TAILIEUCHUNG - Báo cáo lâm nghiệp: "Frost resistance of seeds in Mediterranean oaks and the role of litter in the thermal protection of acorns"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Frost resistance of seeds in Mediterranean oaks and the role of litter in the thermal protection of acorns. | Ann. For. Sci. 61 2004 481-486 481 INRA EDP Sciences 2004 DOI forest 2004042 Original article Frost resistance of seeds in Mediterranean oaks and the role of litter in the thermal protection of acorns Jordán Esteso-Martínez Eustaquio Gil-Pelegrín Centro de Investigación y Tecnología Agroalimentaria de Aragón Gobierno de Aragón Aptdo 727 50080 Zaragoza Spain Received 19 March 2003 accepted 26 June 2003 Abstract - The endogenous frost resistance of the seeds of four Mediterranean oaks Quercus coccifera Q. faginea Q. ilex and Q. pyrenaica with different leaf abscission phenology was tested. Thermal analysis and polyelectrolytes leakage methodologies were employed to establish lethal temperature thresholds. Results showed a higher frost resistance for evergreen species and lower for deciduous species in this decreasing order Q. coccifera Q. ilex Q. faginea and Q. pyrenaica. The cover of leaf litter generated by deciduous species could be an isolating element which allowed seed survival under cold winter conditions to that species with a lower frost resistance. Differences in temperature above and below a leaf litter cover along a winter season were measured in a Q. faginea stand in this sense the kind effect of leaf litter from a thermal point of view was proved. frost resistance leaf litter polyelectrolytic leakage Quercus thermal analysis Résumé - Resistance au froid des semences de chênes méditerranéens et rôle de la litière comme protecteur thermique des glands. On a testé la resistance intrinsèque à la gelée dans les semences de quatre espèces de chênes méditerranéens Quercus coccifera Q. faginea Q. ilex et Q. pyrenaica différents par la phénologie de l abscission foliaire. Des méthodes d analyse thermique et des mesures de fuite de polyélectrolytes ont été utilisées pour établir les températures létales. Les résultats montrent une meilleure résistance des espèces à feuilles persistantes dans l ordre suivant Q. coccifera Q. ilex Q. faginea Q. pyrenaica . .

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