Comprehensive Evaluation on Cold Resistance of Nine Kinds of Deciduous and Semi-evergreen Dwarf Shrubs from the Freeze to Melt Period in Spring

During the alternation from the freeze to melt period in spring, annual shoots from nine kinds of deciduous and semi-evergreen dwarf shrubs in Beijing, including Jasminum nudiflorum, Ligustrum vicaryi, and Deutzia parviflora, were used to measure six physiological response indices to low temperatures from 4℃ to -20℃ through an artificially-simulated cooling process. Based on correlation analysis among the six physiological indices, relative conductivity, semi-lethal temperature, free proline content and relative water content could be used to evaluate cold resistance. Using principal component analysis and subordinate functions to assess cold resistance comprehensively, the order of all nine dwarf shrubs was: Deutzia parviflora > Berberis thunbergii var. atropurpurea>Philadelphus pekinensis>Weigela florida ‘Red Prince’>Jasminum nudiflorum>Forsythia suspensa > Ligustrum vicaryi>Kerria japonica>Spiraea bumalda ‘Gold Mound’. According to cluster analysis, the nine dwarf shrubs could be divided into three groups. Among them, Deutzia parviflora and Berberis thunbergii var. atropurpurea could be classified as a class that had relatively higher cold resistance. Philadelphus pekinensis, Weigela florida ‘Red Prince’, Jasminum nudiflorum and Forsythia suspensa were categorized with medium cold resistance, and Ligustrum vicaryi, Kerria japonica, and Spiraea bumalda ‘Gold Mound’ were classified with relatively low cold resistance.