GOMES, S. M. S.; SILVANIA MARIA DE SOUZA GOMES; GOMES, Silvânia Maria de Souza.
Abstract:
For the use of plants as agents for remediation of soils contaminated with lead and other
heavy metals (phytoremediation), studies are needed to better understand the
mechanisms of tolerance, uptake, translocation and accumulation of heavy metals by
plants. For both, the analysis of physiological characteristics, of the phytoextraction and
growth-related mechanisms of stress tolerance for metals, becomes an important tool in
this study. Thus, we evaluated the potential of sunflower (Helianthus annuus L.), castor
bean (Ricinus communis L.), milho (Zea mays L) and vetiver [Vetiveria zizanioides (L.)
Nash] as hyperaccumulators of Pb greenhouse and field conditions screenhouse. It was
observed that under correction soil contaminated with lead species of maize and vetiver
have not had their growth potential and fitoextrator affected, being the same species not
observed for castor bean and sunflower demonstrated high sensitivity to the level of soil
contamination. From the biochemical point of view, the correction from the
contaminated soil had values of chlorophyll a, b and total, statistically superior to castor
bean and vetiver species in the analyzed periods, except at 60 days after transplantation
for chlorophyll b and total only for the species vetiver, while plants without correction
showed decreases in all chlorophyll, and the chlorophyll readings determined by
chlorophyll were positively correlated with extractable levels, with good precision and
accuracy. In addition, the largest increase in the synthesis of carotenoids indicated that
under stress the plants develop alternative routes for energy dissipation in order to avoid
problems of photoinhibition and photooxidation. As for the photosynthetic efficiency
results showed that imposing 45 days of stress (contaminated with lead) was not able to
lead to changes in the photosynthetic apparatus of species, sunflower more efficient in
net C02 assimilation and chlorophyll fluorescence maxima than the vetiver. Key work;
phytoremediation, heavy metal, pollution.