title: Physiological responses of saplings of Caesalpinia echinata Lam., a Brazilian tree species, under ozone fumigation.
abstract: The effects induced by long-term (30 day) and short-term (6h) exposures to ozone on the physiological parameters in young plants of Caesalpinia echinata Lam., a Brazilian tree species, were determined. Potted plants were maintained in open-top chambers in Valencia, Spain, under charcoal filtered air (mean O3 level: 29 microg m3), nonfiltered air (NF; 43 microg m3), and nonfiltered air plus O3 (NF + O3; 68 microg m3), simulating prevailing concentrations observed in the city of São Paulo, Brazil, during spring months (50 microg m3 in 2002). In the plants kept in NF + O3 for 30 days, although no foliar visible injuries were observed, the net carbon assimilation rate was reduced to 50%, stomatal conductance 42%, and transpiration 40%, when compared to the results for the NF plants. No changes in antioxidants, in leaf, stem, and root biomass, and in the root/shoot ratio were observed. Significant reductions were observed in gas exchange and in PSII photochemical efficiency (Fv/Fm) after 6 h of exposure to an O3 peak. The species was shown to be sensitive to ambient O3 concentrations measured in São Paulo.
authors: Instituto de Botânica, Caixa Postal 4005, CEP 01061-970 São Paulo, SP, Brazil. regmorae@yahoo.com.br
authors: Regina M
authors: RM
authors: Moraes
authors: Patricia
authors: P
authors: Bulbovas
authors: Cláudia M
authors: CM
authors: Furlan
authors: Marisa
authors: M
authors: Domingos
authors: Sérgio T
authors: ST
authors: Meirelles
authors: Welington B C
authors: WB
authors: Delitti
authors: Maria J
authors: MJ
authors: Sanz