Ecotoxicidade de herbicidas à base de Nicosulfuron e S-Metolachlor: uma abordagem comparativa entre modelos vegetais

Abstract

Studies have been conducted to evaluate the effects of herbicides on the ecosystem due to growing concerns about the environmental impacts caused by their extensive application in agriculture. Nicosulfuron is an herbicide used for post-emergent control of annual or perennial grasses and broadleaf weeds. S-metolachlor is known to be used as a pre-emergence herbicide used mainly to control annual grasses and some broadleaf weeds in intensive crops. The objective of this work was to evaluate the effects of two herbicides, one based on Nicosulfuron and the other based on S-Metolachlor on the initial development of the plant models Lactuca sativa L. (lettuce), Raphanus sativus (radish), Pennisetum glaucum (L.) R. Br (millet), and Triticum aestivum (wheat) through macroscopic bioassays of germination and initial seedling development. Among the four models evaluated, L. sativa showed higher sensitivity regarding germination percentage when exposed to Nicosulfuron-based herbicide followed by T. aestivum., R. sativus and P. glaucum. The same is observed for the germination speed index. For the herbicide based on S-Metolachlor, the model that showed the highest sensitivity was T. aestivum, followed by R. sativus, L.sativa and P. glaucum being the least sensitive model. Regarding initial seedling development, the models P. glaucum showed higher sensitivity and L. sativa showed lower sensitivity in root development when exposed to the herbicide based on Nicosulfuron. Whereas, the R. sativus and L. sativa models showed higher and lower sensitivity, respectively, when exposed to the S-Metolachlor-based herbicide when root growth was evaluated.Considering the seedling development as a whole, the model that showed higher sensitivity when exposed to Nicosulfuron-based herbicide was T. aestivum, and when exposed to S-Metolachlor, P. glaucum. The model R. sativus showed less sensitivity to both herbicides when evaluating the parameter of development of the aerial part of the seedlings.