Biomarcadores morfo-fisiológicos em Cedro Rosa (Cedrela fissilis) expostos ao lodo de esgoto sanitário de Uberlândia (MG)

Abstract

The collection and treatment of sewage play a crucial role in basic sanitation, aiming at public health and the conservation of natural resources. The proper disposal of sewage sludge (SS) generated becomes a concern as it contains different potentially toxic compounds and pathogenic microorganisms. An alternative is the application of SS in agriculture due to its richness in organic material and nutrients, but it is necessary to understand the toxic potential for soil organisms. Considering the possibility of using sanitary SS for the recovery of degraded areas and the use of Cedro Rosa (Cedrela fissilis) due to its potential development in contaminated soils, the objective of this study was to analyze morphophysiological changes after planting seeds and seedlings in substrates containing SS from Uberlândia, Minas Gerais. The experiments used treatments containing soil, SS, soil+SS (50%), sewage sludge stabilized with lime (SSL), and soil+SSL (50%). Seed germination occurred only in soil and soil+SSL (50%), with 7 and 6 germinated plants, respectively, after 60 days of exposure. In the exposure of seedlings for three months, good development was observed in all exposures. It was found that the highest assimilation rate of CO2 was for the soil+SS treatment, with no significant difference (p≤0.05) for transpiration rates (E mmol m-2 s-1) and stomatal conductance (gs mol m-2 s-1). Leaf area showed that treatments containing SS and SSL had higher averages than the soil; however, only soil+SS showed a significant difference. Thus, toxic potential of SS was identified for seed germination, but when stabilized and mixed with soil (50%), it promoted cedar germination. However, SS and SSL were promising in the development of seedlings in all exposures, causing no adverse effects on the studied physiological conditions.