© 1993 Heron Publishing—Victoria, Canada
Cold acclimation of Pinus contorta and Pinus sylvestris assessed by chlorophyll fluorescence
Katarina Lindgren (1, 2) and Jan-Erik Hällgren (1)
1. Department of Forest Genetics and Plant Physiology, Faculty of Forestry, Swedish University of Agricultural Sciences, S-901
83 Umeå, Sweden / Received September 17, 1992
Summary
Needle samples of six provenances each of lodgepole pine (Pinus contorta Dougl. var. latifolia) and Scots pine (Pinus sylvestris L.), originating from latitudes 55 to 68° N in western Canada and northern Sweden, were collected during the autumn and subjected
to freezing temperatures in the range of –8 to –29 °C on three occasions in September and October. Needle injury was assessed
by two different methods: visual assessment and chlorophyll a fluorescence. Chlorophyll a fluorescence data showed a highly
significant correlation with the visual assessments of injury, indicating that the technique can be used as a simple, non-destructive
and objective measure for rapid detection of freezing injury and for ranking of needle materials with respect to development
of cold acclimation. The analyses showed that, during the autumn, lodgepole pine needles were more hardy and acclimated to
low temperatures earlier than Scots pine needles.
Keywords:
chlorophyll a fluorescence, freezing-test, frost-hardening, lodgepole pine, needle injury, Scots pine.
