Tolerância e potencial bioacumulador de Vetiveria zizanioides L. Nash cultivada in vitro sob efeito de zinco e cobre

Cement production represents an industrial activity with high polluting potential, and the emission levels and characteristics are directly related to the technological and operational profile of the production process. Among the pollutants emitted by the cement industry stand out the heavy metals, since they represent a group of contaminants with high toxicity and persistence in natural environments, especially in the soil. Remediation techniques based on chemical, physical and biological principles have been proposed for the rehabilitation of soils contaminated by heavy metals; however, most of them require high investment, which ends up rendering such procedures unfeasible. In this context, phytoremediation can be considered a promising method, since it has a relatively low cost and great efficiency in the stabilization and/or recovery of areas degraded by organic pollutants and heavy metals. However, one of the main difficulties of this technique is the selection of tolerant or accumulating trace element plants, through efficient protocols or methodologies, with representative results and reduced generation of contaminated waste to the environment. Biotechnological techniques, such as plant tissue culture, may represent important tools for the optimization of protocols that evaluate the phytoremediation potential of vegetal species. The present work aimed to identify the main heavy metals emitted by the cement industry, to evaluate the applicability of the plant tissue culture technique in phytoremediation studies, in addition to investigate the tolerance and bioaccumulative potential of Vetiveria zizanioides (vetiver grass) cultivated in vitro under different concentrations of the heavy metals copper (Cu) and zinc (Zn), commonly emitted during the production of cement. For this purpose, the method of Systematic Review of Literature was used to gather studies that evaluated the emission of pollutants - especially heavy metals - during the cement production process, as well as for the selection of works that related the use of the technique of tissue culture in the identification and pre-selection of vegetal species with phytoremediation potential. Finally, an experimental study was carried out to evaluate the morphological and physiological behavior of V. zizanioides, cultivated under controlled microenvironmental conditions and in the presence of increasing doses of Cu and Zn. In the first study, zinc, copper, lead, chromium, nickel and cadmium were identified as the main trace elements identified in soils located around the limestone extraction and processing areas for cement production. In the second study, it was observed that, although there are particularities between the technique of in vitro cultivation and those that use direct planting in the soil, plant tissue culture represents a reliable tool to obtain important information regarding toxicity and tolerance of vegetal species to contaminants, including heavy metals. In the third study, it was observed that, under the conditions of the experiment, V. zizanioides showed a great physiological and anatomical plasticity in the presence of stress caused by excess of Cu and Zn, which supply potential for using it in the recovery of areas contaminated by these metals.