Respostas fisiológicas e anatômicas de plantas jovens de eucalipto expostas ao cádmio

Abstract

Pollution caused by heavy metals, mainly by cadmium (Cd), is generated by mining and industrial activities, and by the use of phosphated fertilizers and sewage sludge in agriculture. Aiming to investigate the Cd effects on physiological and anatomical features, eucalyptus seedlings in Cd-increasing concentrations in nutrient solution. Seedlings of Eucalyptus camaldulensis remained for 20 days in 1L vases with Clark solutions, and the treatments with 0, 15, 25, 45 and 90 mmol Cd L-1 supplied as CdSO4. Water potential, water potential and pigment content evaluations were carried out on dates 1, 3, 6, 12 and 20 days after treatments induction (DAE). Evaluations of mass production, Cd contents and anatomical characteristics were made with vegetal matter collected in the end of the experimental period. There was a decrease on dry matter production, even in the lowest Cd concentration. Total chlorophyll content decreased with the increase of Cd content in nutrient solution at 20 days after exposure (DAE) whereas carotenoid contents were the highest at 45 and 90 mmol Cd L-1. Lipid peroxidation in leaves increased with increasing Cd levels at 20 DAE, whereas in root, the effect of Cd was less pronunciated. Water potential increased at all Cd concentration at 12 and 20 DAE. Root tissues thickness also increased increased as Cd levels increased, but mesophyll and leave blade thickness decreased. Thus, the results indicate that the exposure time and higher doses of Cd accentuate damages in E. camaldulensis for most of the evaluated traits. Some changes observed reveal the tolerance potential of E. camaldulenses to Cd-exposition.