Provenance-family variation in the time of spring bud development in silver birch (Betula pendula Roth)

The aim of this study was to assess the variation of bud development time of the Polish and Latvian silver birch provenances and its impact on tree growth in the juvenile phase. The assessment of bud development was carried out in 2008 and 2009 on three experimental plots with ten Polish and three Latvian provenances using a six-point scale. Browsk, Augustow and Latvian provenances are in the group of provenances that develop early buds, while the provenances from Lobez, Mlynary and Golub develop late buds. The spring development of silver birch buds shows a clinal variation depending on the longitude. The spring leaf development of the eastern provenances begins earlier than the western ones. The dependence of growth traits on the time of bud development has not been sufficiently proven and requires further research.