Dose-response curves of Lolium multiflorum biotypes resistant and susceptible to clethodim

Chemical control with herbicides, especially glyphosate, is the main method used to control ryegrass. However, the repeated use of glyphosate has selected resistant ryegrass biotypes. Thus, the ACCase inhibitor herbicides have become the main alternative to control glyphosate-resistant biotypes, being widely used by farmers in Rio Grande do Sul. Repeated use of ACCase inhibitors, in turn, have selected ryegrass biotypes resistant to this herbicide mechanism. Thus, the objective of this study was to evaluate the response of ryegrass biotypes to different clethodim rates by dose-response curves. Increasing doses (0, 12, 24, 48, 72, 96, 144 and 192 g a.i. ha-1) of the herbicide clethodim were applied at the 3-4 ryegrass leaf stage. The variables control at 14 and 28 days after treatment (DAT) and shoot dry weight were evaluated. The data were fitted by nonlinear regression log-logistic and C50 and GR50 were calculated based on the equation. The resistance factor was obtained by the ratio of C50 or GR50 of the resistant biotype by matching the susceptible biotype. Based on the equation parameters, the doses of GR50 64.7 and 234.5 g a.i. ha-1 clethodim and C50 11.2 and 172.1 g a.i. ha-1 clethodim were obtained, at 28 DAT for the susceptible and resistant biotypes, respectively. The ryegrass biotype denominated Cotril is resistant to clethodim, being controlled with a dose 15.3 times greater than that of the susceptible biotype, and a 50% reduction of this biotype occurs with a dose 3.62 times higher than that of the susceptible one.

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Differential susceptibility of biotypes of conyza sumatrensis to Chlorimuron-ethyl herbicide

Planta Daninha ◽

10.1590/s0100-83582014000200021 ◽

2014 ◽

Vol 32 (2) ◽

pp. 427-435 ◽

Cited By ~ 3

Author(s):

F.M. Santos ◽

L. Vargas ◽

P.J. Christoffoleti ◽

D. Agostinetto ◽

F. Mariani ◽

...

Keyword(s):

Dose Response ◽

Weed Management ◽

Leaf Growth ◽

Differential Susceptibility ◽

Dry Weight ◽

Response Curves ◽

Shoot Dry Weight ◽

Randomized Design ◽

Chlorimuron Ethyl ◽

Dose Response Curves

Horseweed (Conyza spp.) is an annual weed, infesting soybean crops in southern Brazil, with chlorimuron-ethyl being one of the most commonly used herbicides for its control. However, in recent soybean harvests, an unsatisfactory control of this weed using this herbicide was observed, generating suspicion regarding the selection of resistant biotypes. The objective of this study was to evaluate the susceptibility of horseweed biotypes to the herbicide chlorimuron-ethyl. Two experiments were conducted in a greenhouse; in the first one, the biotypes were selected selected, and the second experiment was arranged in a 5 x 5 factorial in a completely randomized design with four replications. The treatments used in the preparation of the dose response curves were doses of the herbicide chlorimuron-ethyl (0.0, 1.56, 3.13, 6.25, 12.5, and 25 g ha-1), applied on the five horseweed biotypes at the 3-4 leaf growth stage. The variables evaluated were visual control percentage and shoot dry weight, compared to the control without herbicide application, and plant acetolactate accumulation. It was concluded that there is a differential susceptibility among the biotypes at doses of less than 20 g ha-1 (dose response curves), which indicates low-level resistance. The practical consequences are the indications of chlorimuron-ethyl application at the maximum doses recomended and that the practice of rotating mechanisms of action must be used in the chemical weed management of these areas.

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DIFFERENTIAL TOLERANCE OF TWO SPECIES OF THE GENUS DIGITARIA TO HERBICIDE RECOMMENDED FOR SUGARCANE CROP

Revista Ciência Agrícola ◽

10.28998/rca.v11i1.737 ◽

2013 ◽

Vol 11 (1) ◽

pp. 13

Author(s):

Renan Cantalice Souza ◽

Marcelo Rodrigues Alves de Figueiredo ◽

Flávio Eduardo Botelhos Obara ◽

Ricardo Victoria Filho ◽

Pedro Jacob Christoffoleti

Keyword(s):

Photosystem Ii ◽

Synergistic Effect ◽

Species Composition ◽

Dose Response ◽

Chemical Control ◽

Response Curves ◽

Sugarcane Crop ◽

Long Time ◽

Dose Response Curves ◽

Herbicide Diuron

The chemical control of crabgrass can be poor depending on the species composition of species in the area. It is known that there is a fault in the control of Digitaria nuda in places where applications of photosystem II inhibitors herbicides by long-time, being necessary to better understand how this tolerance work. The aim of this study was to develop dose-response curves for D. nuda (tolerant) and D. ciliaris (susceptible), with recommended herbicides for sugarcane crop used alone or in mixtures. The experiment was carried out in a greenhouse with the pre-emergence application of diuron + hexazinone, ametryn and mixture of both in increasing doses. The doses were 0; 6,25; 12,5; 25; 50; 100; 200 and 400% of the label for sugarcane diuron + hexazinone (936 +264 g ai ha-1), ametryn (2500 g ai ha-1) and the combination of two herbicides in the same proportions. What can be concluded that application of ametryn in isolation produced similar levels of control in both species. The association of ametryn with the herbicide diuron + hexazinone caused synergistic effect for the control of D. nuda, but for D. ciliaris the effect was antagonistic evaluated by methods.

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Dose-response Curves in the Fibrin Plate Assay Fibrinolytic Activity of Proteases

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647705 ◽

1974 ◽

Vol 32 (02/03) ◽

pp. 356-365 ◽

Cited By ~ 12

Author(s):

F Haverkate ◽

D. W Traas

Keyword(s):

Dose Response ◽

Fibrinolytic Activity ◽

Enzyme Concentration ◽

Response Curves ◽

Agar Gel ◽

Porcine Tissue ◽

Plate Assay ◽

Fibrin Plate ◽

Different Types ◽

Dose Response Curves

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.

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BIOASSAY OF THYROID HORMONE USING HYPOTHYROID TADPOLES

Acta Endocrinologica ◽

10.1530/acta.0.0410143 ◽

1962 ◽

Vol 41 (1) ◽

pp. 143-153 ◽

Cited By ~ 2

Author(s):

U. Henriques

Keyword(s):

Thyroid Hormone ◽

Dose Response ◽

Developmental Rate ◽

Response Curves ◽

Sodium Salts ◽

Dose Response Curves

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.

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Dose Response Curves for Microwave Ablation in the Cardioplegia-Arrested Porcine Heart

The Heart Surgery Forum ◽

10.1532/hsf98.20051011 ◽

2005 ◽

Vol 8 (4) ◽

pp. E269-E274 ◽

Cited By ~ 1

Author(s):

Sydney L. Gaynor ◽

Gregory D. Byrd ◽

Michael D. Diodato ◽

Yosuke Ishii ◽

Anson M. Lee ◽

...

Keyword(s):

Dose Response ◽

Microwave Ablation ◽

Response Curves ◽

Porcine Heart ◽

Dose Response Curves

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Modeling Nonmonotonic Dose-Response Curves

10.21236/ada391664 ◽

2001 ◽

Author(s):

Quinton J. Nottingham ◽

Jeffrey B. Birch ◽

Barry A. Bodt

Keyword(s):

Dose Response ◽

Response Curves ◽

Dose Response Curves

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Comment Concerning the Effects of Light Intensity on Melatonin Suppression in the Review “Light Modulation of Human Clocks, Wake, and Sleep” by A. Prayag et al.

Clocks & Sleep ◽

10.3390/clockssleep3010011 ◽

2021 ◽

Vol 3 (1) ◽

pp. 181-188

Author(s):

Peter Bracke ◽

Eowyn Van de Putte ◽

Wouter R. Ryckaert

Keyword(s):

Phase Shift ◽

Light Intensity ◽

Dose Response ◽

Light Modulation ◽

Response Curves ◽

Practical Applications ◽

Circadian Phase ◽

Melatonin Suppression ◽

Dose Response Curves ◽

Circadian Phase Shift

Dose-response curves for circadian phase shift and melatonin suppression in relation to white or monochromatic nighttime illumination can be scaled to melanopic weighed illumination for normally constricted pupils, which makes them easier to interpret and compare. This is helpful for a practical applications.

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