Genetic variation for frost tolerance in a breeding population of Eucalyptus nitens

Patterns of genetic variation for frost tolerance were studied in a first-generation breeding population of Eucalyptus nitens (DEANE and MAIDEN) MAIDEN. Winter hardened seeds were found to differ significantly in their frost tolerance at all three tested temperatures (-5.0C, - 6.5C and -8.0C). Provenance effects accounted for between 11% (at -5.0C) and 29% (at -8.0C) of the total variation. The most frost tolerant provenance was Northern NSW, with Toorongo being the least tolerant. Significant differences were also found between families within provenances and between seedlings within families. Family effects accounted for 14% to 22% of total variation and seedling effects accounted for 22% and 26% of the total variation. All five provenances were represented in the top seven ranked families. When each provenance was analysed separately, there were significant differences between families but no strong relationship was found with altitude of origin.