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Master's Dissertation
DOI
Document
Author
Full name
Ramiro Fernando López Ovejero
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2000
Supervisor
Title in Portuguese
Desempenho da cultura de milho (Zea mays L.) submetida a diferentes herbicidas na ausência de plantas daninhas
Keywords in Portuguese
DELINEAMENTO EXPERIMENTAL
FITOTOXICIDADE
HERBICIDAS
MILHO
PLANTIO DIRETO
Abstract in Portuguese
Com o objetivo de avaliar o efeito fitotóxico dos herbicidas aplicados em pré e pós-emergência na cultura de milho em plantio direto, mantendo as parcelas experimentais totalmente no limpo, foram realizadas avaliações visuais aos 7, 14 e 21 dias após aplicação dos mesmos, adotando a escala da European Weed Research Council (EWRC, 1964). Para isso, foi semeado o híbrido Pioneer 3027, no qual foram realizadas aplicações com os seguintes princípios ativos: (i) Atrazine + Metolachlor (PréE}, (ii) Atrazine + Metolachlor + Nicosulfuron (PósE), (iii) Nicosulfuron (PósE), (iv) Nicosulfuron + Atrazine (PósE), (v) Atrazine + óleo vegetal (PósE) e (vi) Atrazine + Simazine (PósE), quando a planta apresentou 2 (estádio 0-1), 4(estádio 1) e 8 folhas (estádio 2). O delineamento experimental foi em blocos casualizados com vinte e dois tratamentos e três repetições. Determinou-se o efeito dos herbicidas sobre a fenologia, população, altura de planta, área foliar e nos componentes do rendimento da cultura. Concluiu-se que: (i) os danos dependem dos ingredientes ativos, da dosagem e do estádio fenológico da cultura; (ii) a duração dos estádios fenológicos da cultura de milho não é afetada pelos herbicidas utilizados; (iii) os herbicidas não provocam alterações morfológicas e não comprometem área foliar, porém, quando aplicados no estádio fenológico 2 (8 folhas), reduzem o rendimento devido à alteração do número de fileiras por espiga, número de grãos por fileira, e massa de 1000 grãos; e (iv) o manejo químico de plantas daninhas na cultura de milho deve ser efetuado, com segurança, até 4 folhas (estádio 1), para evitar danos por fitotoxicidade pelos herbicidas e competição por água, nutrientes e luz.
Title in English
Maize (Zea mays L.) crop performance under the application of different herbicides in a weed-free system
Abstract in English
With the purpose of evaluating the toxic effect of pre and post-emergence herbicides on the maize crop using the no tillage system, all experimental plots were kept free of weeds, and a visual evaluation was performed at 7, 14, and 21 days after each application of herbicide adopting the European Weed Research Council scale (EWRC, 1964). The maize hybrid Pioneer 3027 was sowed, and the following herbicides were applied when the plants presented 2 (stage 0), 4 (stage 1), and 8 leaves (stage 2): (i) Atrazine + Metolachlor (PreE), (ii) Atrazine + Metolachlor + Nicosulfuron (PostE), (iii) Nicosulfuron (PostE), (iv) Nicosulfuron + Atrazine (PostE), (v) Atrazine + vegetable oil (PostE) and (vi) Atrazine + Simazine (PostE). The experimental design consisted of randomized blocks with twenty two treatments and three replications. The effects of the herbicides on the phenological stages, plant population, plant height, leaf area, and crop yield components were evaluated. The results supported the following conclusions: (i) the crop damage depended on the herbicide active ingredients, dosage and crop phenological stage at the time of herbicide application; (ii) the herbicides did not affect the duration of the each crop phenological stage; (iii) the herbicides did not cause any morpholopical variation and did not reduce leaf area, even thought when applied at the second phenological stage (8 leaves), all herbicidas caused a reduction in grain yield, due to a decrease in total number of grain rows per ear, total number of grains per row, and mass of 1,000 grains; and (iv) the herbicide management must be performed until stage 1 (4 leaves) to prevent toxic damages and competition for water, nutrients and light.
 
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2019-08-22
 
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