Abstract: Based on 89 cold and freezing injury sample disaster data of wax apple from 2008 to 2014 in Fujian, Guangdong, Guangxi and Guizhou provinces, combined with the morphological standard of cold and freezing injury, the grade index of cold and freezing injury for wax apple was preliminarily obtained by using regression analysis method. Accordingly, the grade index was tested and verified by the morphological changes and physiological and ecological standard of wax apple, which were obtained in the geographical transplantation experiment of natural low temperature, the simulated low temperature experiment of artificial climate chamber, and the investigated disaster data of orchards in 2016. The cold and freezing injury grades of wax apple were determined as: T_min>5.5 ℃, without cold and freezing injury, normal growth; 3.0 ℃<T_min≤5.5 ℃, light injury; 1.0 ℃<T_min≤3.0 ℃, moderate injury; -1.5 ℃<T_min≤1.0 ℃, severe injury; T_min≤-1.5 ℃, most severe injury, no recovery or death. The grade index in this study was verified by the results of typical year experiment, geographical transplantation and artificial climate chamber experiment, with accuracy rates of more than 90%, which could be applied in practice.

Key words: diversity, phyllosphere, Nerium indicum, Osmanthus fragrans, bacterial community