Alterações fisiológicas e ultraestruturais de plântulas de tomate induzidas por chumbo

The aim of this study was to verify the changes in seed viability, early growth, content of photosynthetic pigments and ultra-structural changes of Lycopersicon esculentum Mill seedlings caused by lead. Seeds were exposed to different concentrations of lead acetate (zero; 0.25; 0.5 and 0.75 mM). Percent germination and seedling emergence decreased as Pb concentration increased. In the same way, root length, dry mass and aerial parts also decreased as concentrations of Pb were increased, where the effect was strong on biomass accumulation in roots. Lead negatively affected chlorophyll contents, carotenoids and leaf area. Ultrastructural analyses demonstrated changes in the thylakoids. In conclusion, the increase in Pb concentration causes reduction in seed viability, early seedling growth, and in the photosynthetic pigment contents, as a consequence of changes in chloroplasts, damaging growth in tomato plants.