Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Within-crown variation in leaf conductance of Norway spruce: effects of irradiance, vapour pressure deficit, leaf water status and plant hydraulic constraints. | Ann. For. Sci. 61 2004 419-429 419 INRA EDP Sciences 2004 DOI forest 2004035 Original article Within-crown variation in leaf conductance of Norway spruce effects of irradiance vapour pressure deficit leaf water status and plant hydraulic constraints Arne Sellin Priit Kupper Department of Botany and Ecology University of Tartu Lai 40 51005 Tartu Estonia Received 2 January 2003 accepted 20 August 2003 Abstract - Responses of leaf conductance gL to variation in photosynthetic photon flux density leaf-to-air vapour pressure difference shoot water potential and soil-to-leaf hydraulic conductance Gt were studied in Picea abies L. Karst. foliage with respect to shoot age and position within the canopy. The upper canopy shoots demonstrated on average times higher daily maximum gL as compared to the lower canopy shoots growing in the shadow of upper branches. Functional acclimation of the shade foliage occurred in the form of both a steeper initial slope of the light-response curve and a lower light-saturation point of gL. The mean Gt was times bigger for the upper canopy compared to the lower canopy. We set up an hypothesis that stomatal conductance at the base of the live crown is constrained not only by low light availability but also by plant s inner hydraulic limitations. foliage age leaf conductance photosynthetic photon flux density soil-to-leaf conductance vapour pressure difference Résumé - Variation de la conductance foliaire dans les couronnes de l Epicea effets de l eclairement du deficit de vapeur d eau dans l air de l etat hydrique des feuilles et des contraintes hydrauliques des arbres. Les réponses de la conductance foliaire gL aux variations de la densité de flux photosynthétique de photons du déficit de saturation de l air du potentiel hydrique des rameaux et de la conductance hydraulique Gt dans le transfert Sol-feuille ont été étudiées chez Picea abies L Karst. En relation avec l âge des rameaux et leur position dans la canopée. Les .
