Zmienność wiosennej fenologii polskich i litewskich pochodzeń brzozy brodawkowatej (Betula pendula Roth.)

The aim of this study was to estimate differences in the time of flushing among 16 provenances of birch (Betula pendula Roth.) from Poland (12) and Lithuania (4). Using a six−stage scale budburst and leaf elongation were assessed during three springs (2001−2003). Analysis of variance showed significant differences between provenances both in sites and years. Provenances Augustów, Strzelce and Chełm flush early. Late flushers are birch from Golub and Głusko. Longitude had the most important influence on flushing; more eastern provenances tending to flush earlier. Heritability of budburst and leaf elongation varied from 0,53 to 0,97.