Pinus pinea (L.) nut and kernel productivity in relation to cone, tree and stand characteristics

Pinus pinea stands have been identified as one of the target species for agroforestry systems in Europe. Its fruit yield is of importance to the local development, especially in the Mediterranean basin, due to its highly nutritional kernels and its economic value. The objectives of this study were to analyze the relation between pine nut and kernel weight and its efficiencies in relation to cone and tree traits for different stand structures. The statistical analysis was carried out with correlation, multiple correlation analysis, hurdle-gamma regression, principal component and cluster analysis, with a dataset of about 3300 cones collected in four plots and 3 years. The results indicate that pine nut and kernel and its efficiencies depend on stand structure, year and tree characteristics. The principal component analysis and the cluster analysis enabled the identification of four groups of trees related to the pine nut and kernel efficiencies. The higher efficiencies per tree are attained in stands managed for fruit production, increasing with the decrease of the density.