Changes in germinability, lipid peroxidation, and antioxidant enzyme activities in pear stock (Pyrus betulaefolia Bge.) seeds during room- and low-temperature storage

The aim of this study was to determine if loss of germinability in Pyrus betulaefolia seeds stored at 4A degrees C and at room temperature is associated with a loss of membrane lipid peroxidation or changes in antioxidant enzyme activities. The results indicated that germination percentage clearly decreased when seeds were stored at room temperature rather than at 4A degrees C from 6 to 12 months. Room-temperature storage of the pear stock seed for 12 months decreased germination to 15.52%, but germination percentage was not changed when seed was stored at 4A degrees C for 12 months. MDA, a marker for membrane lipid peroxidation, increased significantly under room-temperature storage conditions. Antioxidant enzyme (SOD, POD, and CAT) activities were a good indicator of germination percentage in pear stock seeds. Antioxidant enzyme activities of pear stock seeds at 4A degrees C were higher than antioxidant enzyme activities in seeds stored at room temperature from 6 to 12 months. Antioxidant enzyme activities of the pear stock seed decreased markedly under conditions of room-temperature storage from 6 to 12 months. The results of this study showed that long-term room-temperature storage was detrimental for maintaining the vigor of P. betulaefolia seeds. The mechanisms responsible for this outcome are a higher level of membrane lipid peroxidation and a lower level of activity of antioxidant enzymes.