Shoot architectural analysis for olive cultivar characterization: an automatic internode measurement procedurent procedure

Abstract

Tree architecture, defined as the arrangement in space of the elements above the ground, is closely related to the biological and physiological processes of the tree. In particular, the quantitative study of the branch consists of classifying branches into orders, estimating lengths, insertion angles, diameters and volumes. In the case of the olive tree (Olea europaea L.), the knowledge of its architecture is important to determine which varieties are suitable for high-density planting systems and to guide canopy pruning, which allow simplification of field management and reduction of costs. Up to date, measurements are mainly done manually, using measuring tape and caliper, with high time expense and operator-related uncertainty. In this study, the analysis is extended to the three-dimensional case using photogrammetry. Next, the point cloud is processed using a modified version of the open-source code TreeQSM (version 2.4.1). Moreover, a new methodology, based on photogrammetry and branch segmentation using TreeQSM, is proposed to measure not only average branch diameter, but also node diameter and internodal distance along the principal axis of the twig point cloud. The main characteristics of the principal axis of the twig are obtained to prove the validity of the proposed method. The node average diameter is 2.94 mm with a standard deviation of 1.20 mm while the average internode is 14.38 mm with a standard deviation of 7.78 mm.