No difference in the maximum frost hardiness of different pedunculate oak populations in Finland

The natural northern distribution limit for pedunculate oak ( L.) is in southern Finland. We hypothesized that the maximum frost hardiness (FH) winter limited cultivation of oaks latitudes. tested hypothesis with controlled freezing tests midwinter. The acorns experiment were collected from four main populations southernmost seedlings raised nursery, hardened field conditions, and then moved to a growth chamber at –2 °C on two occasions FH tests. Frost was assessed by differential thermal analysis (DTA) based low temperature exotherm (LTE) relative electrolyte leakage (REL) stem, visual damage scoring (VD) buds stem. initiation peak LTE took place an average –41 –43 respectively, without differences among populations. variation high, ranging –34.6 –45.5 –37.1 –46.9 respectively. According REL method, ranged –44.0 –46.4 February –40.6 –41.6 March, significant VD, bud least hardy organ, between –19 –33 °C, depending population assessment time. conclude may set northwards, but high within-population offers potential breed more genotypes.Quercus roburmaxmax