Genetic growth parameters and morphological traits of canker-resistant cypress clones selected for timber production

Abstract Common cypress is widespread throughout the Mediterranean area, where since ancient times, it has been used as a multipurpose tree. In the past, cypress woods were also greatly exploited as a source of strong and durable timber, but nowadays, the availability of cypress timber is extremely limited. The creation of new cypress plantations with properly selected genotypes could sustain a valuable market for high- quality timber. In this study, ten 25 year-old Cupressus sempervirens var. horizontalis canker-resistant clones grown in two plantations located in central Italy were assessed for timber production. The aim of the work was to evaluate the genetic and environmental influences on growth and morpho- logical traits for each clone. Growth traits, branch characteris- tics (size and insertion angle) and heartwood content offered potential in the selection for timber quality and quantity, while the selection of clones based upon stem form and branch number did not seem easily practicable. Selection for growth should be based on tree height since it results in fewer adverse effects on other properties such as stem form and branching. Insertion angle resulted the most interesting trait, as it showed very high repeatability values and favourable genetic correla- tions. Heartwood content correlated positively with growth traits, so it may be indirectly favoured in the course of future improvements in clone productivity on the basis of growth. The marked effect exerted by site on all growth traits under- lines the importance of identifying suitable locations for cy- press plantations.