Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài:Physiological responses to. | 604s Ann. Sei. For. 1989 46 suppl. 604S-613S Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Physiological responses to low temperature o. Junttila Department of Plant Physiology and Microbiology University of Tromso Tromso Norway Introduction Temperature is one of the main environmental factors regulating and limiting plant growth. Basic chemical and biochemical processes in plants are temperature dependent and various growth processes have their specific requirements for minimum optimum and maximum temperatures. Distribution of woody plants is often limited by low temperature and we can separate two main effects 1 limitation of growth and development temperature during the growing season is too low and or the growing season is too short for completion of growth and development 2 limitation of survival minimum temperatures during some period of the annual cycle are regularly lower than can be tolerated by the plant. Native species and provenances are normally adapted to local climate but responses to low temperature are of great importance when species or ecotypes are moved from their original location to new areas. Low summer temperature has been suggested to be a limiting factor for distribution of several vascular plants in Scandinavia primarily due to the temperature effect on oxidative phosphorylation Skre 1979 . Generally the temperature require ment for generative development flowering and seed production is higher than that for vegetative growth. Our knowledge on exact temperature requirements for growth of various woody species is limited and very little has been done to characterize the biochemical and physiological bases for growth at low temperature. Much more research has been devoted to studies of low temperature as a limiting factor for survival of the trees. This is partly a question of the maximum level of hardiness in the species partly a question of a proper timing of hardening and dehardening in relation to the annual temperature .
