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

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

Planta Daninha ◽

10.1590/s0100-83582013000400015 ◽

2013 ◽

Vol 31 (4) ◽

pp. 887-892 ◽

Cited By ~ 1

Author(s):

L. Vargas ◽

D.S. Fraga ◽

D. Agostinetto ◽

F. Mariani ◽

T.V. Duarte ◽

...

Keyword(s):

Dose Response ◽

Chemical Control ◽

Lolium Multiflorum ◽

Dry Weight ◽

Rio Grande Do Sul ◽

Response Curves ◽

Main Method ◽

Shoot Dry Weight ◽

Repeated Use ◽

Dose Response Curves

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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Monitoring of Resistance of Sourgrass to Glyphosate Herbicide in Urban Areas of the State of São Paulo, Brazil

Planta Daninha ◽

10.1590/s0100-83582019370100121 ◽

2019 ◽

Vol 37 ◽

Author(s):

T. GAZOLA ◽

M.F. DIAS ◽

C.A. CARBONARI ◽

E.D. VELINI

Keyword(s):

Urban Areas ◽

Shikimic Acid ◽

Dry Weight ◽

Sao Paulo ◽

The State ◽

São Paulo ◽

Response Curves ◽

Shoot Dry Weight ◽

Randomized Design ◽

Glyphosate Herbicide

ABSTRACT: The objective of this work was to monitor the resistance of sourgrass (Digitaria insularis) to glyphosate in urban areas of the State of São Paulo to understand the spread of resistant biotypes. Three experiments were conducted under greenhouse conditions in a completely randomized design, with four replications. In the first experiment, seven sourgrass biotypes were used, and the control of plants was evaluated at 7, 14, 21, 28, and 35 days after application (DAA) of glyphosate. In the second experiment, the shikimic acid accumulation was quantified at 72 hours after the glyphosate application, and the same evaluations of weed control were performed. In the third experiment, rate-response curves were developed, with glyphosate at rates of 0, 90, 180, 360, 720, 1,440, 2,880, and 5,760 g a.e. ha-1 applied on three progenies obtained from self-fertilized seeds; the percentage of control and shoot dry weight of the plants were evaluated at 28 DAA to determine their resistance factor. The results confirmed the occurrence of biotypes of sourgrass resistant to glyphosate in urban areas of Ipaussu and Santa Cruz do Rio Pardo and transmission of this resistance to the progenies obtained from self-fertilized seeds. These results indicate the possibility of resistant sourgrass seeds to be transported and disseminated to other Brazilian regions, thus, contributing to increase cases of resistance of sourgrass to this herbicide. However, it should be confirmed by more detailed studies involving DNA and family trees to determine the genetic proximity between resistant biotypes from different regions, since independent selection may also occur.

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Variable response of kochia [Kochia scoparia (L.) Schrad.] to auxinic herbicides dicamba and fluroxypyr in Montana

Canadian Journal of Plant Science ◽

10.4141/cjps-2015-019 ◽

2015 ◽

Vol 95 (5) ◽

pp. 965-972 ◽

Cited By ~ 13

Author(s):

Prashant Jha ◽

Vipan Kumar ◽

Charlemagne A. Lim

Keyword(s):

Great Plains ◽

Dose Response ◽

Weed Management ◽

Dry Weight ◽

Northern Great Plains ◽

Variable Response ◽

Kochia Scoparia ◽

Management Tools ◽

Herbicide Resistant ◽

Shoot Dry Weight

Jha, P., Kumar, V. and Lim, C. A. 2015. Variable response of kochia [Kochia scoparia (L.) Schrad.] to auxinic herbicides dicamba and fluroxypyr in Montana. Can. J. Plant Sci. 95: 965–972. Herbicide-resistant kochia is an increasing concern for growers in the Northern Great Plains of United States and Canada. The objective of the research was to characterize the response of the three putative auxinic herbicide-resistant kochia inbreds (derived from accessions collected from wheat/chemical fallow fields in northern Montana) to dicamba and fluroxypyr relative to a susceptible (SUS) inbred. A dicamba dose-response study indicated that the three putative resistant inbreds (Chot-01, Chot-02, and Chot-03) had R/S ratios of 1.3 to 6.1 based on the visible control response (I50 values), and R/S ratios of 1.5 to 6.8 based on the shoot dry weight response (GR50 values). Dose-response experiments with fluroxypyr determined I50 R/S ratios of 1.4 to 5.7 and GR50 R/S ratios of 1.6 to 4.0 for the three putative resistant inbreds. The selected inbreds showed variable symptomology (phenotype) in response to dicamba and fluroxypyr. Among the three inbreds, Chot-01 exhibited the least epinasty, stem curling/swelling, and chlorosis/necrosis symptoms, and was resistant to dicamba and fluroxypyr. Growers should diversify their weed management tools to manage further spread of auxinic or multiple herbicide-resistant kochia in the region.

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Pertumbuhan Ludwigia octovalvis (Jacq) Revans pada Berbagai Konsentrasi dan Waktu Aplikasi Alelokimia Kulit Buah Jengkol

Jurnal Hortikultura Indonesia ◽

10.29244/jhi.7.3.204-210 ◽

2016 ◽

Vol 7 (3) ◽

pp. 204

Author(s):

Uswatun Nurjannah ◽

Edhi Turmudi ◽

Helfi Eka Saputra

Keyword(s):

Weed Management ◽

Detrimental Effect ◽

Water Extract ◽

Dry Weight ◽

Fresh Fruit ◽

Shoot Dry Weight ◽

Randomized Design ◽

The Mean ◽

Completely Randomized Design ◽

Four Levels

ABSTRACT Synthetic herbicides is the most profitable option for farmers in weed control however it has detrimental effect to the environment. Using allelochemical compound as bioherbicide is one of the new options for sustainable weed management. Research was conducted to evaluate the potential of the water extract of jengkol fresh fruit pod as bioherbicide on Mexican primrose-willow (Ludwigia octovalvis) growth. The objective of the study was to determine the concentration and time of applications that effectively inhibit of the growth of Mexican primrose-willow. The study was conducted from July to September 2015 in the Greenhouse of University of Bengkulu Agronomy Laboratory with a completely randomized design, three replications and a control for comparison. The treatments tested consisted of four levels: 125 g L-1, 250 g L-1, 375 g L-1 and 500 g L-1. The results showed that at a concentration of 500 g L-1 jengkol fresh fruit pod extract applied at planting time killed Mexican primrose-willow in the first week after treatment. Inhibition of root growth was greater than that of the shoot. The mean reduction in root dry weight, shoot dry weight, root volume, and leaf area were 88.79%, 63.25%, 84.4%, and 85.75%, respectively when compared to control. Keywords: bioherbicide, concentration, growth of Mexican primrose-willow, jengkol fresh fruit pod, time applicationsABSTRAK Herbisida sintetis menjadi pilihan utama bagi petani dalam mengendalikan gulma karena sangat menguntungkan, namun merusak lingkungan. Penggunaan alelokimia sebagai bioherbisida merupakan cara baru dalam pengendalian gulma dan aman bagi lingkungan. Penelitian ini dilakukan untuk menguji potensi ekstrak air kulit buah jengkol segar sebagai bioherbisida pada pertumbuhan lakum air (Ludwigia octovalvis). Penelitian ini bertujuan untuk menentukan konsentrasi dan waktu aplikasi yang efektif menghambat pertumbuhan lakum air. Penelitian dilakukan pada bulan Mei sampai Juli 2015 di Rumah Kaca Laboratorium Agronomi Universitas Bengkulu dengan rancangan acak lengkap, 3 ulangan dan satu kontrol sebagai pembanding. Perlakuan yang diujikan terdiri dari empat aras yaitu 125 g L-1, 250 g L-1, 375 g L-1, dan 500 g L-1. Hasil penelitian menunjukkan ekstrak kulit buah jengkol segar pada konsentrasi 500 g L-1 yang diaplikasikan pada saat tanam dapat mematikan lakum air pada minggu pertama setelah perlakuan. Hambatan pertumbuhan akar lebih besar bila dibandingkan dengan tajuk. Rerata penurunan bobot kering akar, bobot kering tajuk, volume akar, dan luas daun berturut-turut 88.79%, 63.25%, 84.4%, dan 85.75% bila dibandingkan dengan kontrol. Kata kunci: bioherbisida, konsentrasi, kulit buah jengkol segar, pertumbuhan lakum air, waktu aplikasi.

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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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