Picloram drift in Peltophorum dubium, a species native to the Brazilian Cerrado

Peltophorum dubium, a common tree in areas close to agricultural activity in the Brazilian Cerrado, is vulnerable to damage from the drift of picloram, an herbicide widely used in pastures and agriculture in Brazil. The aim was to evaluate the application of 0.0; 19.2; 38.4; 76.8; 153.6; 307.2 g e. a. ha⁻¹ of picloram, in simulated drift, on P. dubium, as well as its use as a bioindicator plant for herbicide contamination. The doses of picloram applied to the plants caused symptoms typical of the action of picloram on sensitive plants and led to the death of P. dubium at the highest doses tested. At its highest dose, picloram caused a 52.86% reduction in photosynthetic rate, 42.51% in transpiration rate, and 64.28% in stomatal conductance compared to the non-treated control. Picloram at a dose of 19.2 g e. a. ha⁻¹ caused a reduction in N content and utilization and reduced plant protein. Picloram drift causes severe damage to P. dubium, reinforcing the concern about the risks of contamination with the herbicide. The species acted as a bioindicator of picloram in the environment and could be used in biomonitoring herbicide contamination.