Relações da anatomia radicular na absorção, no acúmulo e na tolerância ao chumbo em Echinodorus grandiflorus

Abstract

Lead (Pb) contamination is a growing concern worldwide and water environment is particularly subjected to many sources of pollution. This study aimed to evaluate the tolerance of Pb in Echinodorus grandiflorus and its capacity to absorb and accumulate this pollutant, as well as the relationship of these characteristics with root anatomy. Experiments were conducted using E. grandiflorus plants exposed to the following Pb levels in nutrient solution: [0, 0.75, 1.5, 3.0, and 9.0 μM of Pb(NO3)2]. Plants were maintained in these conditions for 60 days. At the end of the experiment Pb levels in plant biomass as well as the modifications in the root anatomy were evaluated. E. grandiflorus accumulated 113.74 mg Pb kg-1 of dry matter and reduced translocation to shoots. Xylem modifications in roots showed increased water and nutrient conduction capacity in plants exposed to Pb. Exodermis and root cortex thickening were detected and may be related to lead allocation in roots. Echinodorus grandiflorus plants are able to absorb and accumulate Pb mainly in roots and this absorption is modulated by root anatomy.