Original article Selection of Pinus pinea L. plus tree candidates for cone production

discriminant analysis / cluster analysis / plus trees / cone production • Multivariate statistical analysis was used to define different developmental stages for stone pine (Pinus pinea L.) considering tree size and cone production, without site-specific information. • This was achieved in two steps. First, trees from permanent plots were classified using cluster anal-ysis in five different stages. Second, discriminant analysis was applied to confirm the robustness of the groups generated by cluster analysis and to allow the assignment of new stone pine trees to one of the five development stages. Each development stage was associated with an average cone produc-tion. • A methodology for selecting candidates for plus trees was suggested. Trees belonging to the 90th quartile or higher for the number of cones per crop and for cone crop weight were identified through-out the three years of the study. • Trees were evaluated as potential candidates for plus trees using the following variables: the num-ber of cones, cone crop weight and relative production capacity. The relative production capacity was defined as the cone crop weight per square meter of the crown area. 1