Fitotoxicidade e citogenotoxicidade da água e sedimento de córrego urbano em bioensaio com Lactuca sativa

Abstract

RESUMOObjetivou-se, com este trabalho, avaliar a influência espacial e temporal da fitotoxicidade e da citogenotoxicidade da água e do sedimento de córrego urbano quanto às características germinativas e de crescimento inicial de Lactuca sativa. Amostras de água e de sedimento foram coletadas em 5 pontos do Córrego do Pântano (Alfenas, Minas Gerais), no período de outubro de 2010 a julho de 2011 e as concentrações dos metais Cd, Pb e Zn foram quantificadas. Os ensaios de fitotoxicidade e de citogenotoxicidade foram realizados com as amostras de água e extratos aquosos dos sedimentos. Os parâmetros avaliados foram taxa de germinação, comprimento de raízes, biomassa fresca e seca, índice mitótico e a frequência de anormalidades cromossômicas. Constataram-se maiores concentrações de Cd e Pb nas amostras de água coletadas nos meses com a ocorrência de precipitações pluviométricas. Água e sedimento apresentaram efeito fitotóxico sobre germinação, biomassa fresca e seca de Lactuca sativa. O comprimento de raízes foi estimulado e apenas as amostras de água reduziram o índice mitótico. Evidenciou-se, também, variação temporal significativa relacionada com o regime pluviométrico apenas para o teste de fitotoxicidade. Palavras-chave: alface, toxicidade, sazonalidadePhytotoxicity and cytogenotoxicity of water and sediment of urban stream in bioassay with Lactuca sativa ABSTRACT The aim of this study was to evaluate the spatial and temporal influence of the phytotoxicity and cytogenotoxicity of water and sediment of urban stream on the germination and initial growth of Lactuca sativa. Samples were collected from water and sediment at five sites of the Pântano Stream (Alfenas, Minas Gerais) during the period from October 2010 to July 2011. The concentrations of the metals Cd, Pb and Zn were quantified. Moreover, phytotoxicity and cytogenotoxicity were tested with samples of water and aqueous extracts of sediments. The evaluated end points were the germination rate, root length, fresh and dry weight, mitotic index and frequency of chromosomal abnormalities. Higher levels of Cd and Pb were verified in water samples collected during the rainy months. Water and sediment showed phytotoxic effect on germination, fresh weight and dry weight of Lactuca sativa. Root length was stimulated and only samples of water reduced the mitotic index. Significant temporal variation related to rainfall was observed only for phytotoxicity tests.

Biomonitors to evaluate the toxic potential of urban solid waste landfill leachate

“…The lower concentration of leachate (50%) led to a higher average in root growth in L. sativa (5.70 cm) and L. esculentum (8.28 cm). Rodrigues et al (2013) also noted root growth stimulation for L. sativa when analyzing the water from an urban stream located in the municipality of Alfenas, in the state of Minas Gerais, Brazil, and attributed this result to a greater offer of nutrients provided by the organic load in water. Averages followed by the same letter on the line do not differ significantly in accord with the Duncan test at 5% probability / n.a.…”

DISINFECTION PROTOCOL AND IN VITRO GERMINATION OF SEEDS OF Dalbergia nigra

“…L. sativa seeds are used for bioassays because they are highly sensitive to the environment, presenting low reserve tissues that allow them to easily absorb the compounds to which they are subjected (Andrade et al, 2010;Rodrigues et al, 2013).…”

“…Glyphosate is a systemic herbicide, used as a positive control in phytotoxicity and cytotoxicity assays as it acts directly on the roots in a negative and prolonged manner, also presenting genotoxicity (Andrade et al, 2010;Rodrigues et al, 2013;Loren et al, 2019). When in contact with plant tissue, glyphosate enters the extracellular matrix and, upon reaching the cytoplasm, it is transported via phloem and distributed to the cellular tissues, causing lethal effects to the plant and also inhibiting the shikimate pathway in plants, consequently interfering with the biosynthesis of lignins and aromatic amino acids, such as tryptophan (Bochkov et al, 2012).…”

Influence of the seasons on the water quality of the Marmeleiro River (Paraná, Brazil) using different bioindicators

“…These results obtained from Points 3 and 4 of the Marmeleiro River can be justified by the uses of the basin Table 2 Averages and standard deviation of the physicochemical parameters analyzed for the different collection points of the Marmeleiro River (Points P1-P6) in the four seasons COD Chemical Oxygen Demand; OG oils and greases; DO dissolved oxygen; TS total solids; VA virtually absent in the region of these collection points, predominantly urban, which may have resulted in the carrying of substances with mitogenic capacity to the waters of the Marmeleiro River. According to [22], the urban occupation can cause the accumulation of organic matter coming from urban effluents, and for [7], domestic effluents are rich in organic matter, which may have stimulated the cell divisions of A. cepa meristematic cells. Points 5 and 6 (24 h) showed mitotic indices statistically higher than the controls of the bulb itself (0 h) in summer and autumn, indicating the stimulus of cell proliferation caused by exposure to these water samples.…”

“…Seeds of Lactuca sativa L. (lettuce), present themselves as a test organism used for ecotoxicological assessments in effluents and tributaries, thus serving as a good bioindicator of environmental quality [6,7]. According to [8], the seeds of Allium cepa L. are also used as an indicator of public safety, because mutagenic substances can be identified through the use of this bioindicator.…”