Phenotypic differences in development of cold hardiness in three latitudinal populations of Acer platanoides L.

Abstract

Variation in cold hardiness, assessed using the electrolyte leakage method, of three 6–7-year-old seedling populations of Acer platanoides (L.) originating from Sweden, Denmark and Germany (northern, central and southern population, respectively) was investigated in a Danish field trial during autumn and early winter. Simultaneously, autumnal changes in cold hardiness, stem water content and annual height growth were investigated in field-grown 3-year-old seedlings of the Danish population. The variation in cold hardiness among populations was structured as a moderate latitudinal cline, with the northern population cold acclimating earlier and/or faster than the other populations. Among the central and southern populations the latitudinal gradient was not apparent, resulting in approximately the same percentages of frost damage in the autumn. In early winter no differentiation in cold hardiness was observed among the three populations. In the Danish population cold acclimation was correlated with reduced water content and seedlings that grew longer in the autumn tended to dehydrate late. The results are discussed in relation to the transfer of A. platanoides seeds.