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Báo cáo lâm nghiệp: "The effects of elevated CO 2 and water stress on whole plant CO 2 exchange, carbon allocation and osmoregulation in oak seedlings"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài: "The effects of elevated CO 2 and water stress on whole plant CO 2 exchange, carbon allocation and osmoregulation in oak seedlings. | Ann Sci For 1996 53 447-459 Elsevier INRA 447 Original article The effects of elevated co2 and water stress on whole plant co2 exchange carbon allocation and osmoregulation in oak seedlings p Vivin JM Guehl A Clement G Aussenac Unite écophysiologie forestiere equips bioclimatologie et écophysiologie Centre de Nancy Inra 54280 Champenoux France Received 18 January 1995 accepted 29 June 1995 Summary Seedlings of Quercus roburL grown under present 350 pmol moH or twice the present 700 pmol mol-1 atmospheric co2 concentrations were either maintained well-watered or subjected to a drought constraint late in the growing season 25 August 1993 . Despite an initial stimulation of biomass growth 44 by elevated co2 there was no significant difference in plant dry weight at the end of the growing season 15 October 1993 between the two co2 treatments irrespective of watering regime. Under drought conditions although there was no growth increase in response to elevated co2 concentration there was a stimulation in net photosynthesis. In addition the respiration rate of the root soil system root dry matter basis was slightly lower in the elevated than in the ambient co2 concentration. These results together with the results from short-term 13c labelling suggest enhanced plant carbon losses through processes not assessed here aerial respiration root exudation etc under elevated co2 concentration. In the draughted conditions new carbon relative specific allocation values RSA were greater under elevated co2 than under ambient co2 concentration in both leaf and root compartments. Osmotic potentials at full turgor n0 were lowered in response to water stress in leaves by 0.4 MPa for the elevated co2 treatment only. In roots osmotic adjustment 0.3 MPa occurred in both the co2 treatments. elevated co21 water stress osmoregulation carbon allocation Quercus robur Resume Effets de I augmentation de la concentration atmosphérique en co2 et d un deficit hydrique sur les échanges gazeux la .