Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:"Comparison between the structure and function of chloroplasts at different levels of willow canopy during a growing season. | 815s Ann. Sci. For. 1989 46 suppl. 815S-818S Forest Tree Physiology E. Dreyre et al. eds. Elsevier INRA Comparison between the structure and function of chloroplasts at different levels of willow canopy during a growing season E. Vapaavuori1 A. Nurmi2 H. Vuorinen1 and T. Kangas1 1 The Finnish Forest Research Institute Suonenjoki Research station SF-77600 Suonenjoki and 2 University of Helsinki Department of General Botany SF-00710 Helsinki Finland Introduction Light climate has a strong impact on the ultrastructure of chloroplasts. There is plenty of evidence that the degree of grana stacking in chloroplasts of plants grown in high light is less than in plants grown in low light . Lichtenthaler ef al. 1981 which is also the case for plants adapted to sunny or shady habitats Boardman 1977 Aro et al. 1986 . Very little is however known about the seasonal acclimation process of the photosynthetic apparatus in the canopy where leaves that are initially exposed to full sunlight are transferred through half-shade into full shade. In conditions under which water and nutrient availability are not limiting growth the shaded leaves remain intact for most of the growing season. This suggests that the leaves retain a positive carbon balance by acclimating to the changing light climate. In this study we quantified the seasonal changes in the chloroplast ultrastructure at several heights of a willow Salix cv. Aquatica gigantea canopy. We also determined how changes in chloroplast ultrastructure fit with their function by measuring the rate of gas exchange under the prevailing environmental conditions in the canopy. Materials and Methods The willow stand established in 1980 125 m2 in area was cut down before the growing season 1986 and measurements were made on leaves that emerged on new shoots successively throughout the growing season. The stand was fertilized with a commercial fertilizer Pu-utarhan Y-lannos 10-16-17 once a week during the growing season so that it received
