Efeito da poeira de cimento na anatomia foliar e trocas gasosas de Myracrodruon urundeuva (Fr. All.) (Anacardiaceae) e Enterolobium contortisiliquum (Vell.) Morong (Fabaceae)

Abstract

After the installation and rapid growth of industries, concern for the environment became scarce, and there were no concrete environmental plans for the future. The cement industries stand out as the major sources of emission of particulate pollutants, Brazil being one of the main producers of this raw material. The native species that do not have plasticity to these environments that have large emissions of pollution by cement dust face a great risk of extinction due to both the exploitation and the industrial pollution. These species suffer great losses in the photosynthetic rate, mineral nutrition and biomass, in addition to anatomical damages. In this way, the present work aimed to evaluate the impact of cement dust deposition on the anatomical structure and physiological processes of the leaves of the species Myracrodruon urundeuva and Enterolobium contortisiliquum in order to evaluate the possible tolerance to cement dust pollution. The plant material was collected taking into account the distance of the areas of interest in relation to a cement factory, where three areas for each species were analyzed. The anatomical analyzes were based on the paradermico and cross sections of the leaves under light microscopy. Scanning electron microscopy analyzes of leaf surface and analysis of gas exchange and chlorophyll content were also carried out. The specific leaf area was analyzed as well as leaf and soil nutrient analyzes in each of the areas under the influence of cement dust. The microclimatic information was provided by a weather station near the study site. Data were submitted to analysis of variance and the mean test. The Enterolobium contortisiliquum species had a lower thickness in the adaxial epidermis and cuticle, as well as a lower stomatal density in area 1, whereas intercellular carbon concentration and chlorophyll concentration were lower in area 3. While Myracrodruon urundeuva obtained a greater thickness in the adaxial epidermis, abaxial and cuticle in area 3, the photosynthetic rate and stomatal conductance were higher in area 1 and the greater sweating in area 3. Exposure to cement dust did not cause changes in the mineral composition of the leaves of both species. The nutritional characteristics of the soil did not vary in the three study areas. Both species show signs of tolerance to cement dust pollution, with some structural and physiological modifications in the leaves of the different areas studied. Due to this, the native species Myracrodruon urundeuva and Enterolobium contortisiliquum can be indicated for use in environmental reforestation in areas that are impacted by the cement industry.