Data/hora: 21/09/2024 13:38:13

Biblioteca(s): 	Embrapa Cerrados.	
Data corrente: 	08/04/1999	
Data da última atualização: 	08/04/1999	
Autoria: 	MATTOS, E. A. de; REINERT, F.; MORAES, J. A. P. V. de.	
Título: 	Comparison of carbon isotope discrimination and CO2 and H2O gas exchange between the dry and the wet season in leaves of several cerrado woody species.	
Ano de publicação: 	1997	
Fonte/Imprenta: 	Revista Brasileira de Fisiologia Vegetal, Brasilia, v.9, n.2, p.77-82, 1997.	
Idioma: 	Inglês	
Conteúdo: 	Carbon isotope discrimination (X) was studied in leaves of 13 woody species occurring in the Brazilian cerrado sensu stricto vegetation. Sun leaves were collected at the onset of the wet season and at the middle of the wet season prior to leaf senescence. The values among species that their leaves growing during the dry season ranged from 14.80%o in Tocoyena formosa to 20.86%o in Casearia sylvestris. In contrast, at the middle of the wet season the values ranged from 17.19%o in both Aspidosperma tomentosum and Tocoyena formosa to 22.4%o in Stryphnodendron barbadetiman. Median values of the dry season (17.69%o) were significantly lower than those of the wet season (19.24%o). The effect of the dry season on predawn leaf water potential, integrated net CO2, uptake (Aint), stomatal conductance to water vapor (Gint), intrinsic water use efficiency (Aint/Gint) and assimilation-weighed average ratio of intercellular to ambient CO2 concentration (Ci/Ca) were also assessed in Annona coriacea and Rapanea umbellata, two common woody species of the Brazilian cerrado. A decrease in was observed during the dry season. However, the values were not lower than -0.50 and -0.70 MPa in A. coriacea and R. umbellata, respectivelly. In both species, decreasing A during the dry season was associated with increasing Aint/Gint and with decreasing Ci/Ca ratio, suggesting a stomatal limitation on net CO2 uptake during the dry season. The results do not support the established idea of no stomatal restriction during the dry season for cerrado sensu stricto plants. However, it remains to be investigated if the marked decrease in stomatal conductance found here in A. coriacea and R. umbellata during the dry season can be generalized to other cerrado sensu stricto species.	
Palavras-Chave: 	Estacao chuvosa; Estacao seca; Troca gasosa.	
Thesagro: 	Cerrado; Planta Lenhosa.	
Thesaurus Nal: 	dry season; gas exchange; wet season; woody plants.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Cerrados (CPAC)	
Exemplares: 	CPAC - (2203-1) - ADD - SP - -- - CRI4804 -  - CRI4804 - DIS