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Background. Fluoride (F) is one of the main environmental pollutants, and high concentrations are commonly detected in the air and in both surface and groundwater. However, the effects of this pollutant on seed germination and on the initial growth of crop seedlings are still poorly understood. In this context, the aim of this study was to assess morphoanatomical, physiological and biochemical fluoride effect indicators in Phaseolus vulgaris L. seeds and seedlings. Methods. P. vulgaris seeds were exposed to a liquid potassium fluoride solution (KF, pH 6.0) at concentrations of 0 (control), 10, 20, 30 mg L-1 for 7 days. A completely randomized experimental design was applied, consisting of four treatments with four replications each. During the experimental period, physiological (7 days) anatomical and histochemical (2 days), biochemical and chemical (4 days) assessments. An analysis of variance was performed followed by Dunnett's test. to determine significant differences between the KF-exposed groups and control seeds; and a multivariate analysis was performed. Results. The germination parameters, and anatomical, morphological, physiological, biochemical and nutritional characteristics of the seedlings did not show negative effects from exposure to KF at the lowest doses evaluated. On the other hand, treatment with the highest dose of KF (30 mg L-1) resulted in a lower germination rate index and increase in abnormal seedlings, and higher electrical conductivity. A lower root length, magnesium content and photochemical efficiency were also observed. The exposure of P. vulgaris to KF, regardless the dose did not affect seeds anatomy and the accumulation of starch and proteins, in relation to the control group. Conclusions. Our findings demonstrated that P. vulgaris seedlings were tolerant to KF solutions up to 20 mg L-1, and sensitive when exposed to 30 mg KF L-1. [ABSTRACT FROM AUTHOR]

Background: Fluoride pollution is a global problem because of its high phytotoxicity. Fluoride is released in air, water and soil through industrial processes, where it damages various plant species. Ricinus communis is widely distributed in Brazil, India and China and has been extensively used as a phytoremediation species in heavy metal-contaminated soils. However, few studies regarding the effect of air pollutants on R. communis have been published, and no information about the exposure of this species to fluoride is available. Therefore, the aim of the present study was to investigate the effects of fluoride on R. communis morphoanatomical and physiological responses using simulated rainfall containing potassium fluoride (KF). Methods: Young plants at approximately 10 days after emergence were treated daily with KF using simulated rainfall at 0, 1.5, 3.0 and 4.5 mg L-1, for 37 consecutive days. Chlorophyll a fluorescence, gas exchange, anatomical characteristics and fluoride accumulation in the roots and leaves were evaluated after this period. Results: No visual or anatomical symptoms were observed for the first three treatments. Necrosis and chlorosis were visually evident after the 37th day of KF application at 4.5 mg L-1, followed by changes in parenchyma tissues, cell collapse and phenolic compound accumulation at the end of the experiment. No damage was observed in terms of photosynthetic photochemical and biochemical stages. Maintenance of physiological characteristics in the presence of fluoride accumulation in roots and leaves were shown to be important fluoride biomarkers. These characteristics suggest that R. communis is tolerant to 1.5 and 3.0 mg L-1 KF, and is anatomically sensitive at 4.5 mg L-1 KF. [ABSTRACT FROM AUTHOR]

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