Identifying and screening cold tolerance genetypes of Phalaenopsis varieties

Four different offspring varieties of Phalaenopsis ‘Taida Salu'P. ‘Dinghan Orange Anne'and their parentals were selected to compare their tolerance to coldness. Their antioxidase activities, osmoregulation substance and membrane lipid peroxidation were detected under low temperature stress and recovery. And their tolerance to coldness was evaluated comprehensively using principal component analysis. The results showed that the differences of SOD, POD and CAT activities among varieties were significant. The contents of soluble sugar, free proline and MAD, electrolytic leakage in stronger cold resistance varieties could be equal and even higher than that before treatment, but the cold sensitive varieties were the contrary in the temperature recovery period. The final scores got from principal component analysis showed that P6 had strong tolerance to coldness, P4 and P3 had moderate and others had weak tolerance to coldness.