Abstract:

Eight evergreen broad-leaf tree species such as Michelia chapensis,Myrica rubra,Citrus medica,Laurus nobilis,Camellia sasangua,Elaeocarpus decipiens,Quercus virginiana and Citrus reticulate were used as experimental materials.The chlorophyll content,plasma membrane relative permeability,malondialdehyde content,soluble sugar content,the activity of superoxide dismutase and peroxidase were measured during the wintering period in order to study their ability to overwinter in the Xuhuai region .The main results are as follows:The chlorophyll content of the eight tree species decreased,and the leaf relativity membrane permeability,malondialdehyde content and soluble sugar content increased with decreasing temperature.The SOD activity and POD activity did not change uniformly.Among the eight introduced evergreen broad-leaved tree species,Camellia sasangua has strong cold resistance in Xuzhou region and is suitable for local planting.Quercus virginiana,Laurus nobilis and Myrica rubra have general cold resistance and need to be further domesticated.Elaeocarpus decipiens,Michelia chapensis,Citrus medica and Citrus reticulata have poor cold resistance and are not suitable for introduction and cultivation in Xuzhou region.

Key words: Xuzhou region, introduction, evergreen broadleaved species, overwintering process, cold resistance