Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Effects of water deficit on leaf in fast-growing tree species growth and initiation. | 366s Ann. Sci. For. 1989 46 suppl. 366s-368s Forest Tree Physiology E. Dreyer etal. eds. Elsevier INRA Effects of water deficit on leaf growth and initiation in fast-growing tree species . Metcalfe1 . Davies1 and . Pereira2 1 Institute of Environmental and Biological Sciences University of Lancaster Lancaster LA1 4YQ . and 2 Department of Forestry Institute Superior de Agronomia P-1399 Lisboa Codex Portugal Introduction Eucalyptus globulus is becoming increasingly important in Mediterranean regions for pulpwood production. Although the plant is highly drought tolerant its high productivity seems to be particularly sensitive to water shortage Pereira et al. 1986 . These researchers have shown that biomass production in young E. globulus growing in the field in Portugal can be increased by a factor of 3 under irrigation and this has been related to an increase in foliage area Borralho et al. 1987 Most of our knowledge on the growth of tree seedlings to date comes from field experiments such as the above. In order to further our understanding of seedling growth the early growth patterns of juvenile E. globulus have been investigated under conditions of water deficit in conjunction with detailed measurements of gas exchange. Materials and Methods Experiments were conducted in Lisbon Portugal where E. globulus seedlings were grown outside in 51 plots of nutrient-rich soil. Plots were covered with plastic to prevent surface evaporation from the soil or rewetting by rain or dew. Plants were either watered to drip point every day or received no water from d 0. Leaf areas were calculated from regression equations constructed using caliper measurements of leaf length and width and direct values of leaf areas obtained with a Li-cor leaf area meter. Gas exchange studies were conducted using a portable COj HjD porometer H Walz Messund Regeltechnick Effeltrich . . Results and Discussion Stomatai conductance and photosynthesis were both clearly reduced by soil .
