tailieunhanh - Báo cáo lâm nghiệp: "Physiological aspects of seed conservation"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Physiological aspects of seed conservation. | 72s Ann. Sci. For. 1989 46 suppl. 72s-84s Forest Tree Physiology E. Dreyer etal. eds. Elsevier INRA Physiological aspects of seed conservation B. Suszka Institute of Dendrology 62-035 Kórnik Poland Introduction Seeds of most woody-plant species are dormant when fully ripe germination and seedling formation assumes breaking of this dormancy. Preservation of seed viability by proper conservation generally does not contribute to dormancy breaking. After storage seeds can be as dormant as they were before storage was started. However whether dormancy is broken before during or after storage - breaking of dormancy and conservation of seeds should not be regarded separately. Seedling production is not possible from dormant seeds if both dormancy and the tendency to lose viability are not dealt with by proper treatments. We cannot discuss conservation of seeds leaving their dormancy aside. Storage of non-dormant seeds is except for recalcitrant seeds much easier. Recent trends in seed physiology In the last few decades intensive work has been conducted to understand better some basic facts and processes occurring during the development of seeds when they are still on the mother plant and later after separation from it in the period between dissemination and formation of seedlings. This period is characterized by breaking of the developmental processes causing dormancy followed by overcoming this dormancy under conditions making the latter possible. This happens both when dormancy alone is imposed and when it is a very deep dormancy making immediate germination and further growth of the seedling impossible. The reasons for these phenomena can differ. They are mostly multifactorial. Investigators concerned with these problems try to separate the action and effects of individual factors or groups of factors to exclude in this way interactions with other processes. This is perhaps the only way to conduct such studies but it is obvious that in reality such distinctions do not