Com o objetivo de verificar na planta aquática Spirodela punctata o efeito de diferentes concentrações (0,005; 0,05; 0,5 e 5 mgL-1 de ingrediente ativo) dos herbicidas butachlor, glyphosate e propanil sobre os teores de clorofila a, b e na razão clorofila a/b, foram conduzidos, por sete dias completos, bioensaios em sala climatizada. Determinou-se os teores de clorofilas através de leituras espectrofotométricas nas absorbâncias A645 e A663 nm. Os resultados mostraram que o butachlor diminuiu o teor de clorofila b, o glyphosate o teor de clorofila a, enquanto o propanil diminuiu os teores de clorofila a, b e a razão a/b, provocando a maior redução de pigmentos na espécie.

Effect of the herbicides on the chlorophyll content of Spirodela punctata The aim of this study was to verify the effects of the herbicides butachlor, glyphosate and propanil on content of chlorophyll of aquatic plant Spirodela punctata. In order to determine the effect of different concentrations of 0.005; 0.05; 0.5 and 5 mgL-1 (active ingredient) of three herbicides on the contents of chlorophyll a, b and a/b ratio. The bioassays were conducted, for a period of seven full days, in a climatedcontrolled room. Chlorophyll content was determined by spectrophotometric absorbency readings at A645 and A663 nm. Butachlor reduced chlorophyll b, the glyphosate decrease chlorophyll a, while the propanil reduced chlorophyll a, b and a/b ratio, causing the greatest reduction of the pigments in the species.