Morfofisiologia aplicada à caracterização da tolerância de Talinum patens ao chumbo

Abstract

The objective of this work was to evaluate the phytotoxicity of lead in Talinum patens and the morphophysiological mechanisms of tolerance. The following parameters were evaluated: percentage of germination, rate of germination, root and shoot length, fresh and dry masses, lead content in tissues, enzymatic antioxidant system, proline content, lipid peroxidation, root anatomy, analyzes Cytogenetics and chlorophyll fluorescence. The experimental design was completely randomized, containing five concentrations of 0, 50, 100, 250 and 500 μM Pb(NO3)2 and five replicates. Exposure to Pb(NO3)2 solutions did not influence germination, shoot length, fresh and dry biomass. However, a Pb(NO3)2 dependent concentration effect was observed that reduced the cell divisions in the meristematic zone of the root, reducing the length of the roots. In relation to the enzymatic antioxidant system the dismutase of superoxide, catalase and ascorbate peroxidase showed an increase in activity when exposed to lead. The same effect was detected for proline content and lipid peroxidation. There was also an increase in the dissipation of excess energy in the photosystems and an increase in the thickness of the epidermis. It is concluded that the plants of Talinum patens presented morphophysiological characteristics that favor their germination, development and tolerance to heavy metal.