Clonal variation of wood density record of cambium reaction to water deficit in Picea abies (L.) Karst

Water deficit during the growing season affects cambium activity; a water deficit during the first part of the growing season results in the formation of latewood-like cells. If this event is followed by a return to favourable water conditions, a microdensity profile drawn radially through the ring will reveal a density peak in the earlywood. This study proves that some characteristics of the peak formed in the earlywood of the ring 1993 in the trees of a Swedish Norway spruce clonal test (2 sites, 20 clones) are genetically controlled. The peak position in the ring is the most genetically controlled peak characteristic. The observed variability for the peak position in the ring can be related with an hypothesis concerning the presence of some degree of genetic control of the kinetic of the cambium reaction to environmental variation.