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Brazilian Journal of Botany

Print version ISSN 0100-8404On-line version ISSN 1806-9959


MORAES, REGINA MARIA DE; DELITTI, WELINGTON BRAZ CARVALHO  and  MORAES, JOSÉ ANTÔNIO PROENÇA VIEIRA DE. Responses of saplings of Tibouchina pulchra Cogn. to air pollution in Cubatão, SP: net photosynthesis, growth and leaf chemistry. Rev. bras. Bot. [online]. 2000, vol.23, n.4, pp.443-449. ISSN 0100-8404.

Saplings of Tibouchina pulchra, cultivated on standardised conditions, were placed in three sites at the Cubatão region to study the effects of the air pollutants on photosynthesis, growth and leaf concentrations of ascorbic acid, chlorophyll, nitrogen, sulfur and fluoride. The study areas were: Pilões river valley (RP), considered as the reference plot; Caminho do Mar (CM), near the petrochemical industries; and Mogi river valley (VM), near metallurgical and fertilizer industries. Four plants remained in each plot during six months. Compared to the reference plot (RP - 9.81 mmol.m-2.s-1), net photosynthesis was reduced (p < 0.05) in plants at the VM site (8.02 mmol.m-2.s-1), and it was not altered in the other area (CM - 9.29 mmol.m-2.s-1). Plants grown in VM showed reduction in height and the amount of ascorbic acid, alterations on the pattern of biomass distribution in the plant, increased concentrations of chlorophyll a and b, fluoride, nitrogen and sulfur. Plants exposed in CM showed reduction in both height and diameter, and enhanced concentrations of chlorophyll a and b, fluoride, N and S. The results indicate that pollutant concentrations have still been at phytotoxic levels in VM and CM and this problem was more intensive in VM, during the exposure period.

Keywords : Air pollution; Tibouchina pulchra; Cubatão; photosynthesis.

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