist in Xenopus laevis and the pituitary either contains some lightening factor itself ( Hogben's 'W' substance?) or has control over another organ (pineal gland?) where a lightening factor may be present. The unusual linear-logarithmic dose—response curves are discussed.

scholarly journals Sleep duration and health in adults: an overview of systematic reviews

2020 ◽  
Vol 45 (10 (Suppl. 2)) ◽  
pp. S218-S231 ◽  
Author(s):  
Jean-Philippe Chaput ◽  
Caroline Dutil ◽  
Ryan Featherstone ◽  
Robert Ross ◽  
Lora Giangregorio ◽  
...  
Keyword(s):  
Health Outcomes ◽  
Sleep Duration ◽  
Systematic Reviews ◽  
Dose Response ◽  
Health Effect ◽  
Community Dwelling ◽  
Response Curves ◽  
Priority List ◽  
Wide Range ◽  
Overview Of Systematic Reviews

The objective of this overview of systematic reviews was to examine the associations between sleep duration and health outcomes in adults. Four electronic databases were searched in December 2018 for systematic reviews published in the previous 10 years. Included reviews met the a priori determined population (community-dwelling adults aged 18 years and older), intervention/exposure/comparator (various levels of sleep duration), and outcome criteria (14 outcomes examined). To avoid overlap in primary studies, we used a priority list to choose a single review per outcome; reviews that examined the effect of age and those that looked at dose–response were prioritized. A total of 36 systematic reviews were eligible and 11 were included. Reviews included comprised 4 437 101 unique participants from 30 countries. Sleep duration was assessed subjectively in 96% of studies and 78% of studies in the reviews were prospective cohort studies. The dose–response curves showed that the sleep duration that was most favourably associated with health was 7–8 h per day. Modification of the effect by age was not apparent. The quality of the evidence ranged from low to high across health outcomes. In conclusion, the available evidence suggests that a sleep duration of 7–8 h per day is the one most favourably associated with health among adults and older adults. (PROSPERO registration no.: CRD42019119529.) Novelty This is the first overview of reviews that examines the influence of sleep duration on a wide range of health outcomes in adults. Seven to 8 h of sleep per day was most favourably associated with health. Effect modification by age was not evident.

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