Data/hora: 11/06/2024 17:50:08

Provedor de dados: 	Brazilian Journal of Plant Physiology	
País: 	Brazil	
Título: 	Effects of changes in the photosynthetic photon flux density on net gas exchange of Citrus limon and Nicotiana tabacum	
Autores: 	Pimentel,Carlos; Ribeiro,Rafael Vasconcelos; Santos,Mauro Guida dos; Oliveira,Ricardo Ferraz de; Machado,Eduardo Caruso.	
Data: 	2004-08-01	
Ano: 	2004	
Palavras-chave: 	CO2 assimilation rate; Gas exchange; Stomata; Intrinsic water use efficiency.	
Resumo: 	The objective of this study was to evaluate the effects of changes in the photosynthetic photon flux density (PPFD) on net gas exchange of Citrus limon, a woody species, and Nicotiana tabacum, an herbaceous species. When PPFD was increased from 50 to 350 mumol.m-2.s-1 and returned to 50 mumol.m-2.s-1 after 60 min, the CO2 assimilation rate (A) increased and stabilized after 15 min in both species. Stomatal conductance (g s), however, continued to increase. After returning to low PPFD, A immediately diminished to a low value for both lemon and tobacco. Stomatal conductance of lemon diminished slowly over 60 min, whereas g s for tobacco took only 15 min to decrease. This difference in behavior is probably due to over-sensitivity of stomata of woody species, such as Citrus, when exposed to high light, retarding stomatal closure on return to low PPFD. Furthermore, when lemon, growing at a PPFD of 300 mumol.m-2.s-1, was submitted to a step increase of 600 mumol.m-2.s-1, there was an oscillatory behavior of A and g s requiring 150 min to stabilize. The causes of this behavior are discussed with respect to improved intrinsic water use efficiency by stomatal closure.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202004000200002	
Editor: 	Brazilian Journal of Plant Physiology	
Relação: 	10.1590/S1677-04202004000200002	
Formato: 	text/html	
Fonte: 	Brazilian Journal of Plant Physiology  v.16 n.2 2004	
Fonte: 	info:eu-repo/semantics/openAccess