Abstract:

Abstract:Changes of physiology index of two Phalaenopsis cultivars with different heat tolerance which treated at 25℃、35℃、40℃ for 2 day respectively were determined .The results showed that the electrolytic leakage and contents of malondialdehyde(MDA) in two Phalaenopsis cultivars with different heat tolerance were increased continuously with high temperature going up. However, the growing rate of the electrolytic leakage and contents of MDA in cultivar of heat resistance was the smaller than that in cultivar of heat sensitivity. The superoxide dismutase(SOD), peroxidase(POD) activities and solube protein content show a transient rise and then reduce with high temperature going up,but the growing rate of the SOD,POD activities and solube protein content in cultivar of heat resistance was the largest than that in cultivar of heat sensitivity,the range of decrease the SOD,POD activities and solube protein content in cultivar of heat resistance was the smaller than that in cultivar of heat sensitivity.The contents of free proline and soluble sugar were increased continuously with high temperature going up. However, the growing rate of the contents of free proline and soluble sugar in cultivar of heat resistance was the largest than that in cultivar of heat sensitivity. The above results indicated that there were better capability in maintaining osmotic adjustment and eliminating reactive oxygen species (ROS) in cultivar of heat resistance,this is one of all physiological base which cultivar of heat resistance had high heat tolerance.