Data/hora: 05/06/2024 16:15:23

Provedor de dados: 	61	
País: 	Brazil	
Título: 	CO2 assimilation, photosynthetic light response curves, and water relations of 'Pêra' sweet orange plants infected with Xylella fastidiosa	
Autores: 	Habermann,Gustavo; Machado,Eduardo Caruso; Rodrigues,João Domingos; Medina,Camilo Lázaro.	
Data: 	2003-08-01	
Ano: 	2003	
Palavras-chave: 	A/Ci curves; Citrus variegated chlorosis; Citrus sinensis L. Osbeck; Photosynthetic photon flux density; Photosynthetic metabolism; Stomata.	
Resumo: 	Plants with citrus variegated chlorosis (CVC), a disease caused by the xylem-limited bacteria Xylella fastidiosa, have leaves with water deficiency symptoms and are associated with decreases on the net photosynthesis and transpiration rates. Using healthy and CVC-affected 'Pêra' sweet orange plants on 'Rangpur' lime rootstock, the leaf gas exchange variables were measured with an open-gas portable photosynthesis system. All plants were watered and the leaf water potential (Yw) was measured by isopiestic thermocouple psychrometric technique. The net photosynthesis (A) vs. internal leaf CO2 concentration (A/Ci curves) was analyzed. The relative effect of stomatal resistance on photosynthesis (S%) and the estimation of carboxylation efficiency were calculated. The rates of photosynthesis and transpiration, stomatal conductance, and internal leaf CO2 concentration (Ci) were also measured while varying the photosynthetic photon flux density (PPFD). The S% values were approximately 30 % greater in infected plants when compared to healthy ones. The light compensation point for diseased plants was higher than in the healthy ones, and the saturation light point in plants with CVC was twofold lower. The lower Yw in diseased plants favours the hypothesis of xylem occlusion, which probably caused a lower water supply to the mesophyll, thus decreasing the photosynthesis and transpiration rates. Nevertheless, there was also a reduction in the photosynthetic metabolic activities, represented by lower carboxylation efficiency and photochemical disturbances that were detected in diseased plants.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202003000200003	
Editor: 	Brazilian Journal of Plant Physiology	
Relação: 	10.1590/S1677-04202003000200003	
Formato: 	text/html	
Fonte: 	Brazilian Journal of Plant Physiology  v.15 n.2 2003	
Fonte: 	info:eu-repo/semantics/openAccess