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Doctoral Thesis
DOI
https://doi.org/10.11606/T.11.2000.tde-20210104-200704
Document
Author
Full name
Marluce Gonçalves Cortez
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2000
Supervisor
Title in Portuguese
Resistência de biotipos de Brachiaria plantaginea (Link) Hitchc. a herbicidas inibidores da acetil coenzima a carboxilase
Keywords in Portuguese
CAPIM MARMELADA
HERBICIDAS
INIBIDORES DE ENZIMAS
PLANTAS DANINHAS
RESISTÊNCIA GENÉTICA VEGETAL
SOJA
Abstract in Portuguese
A planta daninha Brachiaria plantaginea é uma das mais comuns nas áreas cultivadas com soja. O controle seletivo em pós-emergência é realizado principalmente com os herbicidas inibidores da ACCase. O uso intensivo e repetido destes herbicidas em áreas cultivadas com soja no município de Guarapuava/PR, selecionou populações desta planta daninha com menor tolerância a estes herbicidas. Esta pesquisa foi desenvolvida com o objetivo de estudar a sensibilidade destas populações a herbicidas inibidores da ACCase; bem como a ocorrência de resistência cruzada em biotipos resistentes; verificar se o mecanismo de resistência é originado por alterações na ACCase ou por deficiência na absorção e translocação dos herbicidas; e ainda propor alternativas de manejo para populações resistentes. Através de bioensaios conduzidos em condições de casa-de-vegetação, constatou-se a diferença de sensibilidade entre as populações testadas, a herbicidas vários herbicidas ariloxifenoxipropionatos (APP) e ciclohexanodionas (CHD). Em bioensaios conduzidos em condições de casa-de-vegetação com biotipos resistentes (R) e suscetível (S), foram obtidas curvas de dose-resposta e GR50 que permitiram comprovar a resistência cruzada a herbicidas APP e CHD. Ensaios de laboratório permitiram comprovar que existem diferenças entre a absorção e translocação dos herbicidas testados, entre os biotipos R e S, porem insuficientes para explicar os altos níveis de taxa de resistência observados. Os resultados obtidos em ensaios com a ACCase isolada, permitiram verificar que a ACCase extraídas de plantas R foram insensíveis aos herbicidas CHD testados, quando comparadas com a atividade da ACCase plantas S. Em condições de campo e em casa-de-vegetação, foi avaliado o controle de biotipo resistente de B. plantaginea, a herbicida inibidores da ACCase e outros com mecanismos de ação diferentes. Comprovou-se que o herbicida nicosulfuron, embora não recomendado para a cultura da soja; e sua mistura com trifluralin, foram eficazes no controle do biotipo resistente, no campo e em casa-de-vegetação.
Title in English
Resistance of Brachiaria plantaginea (Link) Hitchc. biotypes to acetil coenzyme a carboxilase inhibitor herbicides
Keywords in English

Abstract in English
The weed Brachiaria plantaginea is one of the most common infesting plant in soybean production areas of Brazil. The selective post-emergence control has been done mainly with ACCase inhibitor herbicides. The intensive and repetitive use of these herbicides in cultivated areas of soybean in Guarapuava/PR - Brazil, had selected population of this weed with lower level of susceptibility to these herbicides. This research project was developed with in order to study the sensibility of these populations to ACCase inhibitor herbicides, as well as the occurrence of cross resistance in the resistant biotypes; verify if the mechanism of resistance is the alteration on the site of the action of the herbicide in the ACCase or lack of absorption and translocation; and indicate alternatives of management of resistant populations. Through bioassay conducted under greenhouse conditions, it was detected a difference of susceptibility among the tested populations, to several ariloxyphenoxypropionates (APP) and cyclohexanodiones (CHD). GR50 values were obtained from the greenhouse experiments, comparing the resistant (R) with the susceptible (S), and that allow conclusion about the cross resistance of APP and CHD herbicides. Laboratory assay proved that there are differences between the biotypes R and S with regard to absorption and translocation, however these differences are not enough to explain the level of resistance presented by the R biotype. Results obtained from isolated ACCase allowed to conclude that ACCase from R plants are insensitive to CHD and APP herbicides, when compared to ACCase from S plants. ln field (resistant site) and greenhouse experiments, it was evaluated the control of B. plantaginea by ACCase inhibitor herbicides and by others with different mechanism of action. The herbicide nicosulfuron alone and in mixture with trifluralin were very efficient in the control of R and S biotype; however, nicosulfuron is not recommended for soybean weed control.
 
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Publishing Date
2021-01-07
 
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