TAILIEUCHUNG - Báo cáo lâm nghiệp: "Effects of defoliation on the frost hardiness and the concentrations of soluble sugars and cyclitols in the bark tissue of pedunculate oak (Quercus robur L.)"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Effects of defoliation on the frost hardiness and the concentrations of soluble sugars and cyclitols in the bark tissue of pedunculate oak (Quercus robur L.). | Ann. For. Sci. 61 2004 455-463 INRA EDP Sciences 2004 DOI forest 2004039 455 Original article Effects of defoliation on the frost hardiness and the concentrations of soluble sugars and cyclitols in the bark tissue of pedunculate oak Quercus robur L. Frank M. THOMASa Gabriele MEYERa Marianne Poppb a Department of Plant Ecology Albrecht von Haller Institute of Plant Sciences University of Gottingen Untere Karspule 2 37073 Gottingen Germany b Department of Chemical Physiology of Plants Institute of Ecology and Conservation Biology University of Vienna AlthanstraBe 14 1090 Vienna Austria Received 9 July 2003 accepted 26 September 2003 Abstract - As a measure of frost hardiness we determined an index of injury Z 30 in living bark tissue of 20-year-old pedunculate oaks Quercus robur L. that had been manually and almost completely defoliated in the first half of May of one or two years and of non-defoliated control trees. I 30 was calculated as a percentage value on the basis of electrolyte leakage from samples artificially frozen at a temperature of -30 C and from unfrozen control samples. In parallel the bark s concentrations of soluble sugars of nitrogen and of quercitol a cyclic polyol were measured. Repeated defoliation significantly reduced the frost hardiness of the bark as well as its concentrations of raffinose stachyose nitrogen and quercitol. The I-30 values were correlated with the total concentration of soluble sugars and with the concentrations of the individual sugar compounds but not with the quercitol concentration. Less tight yet significant correlations were obtained between I-30 and nitrogen concentrations. We conclude that repeated defoliation decreases the bark s capability to acclimatize to winter frost due to a reduction in the concentrations of soluble sugars particularly those of raffinose and stachyose. electrolyte leakage oak decline quercitol raffinose stachyose Résumé - Effets de la defoliation sur la resistance au gel et les .

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