Dynamic changes of cold hardiness in winter in twelve evergreen broad-leaved species from Nanjing
南京地区12种常绿阔叶树种冬季抗寒性动态变化

Cold hardiness of twelve evergreen broad-leaved species that introduced to the open field of Nanjing was evaluated by means of electric conductivity. The results found that the order of cold hardiness in those species is consistent and repeated during the winter from 2003 to 2005. Cold hardiness in these species was increased with a period of low temperature induction in winter from October, 2005 to March, 2006. The highest value was observed in the middle of January, with lowest observed on October or March as usual. The responding speed to the low temperature in winter in these species varies. While Cinnamomum camphora and Cinnamomum japonicum respond fast to low temperature, Ilex purpurea and Ilex latifolia respond slowly. The rest respond normally. The cold hardiness revealed in this study is well agreed with the observation of winter in Nanjing. Therefore, the results obtained may be used as important reference in introducing evergreen broad-leaved species into higher latitude regions.