Cold acclimation in eucalypt hybrids

摘要: We evaluated cold resistance and the capacity for acclimation of different Eucalyptus genotypes. Seedlings half-sib families E. globulus hybrids gunnii x globulus, viminalis cypellocarpa were exposed daily 56 days to a 9-h photoperiod at 14.7 degrees C, followed by 15 h in dark room maintained 2.5 C with root system 8 harden seedlings. Unhardened seedlings about 16 during period. Cold occurred all decreases temperature causing 50% mortality (LT(50)) between 1.5 3 C. Both hardened unhardened plants hybrid more tolerant than globulus. A significant correlation LT(50) leaf osmotic pressure was observed; increase predominantly result an concentration soluble sugars. Exotherm peaks similar plants. These results indicate that hardening increased ability eucalypts endure extracellular ice formation. The maintenance photosynthetic cold-hardened may also play role their response freezing.