Deriva simulada do picloram e glyphosate em Peltophorum dubium, uma espécie nativa do Cerrado Brasileiro | Simulated drift of picloram and glyphoste on Peltophorum dubium, a native species of the Brazilian Cerrado

The herbicide picloram is an auxin mimetic, while glyphosate is an inhibitor of the enzyme 5-enol-pyruvylchiquimate-3-phosphate synthase. Both have the potential to cause damage to non-target species through drift. Peltophorum dubium (Spreng.) Taub. is a frequently occurring specie in Cerrado forest fragments close to large areas of monoculture and has the potential to be used in biomonitoring. The aim was therefore to assess the effect of picloram and glyphosate drift on P. dubium and the bioindicator potential of the species to herbicides. Two experiments were carried out. The first evaluated the effect of picloram drift on P. dubium seedlings. The experimental design was randomized blocks with 4 replications. The doses applied corresponded to underdoses of the recommended commercial dose (960 g a. e. ha-1), simulating herbicide drift, being 19.2; 38.4; 76.8; 153.6; 307.2 g a. e. ha-1 of picloram and the control. In the second experiment, the effect of glyphosate drift on P. dubium seedlings was evaluated. The experiment was set up in randomized blocks with 6 replications. To simulate drift, the plants were subdosed with the recommended commercial dose (1440 g a. e. ha-1), corresponding to 28.8, 57.6, 115.2, 230.4 and 460.8 g a. e. ha-1 of glyphosate and the control. The results of the first experiment showed that at the highest doses at 7 days after application (DAA) the plants subjected to doses of 153.6 and 307.2 g a. e. ha-1 were 40% intoxicated. Over time, the level of intoxication progressed and at 45 days after application, from the dose of 76.8 g. e. a. ha-1, the plants showed intoxication of over 90%, causing total plant death at the highest doses applied. In the second experiment, P. dubium plants also showed changes in morphology and physiology, especially from the dose of 230.4 g a. e. ha-1 . With regard to the intoxication of P. dubium plants, low intoxication (<4%) was observed at doses lower than 115.2 g a. e. ha-1, while plants exposed to 460.8 g a. e. ha-1 showed 40% intoxication caused by the action of glyphosate at 45 DAA, respectively. Therefore, the species has potential as a bioindicator of picloram in the environment and could be used to biomonitor the occurrence of herbicide drift in areas close to agricultural crops. For the herbicide glyphosate, the species showed sensitivity only at the highest doses, making its use as a bioindicator not recommended.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico

FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior