The wood of ring porous oaks is frequently subject to a defect known as shake, which describes the development of extensive longitudinal fissures in the living tree. Previous work had suggested a relationship between the occurrence of shake and cross sectional area of earlywood vessels. This study investigated the degree of genetic control of vessel area in German Quercus robur and Quercus petraea, considered here as a single species. Ramets in a clonal seed orchard and open-pollinated progeny in an unreplicated trial were sampled. Heritability estimates for vessel area were high, ranging from 0.60 plus/minus 0.25 (narrow sense, individual tree basis) to 0.93 plus/minus 0.06 (broad sense, clonal mean basis). Interpretation of these results must acknowledge the limitations of the experimental material. However, the indication of strong additive genetic control of vessel area is consistent with information for other wood characteristics of other species, and suggests that simple selective breeding could be effective in reducing the frequency of shake in oaks.
