Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Direct effects of acidic wet deposition on photosynthesis and stomatal conductance of two Populus clones (P. cv. Beaupré and P. cv. Robusta). | 586s Ann. Sci. For. 1989 46 suppl. 586s-589s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Direct effects of acidic wet deposition on photosynthesis and stomatai conductance of two Populus clones P. cv. Beaupre and p. cv. Robusta c. Martens K. Landuydt and I. Impens Department of Biology University of Antwerp . Universiteitsplein 1 B-2610 Wilrijk Antwerpen Belgium Introduction Poplar characterized by rapid growth is an important source of fiber products in Belgium Steenackers 1982 . Growth reduction due to acidic precipitation may have important economic consequences. Poplar is known to be sensitive to gaseous air pollutants . leaf damage Freer-Smith 1984 Wang eta . 1986 . In this study direct effects of acidic precipitation on leaf gas exchange were determined for two clones. Materials and Methods Poplar cuttings Populus sp. cv. Beaupré and cv. Robusta were grown in a greenhouse in plastic containers I and exposed to simulated acidic rain of pH or to a control solution of pH 3 times a week. The soil was covered with a plastic hood to avoid indirect effects of acid precipitation. The interactive effects of leaf age and exposure to acid rain on leaf gas exchange were studied by measuring net photosynthetic rate and stomatai conductance at different leaf ages . different leaf plastochron index LPI . Measurements were obtained at light saturation using an artificial light source 800 pE m-2-s-i PAfeat and gssat. Light saturated net photosynthesis data were obtained using a portable gas exchange system as described by Ceulemans et al. 1986 . stomatai conductances were measured with an automatic water vapor diffusion porometer. Mean values of 6-12 measurements of each LPI were calculated with 95 confidence limits. Non-overlapping limits indicate significant differences between the two pH treatments. Results Net photosynthesis was decreased by acid rain pH in cv. Beaupre Fig. 1 . The differences compared to the control group were .
