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Curvas de resposta e isobolograma como forma de descrever a associação de herbicidas inibidores do fotossistema II e da síntese de carotenóides Dose-response curve and isobologram used to describe the mixture of herbicides inhibitors of the photosystem II and carotenoid synthesis

By N.D. Kruse, R.A. Vidal and M.M. Trezzi

Abstract

A metodologia de curvas de resposta e isobologramas, feitos a partir dos I50 gerados pelas curvas, tem sido bastante apregoada na comprovação de sinergismo. O experimento foi conduzido em casa de vegetação, com girassol cultivado em solução nutritiva (Hoagland), aplicando-se na solução 27 tratamentos, com os herbicidas metribuzin nas doses de 0, 70, 140, 280, 560 e 1.130 nM e clomazone nas doses de 0, 40, 80, 160, 320 e 640 mM. Combinaram-se as doses dos herbicidas de maneira a produzir os I50 das seis curvas resultantes das associações. Nas plantas coletadas, cinco dias após a aplicação, determinou-se o percentual de dano, a massa fresca e a massa seca das plantas de girassol. Os seis pontos de I50 de cada variável foram utilizados para formar isobologramas, onde os I50 dos herbicidas aplicados isolados, unidos por uma reta, formaram a isobole de aditividade. Em torno desta, foram traçadas faixas de confiança, a partir do produto dos intervalos de confiança dos I50 dos herbicidas isolados, dentro das quais se posicionaram os I50 resultantes das associações. Todas as associações situaram-se na região de sinergismo, abaixo da isobole de aditividade, embora com diferentes probabilidades. Na variável massa seca, a associação das doses de clomazone com 140 nM de metribuzin demonstrou probabilidade de, em torno de 90%, ser uma interação sinérgica.<br>The Dose-Response Curve and Isobolograms methodology, based on the I50 generated by curves has been largely recommended to demonstrate synergism. The experiment was conducted in a greenhouse, with sunflower cultivated in nutrient solution (Hoagland), applying in solution 27 treatments, with the herbicides metribuzin, at the rates of 0, 70, 140, 280, 560 and 1,130 nM and clomazone, at the rates of 0, 40, 80, 160, 320 and 640 mM. The herbicide doses were combined so as to produce the I50 of six resulting curves from the matches. Injury percentage, and fresh and dry weight of sunflower plants were determined five days after application on the collected plants.The six points of I50 from each variable were used to obtain isobolograms, where the I50 of herbicides applied alone, jointed by a straight line, formed the isobole of additivity. Around of it, confidences strips were drawn from the product of confidences intervals of isolated herbicides I50's, where were positioned the I50 resulting from the mixtures. All the I50 mixtures were positioned in the synergism zone, below the isobole of additivity, although with different probabilities. For dry mass variable, the mixture of clomazone rates with 140 nM of metribuzin showed probability around 90% of being a synergistic interaction

Topics: mistura de herbicidas, sinergismo, metribuzin, clomazone, herbicide mixture, synergism, metribuzin, clomazone, Botany, QK1-989, Science, Q, DOAJ:Botany, DOAJ:Biology, DOAJ:Biology and Life Sciences, Biology (General), QH301-705.5
Publisher: Sociedade Brasileira da Ciência das Plantas Daninhas
Year: 2006
DOI identifier: 10.1590/S0100-83582006000300022
OAI identifier: oai:doaj.org/article:36883e8ca760467c80f695e19d75e6ed
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