Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Seasonal variations and acclimation potential of the thermostability of photochemistry in four Mediterranean conifers. | Ann. For. Sci. 61 2004 235-241 235 INRA EDP Sciences 2004 DOI forest 2004016 Original article Seasonal variations and acclimation potential of the thermostability of photochemistry in four Mediterranean conifers Fabienne FROUXa b Michel DUCREYb Daniel EPRONc d Erwin DREYERa a UMR INRA-UHP Écologie et Écophysiologie Forestières 54280 Champenoux France b INRA Unité de Recherches Forestières Méditerranéennes avenue A. Vivaldi 84000 Avignon France c Université de Franche-Comté Institut des Sciences et des Techniques de l Environnement Laboratoire de Biologie et Écophysiologie BP 71427 25211 Montbéliard Cedex France d Present address UMR INRA-UHP Écologie et Écophysiologie Forestières BP 239 54506 Vandreuvre France Received 13 January 2003 accepted 20 August 2003 Abstract - Thermostability of photosynthesis was studied in four Mediterranean conifer species growing in southern France namely Cedrus atlantica and Pinus nigra growing usually on mid elevation areas and Cupressus sempervirens and Pinus halepensis from coastal areas. Chlorophyll a fluorescence was used and lead to two indices assessing the degree of thermostability of the photosynthetic apparatus the critical temperature at ground fluorescence breakpoint Tc and the temperature threshold inducing a 15 decrease in photochemical efficiency T15 . The two indices were correlated and yielded similar rankings among species although mean values of T15 were C lower than that of Tc. Values of Tc were in the range 44 to 52 C and clear interspecific differences were detected. C. atlantica consistently displayed higher Tc than the other species C difference during a seasonal time course . Among the three other species C. sempervirens P. nigra and P. halepensis the differences were smaller and not always significant. Tc also displayed a large intraspecific plasticity with i a seasonal time-course showing significant increases during summer and lower values during Spring and Autumn and ii large responses to
