ISHS Acta Horticulturae 81: Symposium on Winterhardiness in Woody Perennials
FROST HARDINESS DEVELOPMENT IN SPRUCE AND PINE |
| Author: | J. Hellergren |
| Abstract:
The influence of short days and low temperature on the frost hardiness development was investigated in seedlings of Scots pine and Norway spruce, grown for 6 months in greenhouses and climate chambers /Christersson 1976/. The hardiness was tested by a method in which the shoots of the seedlings were frozen to desired temperatures /Christersson 1971, 1973/. After 8 weeks in greenhouse the viability of the seedlings was determined by establishing bud-flushing. The most effective climate for frost hardiness development /Christersson 1977/ was short days and low temperature /2°C/ followed by short days and room temperature /20°C/. But even long days and low temperature had a decided effect on hardiness development. A combination of 3 weeks treatment with short days and 20°C, and 3 weeks at short days and 2°C gave the same results as 6 weeks at short days and 2°C. The results clearly demonstrated the importance of the photoperiod prior to low temperature for frost hardiness development. | |
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