Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài: "Growth dynamics, transpiration and water-use efficiency in Quercus robur plants submitted to elevated CO 2 and drought . | Ann Sci For 1996 53 431 -446 Elsevier INRA 431 Original article Growth dynamics transpiration and water-use efficiency in Quercus robur plants submitted to elevated co2 and drought c Picon JM Guehl G Aussenac Équipe bioclimatologie-écophysiologie unite de recherches en écophysiologie forestiere Centre de Nancy Inra 54280 Champenoux France Received 16 January 1995 accepted 29 June 1995 Summary Seedlings of pedunculate oak Quercus roburL were grown for one growing season under ambient 350 pmol moH and elevated 700 pmol moH atmospheric co2 concentration CO2 either in well-watered or in draughted the water supply was 40 of the well-watered plants transpiration in both CO2 conditions. In the draughted conditions gravimetric soil water content SWC was on average 4 10-2 g g-1 lower under elevated CO2 In well-watered conditions biomass growth was 39 higher in the elevated CO2 treatment than under ambient CO2 . However relative growth rate RGR was stimulated by the elevated CO2 only for 17 days in July at the end of the stem elongation phase third growing flush which corresponded also to the phase of maximum leaf expansion rate. Both the number of leaves per plant and the plant leaf area were 30 higher in the elevated CO2 treatment than under ambient CO2 . In the draughted conditions no significant enhancement in biomass growth and in plant leaf area was brought about by the elevated CO2 Transpiration rate was lower in the elevated CO2 conditions but whole plant water use was similar in the two CO2 treatments reflecting a compensation between leaf area and stomatai control of transpiration. Transpiration efficiency W biomass accumulation plant water use was improved by 47 by the elevated CO2 in well-watered conditions but only by 18 in the draughted conditions. Carbon isotope discrimination A was decreased by drought and was increased by the elevated CO2 A negative linear relationship was found between transpiration efficiency divided by the atmospheric CO2 and A as .
