tailieunhanh - Báo cáo khoa học: "Field comparison of transpiration, stomatal conductance and vulnerability to cavitation of Quercus petraea and Quercus robur under water stress"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: "Field comparison of transpiration, stomatal conductance and vulnerability to cavitation of Quercus petraea and Quercus robur under water stress. | Ann Sci For 1993 50 571-582 Elsevier INRA 571 Original article Field comparison of transpiration stomatai conductance and vulnerability to cavitation of Quercus petraea and Quercus robur under water stress N Bréda H Cochard E Dreyer A Granier INRA Laboratoire de Bioclimatologie et Écophysiologie Champenoux F54280 Seichamps France Received 6 January 1993 accepted 2 June 1993 Summary Water relations were analysed in adult oaks Quercus petraea and o robut during a period of water shortage in a simplified lysimeter. Sap flux densities and stomatai conductance were reduced by 70 at maximal drought intensity. Predawn leaf water potential then ranged from to MPa. The slightly lower transpiration observed in pedunculate oaks could be ascribed to their smaller crown development. Nevertheless no significant difference in stomatai conductance could be observed between the two species. They also had the same percent loss of conductivity 80 in petioles at maximal drought intensity when midday leaf water potential had dropped to MPa. Finally good agreement was found between observed losses of hydraulic conductivity during in situ dehydration and the vulnerability curves obtained under laboratory conditions. The shifts in maximal conductivity observed in some draughted trees probably accentuated discrepancies between field and laboratory data. However a correction procedure helped overcome these artifacts. drought xylem cavitation stomatai conductance sap flux Quercus petraea I Quercus ro-bur Résumé Comparaison en conditions naturelies de la transpiration de la conductance sto-matique et de la vulnérabilité à la cavitation de Quercus robur et Q petraea soumis à un stress hydrique en foret de Champenoux France . L etude compare le comportement hydrique de chênes sessiles Quercus petraea et pédonculés Q robur adultes en conditions de dessèche-ment du sol. Les mesures de flux de sève et de conductance stomatique ont montré une diminution de 65 à 70 de ces paramètres .