Efeitos fisiológicos e bioquímicos causados pela deposição de ferro particulado em Clusia hilariana, uma espécie de restinga / Physiological and biochemical effects of iron ore dust in Clusia hilariana, a plant of restinga

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Clusia hilariana, a CAM plant with crucial ecological role, has a broad distribution in brazilian restingas. With the aim to evaluate the physiological and biochemical effects of iron ore particulate matter (MSPFe), deposited in different fashions, on this species, three distinct experiments were carried out. Young plants were hydroponic cultivated in Hoagland solution at pH 5,5 and 4,0, using two source of iron, iron citrate III (0 and 2,0 mM) and FeEDTA complex (0, 1 and 2,0 mM). On the second experiment the plants were exposed to 6 and 18 mg.cm-2.day-1 of MSPFe, applied directly on the soil surface. On the final experiment, 2,14 mg.cm-2.day-1 of MSPFe was applied on the leaf surface by keeping the plant inside a MSPFe deposition chamber, in order to simulate the phenomenon that takes place in the field. The source of available iron in the hydroponic solution was critical for the stress onset. The gas exchange parameters were only affected on plants treated with FeEDTA. The iron content in plant tissues was greater in plants exposed to MSPFe deposition treatments than the control plants. The deposition of MSPFe on leaf surface caused significant decrease of a number of parameters such as plant height, leaf number, net photosynthesis, stomatal conductance, chlorophyll a fluorescence, pigments content and organic acid accumulation, yonder increment on the relative membrane permeability, reduction of activity of catalase enzyme, without similar effect on lipid peroxidation. These effects were less dramatic on the treatment with MSPFe deposited on the soil surface. The enzymatic activity of superoxide dismutase was enhanced in those plants treated with MSPFe applied on the soil surface, revealing an effective control of the reactive oxygen species. Thus, the set of physiological response of C. hilariana, as a consequence of MSPFe applications depends upon the target of the deposition, as supported by the significant results obtained when the MSPFe was applied directly on the leaves surface. The damages caused by the applications of MSPFe on the leaves of C. hilariana, were probably due to a physical effect rather than a toxic effect of the iron. The tolerance of C. hilariana to the high iron content in the soil, followed by iron accumulation in the plant, reveals the possibility of its use in iron phytoextraction of contaminated environments.

ASSUNTO(S)

cam polution fisiologia vegetal toxic effect poluição iron estresse oxidativo cam

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