Fluoride in simulated rain affects the morphoanatomy and physiology of Eugenia dysenterica (Mart.) DC

Fluorine is found in the atmosphere mainly in the form of hydrofluoric acid, released by industries linked to the production of aluminum, glass and ceramics, in addition to phosphate fertilizers. It is an element of high toxicity, quite harmful to plant growth. Eugenia dysenterica (Mart.) DC. (Myrtaceae) species is a fruit tree native to the Brazilian Cerrado with wide distribution in anthropic regions. Thus, the objective of this work was to investigate the potential of E. dysenterica for fluoride bioindication through the characterization of the effects of KF (potassium fluoride), in simulated rain. The damage caused by KF toxicity were analyzed through morpho-anatomical and physiological alterations in the leaves. Young plants with approximately 40 days-old and standardized height (∼14 cm) were transferred to 5 L individual pots containing substrate composed of washed sand, vermiculite and bioplant (1:1:1). The plants were submitted to KF daily, in simulated rain, at concentrations of 0, 10, 20 and 30 mg L⁻¹ of KF, for a period of 27 days. The experimental design was completely randomized, composed by 1 plant per pot with 4 replicates, i.e., 4 plants per treatment. After the KF exposure period, the E. dysenterica leaves were evaluated visually and physiologically and leaf fragments were collected for anatomical analysis. E. dysenterica presented necrosis formation on the adaxial side, from the border to the center, and tissue degradation with formation of cellular plasmolysis and elongation, intensified with increasing KF dose. Chlorophyll content and photochemical parameters, obtained through chlorophyll a fluorescence, indicated severe damage in photosystem II with increased KF doses. The results showed that exposure of E. dysenterica to fluoride allows to characterize the species as a potential bioindicator of reaction to the pollutant and to be used in environmental biomonitoring programs.