Tolerância de Hancornia speciosa Gomes (Apocynaceae) ao fluoreto de potássio: aspectos fisiológicos e anatômicos

Abstract

Fluoride (F) is considered to be one of the most phytotoxic pollutants, even when present in low concentrations, since 0,6 µg m-¬³ concentrations are toxic to susceptible species. When dispersed in the air, fluoride can be transported to about 100 km from the polluting source, reaching plants, animals and humans and causing serious damage. However, few studies about the fluoride effect on Cerrado species concerning their morphological, anatomical and physiological responses are still scarce. Therefore, the aim of the present study was to investigate the effect of simulated rainfall containing potassium fluoride (KF) on Hancornia speciosa leaves and roots, in order to determine its bioindicator potential. Young plants at approximately 45 days of emergence were treated daily with simulated KF rain at different concentrations (0, 4, 8 and 12 mg L-1) for 40 days. The experimental design was completely randomized, with 4 treatments and 4 replicates. After potassium fluoride exposure, visual, morphological and chlorophyll a fluorescence analyses were performed, alongside fluoride accumulation assessments in roots and shoots. Hancornia speciosa did not present any visual, anatomical and physiological symptoms in response to fluoride, while accumulating phenolic compounds in mesophyll root and leaf cells in all treatments. Physiological characteristic preservation and fluoride accumulation in roots and leaves were proven to be important fluoride tolerance biomarkers in this species. In addition, the evaluated characteristics indicate that Hancornia speciosa displays a tolerance potential at the investigated doses.