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Santa Bárbara d'Oeste, Brazil

Galon L.,Federal University of Pampa | Tironi S.P.,Federal University of Vicosa | Rocha P.R.R.,Federal University of Vicosa | Concenco G.,Embrapa Agropecuaria Oeste CPAO | And 4 more authors.
Planta Daninha | Year: 2011

Characterization of the competitive ability of barley varieties against weed species is relevant for the adoption of the cultural method of weed control; thus, it is possible to reduce both the production costs and environmental impacts caused by other management methods, including the use of chemicals. This work assessed the competitive ability of barley varieties against ryegrass. Trials were installed under greenhouse conditions at the 2008/2009 cropping season, in a completely randomized block design, with four replications. Treatments were arranged in a substitution series design constituted by five proportions of plants of both species: 100:0; 75:25; 50:50; 25:75; and 0:100. Barley varieties BRS Greta, BRS Elis and BRS 225 were tested against ryegrass as the competitor. The competitive analysis was carried out through diagrams applied to the substitutive design, plus determination of relative competitiveness indexes. Plant height, tillering, leaf area and shoot dry mass were evaluated. The presence of ryegrass reduced tillering, leaf area and dry mass accumulation for all varieties of barley tested, showing to be an aggressive competitor. Among the barley varieties tested, BRS Elis showed the highest competitive ability against ryegrass. Ryegrass requires the adoption of control techniques even when present at low proportions in the field. Source


Galon L.,University Federal da Fronteira Sul | Ferreira E.A.,Federal University of Vales do Jequitinhonha and Mucuri | Concenco G.,Embrapa Agropecuaria Oeste CPAO | Silva A.A.,Federal University of Vicosa | And 4 more authors.
Planta Daninha | Year: 2013

The resistance of weeds to herbicides is related to metabolic, enzymatic, physiological and anatomical changes. Coupled with these changes, plants can increase or decrease their physiological activities, which can affect their growth and development. Thus, resistant biotypes may have a higher ecological adaptation in these environments and become predominant due to the elimination of sensitive plants. Under natural selection conditions, biotypes with greater ecological adaptation show higher production than less adapted biotypes. Thus, the aim of this work was to assess the effect of competition on the physiological characteristics of Conyza bonariensis biotypes susceptible and resistant to the herbicide glyphosate. The treatments consisted of plants of two biotypes of C. bonariensis - one proven to be resistant and one susceptible to glyphosate. In the center of the experimental unit, three seeds of the C. bonariensis biotype considered for treatment - resistant (R) or susceptible (S) - were sown, with the plant being surrounded by 0 (no competition), 1, 2, 3, 4, or 5 plants of the opposite biotype. The susceptible biotype presented a higher tolerance to competition with plants of the opposite biotype regarding the physiological characteristics evaluated. The resistant biotype of C. bonariensis has a physiological disadvantage compared to the susceptible one and, therefore, less potential for adaptability in the absence of the selection factor - the herbicide glyphosate. Source


dos Santos A.,State University of Norte Fluminense | Ceccon G.,Embrapa Agropecuaria Oeste CPAO | Chamma Davide L.M.,State University of Norte Fluminense | Martinho Correa A.,State University of Mato Grosso do Sul | Batista Alves V.,State University of Norte Fluminense
Crop Breeding and Applied Biotechnology | Year: 2014

Obtaining correlations and direct and indirect effects of yield components is important for the selection of promising parental and segregating populations. The objective of this research was to estimate the genotypic and phenotypic correlations, and to analyze the direct and indirect effects of yield components on grain yield in 20 cowpea (Vigna unguiculata) genotypes. The experimental design was in randomized blocks with 20 treatments and 4 replications. The character showed low to moderate possibility of gain from indirect selection, with greater possibility for success when joining multiple character and a genotype of better performance. Source


Galon L.,University Federal da Fronteira Sul | Lima A.M.,Federal University of Pampa | Guimaraes S.,Federal University of Pampa | Belarmino J.G.,Federal University of Pampa | And 6 more authors.
Planta Daninha | Year: 2014

Imidazolinone herbicides present physicochemical characteristics that allow them to persist longer in environment, with increased chances of soil and water contamination, as well as carryover effects on subsequent crops. Phytoremediation is shown as a promising technique to decontaminate soils polluted by herbicides. The aim of this study was to assess the potential of some winter grown species in removing residuals from soils contaminated with imazethapyr + imazapic and imazapic + imazapyr, using pre-emergence to control weeds in summer grown rice fields. The experiment was conducted in a completely randomized design, with four replications. All species were subjected to herbicide application at different doses. Imazethapyr + imazapic and imazapyr + imazapic were applied at doses of 0.0, 1.0 and 2.0 L ha-1, and 0.0, 140 and 280 g ha-1, respectively, in pre-emergence of the species. Brassica napus and Festuca arundinaceae are not tolerant to herbicides, with 100% of phytotoxicity (plant death) for all doses assessed. The herbicide imazapyr + imazapic proved to be less selective, causing the highest phytotoxicity in the species tested. The most tolerant species to the herbicides was Vicia sativa, which may be the most suitable one for phytoremediation programs in areas contaminated with imazethapyr + imazapic and imazapyr + imazapic. © 2014 Planta Daninha All rights received. Source

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