| Taken Osmanthusfragrans(Thunb.) Lour., Photiniaserrulata, Euonymus fortune(Turcz.) Hand.-Maza., Hokkaido Chinese little leaf box, Viburnum odoratissimum Ker., PhotiniaserrulataLindl., Ilex crenataLindl.as research material, this paper studied the cold tolerance of eight introduced evergreen broad-leaved species for for landscaping in urbans of northern China. By analyzing the three evergreen broad-leaved species leaf cell membrane electrolyte solutions relative conductivity, soluble sugar, SOD research activity, soluble protein content, proline content and chlorophyll content, and several kinds of plant cold hardiness of comprehensive evaluation, the conclusions were achieved as follows:(1) With temperature decreased, electrolyte leakage rate, soluble sugar, soluble protein, SOD activity and proline were increased, but the content of chlorophyll descended. It was found that the physiological of plants was affected by external environmental factors and factors of plant itself. The changes’ reason is very complex, so all kinds of physiological index should be combined to more accurate evaluation. Comprehensive consideration is needed in evergreen broad-leaved plant introduction and analysis to high latitude.(2) The cold resistance of eight broad-leaved evergreen plants in artificial low temperature was: Viburnum odoratissimum Ker.> Hokkaido Chinese little leaf box > Osmanthusfragrans(Thunb.) Lour.> HederanepalensisK,Kochvar.sin > Photiniaserrulata > Euonymus fortune(Turcz.) Hand.-Maza.> Ilex crenata Lindl.> Photiniaserrulata Lindl. The cold resistance has no significant difference, and all the eight evergreen broad-leaved tree species can be used in urban landscaping.(3) As we only studied the effects of natural low temperature on the metabolism of substances and protective enzyme activity of plants, we suggested that molecular biology and gene engineering technology should be used in this research area to brings new ideas to improve plant resistance. It is believed that if the molecular biological method can be applied in this study of evergreen broad-leaved species of cold resistance, it may provide important evidence for the molecular level to reveal the low temperature physiological ecology, and then through the transformation of a cold resistant related functional genes or regulatory genes, changes in physiological and biochemical responses of plants under stress can improve the purpose of plant in unbans of northern China. |
