TAILIEUCHUNG - Báo cáo lâm nghiệp: "Oak growth, development and carbon metabolism in response to water stress"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài:"Oak growth, development and carbon metabolism in response to water stress. | 181 Ann Sci For 1996 53 181-196 Elsevier INRA Review article Oak growth development and carbon metabolism in response to water stress RE Dickson PT Tomlinson USDA Forest Service North Central Forest Experiment station Forestry Sciences Laboratory 5985 Highway K Rhinelander Wl 54501 USA Received 14 November 1994 accepted 19 June 1995 Summary The genus Quercus Fagaceae contains both deciduous and evergreen species adapted to a wide range of sites differing widely in moisture availability. Different oak species have developed both morphological and physiological adaptations to survive and grow on such sites. Morphological adaptations in leaves stems and roots aid in both drought avoidance and drought tolerance. Physiological adaptations involve control of stomatai conductance leaf water potential osmotic adjustment and photosynthetic carbon fixation. Carbon fixation can be divided into stomatai and nonstomatal responses. Stomatai response is probably the most important factor controlling carbon fixation. The more drought-tolerant species control stomatai function to allow some carbon fixation with stress thus improving water use efficiency or open stomates rapidly when water stress is relieved. Nonstomatal responses of carbon fixation such as photosystem II light energy conversion and the dark reactions of Rubisco carbon fixation are quite resistant to water stress although internal resistance to co2 movement may increase. With water stress soluble sugar starch ratios increase new leaf development decreases or stops altogether and carbon allocated to leaf development shifts to lower stem and root for growth or storage. Many oak species genotypes and hybrids are available that may be adapted to difficult sites. Use of such genotypes could greatly improve current forest management systems and horticultural amenity plantings. Quercus I water-stress tolerance photosynthesis stomatai response nonstomatal response Rubisco carbon allocation genotypes hybrids Resume .

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