Renan Cantalice de Souza1, DÃÆébora Teresa da Rocha Gomes Ferreira1, Hermeson dos Santos Vitorino2, Geraldo VerÃÆÃÂssimo de Souza Barbosa1, LaurÃÆÃÂcio Endres1, Vilma Marques Ferreira
The objected was to assess the relationship of physiological parameters to the susceptibility of Emilia coccinea to a mixture of ametryn and clomazone applied post-emergence. The herbicide mixture was applied in four doses 30 days after sowing (DAS). The physiological parameters studied were photosynthetic pigments, chlorophyll fluorescence, soluble proteins, superoxide dismutase (SOD) activity, ascorbate peroxidase (APX) activity, electrolyte leakage and lipid peroxidation (MDA) 72 hours after application (HAA). Twenty-five days after application, the frequency of dead plants and dry matter accumulation per plant were recorded. The data were analyzed by analysis of variance and linear or nonlinear regression analysis. The total chlorophyll content (CHL), carotenoids (CAR) and maximum quantum efficiency of PSII (Fv / Fm) decreased exponentially with increasing doses of the herbicide mixture. The SOD activity decreased linearly. There was no significant linear increase in APX activity. There were linear increases in the electrolyte leakage and lipid peroxidation with increased doses of the mixture. In relation to plant mortality, a dose of 10 L ha-1 eliminated 100% of the E. coccinea population. Given these observations, we conclude that the membrane damage appeared 72 HAA of a mixture of clomazone + ametryn was closely related to mortality at 25 DAS.
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