Avaliação bioquímica e fisiológica dos efeitos do chumbo em genótipos de Zea mays L.

Abstract

Lead (Pb) is a heavy metal with significant abundance in everyday life, but its inappropriate handling has caused its release into the environment, making it accumulate in ecosystems and ending up affecting human and plants health. There are reported cases of lead contamination of areas in Brazil and in the Northeastern Region, what highlights the importance of the search for solutions for its removal and possible reutilization. Maize (Zea mays L.) is an anual herbaceous crop with great economic importance to Brazil, especially for the Northeastern Region, where its greatest consumption is found. The mechanisms of action of the metal on this plant are not very clear yet. The goal of this work was to analyze the biochemical and physiological effects of Pb on two maize genotypes, BRS – 5033 e BRS – 5011. The seeds were sown in vermiculite, being daily watered for 7 days. Later, the seedlings were transferred to a Hoagland nutrient solution and taken to a greenhouse. 7 days after hidropony, a 0.5 mM solution of EDTA – Pb was applied in some groups. The lead content, the translocation and bioconcentration factors, other ions contents and physiological parameters in 7 and 14 dias in roots, shoots and leaves showed differential profiles in each genótipo. It was not observed any differences among the factors of the genotypes. Lead also inhibited the dry mass and the foliar areas of both genotypes, with distinct values for their parts when compared to their control groups. The eficiency of the photosystem II, the electron transfer rate of PSII, the net photosynthesis, the transpiration and the stomatal conductance were inhibited in both genótipos by Pb. The antioxidant activities in both genotypes showed differential results between roots and leaves. Thus, it can be inferred that both genotypes were significantly inhibited by lead, and for their factor values were low they might not be suitable for phytoremediation.