Effects of Low Temperature in Reactivated Cambial Cells Induced by Localized Heating During Winter Dormancy in Conifers

Effects of low temperature on cambial cells induced by localized heating in Cryptomeria japonica and Abies firma were investigated during winter dormancy in January-February. Localized heating induced cambial reactivation in the stems earlier than natural cambial reactivation. In heated Cryptomeria japonica and Abies firma stems, cambial reactivation occurred after 6 and 2 days of heating, on 14 January 2007 and 15 January 2010, respectively. We stopped the electric heating system just after cambial reactivation in stems. When we stopped the heating system, the minimum atmospheric temperature was about 0C. After cambial reactivation, due to rapid decrease in temperature, cell contents of cambium became coagulated but nucleus was present in ray cambial cells. After one month, the shrunk cambium produced new deformed tracheids with abnormal cell shape. The results suggest that rapid decrease in temperature just after cambial reactivation might induce temporary damage of cambium that produces deformed tracheids indicating that cambium and its derivatives can response directly to changes in temperature which provides a useful experimental model system for studies of cambial biology and xylogenesis.